DESCRIPTION
Title of Invention
COMMUNICATION SYSTEM FOR ALLEVIATING INTERFERENCE
ARISING DUE TO COEXISTENCE
Technical Field
The present invention relates to radio access networks in a cellular or wireless
telecommunication network, and particularly but not exclusively to networks operating
according to the 3GPP standards or equivalents or derivatives thereof. The invention has
particular although not exclusive relevance to the Long Term Evolution (LTE) of UTRAN
(called Evolved Universal Terrestrial Radio Access Network (E-UTRAN)) and to operation of
dual mode base stations operating in accordance with both LTE and non-LTE radio technologies.
Background Art
In a cellular communication network, mobile devices (also known as User Equipment
(UE) or mobile terminals, such as mobile telephones) communicate with remote servers or with
other mobile devices via base stations. An LTE base station is also known as an 'enhanced
NodeB' (eNB), which is coupled to an LTE core network also known as an Enhanced Packet
Core (EPC) network.
In their communication with each other, LTE mobile devices and base stations use
licensed radio frequencies, which are typically divided into frequency bands and/or time blocks.
Depending on various criteria (such as the amount of data to be transmitted, radio technologies
supported by the mobile device, expected quality of service, subscription settings, etc.), each
base station is responsible for controlling the transmission timings, frequencies, transmission
powers, modulations, etc. employed by the mobile devices attached to the base station. In order
to minimise disruption to the service and to maximise utilisation of the available bandwidth, the
base stations continuously adjust their own transmission power and also that of the mobile
devices. Base stations also assign frequency bands and/or time slots to mobile devices, and also
select and enforce the appropriate transmission technology to be used between the base stations
and the attached mobile devices. By doing so, base stations also reduce or eliminate any
harmful interference caused by mobile devices to each other or to the base stations.
Current mobile devices typically support multiple radio technologies, not only LTE.
The mobile devices might include, for example, transceivers and/or receivers operating in the
Industrial, Scientific and Medical (ISM) radio bands, such as Bluetooth or Wi-Fi transceivers.
The term 'Bluetooth' refers to the standards developed by the Bluetooth Special Interest Group,
and the term 'Wi-Fi' refers to the 802.1 1 family of standards developed by the Institute of
Electrical and Electronics Engineers (IEEE). If such a non-LTE communication technology is
supported, instead of communicating via LTE base stations, mobile devices may also
communicate with remote servers or with other mobile devices using non-LTE communication
means, e.g. using an appropriate ISM communication technology. For example, the mobile
devices may communicate via an access point (e.g. a Wi-Fi AP) operating in accordance with the
802.1 1 family of standards by the Institute of Electrical and Electronics Engineers (IEEE).
Recently, a so-called 'dual mode' base station has been introduced comprising an LTE
home base station (HeNB) part (e.g. a pico/femto base station or other low-power node) and a
non-LTE access point part (e.g. a Wi-Fi AP). Such a combined HeNB/AP base station may
also sometimes be referred to as a dual mode femto access point (FAP) or dual FAP.
ISM and other radio technologies (hereafter commonly referred to as non-LTE
technologies) use frequency bands close to or partially overlapping with the LTE frequency
bands, as illustrated in Figure 12. Some of these non-LTE frequency bands are licensed for a
particular use (e.g. Global Positioning Systems (GPS) bands) or might be unlicensed bands and
can be used by a number of radio technologies (such as Bluetooth and Wi-Fi standards using the
same range of ISM frequency bands). The manner in which these non-LTE frequency bands
_are used are, therefore, not covered by the LTE standards and are not controlled by the LTE base
stations (e.g. a HeNB of a dual FAP). However, transmissions in the non-LTE frequency bands
might, nevertheless, still cause undesired interference to (or suffer undesired interference
resulting from) transmissions in the LTE bands, particularly in the overlapping or neighbouring
frequency bands.
In particular, such undesired interference may be experienced between LTE and non-
LTE (ISM) radio communications in at least the following scenarios:
LTE Band 40/41 radio transmitter causing interference to ISM radio receiver;
■ ISM radio transmitter causing interference to LTE Band 40/41 radio receiver;
■ LTE Band 7 radio transmitter causing interference to ISM radio receiver;
■ ISM radio transmitter causing interference to LTE Band 7 radio receiver; and
■ LTE Band 7/13/14 radio transmitter causing interference to GPS radio receiver.
When such undesired interference arises as a result of communication occurring
concurrently in the same mobile device or in the same base station (for example, as a result of
concurrent use of LTE and non-LTE radio technologies) the interference is sometimes referred to
as 'in-device coexistence (IDC) interference' which causes an 'in-device coexistence (IDC)
situation'.
In order to be able to alleviate the problems due to IDC interference, the mobile device
may be configured to attempt to address such IDC problems on its own and, if the mobile device
cannot solve the problem on its own, with the assistance of its serving base station. For
example, an IDC problem may be addressed by the base station selecting a different frequency
(FDM solution) for the mobile device, by reconfiguring its transmissions (e.g. apply
discontinuous reception (DRX) and/or change its subframe pattern) (TDM solution), and/or by
adjusting the base station's (and/or the mobile device's) transmission power (Power Control
solution).
The inventors have realised that difficulties may arise in simultaneously operating both
the LTE and non-LTE parts of such dual FAPs due to the potentially severe interference
experienced in some of the (neighbouring or overlapping) frequency bands used by both the LTE
and the non-LTE communication technologies.
Such difficulties are particularly likely to occur with respect to dual FAPs implementing
both an LTE base station and a non-LTE access point as part of the same network node. In this
case, the above (FDM/TDM/Power Control) solutions are not always applicable because any
change in the operation of the LTE base station (of the dual FAP) may still cause (or continue to
cause) unexpected interference for communications using the access point part of the dual FAP.
The inventors have also realised that whilst it is possible to co-ordinate some of the
operations of LTE base stations and other base stations operating in accordance with an earlier
standard from which LTE has been derived, e.g. due to the inherent backward compatibility
between such related standards, it is particularly difficult to ensure optimal communication
characteristics (e.g. signal quality, error rate, interference level) for dual FAPs implementing
both an LTE base station and a non-LTE access point because of the differences between the
operation of the LTE and the non-LTE parts.
Summary of Invention
There is therefore a need to improve the operation of the mobile device and the dual
FAP in order to overcome or at least alleviate the above problems. Exemplary embodiments of
the present invention aim to provide improved techniques for alleviating interference (hence
improving data throughput) in a communication network and, in particular, for alleviating radio
interference caused to, or by, transmissions via a dual FAP (and/or the like).
In one aspect, the invention provides a communication apparatus comprising: a base
station module for providing wireless connectivity in a communication network, using a first
communication protocol, to at least one mobile communication device; an access point module
for providing wireless connectivity in a communication network, using a second communication
protocol, to the at least one mobile communication device; and an interface for coupling the base
station module and the access point module, wherein said interface is configured for
communication between said base station module and said access point module; wherein said
base station module and said access point module are configured for co-operation with one
another by communicating via said interface, and wherein at least one of said base station
module and said access point module is configured to perform at least one operation to alleviate
interference arising due to coexistence, in said communication apparatus, of said base station
module and said access point module, as part of said co-operation.
In one aspect, the invention provides a method performed by a communication
apparatus comprising: i) a base station module for providing wireless connectivity, using a first
communication protocol, in a communication network to at least one mobile communication
device; ii) an access point module for providing wireless connectivity, using a second
communication protocol, in a communication network to the at least one mobile communication
device; and iii) an interface for coupling the base station module and the access point module,
wherein said interface is configured for communication between said base station module and
said access point module; the method comprising: the base station module and the access point
module co-operating with one another by communicating via said interface, and at least one of
said base station module and said access point module performing at least one operation to
alleviate interference arising due to the coexistence, in said communication apparatus, of said
base station module and said access point module, as part of said co-operating.
In one aspect, the invention provides a system for use in a telecommunication network,
comprising one or more mobile communication devices and the above described communication
apparatus.
Aspects of the invention extend to computer program products such as computer
readable storage media having instructions stored thereon which are operable to program a
programmable processor to carry out a method as described in the aspects and possibilities set
out above or recited in the claims and/or to program a suitably adapted computer to provide the
apparatus recited in any of the claims.
