FIELD OF INVENTION
[0001] The present inve~ition relates generally to the field of wireless
5 communication, alid more particularly to a device a ~ad m ethod in Universal Mobile
Teleconlt~l~u~icationSsy stem (UMTS) Long Term Evolution (LTE) and its
enhancement (LTE-A).
BACKGROUND OF INVENTION
[0002] LTE supports high-speed train scenarios with a maximum speed of 350
10 kmnih. In order to ensure quality of service for mobile terminals in different mobility
states, LTE is not only optimized accordit~gly in the network structure, but also
designed with a corresponding mechanism which e~iables a mobile ternunal to
adaptively optimize the parameter configuration to comply with the requirements in
different scenarios according to its curretlt mobility state.
15 [0003] The above mecha~iism is mobility state estilnatiou (MSE) for a mobile
terminal in LTE. Mobility state estimatiot~ for a mobile terminal in LTE is based on
the count of llutnber of times of cell reselection. In a cot~ventiol~ahlo niogeneous
network, the above mobility state estimation based on the count of nun~bero f times of
cell reselection can provide a relatively accurate estimation of the mobility state of the
20 mobile termitial. However, with the it~troductiolo~f heterogeneous network, the
randomness of sinall cell deployment positions aid the t~ontuliformity of coverages
will greatly affect the accuracy of the above mobility state estimation based on the
count of nuniber of times of cell reselection.
[0004] In a heterogeneous network, a macro cell is deployed with various types of
25 Low Power Nodes (LPNs) such as tlucro base stations, pico base stations, femtocell
base statiotis atid remote radio units. In addition, due to the differei~cesin traismission
power between the various types of small cells, they have different coverages. The
Sally Ref.: SP352212WOOO
Sony China Ref.: CNPA12060W000
Our Ref.: OP131147
-2-
cotlventional mobility state estiniation is under a fundame~ltal assutliption that the
cells in tlie network have substantially the same coverage. However, in a
heteroge~leousn etwork, due to the presence of tlie various types of low power tlodes,
the above assumption does not stand. In addition, a mobile terminal in a
5 heterogeneous network sees a significantly increase in the number of times of cell
switchitig or reselection, which tends to give the illusion that the rnobile terminal is
moving at a high speed. Moreover, the lack of accuracy in mobility state estinlation
will further affect on those nleclianisms relating to tliobility state estimation, such as
speed scale factor, thus failing to meet basic requirements of mobility of mobile
10 ternliuals in a heterogeneous network.
[0005] It is therefore desirable to provide a device and a method in a wireless
com~iltulications ystem, to ensure the stability of niobility performance of a mobile
terminal in a heterogeneous network, so as to provide the user with a seamless and
stable network coverage.
15 SUMMARY OF INVENTION
[0006] According to an embodiment of the present invention, it is provided a
device in a wireless comm~uiication system, the device including: a small cell
denseness evaluation unit configured to evaluate denseness of small cells within a
region in which a tliobile terminal locates; and a mobility state estimation unit
20 configured to determine a mobility state estimation manner according to the evaluated
denseness of the s~nalcl ells so as to estirnate mobility state of the mobile temiinal.
(00071 According to the above device, the small cell denseness evaluation unit is
further configured to receive iuformation of stliall cell clusters itldicating wiiicli small
cells are adjacent to each other from a base station serving the tliobile terminal aid
25 evaluate the denseness of the small cells within the region in which the mobile
terminal locates in accordance with the information of small cell clusters.
[0008] According to tlie above device, the infornlation of small cell clusters is
indicated by iitlformation of small cell identifier indexes added in a list of adjacent
So~iy Ref.: SP352212\VOOO
Sony Cliiiia Ref.: CNPA12060TVO00
Our Ref.: OP131147
- 3 -
cells, the infortllatiotl of the stnall cell identifier indexes including infortllatio~o~f
slnall cell identifiers of adjacent slnall cells to indicate tliat these adjacent small cells
belong to a same cluster
[0009] According to the above device, the sn~allc ell denseness evaluation wit is
5 further configured to evaluate the denseness of the snlall cells within the region in
which the mobile terminal locates according to a history that the mobile ter~ninal
obtains services from the small cells.
[0010] According to the above device, the stnall cell denseness evaluation unit is
configured to determine whether a type of a target cell fro111 which the nlobile
10 terminal obtains services is a small cell and count number of tinles tliat the target cell
from which the lnobile ter~ninal obtains services is the stnall cell within a
predetermined time, and to evaluate the denseness of the small cells within the region
in wllich the mobile terminal locates by conlparitlg the number of titnes with a
predetermined threshold of nuniber of times.
15 [0011] According to ttie above device, the small cell denseness evaluation unit is
configured to determine whether a type of a target cell from which the lnobile
terminal obtains sel-vices is a stnall cell and deternline distances between stnall cells
fro111 which the nlobile terminal obtains services according to position information of
the small cells from which the mobile tertninal obtain services, and to evaluate the
20 denseness of the s~nalcl ells within the region it1 wliich the mobile terminal locates by
comparing the distatlces with a predetermined distance threshold.
[0012] According to the above device, the predetertnitled distance threshold is
deternlined according to coverage of the small cells from which the lnobile terminal
obtains services.
25 [0013] According to the above device, the small cell denseness evaluation unit is
fi~rtllerc onfigured to detertnine a type andlor coverage of a target cell fro111 which the
lnobile tertninal obtain services according to a transtnission power of the target cell.
SOIIR~e f.: SP352212W000
Sons Cluna Ref.: CNPAl2060\\'000
Our Ref.: OP13 1147
- 4 - -
[0014] According to the above device, the stnall cell denseness evaluation unit is
further co~lfigured to receive information of cell type indicating a cell type from a
base station serving the lnobile tetminal aid to determine type of the tat-get cell
according to the information of cell type
5 [0015] According to the above device, if the evaluated denseness of the small cells
is low, the lnobility state estimation unit is further configured to co~uo~ntly t~umbeor f
times that the mobile terminal switches or reselects among macro cells and estimate
the lnobility state of the n~obilete rminal according to the number of times that the
mobile terminal switcl~eso r reselects among the macro cells.
10 [0016] According to the above device, if the evaluated denseness of the small cells
is higl~t,h e nobility state estitnation unit is further cotlfigured to estimate a movenlent
distance of the mobile terminal according to position inforn~ationo f small cells fro111
which the mobile terminal obtains services atid to estimate the mobility state of the
mobile terminal according to the tnoven~entd istance of the tnobile terminal.
15 [0017] According to the above device, the mobility state estitnation unit is further
configured to count number of times that the mobile terminal switches or reselects
atnong macro cells and number of times that the mobile terminal obtains services
froin tlle small cells respectively, and to estimate the mobility state of the tnobile
tenninal according to a weighted sum of the number of times that the mobile terrninal
20 switches or reselects among the macro cells and the number of titnes that the n~obile
terminal obtains services from the stnall cells, wherein cell weight factors of the stnall
cells and the macro cells are adjusted adaptively according to the evaluated denseness
of the slnall cells to calculate the weighted stun.
[0018] According to the above device, the mobility state estimation unit is further
25 configured to accrnnulate number of times that the nob bile ternunal obtains services
from the stnall cells in a unit of a predetermined area, and to determine that the mobile
terminal is able to obtain services ft-on1 the stnall cells within the predetermined area
if a restdt of the accumulating is larger t11a1 a predetermined count thresl~old.
Son). Ref.: SP352212\V000
Son). Cluna Ref.: CNPA12060IV000
Our Ref.: OP131147
- 5 - -
100191 According to the above device, the mobile terminal is able to obtain
selvices from the small cells in at least one manner of switching or reselecting to
small cells, and carrier aggregation, double-connection and coordiuated nlultiple point
transmission through small cells
5 [0020] According to the above device, the mobility state estimation unit is further
configured to accunlulate the number of times that the mobile terminal obtains
services from the small cells in the unit of a small cell cluster, and when the mobile
terminal switches from a first slt~allc ell cluster to another small cell cluster, clear the
accumulating result of the number of times that the mobile terminal obtains services
10 from small cells in the first small cell cluster to restart counting; or store the
accumulating resdt for a predetermined period of time aud contitlue using the stored
accumulating result of the number of times that the mobile terminal obtains services
from small cells in the first sn~allc ell cluster if the mobile tenninal switches back to
the first small cell cluster within the predetermined period of time.
15 [0021] According to the above device, whether the n~obile terminal switches to
alother small cell cluster is determined according to the infonnation of small cell
clusters indicating d i c h s ~nalcl ells are adjacent to each other.
[0022] According to the above device, the distance between the two small cells that
the mobile terminal switches from and to is determined accorclidit~g to position
20 infonnation of the small cells, aid whether the mobile terminal switches to another
stnall cell cluster is determined according the determined distance between the two
small cells.
100231 According to the above device, when the mobile terminal encounters
multiple consecutive switching failures or encounters multiple switchiug failures in a
25 predetermined period of time, the accumulating resdt of the number of times that the
nlobile terminal obtains services fro111 small cells in the small cell cluster is cleared to
restart counting.
Sally Ref.: SP352212\VOOO
Sony Cluna Ref.: CNPA12060\V000
Our Ref.: OP1311.17
- 6 -
[0024] According to the above device, a tnobility iniu~ageme~u~ntit is fu~ther
included, and is configured to control cell reselection for the mobile tert~~iti~n aal free
state according to the evaluated denseness of the small cells, atidor to control cell
switching for the mobile ternunal in a connected state according to the estimated
5 result of the nobility state.
[0025] According to the above device, the mobility tnatlagelnent unit is further
configured to prevent the mobile terminal in the free state fro111 pelforming cell search
andor cell measurement for the small cells in a case that the evaluated denseness of
the st11al1 cells is high, and to allow the mobile terminal in the free state to perfor111 the
10 cell search andor cell measurement for the small cells in a case that the evaluated
denseness of the small cells is low.
[0026] According to the above device, if the evaluated denseness of the small cells
is high, the mobility management unit is further configured to allow the mobile
terminal in the free state to perform cell search and/or cell measurement for the small
15 cells if service quality of macro cells is lower than a first predetermined threshold or a
difference between service quality of the small cells and the service quality of the
macro cells is larger than a second predetermined threshold.
[0027] According to the above device, a business type division nnit is further
included, and is configured to divide businesses at the mobile terminal into different
20 business types according to time delay sensitivity of the businesses at the mobile
terminal, and the mobility rliatlagetnent wit is further cotlfigured to filter switcliable
target cells for the tnobile terminal in the connected state according to the estitnated
result of the n~obilitys tate of the mobile ter~l~inaanld the business type and to perfom
cell measurement andor measurellient report for the filtered target cells to perform
25 cell switchit~gfo r the mobile terminal.
[0028] According to the above device, if at least one of a plurality of businesses in
a cotuiectedstate at the mobile terminal has a high time delay sensitivity, the business
Sony Ref.: SP352212WOOO
Sony China Ref.: CNPA12060\VOOO
Our Ref.: OP1311.17
- 7 - --
type division unit is further configured to determine a collective time delay sensitivity
of the businesses at the mobile terminal to be high.
100291 According to another embodiment of the present invention, it is provided a
method in a wireless communication system, the method including: a small cell
5 denseness evaluation step of evaluating denseness of s~nallc ells within a region in
which a rnobile terminal locates; and a tnobility state estimation step of determining a
mobility state estimation tnanner according to the evaluated denseness of the small
cells so as to estimate mobility state of the mobile terminal.
(00301 According to the above method, in the small cell denseness evaluation step,
10 the denseness of the small cells within the region in wllich the mobile terminal locates
is evaluated according to a history that the mobile terminal obtains services from the
small cells.
[0031] According to the above tnetl~od, in the small cell denseness evaluation step,
whether a type of a target cell from which the mobile terminal obtains services is a
15 small cell is determined, and number of times that the target cell from wl~ich the
mobile terminal obtains services is the small cell within a predetermined time is
counted, and the denseness of the small cells within the region in which the mobile
terminal locates is evaluated by comparing the number of times with a predetermined
tl~resl~ooldf number of times.
20 [0032] According to the above method, in the small cell denseness evaluation step,
whether a type of a target cell from which the mobile terminal obtains services is a
s~nall cell is determined, and distances between s~nall cells from which the mobile
terminal obtains services are determined according to position information of the
sn~alcl ells from ~ d ~ i tchhe mobile tenninal obtain services, and the denseness of the
25 small cells within the region in which the mobile ternunal locates is evaluated by
comparing the distances with a predetermined distance tl~resl~old.
[0033] According to the above method, in the mobility state estimation step, if the
evaluated denseness of the small cells is low, only number of times that the mobile
SOIIR~ef .: SP352212\VOOO
Sons Cluna Ref.: CNPA12060WO00
Our Ref.: OP13 1147
- 8 - ~ -
teinlinal switches or reselects among macro cells is counted, and the mobility state of
the mobile ternlinal is estimated according to the number of times that the mobile
ternlinal switclles or reselects anlong the macl-o cells.
[0034] Accordit~gto the above method, in the mobility state estimation step, if the
5 evaluated denseness of the stnall cells is high, a tnovelnent distance of the mobile
terminal is estimated according to position information of snlall cells from wl~ichtl ie
mobile terminal obtains services, and the tnobility state of the mobile terminal is
estitllated according to the movement distance of the mobile terminal.
[0035] According to the above nletllod, a mobility management step is further
10 included, for cotltrolling cell reselection for the niobile ter~ninal it1 a free state
accorditlg to the evaluated denseness of the small cells, andlor co~ltrolli~c~egll
switching for the mobile tenninal in a connected state according to the estimated
result of the mobility state.
[0036] According to another enlboditllent of the present itivetition, it is provided a
15 device it1 a wireless communication system, the device including: a small cell division
unit co~lfiguredto divide small cells adjacent to each other into small cell clusters and
form infor~natio~olf small cell clusters indicating which small cells are adjacent to
each other; and a sending wit configured to send the infornlatiotl of small cell clusters
to a mobile terminal, wherein the information of small cell clusters is used by the
20 mobile terminal to evaluate denseness of small cells witliitl a region in which the
tnobile termitlal locates.
[0037] According to the above device, tlie infortnation of s~llall cell clusters is
indicated by infortnation of small cell identifier indexes added in a list of adjacent
cells, the information of small cell identifier iudexes including informatiotl of small
25 cell identifiers of adjacent small cells to indicate that these adjacent small cells belotlg
to a same cluster.
S O IR~e f.: SP352212WOOO
Sally Cf~illaR cf.: CNPA12060W000
Our Ref.: OP131147
- 9 -,
[0038] Accorditlg to the above device, the sending unit is further configured to
send position information of the small cells a d o r parameter infor~nation related to
coverage of the small cells to the mobile ternlinal.
100391 According to the above device, the parameter infornlation related to
5 coverage of tlie stnall cells includes infortnation of transnlission power of the sniall
cells.
