DESCRIPTION
NETWORK SELECTION
This application is based upon and claims the benefit of priority from UK
Patent Application No. 1000345.7 filed on January 11, 2010, the content of which
is incorporated by reference.
Technical Field
The present invention relates to network selection and, in particular, to a
method of assisting such selection and a mobile radio communications user device,
and mobile radio communications network device arranged for the same.
Background Art
To reduce network deployment costs, a single mobile radio communications
network device often has the potential to access one of a plurality of networks and,
in particular, Public Land Mobile Networks (PLMNs).
In scenarios where a plurality of networks are available through a single
mobile radio communication network device, problems can arise through
discrepancies between the network that is most likely to be selected by the user
device, and the network that might be preferred, or might be most likely to be
selected, by the radio network communication device. Any such discrepancy can
have a potentially disadvantageous impact upon the ongoing operability of the user
device. Further security and authentication requirements may not be met.
Summary of Invention
The present invention seeks to provide for a method of network selection,
and related operability for a mobile radio communications user device and a mobile
radio communications network device providing access to a plurality of networks,
having advantages over known such devices.
In particular, the present invention can seek to overcome problems known in
the current art having regard to requirements for connectivity security and
authentication.
The above-mentioned problems and limitations as found in the current art
are particularly prevalent in scenarios in which it is required that emergency bearer
services are supported for Use Equipment (UE) operating in limited service mode
and in which selection of one of a plurality of networks is required for access to the
emergency bearer service.
For example, IP Multimedia Subsystem (IMS) emergency calls are
supported in accordance with 3GPP Rel-9 specifications. That is, IMS emergency
call support indication can be arranged to be broadcast by each cell via the available
System Information (SI) such that any UEs operating in a limited service mode can
select a different cell if IMS emergency services are not supported by the current
cell
Further details and requirements for such IMS emergency call support are
found within 3GPP Technical Specification 36.300 at section 23.1 . 1 and wherein
the IMS emergency call support indicator in the SI is set to "true" if any of the
Mobility Management Entities (MMEs) in a non-shared environment, or if one of
the PLMNs in a shared network environment, supports IMS emergency bearer
services.
With regard to 3GPP specifications relating to E-UTRAN, such as
Technical Specification identified as TS 36.300 section 10.1.7, if the E-UTRAN is
shared by multiple operators, the SI broadcast in each shared cell contains the
PLMN identification of each operator. As discussed in the aforementioned
Technical Specification, there can be up to six operators sharing the E-UTRAN.
However, in so far as there can be up to six PLMNs sharing the cell and, as noted,
only a single bit is used for an indication of IMS emergency support, this can lead
to potential problems and related limitations and as discussed in the Liaison
Statement (LS) from 3GPP SA2, i.e. S2-096386. This LS identifies a scenario in
which a UE in limited service mode and camping on a shared E-UTRAN cell,
broadcasts its support for IMS emergency services by way of a single bit identifier.
If an emergency bearer service is required, the UE can issue an emergency attach
signal towards one of the PLMNs within the shared E-UTRAN cell. However, the
eNB within this cell automatically seeks to select a MME of the PLMN that
supports emergency bearer services but which is most likely different from the
PLMN with which the UE has initiated its emergency attach procedure.
However, after a subsequent authentication procedure, the UE and the
MME/HSS employ different PLMN identifiers as input to the master key K ASME
derivation. While the authentication procedure will complete successfully, the UE
will fail to decode any further message from the MME and the MME will fail to
decode any message from the UE.
While various attempts have been made to overcome, or at least limit such
problems, none seek to achieve this goal without introducing further, or associated,
limitations and problems. For example, recent discussions within 3GPP RAN 2 lead
to the proposal of providing an indication of support for emergency calls for each of
the shared PLMNs though of course it is appreciated that this would
disadvantageously the lead to an increase in SI size since six bits would then be
required, rather than the current single bit, for providing the relevant emergency
services. In particular, the size of broadcast data elements remains an important
consideration as these elements are transmitted permanently and frequently so as to
allow fast access by any user device entering a cell. Increasing the size of broadcast
data elements reduces network capacity so it is desirable to keep them as short as
possible.
Further, and as discussed in the above mentioned LS S2-096386, a possible,
but limited requirement would be to have all PLMNs within a shared E-UTRAN
employ the same IMS emergency support. This would of course prevent the eNB
from selecting a different PLMN.
The present invention seeks to provide for a method, and related network
and UE devices for assisting with PLMN selection when the UE is operating in a
limited service mode within a shared network environment and, in particular, when
seeking to place an IMS emergency call by way of an appropriate PLMN.