Brief Description of Drawings
Exemplary embodiments of the invention will now be described, by way of example,
with reference to the accompanying drawings in which:
Figure 1 schematically illustrates a mobile telecommunication system of a type to which
the invention is applicable;
Figure 2 schematically illustrates the relationship between some of the entities forming
part of the mobile telecommunication system of Figure 1;
Figure 3 schematically illustrates various radio transceiver circuits implemented on a
mobile device of the mobile telecommunication system shown in Figure ;
Figure 4 schematically illustrates various radio transceiver circuits implemented on the
base station of the mobile telecommunication system shown in Figure 1;
Figure 5 is a block diagram of a mobile device forming part of the mobile
telecommunication system shown in Figure 1;
Figure 6 is a block diagram of the home base station forming part of the mobile
telecommunication system shown in Figure 1;
Figure 7 is a block diagram of the access point forming part of the mobile
telecommunication system shown in Figure 1;
Figures 8a to 1 are exemplary timing diagrams illustrating various methods performed
by the nodes forming part of the mobile telecommunication system shown in Figure 1; and
Figure 2 illustrates some of the frequency bands and channels that may be affected by
interference arising from the coexistence of LTE and non-LTE technologies in the same base
station.
Description of Embodiments
Overview
Figure 1 schematically illustrates a mobile (cellular) telecommunication system 1 in
which users of mobile devices 3 (for example mobile telephones 3-1 to 3-3) can communicate
with other users via one or more base stations 5 and a core network 7. In the system illustrated
in Figure 1, the base station 5 is a dual mode base station (dual FAP) which comprises an LTE
home base station (HeNB) part 5-1 (e.g. a pico/femto base station or other low-power node) and
a non-LTE access point (AP) part 5-2 (e.g. a Wi-Fi AP). In this example, the HeNB part 5-1
and the AP part 5-2 are co-located (and hence they share at least some hardware and/or software
components), although the HeNB part 5-1 and the AP part 5-2 may also be implemented as two
physically separate units. An appropriate dedicated interface (e.g. an internal interface or an
external one) is provided for communications between the HeNB part 5-1 and the AP part 5-2.
Further details about the relationship (and communication links provided) between the HeNB
part 5-1 and the AP part 5-2 and various associated network nodes are illustrated in Figure 2.
Both the HeNB part 5-1 and the AP part 5-2 operate at least one cell (not shown), each
cell having a number of uplink (UL) and downlink (DL) communication resources (channels,
sub-carriers, time slots, etc.) that are available for wireless communications between the mobile
devices 3 and the dual FAP 5 (i.e. the HeNB part 5-1 and/or the AP part 5-2). In this example,
the Radio Access Technologies (RATs) employed by the dual FAP 5 operate according to either
Frequency Division Duplexing (FDD) or Time Division Duplexing (TDD). In TDD, the time
domain of a communication channel is divided into several recurrent time slots of fixed length in
which communication to/from the dual FAP 5 can be scheduled. In operation in TDD, two or
more data streams may be transferred between the dual FAP 5 (e.g. HeNB part 5-1) and the
mobile device(s) 3, apparently simultaneously, in sub-channels of one communication channel,
by scheduling each data stream in different time slots of the channel (effectively 'taking turns').
In FDD, the bandwidth available to the base station is divided into a series of non-overlapping
frequency sub-bands each comprising frequency resources that may be assigned to mobile
device(s) 3 for communication via the dual FAP 5.
In this example, the first mobile device 3-1 is connected to both the HeNB part 5-1 and
the AP part 5-2, whilst the second mobile device 3-2 is connected to the HeNB part 5-1 only, and
the third mobile device 3-3 is connected to the AP part 5-2 only. Whilst this particular
arrangement is shown in Figure 1 for purely illustrative purposes, it will be appreciated that
compatible mobile devices 3 may connect to either one or both of the HeNB part 5-1 and the AP
part 5-2 (and/or to any further base station) depending on their capabilities, applicable
configurations, and/or network conditions that are outside the scope of the present invention.
As can be seen, at least the mobile devices 3-1 and 3-3 are capable of communicating
using non-LTE radio technologies such as those which use resources of the Industrial, Scientific
and Medical (ISM) frequency bands. In this example, the mobile devices 3-1 and 3-3 can
communicate with the AP part 5-2 of the dial FAP 5 operating according to one of the 802. 11
family of standards (Wi-Fi) defined by the Institute of Electrical and Electronics Engineers
(IEEE). Although not shown in Figure 1, each of the mobile devices 3 may also be able to
communicate with other non-LTE transceivers, e.g. with a wireless headset operating according
to the Bluetooth standard defined by the Bluetooth Special Interest Group (SIG) and/or support
positioning technologies and thus communicate with, for example, a positioning satellite using
GPS signals.
Communications between the mobile device(s) 3 and the AP part 5-2 (and possibly
between the mobile devices 3 and other non-LTE transceivers) might occur substantially
concurrently with the communications between the mobile device(s) 3 and the HeNB part 5-1,
which concurrent communications have the potential to cause undesirable interference (i.e. IDC
interference).
The issue of IDC interference is illustrated further in Figure 3 which schematically
illustrates, purely illustratively, the various radio transceiver circuits implemented on a mobile
device 3 shown in Figure 1. Further, Figure 4 schematically illustrates, purely illustratively, the
various radio transceiver circuits implemented on the dual FAP 5 shown in Figure 1.
As shown in Figure 3, the mobile device (e.g. mobile device 3-1) comprises an LTE
baseband circuit 30a, a GPS baseband circuit 30b, and an ISM baseband circuit 30c. Each
baseband circuit 30a to 30c is coupled to a radio frequency (RF) transceiver (or receiver), i.e.
LTE RF transceiver 31a, GPS RF transceiver 3lb, and ISM RF transceiver 31c, respectively.
Communications in the LTE band are carried out using an LTE antenna 33a. Similarly,
communications in the non-LTE bands are carried out using the respective GPS antenna 33b
and/or the ISM antenna 33c.
As indicated by dashed arrows in Figure 3, any of the transceivers 31a to 31c might
suffer interference from either one of the other transceivers operating in the same mobile device
3. Similarly, as indicated by dashed arrow in Figure 4, the transceivers 51-1 and 51-2 of the
base station 5 might also suffer interference from each other (and/or from the transceivers 31a to
3l c of the mobile device 3).
Returning to Figure 1, the dual FAP 5 is beneficially configured to alleviate any such
in-device coexistence (IDC) interference. Specifically, the HeNB part 5-1 and the AP part 5-2
are configured to co-ordinate their operations, e.g. by exchanging information using the
dedicated interface 100 provided therebetween (e.g. an interface provided directly between the
HeNB part 5-1 and the AP part 5-2 and/or using an external connection, such as a connection
provided via one or more gateways and/or the core network 7).
In particular, the HeNB part 5-1 and the AP part 5-2 are configured to interact with each
other for the alleviation of an (ongoing/potential) IDC interference by exchanging information
relating to one or more of the following functionalities:
interference management;
power control;
- carrier frequency re-selection;
energy saving;
radio transmission state (e.g. on/off); and
load balancing.
For example, by exchanging some of the above information, the dual FAP 5 is
beneficially able to alleviate an IDC interference in LTE Band 40 (which may be caused by
transmissions, in the lower portion of the ISM band, to LTE Band 40, or vice versa). In this
case, one or more of the following solutions may be applied by the dual FAP 5:
i) the HeNB part 5-1 may request the AP part 5-2 not to use one or more channels
close to the lower portion of the ISM band (e.g. ISM Channels 1 to 3), i.e. to
select other channels if possible;
ii) the HeNB part 5-1 may restrict (avoid) scheduling the PRBs in the higher
portion of LTE Band 40 in both uplink and downlink (i.e. in a region close to
ISM Channel 1) when the coexisting Wi-Fi devices, such as the AP part 5-2
and a Wi-Fi capable mobile device 3, use one or more ISM channels close to
LTE Band 40; and
iii) the HeNB part 5-1 may impose power restrictions (for LTE communications)
while scheduling the PRBs in the higher portion of LTE Band 40 in both uplink
and downlink (i.e. in a region close to ISM Channel 1) if it is found necessary
to use these PRBs (e.g. if solution ii) is not or cannot be employed).