[0040] According to yet lulotller enlbodiment of the present invention, it is
provided a ~netllodin a wireless cotnnlunication system, the method including: a small
cell division step of dividing small cells adjacent to each other into stnall cell clusters
10 and fornling information of small cell clusters indicating which small cells are
adjacent to each other; and a sending step of sending the itlfor~natiotlo f sniall cell
clusters to a nlobile ter~ninal, wherein the informatiotl of small cell clusters is used by
the tnobile ternlinal to evaluate denseness of small cells within a region in which the
nlobile ternlitial locates.
15 [0041] According to yet another embodiment of the present invention, it is
provided a method in a wireless commw~ications ystem, the method including: a small
cell division step of a base station apparatus dividing snlall cells adjacent to each
other into small cell clusters and fortning information of small cell clusters indicating
which small cells are adjacent to each other; a sending step of tlie base station
20 apparatus sending the infornlation of small cell clusters to a mobile tet-~nitiaal pparatus;
a stnall cell denseness evaluation step of the tnobile terminal apparahls evaluating
denseness of small cells within a region in which the tnobile terminal apparatus
locates according to the infortnation of small cell clusters received from the base
station apparatus; and a mobility state estitnation step of the nlobile terminal
25 apparatus determining a mobility state estimation manner according to the evaluated
denseness of the small cells so as to estimate mobility state of the mobile terminal
apparatus.
Sony Ref.: SP352212iVOOO
Souy Chit~a Ref.: CNPA12060WO00
Our Ref.: OP1311.17
- 10-
100421 According to the above method, the information of snlall cell clusters is
indicated by information of small cell identifier indexes added in a list of adjacent
cells, the information of slnall cell identifier indexes including infom~ation of small
cell identifiers of adjacent small cells to indicate that these adjacent small cells belong
5 to a same cluster.
[0043] According to yet another e~nboditilent of tlie present invention, it is
provided a computer storage mediu~n including computer-readable instructions, the
cotnputer instructions causing a computer to execute: a small cell denseness
evaluation step of evaluating denseness of small cells within a region in which a
10 mobile terminal locates; and a mobility state estimation step of determining a niobility
state estimation mariner according to the evaluated denseness of the stnall cells so as
to estimate rilobility state of the mobile terminal.
[0044] According to yet another emnbodiment of tlie present invention, it is
provided a computer storage medium including computer-readable instructions, tlie
15 cornpater instructions causing a computer to execute: a stnall cell division step of
dividing small cells adjacent to each other into small cell clusters and forming
information of s~nall cell clusters indicating \vbich small cells are adjacent to each
other; and a sending step of sending the information of small cell clusters to a mobile
terminal, wherein the information of small cell clusters is used by the mobile terlniual
20 to evaluate denseness of stnall cells witlun a region in which the mobile terminal
locates.
[0045] According to yet another embodiment of the present invention, it is
provided a computer storage medium including computer-readable instructions, the
comnputer instructions causing a computer to execute: a small cell division step of a
25 base station apparatus dividing small cells adjacent to each other into stnall cell
clusters and forming infor~nationo f small cell clusters indicating which small cells are
adjacent to each other; a sending step of the base station apparatus sending the
infor~nation of small cell clusters to a mobile terlninal apparah~s; a small cell
denseness evaluation step of the mobile tertninal apparatns evaluating denseness of
Soliy Ref.: SP352212\VO00
Sony Cliilla Ref.: CNPA12060\VO00
Our Ref.: OP131147
- 11 -
small cells within a region in which the ~ilobilete rminal apparatus locates according
to the illformation of small cell clusters received from tlie base station apparatus; and
a mobility state esti~natio~stle p of the mobile ter~ninal apparatus determining a
nlobility state estimation lnatmer according to the evaluated denseness of the small
5 cells so as to estimate mobility state of the mobile terminal apparatus
[0046] Using the present invention, the mobility state estimation lnamler can be
determined based on an evaluated denseness of small cells, so as to estimate the
nlobility state of tlie mobile terminal, ensuring the stability of nlobility performance of
the mobile terminal in a heterogeneous network, thus providing the user wit11 a
10 seamless and stable network coverage.
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] The above and other objects, characteristics and advantages of the present
invention will be u~llderstood better when read in conjunction with the description
below of the enlbodiments of the present invention with reference to the
15 accompanying drawings. III the drawings, the same or correspotlding reference
numerals will be used to denote the same or correspo~ldingfe atures or components.
[0048] Figurre 1 is a block diagram illustrating a cotlfiguration of a device in a
wireless cotm~~unicatiosyns tem accordillg to a11 eetrtbodime~lot f the present itiventiotl;
100491 Figure 2 is a block diagram illustrating another configuration of a device it1
20 a wireless cotlm~~u~icatisoyns tem according to an embodiment of the present
invention;
[0050] Figure 3 is a block diagram illustrati~lgy et mother cotlfiguration of a device
it1 a wireless communication system according to an eelnbodi~nent of the present
invet~tion;
25 [0051] Figure 4 is a flow chart illustrati~lg a method used in a wireless
coriununicatiot~s ystem according to mother embodiment of the present inventiotl;
SOIV Ref.: SP352212WOOO
Sony Cfuiia Ref.: CNPA12060\V000
Our Rcf.: OP131147
-12- -
I00521 Figure 5 is a flow chart illustrating a rnetliod used in a wireless
communication system according to another etnboditnent of the present invention;
[0053] Figure 6 is a flow chart illustrating a method used in a wireless
corlnnunication system according to another enibodiment of the present invention;
5 [0054] Figure 7 is a block diagram illustrating a config~~ratioonf a device in a
wireless con~n~unicatiosny stetn according to another embodiment of the present
invention;
100551 Figure 8 is a flow chart illustrating a niethod used in a wireless
communicatio~s~ys tem according to another embodiment of tlle present invention;
10 [0056] Figure 9 is a flow chart illustrating a tnethod used in a wireless
communication systetn according to another enlboditnent of the present invention;
and
[0057] Figure 10 is an illuskative block diagratn illustrating an information
processing apparatus on wliicli the embodiments of the present invention can be
15 itnpletnented.
DESCRIPTION OF THE EMBODIMENTS
[0058] The embodiments of the present invention will be described below with
reference to tlie acco~npanying drawings. It is noted tliat the representations and
descriptions of tlie coniponents and processes irrelevant to the present invention or
20 known to those skilled in the art have been omitted for clarity.
100591 A configuration of a device in a wireless comnunication systetn according
to an emboditnent of the present invention is described below in conjunction with
Figure 1. Figure 1 is a block diagram illustrating a configuration of a device in a
wireless co~nn~~uucatsiyosnte m according to iul embodinlent of the present invention.
25 [0060] As shown in Figure 1, the device 100 in a wireless comtnunication system
nlay include'a small cell denseness evaluation unit 102 and a mobility state estimation
unit 104.
Sony Ref.: SP352212\VOOO
Souy Clli~~Rae f.: CNPA12060W000
Our Ref.: 0P131147
-13- ~-
[0061] The sn~alcl ell denseness evaluation unit 102 in the device 100 may evaluate
denseness of small cells within a region in which a nlobile ternlinal locates
[0062] The introduction of heterogeneous network has brought change to the
conventional cell architectures, and challenges to the conveutional mobility state
5 estitnatiou tuiatuners. Tl~rougli their studies, the applicants of the present inventiou
fould that heterogeneous networks cal finther be classified according to their
respective attributes. For example, heterogeneous networks cat1 be classified
according to the denseness of sniall cell deployment in a heterogeneous network, e.g.,
into a small cell densely-deployed category and a small cell non-densely deployed
10 category. Tl~ose skilled in the art will understand, the above classification of
heterogeneous net\vorks into a snlall cell densely-deployed categoly and a small cell
non-densely deployed category is exemplaty only, and heterogeneous networks may
as well be classified according to the denseness of s~nall cell deploytnent in a
heterogeneous network into three or more categories. Moreover, those skilled in the
15 art will also lu~derstand that the aboven~entioned classification of heterogeneous
networks based on the denseness of small cell deployment in a heterogeueous network
is also exemplaty, aid heterogeneous networks may as well be classified according to
some other attribute of a heterogeneous network. The descriptiot~ below is given
mainly with the small cell deployment denseness in a heterogeneous network as a11
20 example.
I00631 Different denseness of small cell deployment in a heterogeneous network
causes a different effect on a conventional network. Specifically, a heterogeneous
network wit11 a non-dense small cell deployment may be not much different from a
conventional l~omogeneousn etwork. However, a large demand of businesses usually
25 exist in hot-spot areas such as a city center, a shopping mall, an office and a ofice
building, resulting in a large deinatld of dense deployment of small cells in these areas.
As the denseness of sti~allc ells increases, the effect on the nobility perfor~nat~coef a
mobile terminal in the conventional network is a chauge fro111 quantity to quality. For
example, dense deploytuent of stl~all cells may cause frequent cell switching at the
Sony Ref.: SP352212W000
Sony Clli~ta Ref.: CNPA12060W000
Our Ref.: OP131147
- 14 -
mobile terminal. As the denseness of small cells increases, interfet-ence between the
small cells will increase, causing the probability of switching failure at the mobile
ternlinal to increase accordingly. Furthennore, since the coverage of a snlall cell is
relatively small, the times of switching at the mobile tenninal also increases as the
5 denseness of small cells increases, as well as the probability of ping-pong switch. In
addition, for the mobile terminal user, the number of switching failures at the tnobile
terminal, the nunlber of ping-pong switches and so on directly affect the mobile
ternlinal user's experience of the quality of service; and according to the above
analysis, dense deployment of stnall cells will greatly increase the number of
10 switching failures at the tuobile terminal, the nutl~bero f ping-pong switches md so on,
which significantly degrades the mobile terminal user's experience of service.
Therefore, the denseness of snlall cell deploytnent in a heterogeneous network is an
important factor in the estimation of the nlobility state of a mobile terminal in a
heterogeneous network. 111 order to improve the accuracy of mobility state estimation
15 of a mobile terminal in a heterogeneous network, it is desirable to evaluate the
denseness of snlall cells within a region in which the mobile terminal locates, so as to
determine a tllobility state estimation manner according to the denseness of the small
cells.
[0064] It will be described hereinafter in detail on how to evaluate the denseness of
20 stnall cells within a region in which a mobile terminal locates. Those skilled in the art
will understand, the following specific matlners for evaluating the denseness of snlall
cells within a region in which a mobile terminal locates is illustrative only and not
limiting. Those skilled in the art cat1 make mnodifications, substitutes or variations to
the various specific stnall cell denseness evaluation manners herein as needed,
25 provided that they can determine the denseness of stnall cells within a region in which
a mobile ter~ninalo cates.
[0065] According to at1 e~nbodiment of the present invention, the stnall cell
denseness evaluation wit 102 map receive infor~nation of stnall cell clusters
indicating which small cells are adjacent to each other from a base station serving the
Sony Ref.: SP352212\VOOO
Soliy Cllina Ref.: CNPA12060\V000
Our Ref.: OP131147
- 15 -
n~obilet enninal, a ~ edva luate the denseness of the small cells within the region in
~411~1th1e nlobile terminal locates in accordance with the information of small cell
clusters
[0066] In a heterogeneous network, a large number of snlall cells are deployed in
5 the coverage of a macro cell, and the base station serving the nlobile terminal can
learn the actual position where each small cell is deployed. Therefore, the base station
serving the mobile ter~ninal may, according to the actual position where a small cell is
deployed, divide tnultiple snlall cells adjacent to each other a ~ cdlo sely distributed
into the same snlall cell cluster, aid fonn information of small cell clusters indicating
10 which small cells are adjacent to each other. According to the information of s~nall
cell clusters, the number of small cells included in a small cell cluster and identifier
information of each small cell can be detennined. When the mobile terminal detects
the identifier information of any stiiall cell in a particular small cell cluster, it nlay be
detennined that the mobile terminal is nloving towards the small cell cluster to which
15 the small cell belongs. Therefore, the mobile tertninal may, according to the number
of snlall cells incloded in the small cell cluster, determine the denseness of the small
cells within the region in which the mobile terminal locates. Thus, according to this
embodiment, the determination on whether the small cells is densely deployed is
pelformed at the base station side serving the mobile tenninal; the base station may
20 divide srnall cells closely distributed into the same stnall cell cluster, ald the mobile
terlninal may, according to the number of small cells included in the small cell cluster,
determine the denseness of the deployment of the sniall cells. Furtherniore, according
to this embodiment, because the mobile terminal equivalently discovers a slnall cell
cluster to which a snlall cell belongs as it discovers the stnall cell, the snlall cell
25 denseness evaluation tnalners according to this embodiment is not affected by the
trajectory of tnovement of the mobile tertninal.
100671 According to an embodinlent of the present invention, the infortnation of
stnall cell clusters tnay be indicated by infortilation of small cell identifier indexes
added in a list of adjacent cells, and the infornlation of snlall cell identifier indexes
SOIIJ' Ref.: SP352212\VOOO
Sony Cluna Ref.: CNPA12060\VOOO
Our Ref.: OP131147
- - 16 -
may include inforlnation of small cell identifiers of adjacent s~nall cells to indicate
that these adjacent stnall cells belong to a same cluster.
[0068] The information of small cell clusters may be indicated by adding
inforlnation of small cell identifier indexes in a list of adjacent cells, or it1 some other
5 system infor~ilatiotbl lock. For example, the first 111 stnall cells adjacent to each other
may be divided into the first s~nalcl ell cluster, the next n small cells adjacent to each
other tnay be divided into the second small cell cluster and so on, where m a ~nd a re
both natural numbers greater than or equal to 1. The information of small cell
identifier indexes niay include infortnation of the stnall cell identifier of each adjacent
10 small cell belonging to the sane small cell cluster. For exan~ple, the information of
small cell identifiers of the first small cell cluster may include identifier infortnation
of each small cell of the first In st~~aclelll s belonging to the first small cell cluster, atd
the inforr~iationo f scnall cell identifiers of the second small cell cluster map include
identifier itlformation of each snlall cell of the next n small cells belonging to the
15 second stnail cell cluster. Those skilled in the art will understaid that the above
iilfortnation of small cell identifier indexes added in a list of adjacent cells ii~dicating
the information of small cell clusters is exempla~yo nly a ~ndot limiting, a ~thdat the
information of stnall cell clusters may also be indicated in other ways.
[0069] Specifically, the information of stnall cell clusters may be added to the list
20 of adjacent cells, a ~tdhe list of adjacent cells added with the information of stnall cell
clusters nlay be broadcast in the system information blocks SIB4, SLB5. In addition,
the it~formatioto~f snlall cell clusters may also be added into some other system
inforination block, ald the systetn infor~natio~adl ded with the infor~ilatiotlo f stnall
cell clusters tnay be broadcast. Altertiatively, a new system inforn~ationb lock may be
25 set for the tnobile tertninal, exclusively for indicating the it~fortnation of s~nall cell
clusters.