According to a first aspect of the present invention, there is provided a
method of assisting selection by a mobile radio communications device of a desired
network from a plurality of networks in a multi-network environment, the method
including creating a structured representation of network identifiers for the said
plurality of networks respectively, and locating the identifier of the said desired
network at a predetermined position within the said structured representation.
The invention proves advantageous in as much as a network having the
required characteristic, for example the support of IMS emergency bearer services,
can then be readily selected by the user device such that there are no discrepancies
between the desired, and selected, networks so as to avoid the limitations and
disadvantages that have been identified within the current art.
According to another aspect of the present invention, there is provided a
mobile radio communication network device arranged to operate in a multi-network
environment and for assisting selection by a mobile radio communication user
device of a desired network from a plurality of networks available through the same
mobile radio communications network device, the device further being arranged to
create a structured representation of network identifiers for the said plurality of
networks respectively, and to locate the identifier of the said desired network at a
predetermined position in the said structured representation.
According to a further aspect of the present invention, there is provided a
mobile radio communications user device arranged for selecting a desired network
from a plurality of networks available though a single mobile radio communications
network device, the device being arranged to receive a structured representation of
network identifiers for the said plurality of networks and to select said desired
network by means of the network identifier located at a predetermined position
within the said structured representation.
Of course, it should be appreciated that the present invention can provide for
a computer program, computer program product or computer readable medium
comprising instructions for carrying out a method as defined above and as provided
by the above mentioned mobile radio communications network device and/or
mobile radio communication user device.
Within the above mentioned various aspects of the present invention, it
should be appreciated that the said multi-network environment can comprise a
shared network environment, for example comprising shared PLMNs and a EUTRAN
shared environment.
Also, the said structured representation can comprise a list, matrix and/or
any required bit map representation of the network identifiers.
In one arrangement, the said predetermined position in the said structured
representation can comprise the first position within a list of network identifiers, or
a particular specified position within a list of network identifiers.
In an alternative arrangement, the said structured representation can
comprise the first and the second position within a list of network identifiers and a
2-value indication to select the network identifier in one of these two positions, or
the said representation can comprise a particular specified set of 2 or more positions,
and an indication having N possible values where N is the number of positions in
the set, selecting the network identifier in one of these N positions.
In one preferred arrangement, the method can include a further step of
varying the position of at least two of the network identifiers within the structured
representation so as to change the network identifier found at the said
predetermined position.
In particular, the method can provide for periodic variations in the position
of the said at least two network identifiers.
As will be appreciated, the invention proves particularly useful for the
selection of a desired network by a mobile radio communications device operating
in a limited service mode and seeking emergency bearer services from one, or more,
of the plurality of networks.
The invention is described further hereinafter, by way of example only, with
reference to the accompanying drawings in which:
Brief Description Drawings
Fig. 1 is a schematic representation of a E-UTRAN cell shared by six
networks;
Fig. 2 is a schematic representation of a network device illustrated within
the network arrangement of Fig. 1;
Fig. 3 is a schematic representation of a mobile radio communications user
device arranged for operating within the network environment of Fig. 1: and
Fig. 4 is a signalling diagram illustrating network signalling arising in
accordance with an embodiment of the present invention.
Description of Embodiments
Turning first to Fig. 1, there is provided a schematic view of a shared EUTRAN
cell 10 and within a E-UTRAN environment 12. Within the cell 10, eNB
14 is shared by six different PLMNs, namely PLMN#1, PLMN#2, PLMN#3,
PLMN#4, PLMN#5 and PLMN#6.
The network environment 12 therefore comprises a shared network
environment and a user device such as mobile radio communications user device 16
located within the cell 10 has potential access to at least one of the said six PLMNs.
Within the illustrated example, the shared network environment is one
within which the user device 16 can operate in limited service mode such that, for
example, access to one or more of the six networks is provided for emergency
bearer services only.
The operation of the present invention requires that the eNB 14 and the user
device 16 have specific functionality which is discussed in further detail below with
reference to Figs 2 and 3.
If it is assumed that one or more of the six PLMNs supports IMS emergency
bearer services within the shared network environment the eNB 14 can be arranged
to set the IMS in the SI to "true", i.e. to indicate that such emergency services are
supported. The signalling messaging from the eNB 14 serves to provide a network
identifier for each of the six PLMNs and functionality within the eNB 14 serves to
ensure that the identifier of an PLMN supporting IMS emergency services is
located at a particular position within the representation of the network identifiers.
For example, if the representation comprises a list of the network identifiers, the
desired network, i.e. the, or a, network offering IMS emergency support is located
first within the list. Alternatively, the desired network can be located at a certain
predetermined position/index within the shared PLMN list.