Similarly to the above, the dual FAP 5 is also beneficially able to alleviate an IDC
interference in LTE Band 7 (which may be caused by transmissions, in ISM Channel 14, to LTE
Band 7, or vice versa, since there is only a 5 MHz separation between the uplink portion of LTE
Band 7 and Wi-Fi Channel 14, and almost half of Wi-Fi Channel 14 lies within the LTE guard
band). In this case, one or more of the following possible solutions may be applied by the dual
FAP 5:
iv) the HeNB part 5-1 may request the AP part 5-2 not to use one or more channels
close to the higher portion of the ISM band (e.g. ISM Channels 12 to 14), i.e.
to select other channels if possible;
v) the HeNB part 5-1 may restrict (avoid) scheduling the PRBs in the lower
portion of LTE Band 7 in uplink (i.e. in a region close to ISM Channel 14)
when the coexisting Wi-Fi devices (such as the AP part 5-2 and a Wi-Fi
capable mobile device 3) are using one or more channels close to LTE Band 7;
and
vi) the HeNB part 5-1 may obtain timing information from the AP part 5-2, using
which information the HeNB part 5-1 may be arranged to avoid scheduling any
uplink (LTE) communications (at least in LTE Band 7) at least for the duration
of any ISM transmission by the AP part 5-2 (or the mobile devices 3) in Wi-Fi
Channel 14.
It will be appreciated that solutions iv) to vi) may also be applied to LTE Band 4 1
instead of (or in addition to) LTE Band 7.
Furthermore, the HeNB part 5-1 may be configured to adjust its maximum transmission
power on the downlink (and/or to adjust the maximum transmission power allowed for the
mobile device 3 on the uplink) in accordance with information relating to the operation of the AP
part 5-2 (e.g. channels used, transmit powers, etc.), and thereby alleviate any interference caused
by the LTE transmissions of the HeNB part 5-1 to the AP part 5-2. Similarly, the AP part 5-2
may be advantageously configured to obtain information from the HeNB part 5-1 relating to the
currently used/permitted power (e.g. maximum or average power) by the HeNB part 5-1 for its
downlink and uplink communications with the mobile devices 3, and to adjust its own
transmissions accordingly.
The HeNB part 5-1 may also be configured to alleviate any interference caused by the
LTE transmissions of the HeNB part 5-1 to the AP part 5-2 by initiating carrier frequency reselection
procedures with respect to the mobile devices 3 for which LTE communications are
scheduled in LTE Bands prone to causing interference to (or experiencing interference from) the
ISM communications. For example, the HeNB part 5-1 may be configured to determine, based
on information relating to the operation of the AP part 5-2 (e.g. the ISM channels and/or the
associated transmission power being used), which carrier frequency needs to be re-selected (e.g.
instead of an interfering or potentially interfering carrier frequency currently used).
Moreover, the HeNB part 5-1 and the AP part 5-2 may also be configured to inform
each other when their transceivers are entering and/or exiting a low-power operating mode (e.g.
an energy saving mode) during which transmissions over one or more (e.g. all) frequency bands
are suspended. Using the exchanged information relating to the current power state of the
HeNB part 5-1 and/or the AP part 5-2, the dual FAP 5 is beneficially able to alleviate a potential
interference by restricting/allowing the use of certain frequency bands/channels in dependence
on the current operating mode of the HeNB part 5-1 and/or the AP part 5-2. For example, the
AP part 5-2 may restrict usage of certain ISM channels whilst the HeNB part 5-1 is operating at
normal power (i.e. whilst the HeNB part is not in a power saving mode) and allow usage of such
ISM channels whilst the HeNB part 5-1 is operating in a power saving mode (and this has been
informed by the HeNB part 5-1).
The HeNB part 5-1 and the AP part 5-2 may also be configured to perform load
balancing (e.g. by steering traffic between the HeNB part 5-1 and the AP part 5-2) based on the
information exchanged between them. In this case, the exchanged information may relate to
the number of mobile devices 3 served by the HeNB part 5-1 and the AP part 5-2, respectively
and/or the associated load (or remaining capacity) thereof.
In summary, any of the above approaches may beneficially contribute to the alleviation
(e.g. reduction, prevention) of interference arising due to the co-location of the HeNB part 5-1
and the AP part 5-2 in the dual FAP 5 (and/or the like). This in turn may increase the overall
data throughput that can be achieved by the dual FAP 5 compared to other dual mode base
stations that do not support the above features.
Mobile device
Figure 5 is a block diagram of a mobile device 3 forming part of the mobile
telecommunication system 1 shown in Figure . As shown, the mobile device 3 includes
transceiver circuits 3l a to 3l c which are operable to transmit signals to and to receive signals
from the base station 5 via one or more antennas 33a to 33c. Although not necessarily shown in
Figure 5, the mobile device 3 may of course have all the usual functionality of a conventional
mobile telephone (such as a user interface 35) and this may be provided by any one or any
combination of hardware, software and firmware, as appropriate. The mobile device 3 has a
controller 37 to control the operation of the mobile device 3. The controller 37 is associated
with a memory 39 and is coupled to the transceiver circuits 3l a to 3lc. The controller 37
controls the operation of the transceiver circuits 3l a to 3l c in accordance with software and data
stored in memory 39.
Software may be pre-installed in the memory 39 and/or may be downloaded via the
telecommunications network or from a removable data storage device (R D), for example.
The software includes, among other things, an operating system 41, an LTE module 43, an ISM
module 45, a GPS module 47 (optional), a measurement and reporting module 48, and a traffic
steering module 49.
The LTE module 43 controls the communications of the mobile device 3 using the LTE
radio technologies. The LTE module 43 receives instructions from the base station 5 (via the
LTE transceiver circuit 31a and the LTE antenna 33a) and stores them in the memory 39.
Based on the received instructions, the LTE module 43 is operable to select the appropriate
frequency band, transmission power, modulation mode etc. used in the LTE communications.
The LTE module 43 is also operable to update the base station 5 about the amount and type of
uplink and/or downlink data scheduled for transmission in order to assist the base station 5 in
allocating resources among the mobile devices it is serving.
The ISM module 45 controls the ISM (e.g. IEEE 802.1 1) communications of the mobile
device 3. In doing so, the ISM module 45 might, for example, use data received from the
access point part 5-2 and/or communicate with a wireless headset and/or the like.
If present, the GPS module 47 is operable to obtain a current geographic location of the
mobile device 3 and to control the GPS communications of the mobile device 3. In doing so,
the GPS module 47 might, for example, use data received from a positioning satellite.
The measurement and reporting module 48 is responsible for performing signal
measurements (including interference measurements) and to generate and send (via the LTE
transceiver 31a) a measurement report to the HeNB part 5- 1. In order to do so, the
measurement and reporting module 48 is operable to obtain a measurement configuration from
the HeNB part 5-1 . The measurement and reporting module 48 may also be operable to
indicate the occurrence of in-device interference by sending an associated IDC indication to the
HeNB part 5-1 via the LTE transceiver 31a. In this embodiment the measurement and
reporting module 48 and the HeNB part 5-1 communicates using one or more dedicated radio
resource control (RRC) message although any appropriate signalling may be used.
The traffic steering module 49 is responsible for steering traffic between the HeNB part
5-1 and the AP part 5-2, as instructed by the dual FAP 5. In order to do so, the traffic steering
module 49 is operable to receive and process a steering command from the HeNB part 5-1.
Such steering command may be received, for example, subsequent to (e.g. in response to) the
measurement and reporting module 48 sending a measurement report to the HeNB part 5-1.
LTE Base Station
Figure 6 is a block diagram of the HeNB part 5-1 of the dual FAP 5 forming part of the
mobile telecommunication system 1 shown in Figure 1. As shown, the HeNB part 5-1 includes
a transceiver circuit 51-1 which is operable to transmit signals to and to receive signals from the
mobile devices 3 via one or more antennas 53-1 and to transmit signals to and receive signals
from the core network 7 and other base stations via the network interface 55 (which may be a
copper or optical fibre interface). A controller 57 controls the operation of the transceiver
circuit 51-1 in accordance with software and data stored in memory 59. The software includes,
among other things, an operating system 61, an LTE communication control module 63, a radio
resource control (RRC) module 65, and an ISM interface module 67 (which includes a load
balancing module 70, a channel control module 71, and a power control module 72).
The communication control module 63 controls communications between the HeNB
part 5-1 (i.e. the LTE base station part of the dual FAP 5) and external devices (such as the
mobile devices 3) via the transceiver circuit 51-1 and the one or more antenna 53-1 . The
communication control module 63 also controls communications between the HeNB part 5-1 and
core network nodes (such as the MME 12, the S-GW 14, and/or the P-GW 16) via the transceiver
circuit 51-1 and the network interface 55 (which may comprise e.g. an SI interface).
The RRC module 65 manages (generates, sends, and receives) messages formatted in
accordance with the RRC protocol. For example, the RRC module 65 is operable to
communicate RRC messages with the mobile devices 3 (e.g. RRC messages relating to signal
measurements).