[0070] Small cell cluster identifiers may be defined it1 the inforn~ationo f small cell
clusters, to ut~iquely identify a small cell cluster. Each small cell cluster identifier
includes the physical cell identifiers of the sn~all cells belonging to the small cell
Sons Ref.: SP352212W000
Souy Cluna Ref.: CNPA12060W000
Our Ref.: OP131147
- 17 -
cluster. In order to reduce the system information load, in actual deployment of stnall
cells, sillall cells closely distribnted tnay be assigned with consecutive numbers wliere
applicable. llius, by giving the start position and the range of physical cell identifiers
of small cells within a small cell cluster, the sn~alcl ells can be included into the sniall
5 cell cluster
[0071] Specifically, the infortnation of stnall cell clusters tnay be broadcast by the
niacro base station side. Because small cells are normally distributed in the coverage
of a macro base station, the macro base station cat1 divide the stnall cells into clusters
based on the actual positions where tlie small cells are deployed in the coverage of the
10 macro cell, and broadcast the fornied inforn~atioao f sn~alcl ell clusters. It1 addition, a
case may exist wliere a small cell cluster may be under the coverage of multiple
macro cells; accordingly, in this case, when tlie macro base station broadcasts the
information of small cell clusters, those small cells needs to be included.
100721 In addition, the broadcast of the infonnatiou of small cell clusters may also
15 be perfortned by a small cell. Tiiougl~in formation interaction between sn~alcle ll base
stations, the small cell base stations can self-organize a sn~all cell cluster, or, the
configuration of small cell clusters may be done directly at the network side. After the
small cell clusters are formed, each small cell base station may broadcast pliysical cell
ID identifiers of the other small cells in its small cell cluster. Therefore, upon
20 accessing one small cell, the mobile tern~inal can get infortnation on other small cells
in the sn~alcl ell cluster to wl~ichth e current small cell belongs.
I00731 Furthern~ore, according to an etnbodiment of the present invention, the
mobile terminal may obtain the inforniation indicating tlie denseness of small cells
within a region in which the tnobile tern~inal locates directly fro111 the network side,
25 without estitnating by the tnobile terminal itself the denseness of small cells within a
region in wliich the mobile terminal locates. For example, a tnacro base station at the
network side niay determine wf~ether the tnobile ternlitial is in a stnall cell dense
region accordiug to position information of the niobile tertninal, and notify the tnobile
terminal when the tnobile terminal is determined to be in a stnall cell dense region; the
Soliy Ref.: SP352212\VOOO
Son). Cl~i~iRae f.: CNPA12060\V000
Our Ref.: OP131147
- 18 - -
111obile tenninal obtains the denseness of small cells according to the information
notified from the network-side macro base. Specifically, the macro base station t ~ ~ a y
receive GPS information from the mobile ternlinal, and obtain positiot~i trfort~latiotoi f
the mobile terminal according to the GPS information. Furthern~ore, the macro base
5 station may also generally determine the position information of the mobile terminal
accordit~gto various measuring methods in the prior art, e.g., by measuring methods
like CLD, E-CID, AOA, TDOA or fingerprint.
[0074] According to an embodiment of the preseut invention, the small cell
denseness evaluation unit may evaluate the densetless of the small cells within the
10 region in which the mobile tertnit~al locates according to a history that the mobile
terminal obtains services from the small cells. For exa~nple,a ccording to a specific
embodiment of the present invention, the mobile terminal may obtain services from
the small cells by switching or reselectitig to a small cell; or, it1 at least one of the
manners of: carrier aggregation, double-connection and coordinated ~nultiple point
15 transmissio~th~r ough the small cells.
[0075] In the case of dense deploymet~ot f small cells it1 a heterogeneous network,
tllultiple small cells are densely distributed. If in a certain period of time the mobile
terminal obtains services from the small cells nmltiple times, it is likely that the
mobile terminal is located in a region where small cells are densely deployed.
20 Therefore, the denseness of the small cells within the region in which the mobile
terminal locates can be evaluated according to a history that the mobile terminal
obtains services from the stnall cell. For example, in a heterogeneous network
including stnall cells, a mobile terminal can obtain services from a small cell by
switching or reselecting to the stnall cell.
25 [0076] in addition, in small cell ed~ancetnetlt it1 3GPP, the original scenario has
been further extended. For example, the scenario of carrier aggregation has been
introduced it1 the small cell enhat~cetnent, and ideal backhaul and non-ideal backhaul
cases are further taken iuto accolults it1 the scenario. In addition, the scenario of
double-connectioti has been itltroduced in the small cell enhancement. In addition, the
Sony ~ e fS:P 352212\V000
SOIIC~l lilla Ref.: CNPA12060W000
Our Ref.: OP131147
-19-
scenario of coordinated multiple point transmission has bee11 introduced in the small
cell enhancement, and so on. Thus, in future heterogeneous networks, a large tltu~lber
of low power nodes aud macro cells will jointly serve the mobile terminal thro~~gah
variety of modes. Therefore, in many cases, the tllobile terminal can obtain services
5 from the small cells not only by switching or reselecting to a stnall cell, but also in at
least one of the manners of carrier aggregation, double-connection and coordinated
multiple point tra~~smissio. n
100771 According to an embodinlent of the present invention, the stnall cell
denseness evaluation unit 102 may determine whether a type of a target cell from
10 which the mobile terminal obtains services is small cell and count the number of times
that the target cell from which the mobile ternlinal obtains services is a small cell
within a predetermined time, and evaluate the detlseness of the small cells within the
region in which the mobile terminal locates by comparing the ntunber of times with a
predetermined thresl~oldo f tlutnber of times.
15 [0078] Specifically, d e n the [nobile terminal obtains selvices from the small cells
by switching or reselecting to a stllall cell, it may be determined whether the type of a
target cell that the mobile tenninal switclies or reselects to is a stnall cell; and a
counter may be set at the mobile terminal, and the counter is used to count the number
of titnes that the mobile terminal switches or reselects to a small cell withit1 a
20 predetermined time. In the predetermined time window, the dellseness of the st~lall
cells within the region in which the mobile ternlinal locates may be evaluated by
comparing the counted number of times with a predetermined threshold of number of
titnes. It should be appreciated by the skilled in the art that multiple predetermined
thresholds of number of titnes may be set according to actual needs. Furthermore,
25 wllen the mobile terminal obtain services from the small cells in at least one of the
manners of carrier aggregation, double-connectiotl and coordinated multiple point
trru~smissiotl through the small cells, since all of the carrier aggregation,
double-connection, coordinated mdtiple point transmission and so on as mentioned
herein are related to the scenarios of collaboration between small cells and macro cells
Soily Ref.: SP352212WOOO
Soi~y Cl~ina Ref.: CNPA 12060W000
Our Ref.: OP131147
- 20 - p~
or between small cells, the counting may be done separately for each of the small cells
associated with the n~obilet erminal. For example, when the mobile terminal obtain
services fro111 the snlall cells by carrier aggregation through the small cells, the
plurality of member carriers may be associated with a number of different small cells;
5 accordingly, by different arrival times or physical cell identifiers or the like, it may be
detennined which member carriers belong to \dlich small cells, respectively; then,
counting may be perfonned respectively for each small cell that the mobile terminal is
associated with. In addition, the method is similar for double-connection or
coordinated multiple point transmission, the details of which are therefore omitted.
10 [0079] According to this embodiment, by counting the number of times that the
target cell from wl~ich the tnobile terminal obtains services is a small cell within a
predetermined time, the denseness of the small cells within the region in which the
mobile terminal locates can be evaluated in a sitnple, intuitive way.
[0080] According to an ernbodinlent of the present invention, the small cell
15 denseness evaluation unit 102 may determine wllether the type of a target cell fro111
which the nlobile tertninal obtains services is sinall cell and determine the distances
between snlall cells from which the nob bile terminal obtains services according to
position information of the stnall cells fro111 which the mobile terminal obtain services,
and evaluate the denseness of the snlall cells within the region in which the mobile
20 terminal locates by co~nparingth e distances wit11 a predetermined distance threshold.
[0081] Specifically, wl~enth e mobile teninal obtains services from the stnall cells
by switching or reselecting to a small cell, the cell mobile ter~nit~tailla y identify the
source cell that the mobile terminal was previously corlt~ectedt o and whether the type
of the target cell that the tnobile terminal switches or reselects to is stnall cell, and
25 record the plurality of slnall cells that the mobile terminal recently switches or
reselects to successfully, so as to obtain position information of the small cells that the
mobile tennitla1 switches or reselects to. According to the position infom~ationo f the
small cells that the tnobile terminal switches or reselects to, the distances between the
small cells that the mobile ter~nitlal switches or reselects to can be calculated. By
Sony Ref.: SP352212WOOO
Sony Cl~ina Ref.: CNPA12060WO00
Our Ref.: OP1311.17
-21-
comparing the calct~latedd istances between the stnall cells that the mobile tertiiinal
switches or reselects to with a predeternlined distance threshold, the denseness of the
stnall cells within the region in which the mobile terminal locates car1 be evaluated.
For exanlple, if it is determined by comparison that the distances between the multiple
5 small cells which the mobile terminal switches or reselects to are close, a case may be
determined that the small cells witlin the region in which the nob bile terminal locates
are densely deployed. In addition, when tlie mobile terminal obtain selvices fro111 the
small cells in at least one of the manners of carrier aggregation, double-connection
and coordinated multiple point trans~iiission through the stilall cells, since all of the
10 carrier aggregation, double-connection, coordinated multiple point transtiission and
so on as mentioned herein are related to the scenarios of collaboration between small
cells ald macro cells or between stnall cells, a distance threshold may be calculated
separately for each of the small cells associated with the tnobile terminal, and the
multiple distance tliresholds obtained by the calculation may be averaged. For
15 example, when the mobile terminal obtain services from the small cells by carrier
aggregation through the small cells, the plurality of member carriers may be
associated with a number of different small cells; accordingly, by different arrival
times or pllysical cell identifiers or the like, it may be determined wl~ich member
carriers belong to which small cells; then, a distance thresliold may be calculated
20 separately for each small cell that the mobile terriunal is associated with, and the
multiple distance thresholds obtained by the calcdatioti may be averaged. In addition,
tlie method is similar for double-connection or coordinated nlultiple point
transmission, the details of wliich are therefore omitted.
[0082] The position information of the small cells konl which the mobile terminal
25 obtain services can be obtained in various ways. For example, a parameter related to
the position information of snlall cells may be added in the list of adjacent cells, and
the tnobile terminal may obtain the position infomlation of small cells by querying the
parameter in the list of adjacent cells. As another example, the position information of
stilall cells may be broadcast throng11 a broadcast channel of the small cells, and the
Sony Ref.: SP352212WO00
Sony Cluna Ref.: CNPA12060iVO00
Our Ref.: OP1311.17
- 22 -
tilobile tertninal obtains tlle position iitforn~ation of small cells by receiving the
broadcast. As yet another exanlple, the mobile tertninal may send request infornlation
to a small cell according to its needs, to obtain tlie position infor~nationo f the stnall
cell. 111 addition, the position information of snlall cells may be identified itsing
5 longitude information and latitc~dein formati011
[0083] According to an embodiment of the present invention, tlie predeter~nined
distance threshold is determined according to coverage of the sniall cells from \vhich
tlie tnobile terminal obtaitis services. For example, the predeternlitled distance
threshold tnay be determined by calculating a weighted average of small cell distance
10 tliresholds corresponding to coverages of the small cells fro111 wliich tlie mobile
tertninal obtains services.
[0084] The tnobile terminal may acquire the trmsmission powers of tlie small cells
from whicl~th e mobile terminal obtains services, and estimate the coverages of the
stnall cells from which the nlobile terminal obtains services according to the
15 transnlission powers of the small cells from \vhicli the tnobile tertninal obtains
services. The predetermined distance thresholds may be deter~nitleda ccorditlg to tlie
coverages of the small cells from which the tnobile terminal obtains services, and
different small cell coverage may correspond to different small cell distance threshold.
According to an etnbodiment of the present invention, each small cell distance
20 threshold corresponding to a small sell coverage may be determined as the
predetertnined distance threshold, and the calculated distances between the small cells
from which the tnobile tenninal obtains services may be cotiipared with a
corresponding stnall 'cell distance threshold respectively, so as to evaluate the
denseness of the small cells within tlie region in wllich the mobile tertninal locates.
25 According to another embodiment of the present invention, an arithmetic average of
the small cell distance thresholds corresponding to the respective small sell coverages
may be detennined as the predetermined distance threshold, and the calculated
distances between the small cells fronl which the tnobile terminal obtains services
may be compared with the arithmetic average of the small cell distance thresl~olds, so
Sony Ref.: SP3522121VOOO
Sony China Ref.: CNPA12060W000
Oor Ref.: OP13 1147
- 23 -
as to evaluate the denseness of the stnall cells within the region in which the nob bile
tertninal locates. According to yet another embodiment of the present invention, the
small cell distance thresholds corresponding to the small sell coverages may be
respectively assigned with corresponding weights, atld a weighted average of the
5 small cell distance thresholds corresponding to the slnall sell coverages may be
determined as the predetermined distance threshold, and the calculated distances
between the small cells from which the mobile terminal obtains se~vices may be
compared with the weighted average of the stnall cell distance thresholds, so as to
evaluate the denseness of the small cells within the region in which the mobile
10 terminal locates.
[0085] According to this embodiment, the position information of small cell
deployn~ent is further used to calculate the distances between the small cells from
which the mobile terminal obtains services, thus providing a more accurate estimation
of the denseness within the region in which the small cells locate.
15 [0086] Accorditlg to an embodiment of the present invention, the small cell
denseness evaluation unit 102 may also determine the type and/or coverage of the
target cell according to a transmission power of the target cell from which the mobile
terminal obtains services.
[0087] A heterogeneous network includes a large number of low power nodes such
20 as n~icrob ase stations, pic0 base stations, fetntocell base stations and remote radio
units. The low power nodes are distributed in the coverages of macro cells, and serve
the mobile terminal in different modes along wit11 the macro cells. However, due to
the differences in transmission power, backhanl and carrier type of the low power
nodes, the complexity of the conventional network architecture is significantly
25 increased, greatly affecting the performance of many ~nechatiisms including mobility
state estimation for the mobile terminal. Therefore, in the present invention, according
to the above characteristics of heterogeneous networks, the tnechanisn~s including
mobility state estinlation for the mobile terminal can be itnproved according to the
SOIV Ref.: SP3522121VOOO
Sony Clii~~Rac f.: CNPA12060\V000
Our Rcf.: OP131147
- 24 - -
types of the cell base stations in a heterogeneous network. Hence it is desirable to
identify the types of the cell base stations in a heterogeneous network.