The ISM interface module 67 controls communication with the AP part 5-2 (with the
corresponding LTE interface module 69 thereof) over the dedicated interface 100 provided
between the HeNB part 5-1 and the AP part 5-2. For example, the ISM interface module 67 is
operable to exchange information with the AP part 5-2 in order to assist the alleviation of
interference resulting from the simultaneous use of both the LTE and the non-LTE (ISM)
communication technologies. Specifically, the ISM interface module 67 includes the load
balancing module 70, which is responsible for performing load balancing based in information
exchanged with the AP part 5-2. The ISM interface module 67 also includes the channel
control module 71, which is responsible for performing channel control based in information
exchanged with the AP part 5-2. In this example, the ISM interface module 67 further includes
the power control module 72, which is responsible for performing power control (based in
information exchanged with the AP part 5-2). It will be appreciated that the ISM interface
module 67 may include a number of additional modules and/or that any of the modules 70 to 72
(and/or any such additional modules) may be combined, if appropriate.
Access Point
Figure 7 is a block diagram of the access point part 5-2 of the dual FAP 5 forming part
of the mobile telecommunication system 1 shown in Figure 1. As shown, the access point part
5-2 includes a transceiver circuit 51-2 which is operable to transmit signals to and to receive
signals from the mobile devices 3 via one or more antennas 53-2 and to transmit signals to and
receive signals from the core network 7 and other base stations 5 via the network interface 55
(which may be a copper or optical fibre interface). A controller 57 controls the operation of the
transceiver circuit 51-2 in accordance with software and data stored in memory 59. The
software includes, among other things, an operating system 61, a non-LTE (e.g. ISM)
communication control module 64, and an LTE interface module 69 (which includes a load
balancing module 70, a channel control module 71, and a power control module 72)
The communication control module 64 controls communications between the access
point part 5-2 and external devices (such as the mobile devices 3) via the transceiver circuit 51-2
and the one or more antenna 53-2. The communication control module 64 also controls
communications between the AP part 5-2 and other network nodes (either directly or via one or
more gateways) via the transceiver circuit 51-2 and the network interface 55.
The LTE interface module 69 controls communication with the HeNB part 5-1 (with the
corresponding ISM interface module 67 thereof) over the dedicated interface 100 provided
between the HeNB part 5-1 and the AP part 5-2. For example, the LTE interface module 69 is
operable to exchange information with the HeNB part 5-1 in order to assist the alleviation of
interference resulting from the simultaneous use of both the LTE and the non-LTE (ISM)
communication technologies. Specifically, the LTE interface module 69 includes the load
balancing module 70, which is responsible for performing load balancing based in information
exchanged with the HeNB part 5-1 . The LTE interface module 69 also includes the channel
control module 71, which is responsible for performing channel control based in information
exchanged with the HeNB part 5-1. In this example, the LTE interface module 69 further
includes the power control module 72, which is responsible for performing power control (based
in information exchanged with the HeNB part 5-1). It will be appreciated that the LTE
interface module 69 may include a number of additional modules and/or that any of the modules
70 to 72 (and/or any such additional modules) may be combined, if appropriate.
In the above description, the mobile device 3, the home base station 5-1, and the access
point part 5-2 are described for ease of understanding as having a number of discrete modules
(such as the communication control modules and the LTE/ISM interface modules). Whilst
these modules may be provided in this way for certain applications, for example where an
existing system has been modified to implement the invention, in other applications, for example
in systems designed with the inventive features in mind from the outset, these modules may be
built into the overall operating system or code and so these modules may not be discernible as
discrete entities.
Operation
Examples of methods used for alleviating interference, between the home base station
5-1 and the access point part 5-2 of a dual FAP 5, will now be described. Although for
efficiency of understanding for those skilled in the art, the invention will be described in detail in
the context of a home base station (HeNB part) and an access point part of a dual FAP, the
principles described herein can be applied to a 'multimode' FAP comprising more than one
(home) base station and/or more than one access point part (which may each operate according
to different standards) with the corresponding elements of the system changed as required.
First embodiment
Figure 8a shows an exemplary timing diagram illustrating a method performed by the
HeNB part 5-1 and the AP part 5-2 of the mobile telecommunication system 1 shown in Figure
1. In this example, the HeNB part 5- 1 and the AP part 5-2 are configured to apply channel
restriction, e.g. in order to alleviate (on-going or potential) interference resulting from the
simultaneous use of both the LTE and the non-LTE (ISM) communication technologies.
As mentioned above, the HeNB part 5-1 and the AP part 5-2 are configured to alleviate
any IDC interference (ongoing and/or potential) by exchanging information (either within the
dual FAP 5 or using an external connection, such as a connection provided via one or more
gateways and/or the core network 7).
In this example, the HeNB part 5-1 requests the AP part 5-2 not to use one or more
channels close to the lower portion of the ISM band (e.g. ISM Channels 1 to 3). In order to do
so, the HeNB part 5-1 generates (using its ISM interface module 67 / channel control module 71)
and sends, in step S801, an appropriately formatted message (e.g. a 'Restrict Channel Request'
message) to the AP part 5-2, requesting the AP part 5-2 to apply channel restriction with respect
to one or more ISM channels. The HeNB part 5-1 also includes in the message sent at S801
information identifying the channels to be restricted (e.g. a channel ID associated with the ISM
channel and/or a band ID associated with the interfering LTE band).
In response to the HeNB's 5-1 request, the AP part 5-2 determines (using its channel
control module 71) whether or not it is able to apply the requested restriction. If the AP part 5-
2 determines that it is able to proceed with the HeNB's 5-1 request, it begins to apply (in step
S803) the channel restriction (using its channel control module 71) with respect to the ISM
channel(s) identified in the request received at S801 . Such a channel restriction may be
maintained by the AP part 5-2 at least until receiving a further message from the HeNB part 5- 1
lifting the restriction and/or until the expiry of an associated 'channel restriction' timer (which
may be set to e.g. a default timer value and/or a timer value configured by the message at S801).
Once the AP part 5-2 has complied with the requested channel restriction, it generates
(using its LTE interface module 69) and sends, in step S805a, an appropriate signalling message
(e.g. a 'Restrict Channel Acknowledgement' message) informing the HeNB part 5-1 that the
restriction is in place. Advantageously, the HeNB part 5-1 is able to communicate with the
mobile devices 3 using the LTE channels neighbouring or overlapping with the ISM channel(s)
operated by the AP part 5-2 without causing unnecessary interference to these communications.
It will be appreciated that any communications already allocated to the restricted ISM
channel(s) may be either terminated or moved (handed over, steered, etc.) to a different (i.e. nonrestricted)
channel.
In this embodiment, the HeNB part 5-1 may use, for example, LTE frequency Band 40
and it may request the AP part 5-2 to restrict usage of at least one of ISM Channels 1 to 3. The
HeNB part 5-1 may also use LTE frequency Band 7 (and/or LTE Band 41), in which case it may
request the AP part 5-2 to restrict usage of at least one of ISM Channels 12 to 14.
Second embodiment
Figure 8b shows a modification of the method shown in Figure 8a. In this case, the AP
part 5-2 is unable to comply with the requested channel restriction and the HeNB part 5-1 is
configured to alleviate interference on its own.
Step S801 of Figure 8b is identical to step S801 of Figure 8a. However, in this case
the AP part 5-2 (using its channel control module 71) determines that the requested channel
restriction cannot be applied. This may happen, for example, when such restriction is already
in place, the channel to be restricted is not supported by the AP part 5-2, the channel is used by
communications that cannot be interrupted/moved to other channels, and/or the like.
As shown generally in step S803, the AP part 5-2 does not apply the requested channel
restriction. Instead, the AP part 5-2 generates (using its LTE interface module 69) and sends, in
step S805b, an appropriate signalling message (e.g. a 'Restrict Channel Negative
Acknowledgement (Nack)' message) informing the HeNB part 5-1 that the requested restriction
cannot be complied with (at least with respect to some of the channel identified in the message at
S801).
Advantageously, in this case the HeNB part 5-1 is able to apply a scheduling restriction
(using its channel control module 71) and/or apply power control (using its power control
module 72) to its own communications (e.g. with the mobile device 3-1) over the affected LTE
Band. Thus, for example, if the AP part 5-2 is unable to restrict usage of at least one of ISM
Channels 1 to 3, the HeNB part 5-1 may restrict usage of its own LTE frequency Band 40 (in
downlink, uplink, or both). If the AP part 5-2 is unable to restrict usage of at least one of ISM
Channels 12 to 14, the HeNB part 5-1 may restrict usage of its own LTE frequency Band 7
(and/or Band 41), in downlink and/or uplink.
The HeNB part 5-1 is thus able to communicate with the mobile devices 3 without
causing unnecessary interference to these communications using appropriate LTE bands (i.e.
non-restricted bands) even if the AP part 5-2 cannot or does not comply with the requested
restriction.
Third embodiment
Figure 9a shows another modification of the method shown in Figure 8a. Similarly to
Figure 8b, in this case the AP part 5-2 is unable to comply with the requested channel restriction
and the HeNB part 5-1 is configured to alleviate interference on its own.
Steps S901 to S905a correspond to steps S801 to S805b of Figure 8b, respectively,
hence their description will not be repeated here.
In this case however, as shown in step S907, the HeNB part 5-1 (using its channel
control module 71) applies a scheduling restriction and/or intelligent uplink scheduling to its
own communications (e.g. with the mobile device 3-1) over the affected LTE Band(s). This
may be particularly beneficial in case of LTE Band 7 in the uplink in case the AP part 5-2 is
unable to restrict usage of at least one of ISM Channels 12 to 14. However, it will be
appreciated that this modification may also be applied to downlink communications in LTE
Band 7 and/or communications in other bands, e.g. LTE Bands 40/41, as described above.
Additionally, the HeNB part 5-1 may also be configured to obtain from the AP part 5-2
(e.g. in step S905a or in a separate step) information identifying a frame timing applied by the
AP part 5-2, i.e. information identifying the transmission pattern (if any) and/or duration used by
the AP part 5-2 over the interfering channel. Beneficially, the HeNB part 5-1 is able to apply
intelligent uplink scheduling for the affected LTE Band(s) using the obtained frame timing
information, e.g. by avoiding scheduling L transmissions in the affected LTE band(s) (e.g.
Band 7/41) for the duration of the AP's 5-2 transmissions in the interfering ISM Channel(s) (e.g.
Channel 12/13/14).
Fourth embodiment
Figure 9b shows an exemplary timing diagram illustrating a method performed by the
HeNB part 5-1 and the AP part 5-2 of the mobile telecommunication system 1 shown in Figure
1. In this example, the HeNB part 5-1 is configured to control its maximum transmit power
based on information obtained from the AP part 5-2.
Initially, as generally shown in step S910, the HeNB part 5-1 receives the applicable
maximum transmission ('Tc' ) power value from the Home eNodeB Management System
(HeMS). The HeNB part 5-1 is configured to adjust, based on information obtained from the
AP part 5-2, its maximum transmission power, thereby reducing (as much as possible) the
amount of interference to the coexisting AP part 5-2.
Specifically, in this example the AP part 5-2 (using its power control module 72)
generates and sends, in step S91 1, an appropriately formatted message (e.g. a 'Channel/Transmit
Power Information Request' message) to the HeNB part 5-1, e.g. over the dedicated interface
100. The AP part 5-2 includes in this message information identifying one or more channel
(e.g. at least one of ISM Channels 1 to 3, and 12 to 14) used by the AP part 5-2 in its
communications with the mobile devices 3, and a respective associated transmit power used in
the identified one or more channel.
Next, in step S 1 , the HeNB part 5-1 configures its power control module 72 to apply
an appropriate UL/DL maximum transmit power, which also takes into account the received
information identifying the one or more channel used by the AP part 5-2 and the respective
associated transmit power.
Specifically, the HeNB part 5-1 is configured to adjust the value of the so-called 'Pmax'
parameter (which determines the HeNB's 5-1 maximum transmission power) based on an offset
that is dependent on the channel information and/or power used by AP part 5-2. Further, the
HeNB part 5-1 is configured to adjust/set the maximum allowed UL transmit power of the
mobile devices 3 within the cell operated by the HeNB part 5-1, also based on the received
information identifying the one or more channel used by the AP part 5-2 and the respective
associated transmit power. It will be appreciated that in determining an appropriate UL/DL
maximum transmit power the HeNB part 5-1 may be configured to take into account other
information as well, for example, information relating to network monitor mode (NMM)
measurements (also referred to as Network Listen Mode (NLM) measurements).
Once the HeNB part 5-1 has successfully configured its power control module 72 with
the appropriate UL/DL maximum transmit powers, it generates (using its ISM interface module
67) and sends, in step S915, an appropriate signalling message (e.g. a 'Channel/Transmit Power
Information Acknowledgement' message) to the AP part 5-2.
Beneficially, by applying an appropriate transmit power setting (to the HeNB's 5-1
transmissions) that also take into account the information identifying the AP's 5-2 channel(s) and
associated transmit power(s), the HeNB part 5-1 is able to alleviate (on-going or potential)
interference resulting from the simultaneous use of both the LTE and the non-LTE (ISM)
communication technologies in the dual FAP 5.
Fifth embodiment
Figures 10a and 10b show exemplary timing diagrams illustrating a method performed
by the HeNB part 5-1 and the AP part 5-2 of the mobile telecommunication system 1 shown in
Figure 1. In this example, the HeNB part 5-1 is configured to control the AP's 5-2 band
restriction based on the current operating state of the HeNB part 5-1.
The procedure begins in step SI000, in which the HeNB part 5-1 enters an energy
saving mode (ESM), e.g. during which transmissions over one or more (e.g. all) LTE frequency
bands are suspended. In response to this change of operating mode, the HeNB part 5-1 (using
its ISM interface module 67) generates and sends, in step S1001, an appropriately formatted
message (over the dedicated interface 100) informing the AP part 5-2 about the activation of the
energy saving mode. The HeNB part 5-1 may also include in this message information
identifying the LTE Bands in which its transmissions are suspended (e.g. if not all LTE Bands
are suspended) and/or for which the ESM is applicable.
In response to this message, as shown in step SI003, the AP part 5-2 (using its channel
control module 71 and/or power control module 72) discontinues the enforcement of any
restriction that has been applied to its ISM transmissions (e.g. in any of Channels 1 to 3, and 12
to 14). The AP part 5-2 (using its LTE interface module 69) generates and sends, in step
SI005, an appropriately formatted message (e.g. an 'Entering ESM Response' message) to the
HeNB confirming that the ISM band restrictions have been lifted.
Figure 10b illustrates the reverse of this procedure, in which the HeNB part 5-1 exits the
energy saving mode of operation and notifies the AP part 5-2 to start applying one or more
restrictions to its ISM communications thereby alleviating a potential interference arising due to
the concurrent use the LTE and non-LTE technologies.
As shown in step SI010, this procedure begins when the HeNB part 5-1 exits the energy
saving mode of operation (e.g. the ESM mode described above). In response to this change of
operating mode, the HeNB part 5-1 (using its ISM interface module 67) generates and sends, in
step S101 1, an appropriately formatted message (e.g. over the dedicated interface 100) informing
the AP part 5-2 about the HeNB part 5-1 resuming its normal (i.e. non-ESM) mode of operation,
in which the HeNB's 5-1 transmissions over the LTE frequency bands are no longer suspended
(e.g. the de-activation of the energy saving mode entered in step S1010). The HeNB part 5-1
may also include in this message information identifying the LTE Bands in which its
transmissions are no longer suspended and/or LTE Bands in which its transmissions are
suspended (e.g. if some LTE Bands remain suspended).
In response to this message, as shown in step S101 3, the AP part 5-2 (using its channel
control module 7 1 and/or power control module 72) begins applying an enforcement of the
restriction to its ISM transmissions (e.g. in any of Channels 1 to 3, and 12 to 14). It will be
appreciated that the required restrictions may be identified by the HeNB part 5- including
appropriate information in the message sent at S101 1 and/or in any other suitable message (such
as the messages described above with reference to Figures 8a to 9b).
Next, the AP part 5-2 (using its LTE interface module 69) generates and sends, in step
S101 5, an appropriately formatted message (e.g. an 'Exiting ESM Response' message) to the
HeNB confirming that the ISM band restrictions have been (re-) applied.
It will be appreciated that at this point the procedure may return to step S1010, e.g. if
the HeNB part 5-1 subsequently enters its energy saving mode.