[0088] In the curretit LTE standards, the tnobile terminal cat1 distinguish different
cell base stations through cell identifiers. However, the cell identifier does not include
information about the type of the cell base stations. Tllus, it1 the prior art, the tilobile
terminal canlot identify the type of the cell base station. To this end, a number of
methods to identify tlie type of a cell base statiou are provided in tlie presetit inventiou
as follows
[0089] According to at1 embodiment of tlie present invention, the tnobile terminal
may identify tlie type of a cell base station accorditig to the tratlstnission power of the
cell base station. Different types of cell base stations liave different tratismission
powers; and according to the tratlstnission powers, cell base stations may be divided
into ~nicrob ase stations, pica base stations, relay base stations, femtocell base stations,
remote radio units, etc. Typical values of the tratismission powers of cell base stations
are shown in Table 1 below.
Table 1 Typical values of transtnissiotl powers of cell base stations
Sony Ref.: SP352212LV000
Soi~y Cllil~a Ref.: CNPA12060W000
Our Ref.: OP13 1147
- 25 - ~p
[0090] As shown in Table 1, low power nodes and tnacro base stations can be
distinguished according to the transmission powers of the cell base stations. It is
described below in detail on how to identify tlle type of the cell base station based on
the transmissiot~p ower of the cell base station
5 [OO91] The transmission power of the cell-specific reference signal CRS by a cell
base station cm be indicated in the system information block SIB2, which can be used
to calculate tl~ep ath loss between the mobile terminal and the cell base station. Thus,
the transmnission power of the cell base station can be calculated based on the above
transmission power of the cell-specific reference signal CRS by the cell base station,
10 so as to distinguish between low power nodes and macro base stations. 111 addition,
the transtnission power of cell base stations can be mapped into cell coverages, so as
to obtain the cell coverages.
[0092] According to this embodiment, the type of a cell base station cat1 be
identified at the tnobile terniinal according to the transmission power of the cell base
15 station, which is simple, effective and does not change the existing standards.
[0093] According to at1 embodiment of the present invention, the small cell
denseness evaluation unit 102 tnay futiher receive information of cell type indicating
a cell type from a base station serving the mobile tertninal and determine the type of a
target cell according to the infornlation of cell type.
20 100941 The information of cell type tnay be added in a systenl information block,
e.g., a cell level identifier, for directly indicating the type of a cell base station, and
thus the type of the cell base station can be determined according to the infornlation of
cell type. For example, different levels of cells may be nutnbered so that, for exatnple,
a tnacro base station is set with a cell level nutnber 00, a micro base station is set with
25 a cell level number 01, a pico base station is set with a cell level number 10, and a
relay base station is set with a cell level number 11, etc. In addition, the information
of cell type may be broadcast in system infonnation of a current cell, or added to the
adjacent cell configuration infonnation of measuren~enct ontrol infortnation.
S O IR~ef .: SP3522121V000
Sony Cliitla Ref.: CNPA1206OW000
Our Ref.: OP131147
-26- -
[0095] Referring back to Figure 1, the mobility state estinlation unit 104 in the
device 100 may determine a n~obility state esti~nation manner according to the
estimated denseness of the small cells so as to estimate n~obility state of the n~obile
terminal.
5 [0096] As described above, after the small cell denseness evaluation unit 102
evaluates the denseness of stnall cells within a region in which a mobile terminal
locates, the mobility state esti~nation unit 104 may determine a mobility state
estinlation maruler for the mobile ternlinal according to the evaluated denseness of the
stnall cells so as to estitnate mobility state of the tnobile terminal, thereby itnproving
10 the performance of tnobility state estitnation for the tnobile ter~ninal. It will be
described hereinafter in detail on how to deternline a mobility state estitnation manner
according to the evaluated denseness of the small cells.
100971 According to an embodiment of the present invention, if the evaluated
denseness of the small cells is low, the mobility state estimation unit 104 nlay count
15 only the n~unbero f times that the tnobile terminal switches or reselects among tnacro
cells and estitnate the tnobility state of the mobile ternlinal according to the number of
times that the tnobile tet-minal switches or reselects among the macro cells.
[0098] If the evaluated denseness of the stnall cells is low, the heterogeneous
network with non-densely deployed snlall cells may be not much different from a
20 conventional hotnogeneous network. Therefore, in this case, due to the low denseness
of the stnall cells, the small cells have limited effects on the network, making it
feasible to count only the nutnber of times that the tnobile terminal switches or
reselects anlong macro cells. Then, according to the number of times that the tnobile
ternlitla1 switches or reselects anlong macro cells, the mobility state of the tnobile
25 terminal can be estimated. The method according to this embodimnent yields good
results in the cases where stnall cells are sparsely distributed, and is relatively easy to
implement.
Son). Ref.: SP352212\V000
Sony Clii~~Rae f.: CNPA12060\\~000
Om Ref.: OP131147
-27-
100991 According to a11 embodiment of the present invention, if the evaluated
detlseness of the sn~all cells is high, the mobility state estimation itnit 104 may
estinlate a movement distance of the lnobile terminal according to position
infornlation of small cells fro111 which the tnobile ternlit~al obtains services and
5 estimate the tnobility state of the nlobile terminal according to the nlovement distance
of the lnobile terminal.
[00100] As the denseness of srnall cells deployed in a lleterogeneous network
increases, the effect of small cells on the heterogeneous network increases. Therefore,
when the denseness of small cells in a heterogeneous network is high, in order to
10 increase the accuracy of tnobility state estiination for the mobile terminal, the
movement distance of the nlobile tenninal may be estimated according to position
information of small cells from whicll the mobile terminal obtains services. As
described above, the mobile terminal can obtain services from the sn~all cells by
switching or reselecting to a small cell; or, in at least one of the tnatulers of carrier
15 aggregation, double-connection at~dc oordinated tnultiple point transmission through
the small cells. Then, the mobility state of the tnobile terminal may be estimated
according to the movement distance of the mobile terminal. According to tlus
embodiment, due to the further use of the position information of the sn~alcl ells, the
accuracy of n~obilitys tate estimation for the mobile terminal can be improved.
20 [00101] It can be seen from the above analysis that a mobility state estimation
manner can be determined according to the evaluated denseness of the small cells, and
the deternlined mobility state estimation manners can selve as good conlpletnents
with each other, jointly ensuring the perfomlance of mobility state estimation under
different circumstat~ces, thereby elilninating the problerns encountered in nlobility
25 state estimation in heterogeneous networks.
[00102] According to an embodiment of the present invention, the n~obility state
esti~nation unit 104 nlay count the nutnber of times that the mobile terminal switches
or reselects anlong macro cells and the nlunber of times that the nlobile ternlinal
obtains services fro111 the sn~alcl ells respectively, atld estimate the nlobility state of
Sony Ref.:' SP352212JV000
SOIIJ' Clu11a Ref.: CNPA12060W000
Our Ref.: OP131147
-28-
the mobile tern~inal according to a weighted sum of the ~ ~ u ~ nobfe trim es that the
mobile tenninal switches or I-eselects anlong the macro cells and the nunlber of times
that the mobile terminal obtains services fro111 the snlall cells, wliere the cell weight
factors of the small cells and the tnacro cells are adjusted adaptively according to the
5 evaluated denseness of the small cells to calculate the weighted sum
[00103] In order to estimate the mobility state of the mobile ternunal, the number of
titnes that the mobile ternlinal switches or reselects atnong niacro cells and the
nun~bero f times that the mobile terminal obtains services fl-om the sn~alcl ells nlay be
counted respectively; a weighted sutn of the number of times that the mobile tern~inal
10 switches or reselects an~ongth e macro cells and the nun~bero f titnes that the n~obile
ternlinal obtains services frotn the small cells can be calculated according to cell
weight factors of the small cells and the macro cells; and the niobility state of the
mobile terminal may be estimated according to the calculated weighted sum. Thus,
the configuration of the weight factors of the sniall cells and the macro cells has a big
15 impact on the perforn~ance of mobility state estimation for the tnobile tertninal, and
hence a single set of cell weight factors will not fit with the various situations in a
variety of heterogeneous networks. In order to improve the performance of mobility
state estin~ahonf or the mobile terminal, the cell weight factors of the small cells and
the macro cells may be adjusted adaptively according to the evaluated denseness of
20 the sniall cells to calculate the weighted sum. According to this embodiment, the cell
weight factors of the s~nall cells and the macro cells may be adjusted adaptively
according to the deuseness of the sniall cells, so as to fit with the various situations in
a variety of heterogeneous networks.
[00104] In addition, as described above, in small cell enhancement in 3GPP, the
25 original scenario has been f~uther extended. For example, the scenario of carrier
aggregation has been introduced in small cell enhancen~en~at,n d the scenario further
takes ideal backhaul and non-ideal backhaul cases into account. In addition, the
scenario of double-connection has been introduced in stnall cell enhancen~ent. h1
addition, the scenario of coordinated multiple point transtnission has been introduced
Sony Ref.: SP352212WO00
Sony Clli~la Ref.: CNPA12060\V000
Our Ref.: OP131147
- 29 -
in small cell enhancement, and so on. Thus, in future heterogeneous networks, the
collaboration modes between slnall cells and macro cells will be enriched, and
nobility state estimation in scenarios such as carrier aggregation, dot~ble-co~u~ection
and coordinated multiple point transmission has to be fnrther extended
5 [00105] Conventional mobility state estimation is based on the number of times of
successful cell reselection or switching. However, in future heteroge~~eounse tworks, a
large number of low power nodes aid macro cells will jointly serve the n~obile
terminal tliroigl~ a vat-iety of modes. Therefore, in many cases, the mobile ternunal
does not obtain services from the small cells by switching or reselecting to a small cell;
10 instead, the mobile terminal in a connected state obtains se~vicesfr om the small cells
in at least one of the manners of carrier aggregation, double-connection and
coordinated tunltiple point transmission.
[00106] A niobile ternunal in a connected state obtaining services fro111 a particular
small cell means the mobile terminal is within tlie coverage of the small cell. However,
15 according to the conventional manner of mobility state estimation, switching or
reselecting is counted only when the mobile ternlinal switches or reselects to a small
cell through cell switching or reselectioti, i.e., the priniary service cell of the mobile
terminal is the small cell. Thus, many other scenarios such as carrier aggregation,
double-connection and coordinated multiple point transmission would be excluded
20 from consideration of niobility state estimation. Therefore, when taking into account
of the change in future heterogeneous networks, in the mobility state estimation for
the mobile tern~inal according to the present invention, the mobile terminal can obtain
services from small cells by switching or reselecting to a small cell, or in at least one
of the mantiers of carrier aggregation, double-connection and coordinated multiple
25 point transniission through the small cells.
[00107] Specifically, in mobility state estimation for the lndbi~ete rnlinal, it is not
linuted to the number of times that the niobile ternunal switches or reselects to cells;
but also should take into account of the number of titiles that tlie mobile tertiunal in a
connected state obtains the se~vicefr om a small cell in at least one of the tnamiers of
Salty Ref.: SP352212\VO00
Son). China Ref.: CNPA12060WO00
Our Ref.: OP131147
-30-
carrier aggregation, double-connection and coordinated multiple point trans~~~ission
(for example, in the carrier aggregation nianner, the mobile terminal is assigned with a
tnen~berc arrier by the s~nalcie ll.).
(001081 According to a11 emnbodilnent of the present invention, the mobility state
5 estimation unit 104 may further accumnulate the uumber of times that the mobile
terminal obtains services from the small cells it1 the wit of a predetermined area, aud
determine that the n~obile tenninal is able to obtain sewices from the small cells
within the predetermined area if the result of the accunlulating is larger than a
predetermined count tlueshold.
10 [00109] The nu~n~beorf times that the target cell from which the mobile tenninal
obtains services within a predetern~ineda rea is a small cell tuay be accumulated, and
the result of the accumulating may be used as another criterion for deternutling
whether the mobile terminal is able to obtain service froin a small cell, wliich is
parallel to mobility state estimation. As a more specific example, the accumlating
15 may be performed in the unit of a small cell cluster, aud when the mobile terminal
s\.vitches from the first stnall cell cluster to another small cell cluster, the
acc~unululatingr esult of the number of times that the mob~lete rminal obtains services
from small cells in a first small cell cluster is cleared to restart counting; or the
accumulating result is held for a predetermined period of time, and the stored
20 acc~unulatit~regs ult of the number of tinles that the mobile terminal obtains services
from small cells in a first s~nalcl ell cluster is continuously used if the mobile terminal
switches back to the first stnall cell cluster within the predetermined period of time. In
addition, since a macro cell does not belong to any small cell cluster, the case where
the mobile terminal switches back to a macro cell does not constitute a switching
25 between small cell clusters. Those skilled in the art shall understand that the above use
of small cell cluster as a predetermined area is exelnplary only; and other regions nlay
as well be used as the predetermined area, e.g., the coverage of a tuacro base station.
[00110] It is described below it1 detail on how to determine that the mobile terminal
switches to another small cell cluster.
SOIIJR' ef.: SP352212\VOOO
SOIIJ' Cluna Ref.: CNPA12060W000
Our Ref.: OP1311.17
-31- -
[00111] According to at1 en~bodi~~o~fe tnhet present invention, whether the mobile
terminal switches to another small cell cluster may be deter~nined according to the
itiformation of small cell clusters indicating which small cells are adjacent to each
other
5 [00112] For exan~ple, the identifier of the small cell that the mobile tennitial
switches to may be compared with the identifiers of the su~allc ells included in tlie
information of small cell clusters, so as to determine \ðer tlie mobile terminal
switches to another stnall cell cluster.
[00113] According to an eti~boditi~eonft the present invention, the distance between
10 the two s~nalcl ells that the mobile terminal switches from and to may be determined
according to position infomlation of tlie small cells, and wllether tlie mobile terminal
switches to another small cell cluster lnay be deternuned according tlie determined
distance between the two sniall cells.
[00114] For example, the distance between the two s~nall cells that the mobile
15 terminal switches from and to may be determined according to position information of
tlie source cell that the mobile ternunal is previously connected to atid position
inforniation of the target cell that the nob bile terminal sultches to. If the distance
between the two small cells involved in the switching is too large, it is determined that
the mobile terminal switches to another stnall cell cluster.
20 [00115] According to an embodiment of the present invention, when tlie mobile
terminal encounters multiple cotisecutive switching failures or encounters n~ultiple
switching failures in a predetermined period of time, the accutiiulatitig result of the
number of times that the mobile terminal obtains services from small cells in the small
cell cluster may be cleared to restart counting.
25 [00116] In addition to the case where the rnobile terminal switcl~esto another s~nall
cell cluster, the accu~nulatingr esult of tlie number of times that the tnobile terminal
obtains services from small cells in the first small cell cluster also needs to be cleared
to restart counting when the tl~obile terminal enconters multiple consecutive
SOIIR~e f.: SP352212\V000
Sony Clulla Ref.: CNPA12060\V000
Our Ref.: OP131147
- 32 -
switchi~lgf ailures or encounters tnultiple switching failures in a predetermined period
of time.