Thus, in summary, whenever the HeNB part 5-1 enters the energy saving mode, it may
inform the AP part 5-2 (e.g. over the dedicated interface 100) about its current energy saving
mode (and/or its mode transition) so that the AP part 5-2 can beneficially lift any restriction (e.g.
a restriction on ISM channel usage, transmission power, and/or scheduling) that have been
imposed by the HeNB part 5-1 in order to alleviate an interference arising due to the coexistence
of the LTE and non-LTE transmissions. Similarly, whenever the HeNB part 5-1 exits the
energy saving mode, it may inform the AP part 5-2 about its current energy saving mode (and/or
its mode transition) so that the AP part 5-2 can beneficially apply (or re-apply, as appropriate)
any requested restriction (e.g. a restriction on ISM channel usage, ISM transmission power,
and/or ISM scheduling) in order to alleviate an interference (or potential interference) arising
from the coexistence of the LTE and non-LTE technologies in the dual FAP 5.
It will be appreciated that, by effectively mirroring the above described procedures, the
AP part 5-2 may also be configured to inform the HeNB part 5-1 about its current energy saving
mode (and/or energy saving mode transition), in which case the HeNB part 5-1 may apply/lift an
appropriate restriction to its own transmissions in an LTE Band affected by the AP's 5-2 ISM
transmissions, in dependence on the AP's 5-2 actual energy saving mode.
The state transitions and the associated notifications sent between the HeNB part 5-1
and the AP part 5-2 (in either direction) are further illustrated in Figure 10c.
Using the exchanged information relating to the current power state of the HeNB part 5-
1 and/or the AP part 5-2, the dual FAP 5 is beneficially able to alleviate a potential interference
by restricting/allowing the use of certain frequency bands/channels in dependence on the current
operating mode of the HeNB part 5-1 and/or the AP part 5-2.
Sixth embodiment
Figure 11 shows an exemplary timing diagram illustrating a method performed by the
HeNB part 5-1 and the AP part 5-2 of the mobile telecommunication system 1 shown in Figure
1. In this example, the HeNB part 5-1 is configured to control the steering of traffic to/from the
AP part 5-2 based on load information obtained from the AP part 5-2.
It will be appreciated that in this embodiment the messages used between the HeNB
part 5-1 and the mobile device 3 (denoted 'UE' in Figure 11) conform to the RRC protocol
specified in 3GPP TS 36.331. Specifically, the message sent at SI 101 may comprise an
'RRCConnectionReconfiguration message' described in Section 5.5.1 of TS 36.331 and the
message sent at SI 104 corresponds to the message described in Section 5.5.5 "Measurement
reporting" of TS 36.331. Step SI 102 may correspond to any of the event triggers Al to A6,
Bl, and B2 described in sections 5.5.4.2 to 5.5.4.8 of TS 36.331. The contents of the above
sections of TS 36.33 1 are incorporated herein by reference. Further, step SI 102 may comprise
an event trigger relating to a non-LTE (e.g. ISM) measurement, such as a Wi-Fi signal strength
measurement, a Wi-Fi interference measurement, and/or the like.
In this case however, as generally illustrated in step S 100, the HeNB part 5-1 is
operable to obtain load information (e.g. congestion status information) from the AP part 5-2.
It will be appreciated that although in Figure 11 step SI 100 is shown to take place between steps
SI 104 and SI 105, step SI 100 may take place any time before step SI 105, e.g. prior to or after
S1101. Further, it will be appreciated that the message at step S1100 may be sent by the AP
part 5-2 in response to an associated request (not shown in Figure 11) received from the HeNB
part 5-1 (e.g. over the dedicated interface 100).
In any case, the HeNB part 5-1 is configured to take into account the load information
obtained from the Wi-Fi AP part 5-2 (e.g. instead or in addition to the measurement report
received at SI 104) in its decision to trigger the steering of traffic to/from the Wi-Fi AP part 5-2.
Thus, when the HeNB part (using its load balancing module 70) determines that some or all
mobile devices 3 may be steered to/from the Wi-Fi AP part 5-2, it generates (using e.g. its RRC
module 65) and sends, in step SI 105, an appropriately formatted signalling message requesting
the mobile devices 3 to steer to/from the Wi-Fi AP part 5-2 in dependence on the load (e.g.
congestion status / capacity) of the AP 5-2 part indicated by the load information received at
SI 100, thereby alleviating the (potential) interference arising from the coexistence of the LTE
and non-LTE technology in the dual FAP 5.
For example, if the load information from the AP part 5-2 indicates that the load of the
AP part 5-2 (e.g. the number of mobile devices served in the AP's 5-2 cell and/or the amount of
its capacity used) is above a predetermined threshold, then the HeNB part 5-1 instructs the
mobile device 3 to steer away from the AP part 5-2 (and to possibly use another AP part and/or
to use the LTE technology instead). However, if the load information from the AP part 5-2
indicates that the load of the AP part 5-2 is not above (e.g. it is below) a predetermined
threshold, then the HeNB part 5-1 instructs the mobile device 3 to steer to the AP part 5-2 and/or
another access point part (e.g. from the HeNB part 5-1).
As shown generally in step SI 107, the mobile device 3 complies with the HeNB's 5-1
steering command, and performs an appropriate steering of its communications to/from the
wireless local area network (WLAN) that the AP part 5-2 belongs to. Finally, the mobile
device 3 acknowledges / confirms successful receipt of the steering command.
In either scenario, by steering the mobile device 3 to/from the AP part 5-2 / WLAN, the
dual FAP 5 is beneficially able to alleviate an undesired interference arising from its concurrent
use (the coexistence) of the LTE and non-LTE technology.
Modifications and Alternatives
A detailed exemplary embodiment has been described above. As those skilled in the
art will appreciate, a number of modifications and alternatives can be made to the above
embodiment whilst still benefiting from the inventions embodied therein.
Although the mechanism described here is for co-located dual mode FAPs, it can also
be extended to the FAP devices that are not co located but e.g. in close proximity. It will be
appreciated that in this case the messages may be exchanged, for example, through a common
gateway and/or a controlling node.
In the above exemplary embodiment, a mobile telephone based telecommunication
system was described. As those skilled in the art will appreciate, the techniques described in
the present application can be employed in other communication systems. Other
communication nodes or devices (both mobile and stationary) may include user devices such as,
for example, personal digital assistants, smartphones, laptop computers, web browsers, etc.
In the above exemplary embodiments, a number of software modules were described.
As those skilled will appreciate, the software modules may be provided in compiled or uncompiled
form and may be supplied to the dual FAP or to the mobile device as a signal over a
computer network, or on a recording medium. Further, the functionality performed by part or
all of this software may be performed using one or more dedicated hardware circuits. However,
the use of software modules is preferred as it facilitates the updating of the dual FAP (HeNB
part/AP part) and the mobile device in order to update their functionalities.
In the above exemplary embodiments, the concurrent LTE and non-LTE
communications are carried out by the same dual FAP. However, whilst the above exemplary
embodiments have particular benefit for alleviating in device coexistence interference issues, it
will be appreciated that some aspects of the invention may be employed to alleviate interference
in situations where one base station communicates using the LTE RAT and another but separate
base station / access point in the vicinity communicates using a non-LTE radio technology.
Further, it will be appreciated that the above mechanisms may also be applicable to a base station
operating in an unlicensed spectrum, such as a base station (of a dual FAP) conforming to a
future release of the LTE Advanced (LTE-A) set of standards (in addition to the LTE and/or ISM
standards).
In the above exemplary embodiments, the dual FAP 5 comprises separate LTE and ISM
baseband circuits 50-1 and 50-2. Each baseband circuit 50-1 and 50-2 is coupled to its own
radio frequency transceiver 1- 1 and 51-2 and uses its dedicated antenna 53-1 and 53-2. It will
be appreciated that the baseband circuits 50-1 and 50-2, the transceivers 51-1 and 51-2, and the
antennas 53-1 and 53-2 might be combined in one component. Alternatively, the dual FAP 5
might employ separate circuits and/or separate transceivers and/or separate antennas for each
type of RAT that it supports. For example, although both Bluetooth and Wi-Fi are ISM radio
access technologies, these standards may be implemented using separate circuits and/or separate
transceivers and/or separate antennas. It is also possible that a given RAT requires more than
one antenna or uses a separate transmitter and/or receiver part.
The exemplary embodiments have been described using Wi-Fi transceivers as an
example of a non-LTE (in this case, ISM) radio technology. However, the mechanisms
described herein can be applied to other non-LTE radio technologies (e.g. other ISM
technologies, such as Bluetooth, NFC, etc. and/or GPS technologies).
For example, the mechanisms may be applied to the following ISM technologies:
■ Bluetooth devices;
■ Cordless phones;
■ Near field communication (NFC) devices;
■ Wireless computer networks, such as HIPERLAN, Wi-Fi (IEEE 802. 11);
■ Wireless technologies based on IEEE 802. 15.4, such as ZigBee, ISA100. 1la,
WirelessHART, and MiWi.
The mechanisms may also be applied to the following Global Navigation Satellite
System (GNSS) technologies:
■ Global or regional satellite navigation systems, such as GPS, GLONASS,
Galileo, Compass, Beidou, DORIS, IRNSS, and QZSS;
■ Global or regional Satellite Based Augmentation Systems, such as Omnistar,
StarFire, WAAS, EGNOS, MSAS, and GAGAN;
■ Ground based augmentation systems, such as GRAS, DGPS, CORS, and GPS
reference stations operating Real Time Kinematic (RTK) corrections.
In the above exemplary embodiment described with reference to Figure 9b, the HeNB
part is described to adjust/set its own transmit power (DL) and the transmit power (UL) for the
mobile devices in the HeNB ' s cell based on information obtained from the AP part. It will be
appreciated that the HeNB part may be configured to adjust the value of ' eMax' as described in
3GPP TS 36.331, based on an offset that is dependent on the channel information/power used by
the Wi-Fi AP part (obtained in step S91 1). It will also be appreciated that the so calculated
P e ax may be used for calculating the value of 'PCMAX', which is defined in 3GPP TS 36.101.
Further, the HeNB part may be configured to derive the power ('PPUSCH') used on the
physical uplink shared channel (PUSCH), e.g. using the following formula (in accordance with
3GPP TS 36.213):
-^PUSCH (0 = min {PCMAX ,10 log ( PUSCH ( )) + PUSCH
The HeNB part may also be configured to derive the power ('PPUCCH') used on the
physical uplink control channel (PUCCH), e.g. using the following formula (in accordance with
3GPP TS 36.2
However, it will be appreciated that, irrespective of whether or not the AP part has
provided its channel information/transmit power information to the HeNB part, the HeNB part
may be configured to autonomously perform power control/adjustment, i.e. without taking into
account any information received from the Wi-Fi AP part. This may be the case, for example,
if LTE service is prioritized over Wi-Fi service. It will be appreciated that the HeNB part may
perform power control purely based on NMM measurements / UE reports.
In the above exemplary embodiments described with reference to Figures 8a to 9a, and
10a to 11, the HeNB part is described to initiate procedures by sending an appropriately
formatted message to the AP part (e.g. a restrict channel request, a power info request,
entering/exiting ESM notifications, etc.) or to the mobile device (e.g. a steering command).
However, it will also be appreciated that similar actions may also be triggered by the AP part
(instead of the HeNB part) by the AP part sending an appropriately formatted message to the
HeNB part (or the mobile device).
It will be appreciated that if the HeNB's current frequency is experiencing an IDC
interference (and assuming that the HeNB part is able to use a different frequency), then the
HeNB part may be configured to perform a so-called carrier frequency reselection procedure.
Carrier frequency reselection may be required if excessive interference is experienced by the
HeNB part either due to co-existing transmissions by the AP part and/or neighbouring HeNB
parts/Wi-Fi AP parts. In this case, the HeNB part may be configured to perform an appropriate
NMM operation and use any information received from the AP part (e.g. over the internal
interface) about the AP's channels and the associated transmission powers in order the HeNB
part to be able to assess the interference situation and evaluate which carrier frequency it needs
to reselect. Additionally, on changing (reselecting) the carrier frequency, the HeNB part may
be configured to inform the co-existing Wi-Fi AP part about its newly selected operating
frequency so that any restriction can be lifted by the AP part if the new HeNB part operating
frequency is away from the lower portion of FDD band 7, the upper portion of TDD Band 40,
and/or the lower portion of Band 4 1.
In the above exemplary embodiment described with reference to Figures 10a and 10b,
the HeNB part is described to control the AP's restrictions to use certain parts of the ISM band
by sending an appropriate notification about its current energy saving state (i.e. whether or not its
LTE transmissions are suspended). In a modification of this exemplary embodiment, it will be
appreciated that the HeNB part may also notify the co-located AP part whether or not its LTE
radio transmissions are turned off (instead of being suspended). For example, the HeNB part
may be required to turn off its LTE transceiver in response to a command (e.g. a 'Radio
Transmission OFF' command) received from an HeMS entity and/or the like. The HeNB part
may also be required to turn off its LTE transceiver (e.g. automatically or upon user action) in
case of an HeNB failure and/or an HeNB location change. It will be appreciated that in such
cases the procedures described with reference to Figures 10a and 10b may be adapted to inform
the AP part about the turning off and a subsequent turning on of the HeNB's LTE transceiver,
similarly to the indications sent upon the HeNB part entering/exiting the energy saving mode.
In the above exemplary embodiments, the interference issues have been described with
respect to one device (e.g. dual FAP) operating both the LTE and the non-LTE transceivers.
However, it will be appreciated that the exemplary embodiments are applicable to interference
issues involving multiple devices, e.g. one device operating an LTE transceiver and another
device operating an ISM transceiver. The exemplary embodiments are also applicable to dual
FAPs which do not have any ongoing LTE transmissions (but e.g. their ISM transmissions suffer
from interference by another device).
The at least one operation to alleviate interference may comprise at least one of:
- an operation to restrict a channel operated by at least one of said base station
module and said access point module;
- an operation to restrict a transmit power usable by at least one of said base
station module and said access point module;
- an operation to schedule communications via at least one of said base station
module and said access point module;
- an operation to reselect a carrier frequency used by at least one of said base
station module and said access point module; and
- an operation to steer traffic to/from at least one of said base station module and
said access point module.
In one possibility, the co-operation to alleviate interference may comprise one of said
base station and said access point modules sending a request, via said interface, for the other of
said base station and said access point modules to restrict a channel operated by the other one of
said base station and said access point modules.
In one possibility, when said other of said base station and said access point modules
restricts said channel, in accordance with said request, said at least one operation to alleviate
interference may comprise said other of said base station and said access point modules
restricting communications via said channel in response to said request.
In one possibility, one of said base station and said access point modules may be
configured: i) for entering an energy saving mode in which transmission in at least one channel
is suspended; and ii) when in said energy saving mode, for leaving said energy saving mode and
to resume said transmission in said at least one channel. In this case, the other of said base
station and said access point modules may be configured: i) when said one of said base station
and access point modules enters said energy saving mode, to lift a communication restriction
with respect to said at least one channel; and ii) when said one of said base station and access
point modules leaves said energy saving mode, to perform at least one operation, to alleviate
interference, comprising imposing or re-imposing a communication restriction with respect to
said at least one channel.
In one possibility, when said other of said base station and said access point modules
does not restrict said channel, in accordance with said request, it may send as part of said co
operation, via said interface, a response to said request. In this case, said one of said base station
and said access point modules may be configured to perform, based on said response, an
operation, to alleviate interference, comprising restricting communications via at least one
channel operated by said one of said base station and said access point modules.
In one possibility, the other of said base station and said access point module may be
configured to, when said other of said base station and said access point modules does not
restrict said channel, in accordance with said request, send as part of said co-operation, via said
interface, a response to said request; and said one of said base station and said access point
modules may be configured to perform, based on said response, an operation, to alleviate
interference, comprising restricting a transmit power of said one of said base station and said
access point modules.
In one possibility, said other of said base station and said access point module may be
configured to, when said other of said base station and said access point modules does not
restrict said channel, in accordance with said request, send as part of said co-operation, via said
interface, a response to said request; and said one of said base station and said access point
modules may be configured to perform, based on said response, an operation, to alleviate
interference, comprising scheduling communications via said one of said base station and said
access point modules to avoid said interference.
In one possibility, the co-operation may comprise said base station module obtaining,
via said interface, information identifying a load level of said access point module, and said at
least one operation to alleviate interference may comprise at least one operation based on said
information identifying a load level of said access point module. In this case, the at least one
operation to alleviate interference may comprise steering communication traffic to/from at least
one of said base station module and said access point module based on said information
identifying a load level of said access point module.
In one possibility, the co-operation may comprise said base station module obtaining,
via said interface, information identifying at least one channel operated by said access point
module, and said at least one operation to alleviate interference may comprise at least one
operation based on said information identifying at least one channel operated by said access
point module. In this case, the at least one operation based on said information identifying at
least one channel may comprise reselecting a carrier frequency used by said base station module
based on said information identifying at least one channel operated by said access point module
whereby to alleviate interference.