[00117] According to & embodiment of the present invention, the mobility state
estimation unit 104 may further compare the accun~ulating result of the number of
5 times that the mobile tenninal obtains services from stnall cells in a small cell cluster
with a predetermined count threshold, and determine that the mobile ternlitla1 is able
to obtain services from the small cells once the accumulati~lg result is greater thax a
predetermined coutlt tl~resl~oldre,g ardless of any other determination criterion on
whether the mobile tenninal is able to obtain services from the small cells (e.g.,
10 mobility state estimation result).
[00118] Currently, tlle type of stnall cell switching at the mobile tenninal depends
on the mobility state estinlation result; however, the mobility state estitnation
mechanism may result in estimation error. For example, it1 the case where a mobile
terminal is moving with an elevator it1 a builditlg, each floor may cause a switching or
15 a reselection. For the mobility state estimation strategies based only on the count of
switches or reselectiotls, this situation may be tnisclassified as a high-speed moving
state, preventing the mobile terminal from accessing the stnall cell. Actually, however,
if the tnobile terminal can switch successfully many times in a small cell cluster, the
mobility state of the mobile terminal is proved suitable for small cell switching.
20 Therefore, the accumulating result of the number of titnes that the tnobile terminal
obtains services from the small cells in a predetennined area can be used as a separate
estimation criterion parallel to mobility state estimation. If, within a predetermined
range, e.g., within a small cell cluster, the accumulating result of the number of times
that the mobile terminal obtains services from the stnall cells exceeds the
25 predetermined count threshold, then it indicates that the tnobile terminal successftdly
receives services frotu the small cells withit1 the small cell cluster. Moreover, since
the mobile terminal can obtain sewices fro111 the small cells lnatly times, the tnobility
state of the mobile ternlitla1 is bound to meet the mobility requiretnents it1 the small
cell deployment scenario. Therefore, in this case, even if it is determined that the
Sony Ref.: SP3522 12\\10OO
So~iy Cliiua Ref.: CNPA12060WOOO
Our Ref.: 0P1311.17
- 33 - -
mobile terminal cannot obtain selvices from the small cells according to the current
result of mobility state estimation, the result of mobility state esti~nation can be
ignored. That is, as long as the accumulating result of the number of times that the
mobile terininal receives se~vicesfr om the stnall cells within tlie predetermined area
5 is greater than the predetermined count threshold, it is determined that that the mobile
terminal can obtain services fro111 the small cells, regardless of any other
determination criterion on whether tlie mobile terminal can obtain services frotn tlie
small cells, e.g., no matter what the mobility state esti~natiotrie sult is.
[00119] Another configuration of a device in a wireless comtnunication system
10 according to an embodiment of the present invention is described below with
reference to Figure 2. Figure 2 is a block diagram illustrating another configuration of
a device in a wireless co~mnunication systetii according to an embodiment of the
present invention.
[00120] As shown it1 Figure 2, the device 200 in a wireless comn~uucatiosy~s~te m
15 iticludes a snlall cell denseness evaluation unit 202, a mobility state estitnation unit
204 and a mobility management unit 206. Among the units, the configurations of the
small cell denseness evaluation unit 202 and the tnobility state estimation unit 204 of
the device 200 are the same as the configurations of the small cell denseness
evaluation unit 102 and the mobility state estimation unit 104 of the device 100 sliom
20 in Figure 1, respectively, the specific details of wliicli are tlierefore omitted here. The
mobility management wit 206 in the device 200 will be described hereinafter in
detail.
[00121] As show1 in Figure 2, the mobility ma~lagement unit 206 may control cell
reselection for the mobile terminal in a free state according to the evaluated denseness
25 of the small cells and/or to control cell switching for tlie tnobile terminal in a
connected state according to the estimated result of tlie mobility state
[00122] In a free mode, rnobility ~nalage~neinst controlled by the tnobile terminal,
mainly relating to the cell reselection mecl~anism. Cell reselectiori for the mobile
S O IR~e f.: SP352212\V000
Sally Clliua Ref.: CNPA12060W000
Our Ref.: OPE31147
- 34-
terminal in a free state may be controlled according to the evaluated denseness of the
small cells. It is described below in detail on how to control cell reselection for the
mobile ter~nitlailn a free state according to the denseness of the small cells.
[00123] According to an embodiment, the mobility management unit 206 may
5 further prevent the mobile terminal in a free state fro111 performing cell search a d o r
cell measurement for the small cells in the case where the evaluated denseness of the
slnall cells is high, and allow the nlobile terminal in a free state to perfonn cell search
and/or cell measurement for the snlall cells in the case where the estimated denseness
of the small cells is low.
10 [00124] When the lnobile terminal is in the scenario where the denseness of the
small cell deploy~nenits high, the signal quality of a snlall cell is normally higher than
the signal quality of a macro cell, thus triggering cell reselection at the lnobile
terminal. However, as the small cells are densely deployed, cell reselection may be
triggered frequently, increasing power consumption of the mobile terminal. Therefore,
15 in the case where the denseness of the small cells is high, in order to reduce power
consumption of the nlobile terminal, a mobile terminal in a free mobile may be
prevented from performing cell search and/or cell measurement for the small cells; in
stead, remaining connecting to the macro cell is preferable. In addition, in the case
where the denseness of the sinall cells is low, a mobile terminal in a free mobile may
20 be allowed to perfornl cell search and/or cell measurement for the small cells.
[00125] According to an etnbodiment, if the evaluated deilsetless of the snlall cells is
high, the tnobility management unit 206 may further allow the tnobile terminal in a
free state to perform cell search and/or cell measurement for the small cells if service
quality of tnacro cells is lower than a first predetermined tllreshold or the difference
25 between service quality of the stnall cells and the service quality of the macro cells is
larger than a second predetermined threshold.
[00126] In addition, in sonle cases, small cells are for a better network coverage.
Therefore, taking such cases into account, if the denseness of the small cells is high,
Sony Ref.: SP352212WOOO
Solly Cllina Ref.: CNPA12060\VOOO
Our Ref.: OP131147
- 35 -
tlie mobile terminal in a free state may be allowed to perform cell search and/or cell
measurement for the small cells if service quality of macro cells is lower thlul a first
predetermined threshold or the difference between service quality of the s~ilallc ells
and the service quality of the macro cells is larger tllatl a second predetermined
5 threshold.
[00127] It1 a connected state, the conventional mobility management is controlled by
tlie base station, mainly relating to the cell switching mecl~anism. As described above,
the introduction of heterogeneous network lias a significant impact on cell switching,
wilerein the increase of switching failure probability makes it impossible to ensure the
10 mobility perforniatlce of the mobile tenninal. In a network, instead of the switching
failure probability, it is switching failures and the number of switcliing failures that
directly affect the tnobile terminal user's experience. Therefore, one of the most
important aspects in mobility tnanagetnent is how to improve the mobile teriiiinal
user's experience in a heterogeneous network. In the process of cell switching, a
15 niajor affecting factor is tlie mobility state of the mobile terminal. Therefore, cell
switching for a mobile terminal in a connected state may be controlled according to
the estimation result of the niobility state of tlie mobile terminal by the mobile
terminal.
[00128] Switching in a heterogeneous network has tlie following characteristics: the
20 higher tlie speed of the mobile terminal, the less appropriate for it to switch to a small
cell. As tlie speed of tlie mobile terminal increases, the residence time within the sniall
cell and the reaction time for switchitig of tlie tnobile ternlitla1 are both greatly
reduced. In addition, due to their limited transmission power, small cells have limited
coverages. Thus, for a high-speed tnobile terminal, if it attempts to access a small cell,
25 the mobile tenninal is likely to etlcotulter wireless link failure, causing tlie switching
to fail, and may easily be switched back to the macro cell, resulting in ping-pong
switches. Therefore, in the control of cell switching for tlie mobile terminal in a
connected state, it is desirable to consider the result of niobility state estinlation for
the tilobile terminal.
Sony Ref.: SP352212WOOO
Sony Cluna Ref.: CNPA12060\VO00
Our Ref.: OP131147
- 36 -
[00129] Another cotlfiguratioll of a device in a wireless communication systetn
according to an embodiment of the present invention is described below with
reference to Figure 3. Figure 3 is a block diagram illustrating iu~otherc onfiguratiotl of
a device in a wireless communication system accot-ding to an embodiment of the
5 present invention.
[00130] As shown in Figure 3, the device 300 in a wireless communication system
includes a small cell denseness evaluatioti unit 302, a mobility state estimatio~lu nit
304, a mobility nlanagenlent unit 306 and a business type division unit 308. Among
these units, the configurations of the small cell denseness evaluation unit 302, the
10 mobility state estimation wit 304 aud the mobility managemetlt unit 306 of the device
300 are the same as tlie configurations of the stnall cell denseness evaluation unit 202,
the nlobility state estimation unit 204 atld the nlobility mauagement unit 206 of the
device 200 sl~ownin Figure 2, respectively, the specific details of which a et herefore
omitted here. The busitless type division unit 308 in the device 300 will be described
15 hereinafter in detail.
[00131] As shoun in Figure 3, the business type division unit 308 tnay divide
businesses at the mobile terminal into different business types accorditlg to time delay
sensitivity of the businesses at tile mobile terminal.
[00132] It1 tlie prior art, in cell switching, normally otlly the quality of link where the
20 mobile terminal is located is considered, but the business type of the mobile terminal
is not considered. However, actually, the business type of the mobile terminal will
affect the cell switching at the mobile terminal, especially in a heterogeneous network
environment. For exan~plet,h e business types of the mobile terminal cat1 be classified
into a type of high time delay sensitivity and a type of low time delay seusitivity. For
25 example, busit~esses with high time delay setlsitivity tnay include session-type and
streanutig-media-type businesses, while busitlesses witli low time delay sensitivity
may include interaction-type and backgromld-type businesses. Businesses witli high
time delay sensitivity have a low tolerance to time delay; hence it is preferable to
prevent a aillobile terminal performing a business wit11 high time delay sensitivity from
Sony Ref.: SP352212WOOO
Sony Cluna Ref.: CNPA12060\VOOO
Our Ref.: OP131147
- 37 - ~ ~p
kequent cell switching. 111 addition, businesses with low time delay sensitivity have a
high tolerance to time delay; hence a mobile tenninal perfornung a business wit11 low
time delay sensitivity may be switched to a s~nallc ell, for diversion. Therefore, the
business type of the nlobile terminal may be taken into account in the control of cell
5 switching for a mobile terlnitial in a connected state.
[00133] For example, according to time delay sensitivity of tlie businesses at the
n~obile ternunal, the businesses at the mobile ternutial lnay be classified into a
business of high time delay sensitivity and a business of low time delay sensitivity.
In addition, the businesses with high time delay sensitivity may be set wit11 a time
10 delay sensitivity coefficient 0, and the businesses with low time delay sensitivity tnay
be set with a time delay sensitivity coefficient 1. The time delay sensitivity
coefficients of the businesses at the mobile terminal are used only inside the mobile
terminal, providing a reference for determining tlie cell switching mode for the mobile
tel-minal. Tliose skilled in the art will understand, the classification of the businesses
15 at the ruobile terminal into a business of i~igltii me delay sensitivity and a business
of low time delay sensitivity based on the time delay sensitivity of the businesses at
the mobile ternlinal is merely exetnplary and not limiting; and tlie businesses at the
mobile ternlinal may be classified into more types according to the time delay
sensitivity of a business at the mobile terminal.
20 [00134] According to at1 embodiment of the present invention, if at least one of the
plurality of businesses in a connected state at the mobile ternutial has a big11 time
delay sensitivity, the business type division unit 308 may further deternline a
collective time delay sensitivity of the businesses at tlie tnobile terminal to be high.
[00135] JVhen multiple businesses are connected at the tnobile tenninal, a collective
25 time delay sensitivity of the busillesses at the tnobile terminal may be deternlined to
be high if at least one of the plurality of businesses in a connected state at the rnobile
terminal has a high time delay sensitivity. This ensures that the time delay sensitivity
requirement of the businesses at the tnobile terminal is met collectively.
Sot~y Ref.: SP352212WOOO
Sony Clii~ia Ref.: CNPA12060WO00
Our Ref.: OP1311.17
- 38 - ~-~
[00136] According to enlboditnent of the present invention, the tnobility
tna~~agetnetulnt it 306 may filter switchable target cells for the mobile terniinal in a
connected state according to the estimation result of the mobility state of the tnobile
terminal and the business type and perform cell nleasurement and/or measuretnent
5 report for the filtered target cells to perform cell switching for the mobile terminal
[00137] When the mobile tertninal receives adjacent cell list configuration
information provided by the measurement control it~for~natiforlo~tn the network side,
the lnobile terminal lnay determine the type of an adjacent sniall cell accordingly, e.g.,
by querying a cell level identifier of the adjacent stnall cell. Then, the mobile ternunal
10 may estimate its mobility state, and filter switchable target cells for the mobile
tertninal in a colu~ecteds tate according to the estimation result of the mobility state of
the mobile tertninal and the business type, and perform cell nleasurement and/or
measurement report for the filtered target cells to perfonn cell switching for the
mobile terminal, thereby reducing unnecessary measusenlent so that cell switching at
15 the tnobile terminal can be more puyosefid.
[00138] For the cell switching methods in a heterogeneous network, a specific
example is given in Table 2. Those skilled in the art will tulderstand, the cell
switching tnetllods in a heterogeneous network shown in Table 2 are exemplary
only and not limiting; and other cell switching methods may be adopted.
20 Table 2 cell switching strategies it1 a heterogeneous network
Mobile terminal
type to be connected
to a base station
High time delay
I sensitivity I speedlLow speed I speedLow speed ( speedLow speed I
Base station type
sensitivity
Low titne delay
Macro base station
High speedfMedium
speedLow speed
High speedhiediun~
Relay base station
High speed/Medium
Micro base
station
Low speed
speed/Low speed
High speediMediutn Mediunl
Soliy Ref.: SP352212W000
SOIF Clii~ia Rcf.: CNPA12060W000
Our Ref.: 0P131147
-39- ~-
[00139] In the cell switching methods show~in Table 2, the estin~ationre sults of the
mobility state of the mobile terminal may be classified as High speed, Medium speed
and Low speed. According to an embodiment of the present invention, cell switching
for a tnobile terminal in a connected state may be controlled according to o111y the
5 estimation result of the mobility state of the mobile terminal. For example, as showm
it1 Table 2, for a high speed mobile ternunal, only macro base stations atld relay base
stations can be its target cell in cell switchitlg, i.e., a high speed mobile terminal can
only be switched to a macro base station or a relay base station. For a low-speed
mobile terminal, macro base stations, relay base stations and tnicro base stations cat1
10 be its target cell in cell switching, i.e., a low speed tnobile terminal can be switched to
any one of macro base station, relay base station and micro base station. III addition,
in the cell switching methods s h o ~ inn~ T able2, the businesses at the mobile terminal
can be classified into a business type of high time delay sensitivity and a business type
of low time delay sensitivity. According to an etnbodiment of the present invention,
15 the switchable target cells for the mobile terrninal in a connected state tnay be filtered
according to the estimation result of the mobility state of the tnobile terminal and the
business type, and cell switching may be performed for the mobile terminal accorditlg
to the filtering result. For example, as shown in Table 2, for a business type of high
time delay sensitivity it1 a medium speed mobile terminal, o ~ ~ml yac ro base stations
20 and relay base stations cat1 be its target cell it1 cell switching; while a busitless type of
low time delay sensitivity in a n~ediutn speed mobile terminal, macro base stations,
relay base stations and micro base stations can be its target cell it1 cell switching.
[00140] The process of a method used in a wireless commlinicatiotl system
according to at1 embodiment of the present invention is described below with
25 reference to Figure 4. Figure 4 is a flow chart illustrating a method used in a wireless
connnunication syste~na ccording to an embodiment of the present invention.
[00141] As shown in Figure 4, the nlethod starts at step 400. The method proceeds
to step 402 after step 400.
Sony Ref.: SP352212\VOOO
Sally Cl~i~iRae f.: CNPA12060W000
Our Ref.: OP1311.17
-40- ~p
[00142] Step 402 is a small cell denseness evaluation step. In step 402, the
denseness of snlall cells within a region in wllich a mobile ter~ninal locates tnay be
evaluated
[00143] The method proceeds to step 404 after step 402.
5 [00144] Step 404 is a mobility state estimation step. In step 404, a mobility state
estitnation nnlanner may be deternutled according to the evaluated denseness of the
s~nalcl ells so as to estimate the tnobility state of the mobile terminal.
[00145] Then, the method ends at step 406.
[00146] The method shorn in Figure 4 is a method corresponding to the device
10 shown in Figure 1, the siecific details of which are omitted here.
[00147] According to an embodiment of the present invention, in the stnall cell
detnlseness evaluation step 402, infornnlation of small cell clusters indicating which
small cells are adjacent to each other nlay be received from a base station serving the
mobile terminal, and the denseness of the small cells within the region in which the
15 mobile terminal locates may be evaluated in accordance with the information of stnall
cell clusters.
[00148] According to MI emboditnent of the present invention, the infortnation of
stnall cell clusters may be indicated by information of small cell identifier indexes
added in a list of adjacent cells, and the information of the small cell identifier indexes
20 may include information of stnall cell identifiers of adjacent small cells to indicate
that these adjacent small cells belong to a sarne cluster.
[00149] According to an e~nbodinlent of the present invention, in the small cell
denseness evaluation step 402, the denseness of the small cells within the region in
which the mobile tertninal locates may be evaluated according to a history that the
25 mobile tenninal obtains services from the s~nalcl ells.
[00150] According to an ernbodinlent of the present invention, in the small cell
denseness evaluation step 402, wllether the type of a target cell from which the mobile
Soriy Ref.: SP352212\VO00
SOIIC~l lil~aR ef.: CNPA1206OWOOO
Our Ref.: OP13 1147
-41 -
terniinal obtains setvices is stnall cell may be detertnitied, and the number of times
that the target cell from wliich the tilobile terminal obtains services is a sn~all cell
within a predetermined time tilay be counted; and the denseness of the s~iiall cells
within the region in which the mobile terminal locates may be evaluated by
5 cotnparing the number of times with a predetermined threshold of number of times.
[00151] According to ai embodiment of tlie present invention, in the stnall cell
denseness evaluation step 402, wl~etl~tehre type of a target cell from which the mobile
terminal obtains services is small cell may be detennined, and the distances between
stnall cells froni which the mobile tenninal obtains services nlay be determined
10 according to position information of the small cells from which tlie mobile terminal
obtain services; and the denseness of the stnall cells within the region in which the
mobile terminal locates may be evaluated by cotnparing the distances with a
predetermined distance tliresl~old.
(001521 According to an embodiment of tlie present invention, the predetermined
15 distance thresl~old may be determined according to the coverages of the stnall cells
from which the mobile terminal obtains services.
[00153] According to an embodiment of tlie present invention, in the small cell
denseness evaluation step 402, the type andlor coverage of a target cell from which
the mobile ternunal obtain setvices may be also determined according to a
20 transmission power of the target cell.
[00154] According to an embodiment of the present invention, in the stnall cell
denseness evaluation step 402, information of cell type indicating a cell type may be
received from a base station serving tlie tilobile terminal, and the type of a target cell
may be determined according to the information of cell type.
25 [00155] According to an etnbodiment of the present invention, in the mobility state
estimation step 404, it is possible that, if the evaluated denseness of the small cells is
low, only the nurnber of times that the mobile terminal switches or reselects among
macro cells is counted, and the mobility state of the mobile terminal can be estitnated
Sony Ref.: SP352212WOOO
So~q China Ref.: CNPA12060W000
Our Ref.: OP131147
-42-
according to tlie number of times that the mobile terminal switches or reselects among
the tnacro cells.
[00156] According to an etnboditnent of the present invention, in the tnobility state
estimation step 404, if the evaluated denseness of the small cells is high, a nlovenlent
5 distance of tlie mobile ter~ninalc an be estimated according to position infornlation of
sniall cells from which the mobile terminal obtains services, and tlie mobility state of
the mobile tenninal can be estimated according to the movement distance of the
mobile tenninal.
[00157] According to a11 embodiment of the present invention, in the mobility state
10 estimation step 404, the number of times that the mobile ternlitla1 switches or reselects
among macro cells and the nunlber of times tliat the mobile ter~ilinal obtains services
from the small cells can he counted respectively, and the mobility state of the mobile
terminal can be estimated according to a weighted sum of the number of times tliat tlie
mobile terminal switches or reselects among the macro cells and the number of times
15 that the mobile terminal obtains services from the small cells, ~11erec ell weight
factors of the small cells and the macro cells are adjusted adaptively according to tlie
evaluated denseness of the small cells to calculate the weighted sum.
[00158] According to an embodiment of tlie present invention, in the mobility state
estimation step 404, the number of times that tlie mobile terminal obtains services
20 from the small cells cai be accumulated in a unit of a predetermined area, and it is
detennined tliat the mobile terminal is able to obtain services from tlie small cells
within the predetermined area if a result of tlie accumulating is larger than a
predetermined count tl~eshold.
[00159] According to an embodiment of the present invention, the mobile terminal
25 is able to obtain se~vicesf rom the stnall cells in at least one manner of switching or
reselecting to small cells, and carrier aggregation, double-connection and coordinated
multiple point transmission througl~s tiiall cells.
Sot~y Ref.: SP352212\VOOO
Sol~y Cluna Ref.: CNPA12060\\'000
Our Ref.: OP13 1147
-43- ~ -
[00160] The process of a method used in a wireless cotnmunicatiot~ system
according to atlother embodiment of the present itlve~itioti~s described below with
reference to Figure 5. Figure 5 is a flow chart illustrating a method used in a wireless
conunut~ications ystem according to another enlbodinlent of the present inventiot~
5 [00161] As showm it1 Figure 5, the method used in a wireless communicatiot~s ystem
itlcl~tdes a small cell denseness evaluation step 502, a mobility state estimation step
504 and a tnobility management step 506. Atllot~gth e steps, the process of the stnall
cell denseness evaluatiot~ step 502 and the tnobility state estimatiotl step 504 in the
n~etl~oadre the same as that of the stnall cell dense~~eesvsa luation step 402 and the
10 tllobility state estitnatiol~ step 404 in the method shown in Figure 4, the specific
details of which are therefore onutted here. The mobility tnanagemetlt step 506 in the
method is described in detail below.
[00162j As shown in Figure 5, in the n~obilitym anagement step 506, cell reselection
for the mobile terminal in a free state tnay be controlled accordit~gto the evaluated
15 denseness of the small cells, and/or cell switchit~g for the mobile tertninal in a
connected state tnay be controlled according to the estimated result of the mobility
state.
[00163] According to an embodiment of the present itlve~~tionin, the tnobility
managetnetlt step 506, the mobile tertninal in a free state can be prevented from
20 perfomling cell search and/or cell measurement for the stnall cells in the case where
the evaluated detlsetless of the stnall cells is high; the mobile terllitlal in a free state
can be allowed to perfornl cell sedrch and/or cell lneasttrement for the small cells in
the case where the evaluated denseness of the small cells is low.
[00164] Accordit~gt o an etnboditnetlt of the present iave~~tionit1, the mobility
25 rnanagemetlt step 506, it is also possible that, if the evaluated denseness of the small
cells is high, the mobile tertnillal in a free state is allowed to perform cell search
and/or cell tneasuretnent for the small cells if service quality of tnacro cells is lower
than a first predetermined threshold or a difference between service quality of the
Sally Ref.: SP352212\VOOO
Souy Clliua Ref.: CNPA12060WO00
Our Ref.: OP13 1147
- 44 - ~-
small cells and the service quality of the tnacro cells is larger than a second
predetermined threshold which is set in advance.
[00165] The process of a method used in a wireless comnnlunication system
according to another embodiment of the present invention is described below with
5 reference to Figure 6. Figure 6 is a flow chart illustrating a method used in a wireless
com~nunication systetn accorditig to another etnbodiment of the present invention.
(00166j As shon~iln Figure 6, the nietl~odu sed in a wireless conitnunication system
includes a small cell densetless evaluation step 602, a mobility state estitnation step
604, a mobility management step 606 and a business type division step 608. Among
10 tlie steps, tlie process of the small cell denseness evaluation step 602 and the mobility
state estimation step 604 in the method are the same as that of the small cell denseness
evaluation step 502 and the mobility state estitnation step 504 in the method shown in
Figure 5, the specific details of which are therefore omitted here. The tnobility
management step 606 and the business type division step 608 in the method are
15 described in detail below.
[00167] As sho\wi in Figure 6, in the business type division step 608, busit~esses at
the mobile tertninal can be divided into different business types according to time
delay sensitivity of the businesses at the mobile terminal; in the mobility management
step 606, switchable target cells for the tnobile ternlinal in a connected state can be
20 filtered according to the estimated result of the tnobility state of the mobile terminal
and the business type, and cell measuremetit and/or tneasuretnelit report can be
performed for the filtered target cells, so as to perform cell switcliing for tlie nlobile
terminal.
[00168] A configuration of a device in a wireless conitnunication system according
25 to another enlboditnent of the present invention is described below in conjunction
wit11 Figure 7. Figure 7 is a block diagram illustrating a callfiguration of a device in a
wireless comtnunicatiot~ system according to another embodiment of the present
invention
Sony Ref.: SP3522121VO00
Sony Cluna Ref.: CNPA12060WO00
Our Ref.: OP131147
-45-
[00169] As sliowr~ in Figure 7, the device 700 in a wireless comn~unications ystetn
nlay include a sn~alcl ell division unit 702 and a sending unit 704.
[00170] The small cell division unit 702 in the device 700 nlay divide small cells
adjacent to each other into small cell clusters and form information of small cell
5 clusters indicating which small cells are adjacent to each other.
[00171] In a heterogeneous network, a large number of small cells are deployed in
the coverage of a macro cell, and the base station serving the tnobile terminal can
learn the actual position wllere each small cell is deployed. Therefore, the base station
serving the mobile terminal may divide, according to the actual position wl~erea small
10 cell is deployed, tnultiple small cells adjacent to each other and closely distributed
into the same stnall cell cluster, aud form information of small cell clusters indicating
wl~icslm~a ll cells are adjacent to each other. The nutnber of small cells included in the
small cell cluster and the identifier infor~nationo f the respective stnall cells cat1 be
determined based on the infonnation of the small cell cluster.
15 [00172] According to an embodiment of the present invention, the information of
stnall cell clusters is indicated by infonnation of sn~alcl ell identifier indexes added in
a list of adjacent cells, the infornlation of small cell identifier indexes including
information of small cell identifiers of adjacent stnall cells to indicate that these
adjacent small cells belong to a same cluster.
20 1001731 The information of stnall cell clusters may be indicated by adding
inforn~atioot~f small cell identifier indexes in a list of adjacent cells, or in some other
systetn information block. For example, the first tn small cells adjacent to each other
may be divided into the first small cell cluster, the next 11 small cells adjacent to each
other tnay be divided into the second slnall cell cluster and so on, where In and 11 are
25 both natural numbers greater than or equal to 1. The infortnatiot~ of small cell
identifier indexes may include information of the sulall cell identifier of each adjacent
small cell belonging to the same snlall cell cluster. For example, the information of
stnall cell identifiers of the first small cell cluster may include identifier information
Sony Ref.: SP352212\V000
Sony Ctii~~Rae f.: CNI'A12060W000
Our Rcf.: OP131147
-46-
of each stnall cell of the first m stnall cells belonging to tlie first stnall cell cluster, and
the information of snlall cell identifiers of the second stnall cell cluster tnay include
identifier information of each small cell of the next n small cells belonging to the
second stnall cell cluster. Those skilled in the art will understand that the above
5 infonnation of snlall cell identifier indexes added in a list of adjacent cells indicating
the infor~nation of small cell clusters is exenlplary only and not limiting; tlie
informatioti of small cell clusters nlay also be indicated in other ways
[00174] Referring back to Figure 7, tlie sending unit 704 in device 700 may send
position informatiot~ of the small cells and/or parameter infornlation related to
10 coverage of the stnall cells to the mobile terminal. For example, according to an
embodiment of the present invention, the parameter infortnation related to coverage of
the stnall cells may include itiformation of trans~nissionp ower of the stnall cells.
[00175] As described above, in a heterogeneous network, a large number of small
cells are deployed in the coverage of a tnacro cell, and tlie base station serving tlie
15 mobile terminal can lean1 the actual positioti where each small cell is deployed and/or
parameter inforniation related to the coverages of the small cells. For example, the
parameter information related to coverage of the small cells may include it~forination
of transmission power of tlie snlall cells. Hence, the base station serving the tnobile
tertnitial may send the position infonnation of the small cells and/or the parameter
20 inforniation related to coverage of the stnall cells to the tnobile terminal. In addition,
as described above, the trat~stnissionp ower of the cell-specific reference signal CRS
by a cell base station can be indicated in the system information block SIB2, which
can he used to calculate the path loss between the mobile tertninal and the cell base
station. Thus, the base station sewing the mobile terminal may also send to the mobile
25 terminal tlie transmissio~lp ower of tlie cell-specific reference signal CRS by tlie cell
base station, and the tnobile terminal may calculate the transtnissioti power of the cell
base station according to the tratismission power of the cell-specific reference signal
CRS by tlie cell base station.