In one possibility, the co-operation may comprise said base station module obtaining,
via said interface, information identifying a transmission power associated with at least one
channel operated by said access point module, and said at least one operation to alleviate
interference may comprise at least one operation based on said information identifying a
transmission power. In this case, the at least one operation based on said information
identifying a transmission power may comprise reselecting a carrier frequency used by said
base station module based on said information identifying a transmission power. In one
possibility, the at least one operation to alleviate interference may comprise applying at least one
modified transmission power level for communications between said base station module and
said one or more mobile communication devices based on said information identifying a
transmission power.
The base station module and the access point module may be mounted within a
common housing. The communication apparatus may comprise a dual mode femto access
point. The base station module may comprise a home base station operating in accordance with
the long term evolution (LTE) family of standards. The access point module may comprise an
access point operating in accordance with the 802. 11 family of standards by the Institute of
Electrical and Electronics Engineers (IEEE).
Various other modifications will be apparent to those skilled in the art and will not be
described in further detail here.
Glossary of 3GPP terms
AP Access Point
BT Bluetooth
DRX Discontinuous Reception
eNB Evolved NodeB - base station
E-UTRA Evolved UMTS Terrestrial Radio Access
E-UTRAN Evolved UMTS Terrestrial Radio Access Network
FAP Femto Access Point
FDM Frequency Division Multiplexing
GNSS Global Navigation Satellite System
GPS Global Positioning System
GW Gateway
HeMS Home eNodeB Management System
HeNB home base station
IDC In Device Coexistence
ISM Industrial, Scientific and Medical (radio bands)
LTE Long Term Evolution (of UTRAN)
MME Mobility Management Entity
RAT Radio Access Technology
RRC Radio Resource Control
RRM Radio Resource Management
SeGW Security Gateway
SIR Signal to Interference Ratio
TDM Time Division Multiplexing
UE User Equipment
DL Downlink - link from base station (dual FAP) to mobile device
UL Uplink - link from mobile device to base station (dual FAP)
This application is based upon and claims the benefit of priority from UK patent
application No. 1410538.1, filed on June 12, 2014, the disclosure of which is incorporated herein
in its entirety by reference.
CLAIMS
1. A communication apparatus comprising:
a base station module for providing wireless connectivity in a communication network,
using a first communication protocol, to at least one mobile communication device;
an access point module for providing wireless connectivity in a communication network,
using a second communication protocol, to the at least one mobile communication device; and
an interface for coupling the base station module and the access point module, wherein
said interface is configured for communication between said base station module and said access
point module;
wherein said base station module and said access point module are configured for co
operation with one another by communicating via said interface, and wherein at least one of said
base station module and said access point module is configured to perform at least one operation
to alleviate interference arising due to coexistence, in said communication apparatus, of said base
station module and said access point module, as part of said co-operation.
2. The communication apparatus according to claim 1 wherein said at least one operation to
alleviate interference comprises at least one of:
- an operation to restrict a channel operated by at least one of said base station module
and said access point module;
- an operation to restrict a transmit power usable by at least one of said base station
module and said access point module;
- an operation to schedule communications via at least one of said base station module
and said access point module;
- an operation to reselect a carrier frequency used by at least one of said base station
module and said access point module; and
- an operation to steer traffic to/from at least one of said base station module and said
access point module.
3. The communication apparatus according to claim 1 or 2 wherein said base station module
and said access point module are configured for co-operation, to alleviate interference,
comprising one of said base station module and said access point module sending a request, via
said interface, for the other of said base station module and said access point module to restrict a
channel operated by the other one of said base station module and said access point module.
4. The communication apparatus according to claim 3 wherein, when said other of said base
station module and said access point module restricts said channel, in accordance with said
request, said at least one operation to alleviate interference comprises said other of said base
station module and said access point module restricting communications via said channel in
response to said request.
5. The communication apparatus according to any of claims 1 to 4 wherein said one of said
base station module and said access point module is configured:
i) for entering an energy saving mode in which transmission in at least one channel
is suspended; and
ii) when in said energy saving mode, for leaving said energy saving mode and to
resume said transmission in said at least one channel;
and wherein said other of said base station module and said access point module is
configured:
i) when said one of said base station module and said access point module enters
said energy saving mode, to lift a communication restriction with respect to said at
least one channel; and
ii) when said one of said base station module and said access point module leaves
said energy saving mode, to perform at least one operation, to alleviate
interference, comprising imposing or re-imposing a communication restriction
with respect to said at least one channel.
6. The communication apparatus according to claim 3 wherein, said other of said base
station module and said access point module is configured to, when said other of said base
station module and said access point module does not restrict said channel, in accordance with
said request, send as part of said co-operation, via said interface, a response to said request; and
wherein said one of said base station module and said access point module is configured to
perform, based on said response, an operation, to alleviate interference, comprising restricting
communications via at least one channel operated by said one of said base station module and
said access point module.
7. The communication apparatus according to claim 3 or 6 wherein, said other of said base
station module and said access point module is configured to, when said other of said base
station module and said access point module does not restrict said channel, in accordance with
said request, send as part of said co-operation, via said interface, a response to said request; and
wherein said one of said base station module and said access point module is configured to
perform, based on said response, an operation, to alleviate interference, comprising restricting a
transmit power of said one of said base station module and said access point module.
8. The communication apparatus according to any of claims 3, 6 or 7 wherein, said other of
said base station module and said access point module is configured to, when said other of said
base station module and said access point module does not restrict said channel, in accordance
with said request, send as part of said co-operation, via said interface, a response to said request;
and wherein said one of said base station module and said access point module is configured to
perform, based on said response, an operation, to alleviate interference, comprising scheduling
communications via said one of said base station module and said access point module to avoid
said interference.
9. The communication apparatus according to any one of claims 1 to 8 wherein said co
operation comprises said base station module obtaining, via said interface, information
identifying a load level of said access point module, and wherein said at least one operation to
alleviate interference comprises at least one operation based on said information identifying a
load level of said access point module.
10. The communication apparatus according to claim 9 wherein said at least one operation to
alleviate interference comprises steering communication traffic to/from at least one of said base
station module and said access point module based on said information identifying a load level
of said access point module.
11. The communication apparatus according to any one of claims 1 to 10 wherein said co
operation comprises said base station module obtaining, via said interface, information
identifying at least one channel operated by said access point module, and wherein said at least
one operation to alleviate interference comprises at least one operation based on said information
identifying at least one channel operated by said access point module.
12. The communication apparatus according to claim 11 wherein said at least one operation
based on said information identifying at least one channel comprises reselecting a carrier
frequency used by said base station module based on said information identifying at least one
channel operated by said access point module whereby to alleviate interference.
13. The communication apparatus according to any one of claims 1 to 12 wherein said co
operation comprises said base station module obtaining, via said interface, information
identifying a transmission power associated with at least one channel operated by said access
point module, and wherein said at least one operation to alleviate interference comprises at least
one operation based on said information identifying a transmission power.
14. The communication apparatus according to claim 13 wherein said at least one operation
based on said information identifying a transmission power comprises reselecting a carrier
frequency used by said base station module based on said information identifying a transmission
power.
15. The communication apparatus according to claim 13 or 14 wherein said at least one
operation to alleviate interference comprises applying at least one modified transmission power
level for communications between said base station module and said at least one mobile
communication device based on said information identifying a transmission power.
16. The communication apparatus according to any one of claims 1 to 15, wherein the base
station module and the access point module are mounted within a common housing.
17. The communication apparatus according to any one of claims 1 to 16, wherein the
communication apparatus is a dual mode femto access point.
18. The communication apparatus according to any one of claims 1 to 17, wherein the base
station module comprises a home base station operating in accordance with the long term
evolution, LTE, family of standards, and wherein the access point module comprises an access
point operating in accordance with the 802.1 1 family of standards by the Institute of Electrical
and Electronics Engineers, IEEE.
19. A system for use in a telecommunication network, comprising at least one mobile
communication device and a communication apparatus according to any one of claims 1 to 18.
20. A method performed by a communication apparatus comprising: i) a base station module
for providing wireless connectivity, using a first communication protocol, in a communication
network to at least one mobile communication device; ii) an access point module for providing
wireless connectivity, using a second communication protocol, in a communication network to
the at least one mobile communication device; and iii) an interface for coupling the base station
module and the access point module, wherein said interface is configured for communication
between said base station module and said access point module; the method comprising:
the base station module and the access point module co-operating with one another by
communicating via said interface, and at least one of said base station module and said access
point module performing at least one operation to alleviate interference arising due to
coexistence, in said communication apparatus, of said base station module and said access point
module, as part of said co-operating.
21. A computer program product comprising instructions for causing a computerprogrammable
device to perform a method according to claim 20.