Sony Ref.: SP352212IVOOO
Son). China Ref.: CNPA12060W000
Om Ref.: OP131147
- 47 --
[00176] A method used in a ~GI-elescs omn~unicatiots~y stem according to ailother
enlbodimet~to f the present inve~~tioisn described below with reference to Figure 8.
Figwe 8 is a flow chart illustrating a method used in a mireless comtnunicatio~~
system according to another embodiment of the present invention
5 [00177] As shown in Figure 8, the method starts at step 800. The method proceeds
to step 802 after step 800.
(001781 Step 802 is a small cell division step. In step 802, small cells adjacent to
each other can he divided into small cell clusters, and information of small cell
clusters indicating which stnall cells are adjacent to each others is fonned.
10 [00179] The method proceeds to step 804 after step 802
[00180] Step 804 is a sending step. In step 804, the inforn~ationo f small cell clusters
can be sent to a mobile ternunal, where the itiformation of small cell clusters is used
by the mobile terminal to evaluate the denseness of small cells within a region in
which the mobile terminal locates.
15 [00181] Then, the method ends at step 806
[00182] The method shown in Figure 8 is a method corresponding to the device
showl it1 Figure 7, the specific details of which are omitted here.
[00183] A method used in a wireless cotnmunication system according to another
embodiment of the present itlvention is described below with reference to Figure 9.
20 Figure 9 is a flow chart illustrating a method used in a wireless conimunication
system according to another embodiment of the present invention.
[00184] As shown in Figure 9, the method starts at step 900. The method proceeds
to step 902 after step 900.
[00185] Step 902 is a stliall cell division step. In step 902, a base station apparatus
25 may divide stuall cells adjaceut to each other into small cell clusters, atld form
information of stnall cell clusters iudicating which stnall cells are adjacent to each
others.
Sony Ref.: SP352212WOOO
Sony Cl~i~Riae f.: CNPA12060WOOO
Our Ref.: OP131147
-48-
[00186] The method proceeds to step 904 after step 902.
[00187] Step 904 is a sending step. In step 904, the base station apparatus may send
the inforination of small cell clusters to a tnobile tet-n~inaal pparatus.
[00188] The method proceeds to step 906 after step 904
5 [00189] The step 906 is a small cell denseness evaluation step. In step 906, the
mobile terlninal apparatus tilay evaluate the denseness of small cells within a region
in which the mobile terminal apparatus locates according to the infortnation of small
cell clusters received from the base station apparatus.
[00190] The method proceeds to step 908 after step 906
10 [00191] The step 908 is a mobility state estimation step. In step 908, the tnobile
terminal apparatus may determine a tnobility state estimation nlarltler according to the
evaluated denseness of the small cells so as to estimate mobility state of the mobile
ternunal apparatus.
[00192] Then, the method ends at step 910
15 [00193] Specific etnboditnent examples of the present applicatiot~a re given below in
detail. The following specific embodiment examples are exemplary only, and not
litniting.
Etnboditnent examvle I
[00194] After a mobile tenninal is connected to a network, the denseness of stnall
20 cells within a region in which the tnobile terminal locates is to be determined.
[00195] When a base station-assisted determination tnethod is used, if the
infortnation of stnall cell clusters is broadcast by a tnacro base station, the specific
steps for determining the denseness of small cells are as follows:
[00196] (1) After connecting to a nlacro base station, the mobile tenninal obtains the
25 inforlnatiotl of stnall cell clusters within the region it1 which the tnobile terminal
locates according to the system infortnation broadcast by the tnacro base station;
Soil)' Ref.: SP352212WOOO
Son)' Cluna Ref.: CNPA 12060W000
Our Ref.: OPlRll.17
-49-
[00197] (2) When the mobile ternlitla1 is close to the coverage of a particdm small
cell, the physical cell identifier of the small cell is matched wit11 the information of
small cell clusters broadcast by the tnacro base station; and
(001981 (3) The denseness of the stnall cells within the region in which the tnobile
5 terrnitlal currently locates is determined according to the number of small cells
contained in the information of small cell clusters.
[00199] When a base station-assisted determination method is used, if the
infor~nationo f small cell clusters is broadcast by a snlall cell base station, the specific
steps for determining the denseness of small cells are as follows:
10 [00200] (1) after switchitlg from a macro cell to a particular small cell, the mobile
terminal den~odulatest he system information broadcast by the small cell, the system
information including the infornlation of stnall cell cluster for the small cell cluster to
wllich the small cell belongs; and
[00201] (2) the mobile terminal demodulates the information of small cell cluster,
15 and detennines the denseness of the small cells within the region in which the mobile
terminal currently locates according to the number of small cells included in the
infortnation of stnall cell cluster.
[00202] When a determination method based on the count of number of times of
stnall cell switching is used, the specific steps for determining the denseness of small
20 cells are as follows:
[00203] (1) the mobile terminal identifies the types of the source cell and the target
cell;
[00204] (2) the mobile tertninal counts the number of times that it switches or
reselects to a small cell, incrementing the counter by one when the mobile tenninal
25 successfully switches or reselects to a small cell;
(00205j (3) the tnobile terminal compares the counting result with a plurality of
predetermined thresl~olds which have been set, and determines the denseness of the
Sony Ref.: SP352212\V000
So~iy China Ref.: CNPA12060\V000
Our Ref.: OP13 1147
- 50 - ~-
small cells within the region in which the mobile terminal currently locates according
to the cotnparisotl result; and
[00206] (4) when the mobile terminal switches or reselects to another macro cell, tlie
counter is cleared.
5 [00207] When a deter~ninatiotl niethod with the assistance of the positiotlal
infortnation of the cell base station is used, the specific steps for deternlining the
denseness of small cells are as follows:
[00208] (1) tlie mobile tertnitial identifies the types of the source cell and the target
cell, and records a plurality of small cells that the mobile terrninal is recently
10 successfully connected to;
[00209] (2) the mobile terminal deduces the transmission power of the cell base
station, and estimates the coverage of the cell base station according to the
transmission power of the cell base station; the tnobile terminal detertnir~esw hether
two of the small cells that the nob bile terminal is successfully connected to are close to
15 each other according to position information of the cell base station and the estimated
coverage of the cell base station; and
[00210] (3) if tlie mobile tenninal determines that the plurality of small. cells
which it is connected to are all close to one another, it is determined that the
detlsetless of the small cells withitl the region in which the mobile terminal currently
20 locates is high.
Embodiment example 11
[00211] After determining tlie denseness of stnall cells, the mobile terminal tnay
determine a mobility state estitnation nianner for the mobile terminal according to the
denseness of the small cells within a region in which the tnobile terminal locates, and
25 the specific steps are as follows:
Souy Ref.: SP352212WOOO
SOIIC~h ina Ref.: CNPA12060W000
Our Ref.: OP131147
-51- ~~p
[00212] (1) If the denseness of the s~nalcl ells within a region in which the mobile
terminal locates is low, the mobile ternu~~iadle ntifies the types of the source cell and
the target cell;
[00213] (2) within a predeternlined time window, the mobile terminal cou~lts the
5 number of times that it switches to a macro cell, and performs mobility state
estimation for the mobile ternunal according to the counting result;
[00214] (3) upon entering a region where small cells are densely deployed, the
nob bile terminal obtains and records positiot~ information of the small cell that the
mobile terminal is connected to, estimates a tnovetnent distance of the mobile
10 terminal in conjunction with the position information of the latest recorded small cell,
and compares an accumulative movement distance with a plurality of predetermined
thresholds which have been set, so as to perform nlobility state estimation for the
mobile terminal; and
[00215] (4) after the mobile terminal returns to a region where small cells are not
15 densely deployed, the n~obility state evaluation tnarlner may be switched back to the
method based on the count of number of times of switching between macro cells.
Embodiment example III
[00216] Embodiment example III differs from Enlbodiment example II in that, the
mobile terminal does not need to switch the mobility state estitnation manner
20 according to the denseness of the small cells; instead, different weight factor
configurations are set according to different scenarios. The specific steps are as
follows:
[00217] (1) When in a region where small cells are not densely deployed, the mobile
terminal identifies the types of the source cell and the target cell;
25 [00218] (2) within a predetermined time window, the mobile terminal performs cell
weight factor-based counting of the number of times that the mobile terminal switches
or reselects successfirlly between tnacro cells and the number of time that the mobile
Sony Ref.: SP352212WOOO
Sou). China Ref.: CNPA12060\V000
Our Ref.: OP1311.17
- 52 -
terlninal receives setvices from a small cell, with small cells iuld tnacro cells assigned
witb different cell weight factors, and perfornls mobility state estimation according to
the counting result; and
[00219] (3) upon entering a 1-egion where small cells are densely deployed, the
5 mobile tertninal selects another set of cell weight factors according to the denseness of
the small cells so that the cell weight factors for small cells are appropriately
increased while the cell weight factors for the macro cells are accordingly decreased,
performs cell weight factor-based counting of the number of times that the mobile
terminal saccessfi~llys witches or reselects between macro cells and the number of
10 time that the mobile terminal receives services from a small cell with the adjusted cell
weight factors, and performs mobility state estimation according to the counting
result.
Ernbodilllent example n7
[00220] The mobile terminal is located in a high-rise ofice building, each floor of
15 the ofice building being covered by a small cell.
[00221] (1) The mobile terminal moves between different floors of the oftice
building, which causes the tnobile terminal to encounter cell switching or reselection
multiple times in a short period due to the presence of the coverage of the plurality of
small cells in the office building.
20 [00222] (2) If the nlobility state estitnatiotl manner based on the count of nonlber of
times of cell switching or reselection is used, the n~obilete rminal would be classified
as a medium-to-high speed mobile ternlinal based on the mobility state estimation
result. Hence, by a mobility management strategy according to the present invention,
the mobile terminal of such a kind would not be switched to a small cell.
25 [00223] (3) However, when the mobile terminal enters a small cell cluster, the
tlutnber of times that the mobile terminal obtains services fiorn a small cell within the
small cell cluster starts to be accumulated, adding one to the value of the counter each
Sony Ref.: SP352212W000
Souy Clu~ia Ref.: CNPA12060W000
Oor Ref.: OP131147
-53-
time the mobile terminal successfully obtaitls small cell services from a new small
cell.
[00224] (4) If the mobile terminal leaves the first stnall cell cluster or enters another
new small cell cluster, the counter is cleared; or, the result from the latest co~ultirlgfo r
5 the snlall cell cluster is stored for a predeternuned period of time, and the
accumulating result of the number of times that the mobile terminal obtains small cell
services within the first small cell cluster is cotltinuously used when the mobile
terminal switches back to the first small cell cluster within the predetermined period
of time.
10 [00225] (5) If the mobile terminal encounters multiple consecutive switchiag
failures, the acctunulating result of the number of times that the mobile terminal
obtains sinall cell seivices within the small cell cluster will be cleared.
1002261 (6) However, in the above scenario, the accumulating result of the number
of times that the mobile terminal obtains small cell services within the small cell
15 cluster exceeds the predetermined threshold, which shows that the mobile terminal
successfillly obtains services from the small cells multiple titnes in the region where
the stnall cells are densely deployed, hence the mobile terminal being capable of
obtaining services from the small cells. Therefore, althougll it appears according to
the tnobility state estimation result that the tnobile terminal cannot obtain services
20 from the stnall cells, based on the acc~unulatingr esult of the number of times that the
mobile terminal obtains small cell services within the small cell cluster , it can be
determined that the mobile tenninal can obtain se~vices from the small cells,
regardless of any other deternunation criterion for determining whether the mobile
terminal can obtain services from the small cells, e.g. the mobility state estimation
25 result.
Embodiment examule V
[00227] I~litially, the mobile terminal is not powered on. The following specific
steps implement a switching strategy:
Sony Ref.: SP352212W000
Sony Cl~il~Rae f.: CNPA12060\V000
Our Ref.: OP131147
- 54 - --
[00228] (1) The mobile terminal is powered on, and then connected to the network
after initial synchronization, rand0111 access aid resource allocation
[00229] (2) The mobile terminal establishes a RRC connection with the network,
and is in a RRC connected state when a business is currently transmitted, or in a RRC
5 idle state wl~etnl o btlsiness is transmitted.
[00230] (3) The mobile terminal identifies the type of the current cell, e.g., by
deducting from the transmission power of the cell base station, or by quelying a cell
level identifier of the cell, or the like.
[00231] (4) The mobile terminal determines whether it is in a region where small
10 cells are densely deployed.
[00232] (5) The mobile terminal determines a mobility state estimation manner for
the mobile terminal according to the denseness 6f the small cells in the region where
mobile terminal locates.
[00233] (6) Cell reselection occurs when the mobile terminal is in a RRC idle state;
15 cell switching occurs when the mobile terminal is in a RRC connected state. When the
quality of service of the current cell degrades to a degree such that a preconfigured
event triggering condition is met, the process of cell reselection or cell switclung is
triggered, at which time the niobile tertninal perfornls a corresponding strategy
according to the specific circumstrulces to enstxe tlie mobility performance of the
20 tilobile ter~ilinal.
[00234] (7) When the mobile tenninal is in a RRC idle state, if it is detected that tlie
mobile tertninal is located in a region where small cells are densely deployed, the
mobile terminal in the idle state is prevented from performing cell search andlor cell
measurement for tlie sniall cells; if it is detected that the mobile terminal is located in
25 a region where small cells are not densely deployed, the mobile terminal in the idle
state is allowed to perform the cell search andlor cell nleasureinent for the small cells.
Sony Ref.: SP352212W000
Soil). Clrina Ref.: CNPA12060\V000
Our Ref.: OP1311.17
-55-
[00235] (8) The mobile tertni~lald ivides the businesses at the mobile terminal into a
busitless type of high time delay sensitivity and a business type of low time delay
sensitivity according to the sensitivity of the businesses at the nob bile terminal.
[00236] (9) The mobile terminal filters switchable target cells for the mobile
5 ternlinal in the connected state according to the mobility state estimation result and
the business type at the mobile terminal, and performs cell measurement and/or
tneasurement report for the filtered target cells to perfonn cell switching for the
mobile terminal, thereby reducing unnecessary nleasurement so that cell switching
cal be more pputposefd.
10 [00237] Moreover, an etnbodiment of the present invention provides a program
product, the program product carrying machine-executable instructions which causes
an information processing device to execute the method used in a wireless
commu~~icatiosny stem according to an emboditnent of the present invention as
described above when executed on the information processing device.
15 [00238] In addition, an embodiment of the present invention further provides a
storage medium, the storage medium including machine-readable program codes
which cause an information processing device to execote the method used in a
wireless cotnrl~utlication system according to an embodiment of the present invention
as described above when executed on the information processing device.
20 1002391 Accordingly, the storage nlediutn for carrying a program product on which
the machine-readable instruction codes are stored is also included in the disclosure of
the present invention. The storage tnedium includes, but is not limited to, a floppy
disk, a magnetic disk, a magneto-optical disk, a menlory card and a memory stick.
[00240] The device in a wireless comtn~u~icationsy stem and its components
25 according to the embodinlents of the present invention can be implemented with
software, firmware, hardware or any combination thereof. The specific
implementations for the cotlfiguration are known to those skilled in the art and
therefore omitted. 111 the case where the present invention is implenlented with
Soi~y Ref.: SP352212\V000
Souy China Ref.: CNPA12060\V000
Our Ref.: OP131147
- 56 - -
software or firmware, a program constituting the software may be installed into a11
infonnatio~pi rocessing device (e.g., the ir~formatiolpl rocessilig device 1000 it1 Figure
10) with a dedicated hardware structure from a storage ~nediu~oirl a network, and the
computer is capable of perfonnitig various functions when installed with various
5 programs
[00241] Figure 10 is a11 exetnplary block diagram illustrating an inforli~atio~i
processing apparatus on whlch tlie etnbodi~ilents of the present invention can be
implemented.
[00242] Iu Figure 10, a Central Processing Unit (CPU) 1001 performs various
10 processes based on a program stored in a Read Only Memory (ROM) 1002 or a
program loaded from a storage sectioli 1008 to a Random Access Memory (RAM)
1003. In the RAM 1003, data for the CPU 1001 to perform the various processes or
the like is also stored as needed. Tlie CPU 1001, the ROM 1002, and the RAM 1003
are comlected to one another via a bus 1004. An inputloutpat iuterface 1005 is also
15 cont~ectedto the bus 1004.
1002431 To the inputloutput interface 1005 are connected: a11 input section 1006
(including a keyboard, a mouse, aid the like); an output section 1007 (including a
display sucli as a Cathode Ray Tube (CRT),a Liquid Crystal Display (LCD), and the
like, and a loudspeaker and the like); the storage section 1008 (including a hard disk
20 a11d the like); and a com~utu~icatiosnec tion 1009 (it~cludinga network interface card
such as a LAN card , a modem, at~dth e like). The colmnutiication section 1009
perfornis coininunicatiot~p rocesses via a network sncli as the Internet. A drive 1010
may also be connected to the input/output interface 1005 as needed. A removable
medium 1011, such as a magnetic disk, an optical disc, a magneto-optical disk, a
25 semiconductor memory and the like, may be loaded onto the drive 1010 as needed, so
that the computer program read therefrom can be installed into the storage sectioll
1008 as needed.
Sony Ref.: SP352212\0OO
Sony Cluna Ref.: CNPA12060\VOOO
Our Ref.: OP131147
-57- -
1002441 In tlie case diere tlie above-described series of processes is impleme~lted
with software, tlie program that constitutes the software can be installed fro111 a
network such as the Internet or a storage n~edi~suu~chl as the removable n~ediu~r~
5 [00245] Those skilled in the art would appreciate that, the storage medium is not
limited to the removable medilun 1011 as illustrated in Figure 10 which has the
prograln stored therein and is distributed separately fro~om the device for providing the
progranl to tlie user. Examples of the removable medium 1011 include a magnetic
disk (including a floppy disk (registered trademark)), an optical disc (including a
10 Co~npacDt isk-Read Only Mernory (CD-ROM) and a Digital Versatile Disk (DVD)),
a magneto-optical disk (including a Mini-Disk (MD) (registered trademark)), and a
se~nico~~ducttnoerm ory. Alternatively, the storage medium may be the ROM 1002,
the hard disk contained in the storage section 1008, or the like, which has tlie program
stored therein and is distributed to the user together with the device contai~iirlgit .
15 1002461 When read and executed by a machine, tlie it~struction codes execute the
method used in a wireless comtnunication system according to an embodiment of the
present invention.
1002471 Apparently, various modifications and alternatives can be made by those
skilled in the art without deviation from the scope and spirit of the present invention.
20 The embodime~~tasr e selected and described for illustrating the principle and tlie
practical application of the present invention it1 a best way, so that those skilled in the
art would appreciate that the present itlvention may adopt various impletnentations
with various modifications suitable for a particular application as desired.

CLAIMS
1. A device in a wireless comlnunication system, the device comprising:
a small cell denseness evaluation unit cotfigured to evaluate denseness of stnall
5 cells withitl a region in wllich a nlobile terminal locates; and
a mobility state estimation wit callfigured to determine a mobility state
estimation manlier according to the evaluated denseness of the snlall cells so as to
estimate mobility state of the mobile terminal.
10 2. The device according to claim 1, wherein the stnail cell denseness evaluation unit is
further configured to receive information of sniall cell clusters indicating wliich stnall
cells are adjacent to each other frotn a base station serving the mobile terminal and
evaluate the denseness of tlie stnall cells within the region in vhich the mobile
tenninal locates in accordance with tlie information of stnall cell clusters.
3. The device according to claim 2, wherein tbe information of small cell clusters is
indicated by information of snlall cell identifier indexes added in a list of adjacent
cells, the information of the stnall cell identifier indexes cornyrising infornlation of
small cell identifiers of adjacent sniall cells to indicate that these adjacent stnall cells
20 belotig to a satne cluster.
4. The device according to claim 1, wherein the stnall cell denseness evaluation wit is
ftrther configured to evaluate the denseness of the snlall cells within the region in
which the mobile ter~ninal locates according to a history that the mobile terminal
25 obtains services frotn the stnall cells.
Sally Ref.: SP352212WOOO
Solly Cluna Ref.: CNPA12060W000
Ot~r Ref.: OP131147
-59- ~~p
5. The device according to claim 4, wherein the small cell detlse~lesse valuation tunit is
configured to determine whether a type of a target cell from wbich the mobile
ternlitla1 obtains services is a small cell and cotult number of tiines that the target cell
from which the mobile terminal obtains se~vices is the small cell within a
5 predetermined time, and to evaluate the denseness of the sillall cells within the region
in which the mobile terminal locates by conlpari~~tgh e number of times with a
predetermined threshold of number of times.
6. The device according to claitn 4, wherein the small cell denseness evaluation unit is
10 configured to determine wllether a type of a target cell from which the mobile
terminal obtains services is a small cell and determine distances between the small
cells fro111 which the mobile terillinal obtains services according to position
itlfornlation of the small cells from which the mobile terminal obtain services, and to
evaluate the de~~sellesosf the small cells within the region in wllich the nlobile
15 terminal locates by comparing the distances with a predetennined distance threshold.
7. The device accor&ng to claim 6, wherein the predetermined distance threshold is
determined according to coverage of the small cells from wllich the lnobile temlinal
obtains services.
8. The device according to any of claitns 4-7, wherein the small cell det~se~less
evaluatioll unit is further configured to determine a type ruld/or coverage of a target
cell from which the mobile terminal obtain services according to a translnission power
of the target cell.
9. The device according to any of claims 4-7, wherein the small cell denseness
evaluation unit is further configured to receive infannation of cell type indicating a
Sony Ref.: SP352212IVO00
Sony Cluna Ref.: CNPA12060WO00
Our Ref.: OP1311.17
- 60:
cell type from a base station serving the n~obilete rnunal and to determine type of a
target cell from which the mobile terminal obtain services according to the
information of cell type.
5 10. The device according to claim 1, wherein if the evaluated denseness of the small
cells is low, the mobility state estimation unit is further configured to co~ult only
number of times that the mobile tenninal switches or reselects atnong macro cells and
estimate the mobility state of the lnobile terminal according to the number of times
that the mobile terminal switches or reselects atnong the macro cells.
11. The device according to claim 1, wherein if the evaluated denseness of the small
cells is high, the mobility state estimation unit is further configured to estimate a
rnovement distance of the rnobile terminal according to position information of the
small cells from which the mobile terminal obtains services and to estimate the
15 mobility state of the tnobile terminal according to the movement distance of the
tnobile terminal.
12. The device according to claim 1, wherein the mobility state estimation wit is
further configured to count nun~ber of times that the mobile terminal switches or
20 reselects atnong macro cells atd number of times that the tnobile telmninal obtains
services from the small cells respectively, a ~ tdo e stimate the mobility state of the
mobile tertninal according to a weighted sun1 of the number of times that the tnobile
terminal switches or reselects among the macro cells and the number of times that the
mobile ternlinal obtains services fi0111 the small cells, wherein cell weight factors of
25 the small cells and the macro cells are adjusted adaptively according to the evaluated
denseness of the small cells to calculate the weighted SIIIII.
Sony Ref.: SP3522 12\V000
Soriy Cl~i~tRae f.: CNPA12060\V000
Oor Ref.: OP1311.17
-61 -
13. The device according to clam 1, wherein the mobility state estimation tulit is
furrther configured to accutnulate number of tinles that the mobile ternunal obtains
services fro111 the stnall cells in a unit of a predeterniued area, and to determine that
the mobile terminal is able to obtain services from the sn~all cells within the
5 predeternuned area if a result of the accumulating is larger than a predetermined coutlt
threshold.
14. The device according to any of claitns 4, 5, 6, 11 and 13, wherein the mobile
terminal is able to obtain services frotn the snlall cells in at least one manner of
10 switching or reselecting to the small cells, and carrier aggregation, double-connection
and coordinated multiple point transnlission throngl~th e small cells.
15. The device according to claim 1, further comprising: a tnobility managemeut unit
configured to control cell reselection for the tnobile terminal in a free state according
15 to the evaluated deuseness of the small cells and/or to control cell switchitlg for the
mobile tenninal in a connected state according to the estimated result of the mobility
state.
16. The device according to claitn 15, wherein the mobility nlanagetnent unit is
20 further configured to prevent the mobile terminal in the free state from performing
cell search and/or cell measurement for the stnall cells in a case that the evaluated
denseness of the small cells is high, and to allow the tnobile terminal in the free state
to perfonn the cell search and/or the cell measurement for the small cells in a case that
the evaluated denseness of the stnall cells is low.
17. The device according to claitn 15, wherein if the evaluated denseness of the small
cells is high, the tnobility tnanagelneut unit is further co~lfiguredto allow the mobile
S O IR~ef .: SP352212\VO00
Solip Clutia Rcf.: CNPA12060W000
Our Ref.: OP1311.17
- 62 -
terminal it1 the free state to perfor111 cell search midor cell measureme~it for the small
cells if service quality of macro cells is lower that1 a first predeternliued threshold or a
difference between service quality of the stnall cells and the service quality of the
niacro cells is larger than a second predetermined threshold
18. The device according to claim 15, further comprising: a business type divisioli
unit configured to divide businesses at the mnobile tertninal into different business
types according to time delay sensitivity of the businesses at the tnobile terminal,
wherein the niobility management unit is further configured to filter switchable
10 target cells for the mobile terminal in the connected state according to the estiniated
result of the niobility state of the mobile terminal and the business type and to perfom1
cell measurement at~domr easurement report for the filtered target cells to perform
cell switching for the mobile tertninal.
15 19. A tnethod in a wireless communication system, the method comprisit~g:
a sn~all cell denseness evaluation step of evaluating denseness of small cells
within a region in which a mobile tertninal locates; and
a mobility state estimation step of determining a mobility state estimation matuler
according to the evaluated denseness of the small cells so as to estimate mobility state
20 of the mobile terminal.
20. The method according to claim 19, wherein in the small cell denseness evaluation
step, the denseness of the small cells within the region it1 which the tnobile ternlinal
locates is evaluated according to a history that the mobile tenninal obtains services
25 from the small cells.
Souy Re[.: SP352212WOOO
Sony Clu~~Rae f.: CNPA120GOW000
Our Ref.: OP131147
- 63 - ~p
21. Tlle method according to clai~n2 0, wherein in the small cell denseness evaluation
step, wliether a type of a target cell from which the mobile tellnilla1 obtains services is
a stnall cell is determined and number of titnes that the target cell from which the
mobile terminal obtains services is the sniall cell within a predeter~nined time is
5 counted, and the denseness of the sn~allc ells within the region in which the mobile
tenninal locates is evaluated by cotnparing the number of times with a predetermined
threshold of number of times.
22. The method according to claim 20, wherein in the small cell denseness evaluation
10 step, whether a type of a target cell from which the mobile terniinal obtains services is
a small cell is determined and distances between the stnall cells from which the
mobile terminal obtains services are determined according to position information of
the small cells from which the mobile ter~ninal obtain services, and the denseness of
the small cells within the region in which the mobile terminal locates is evaluated by
15 comparing the distances with a predetermined distance threshold.
23. The method according to claim 19, wherein in the mobility state estimation step, if
the evaluated denseness of the small cells is low, only number of times that the n~obile
ter~ninals witches or reselects among macro cells is counted and the mobility state of
20 the mobile terminal is estimated according to the number of times that the mobile
terminal switcl~eos r reselects among the macro cells.
24. The n~etl~oacdc ording to claim 19, wherein in the tnobility state estitnation step, if
the evaluated denseness of the sniall cells is high, a movement distance of the mobile
25 terminal is estimated according to position infortnation of the small cells from which
the rnobile terminal obtains services and the mobility state of the mobile terminal is
estimated according to the tnovernent distance of the mobile terminal.
Son)' Ref.: SP352212\V000
Son)' Chit18 Ref.: CNPA12060FV000
Our Ref.: OP1311.17
-64-
25. The method accorditig to claim 19, further cotnprising: a mobility management
step of controlling cell reselection for the mobile ter~ilinal in a free state according to
the evaluated denseness of the small cells andfor controlling cell switching for the
5 rllobile terliiinal in a co~ltlecteds tate according to the estimated result of the mobility
state.
26. A device in a wireless communication system, the device comprising:
a small cell divisiot~u nit configured to divide small cells adjacent to each other
10 into small cell clusters and form information of small cell clusters indicating which
small cells are adjacent to each other; and
a sending utiit configwed to send the infortnatiot~ of small cell clusters to a
mobile terminal, wherein the information of small cell clusters is used by the mobile
terminal to evaluate denseness of small cells within a region it1 which the mobile
15 terminal locates.
27. The device according to claim 26, wherein the information of small cell clusters is
indicated by inforniation of small cell identifier indexes added it1 a list of adjacent
cells, the information of sillall cell identifier indexes comprising information of sniall
20 cell identifiers of adjacent small cells to indicate that these adjacent small cells belong
to a same cluster.
28. The device according to claitn 26, wherein the sending unit is further configured
to send positiotl information of the stliall cells and/or parameter itiformation related to
25 coverage of the small cells to the mobile terminal.
So~i)' Ref.: SP352212W000
So~v Clli~ia Ref.: CNPA12060\V000
Our Ref.: OP131147
- 65 -
29. A method in a wireless communication system, the nletliod cotnprising:
a small cell division step of dividing small cells adjacent to each other into small
cell clusters and forlllitlg infonnation of small cell clusters indicating which small
cells are adjacent to each other; and
5 a sending step of sending the infonnation of srnall cell clusters to a mobile
terniinal, wherein the inforniation of stllall cell clusters is used by the mobile terniinal
to evaluate denseness of sn~all cells within a region in which the mobile terminal locates.