Advantageously therefore, the user device 16 can select a PLMN that
supports emergency bearer services so there is no need for the eNB 14 to select a
different PLMN. In this manner, the MME/HSS and the user device will use the
same PLMN and the derivation security/authentication procedure within the above
mentioned IMS emergency procedure can be completed by way of only a single bit
data overhead.
Even if two or three-bit bit maps are employed to identify the desired
network to be selected by the User Device 16, this still represents a suitably limited
overhead while enhancing the flexibility of positioning of the desired network
identifier within the structured representation.
Turning now to Fig. 2, there is provided a schematic representation of the
eNB 14 of Fig. 1. As noted, the eNB 14 is arranged to be shared by the 6 PLMNs of
Fig. 1 and, within the SI broadcast by the eNB 14, there is provided a single bit
indication as to whether one, or possibly more, of the PLMNs provide emergency
bearer services. However, there are no further specific data bits serving to indicate
which of the six PLMNs offer the desired emergency bearer services but, rather,
and as will be appreciated from the above, it is the positioning of a PLMN offering
that desired surface within the structured representation, such as a shared PLMN list,
that serves to identify the desired PLM for ready selection and access by the user
device 16.
The eNB also includes standard transmission 17 and reception 18 circuitry
which is associated with memory functionality 20 and processor functionality 22
which includes, for example, ordering functionality 24 serving to locate the network
identifier of a network having a predetermined desired characteristic such as an
emergency bearer service at a predetermined position in the PLMN listing to be
transmitted from the eNB 14 within the SI.
Turning now to Fig. 3, there is provided a schematic representation of a user
device 16 which can be employed within the network environment of Fig. 1 to
receive broadcast signalling from the eNB 14. As usual, the user device 16 employs
transmission 26 and reception 28 circuitry and associated storage media 30 and
processor functionality 32. Included within the processor functionality 32 there is
provided selection functionality 34 which serves to identify the PLMN associated
with the PLMN identifier found at a predetermined location within the shared
PLMN list received within the IS broadcast from the eNB 14.
The location of the desired one or more PLMN identifiers within the PLMN
shared list advantageously serves to assist the user device 16 in selecting any
PLMN which offers the required IMS emergency support within the cell 10 but
without the danger of the eNB 14 having selected a different PLMN.
Security and authentication procedures will therefore succeed and not
exhibit the likely failure found in the current art.
Turning now to Fig. 4, there is provided a diagram illustrating signalling
arising between the shared network 10, 12 and the user device 16.
As indicated at 36, if one or more PLMN within the shared network
supports IMS emergency bearer services, the SI broadcast from the eNB 14 can
includes an "emergency services supported" indication, i.e. a "true" flag and the
identifier of the PLMN providing that emergency support is placed at a
predetermined position within the shared PLMN list.
The SI signalling 38 containing such indicators is broadcast as illustrated to
the user device 16.
Assuming that emergency support is indicated as present for that cell 10 of
the shared network, the user device 16 then places the appropriate emergency call
request to the correct PLMN.
As should therefore be appreciated, the invention provides for an
advantageous feature over the current art since the network is advantageously
arranged to ensure that the PLMN identified first in the list comprises one
supporting IMS emergency calls, or the identifier is placed at a certain
predetermined position/index within the shared PLMN list comprises the IMS
emergency call supporting network and the relevant position is either fixed or
indicated by way of a index value in the range 1 to 2, 1 to 3, 1 to 4, 1 to 5 or 1 to 6.
This index can be represented as a numerical integer value binary-coded on 1, 2 or
3 bits according to the range, or as a set of specified values within a numerical
values comprising other information. For example, a 2-bit value is used where one
value (e.g. 00) indicates no support of IMS emergency call, a second value (e.g. 01)
indicates support of IMS emergency in the first PLMN within the shared PLMN list,
and a third value (e.g. 10) indicates support of IMS emergency call in the second
PLMN within the shared PLMN list.
Alternatively, a 1-bit value is used where one value (e.g. 0) indicates
support of IMS emergency in the first PLMN within the shared PLMN list, and the
second value (e.g. 1) indicates support of IMS emergency call in the second PLMN
within the shared PLMN list.
Advantageously, a user device operating in limited service mode within a
shared network then advantageously select the first, or appropriately located PLMN
identifier so as to place an appropriate emergency call request to the network
identified thereby.
As noted above, and if a plurality of the networks offer the required
functionality, the network can advantageously, and if required periodically, vary the
order within which the PLMN identifiers appear in the structured representation of
the PLMNs that provide the desired characteristic, such as IMS emergency bearer
services support.
It will therefore be appreciated that the present invention can provide for
PLMN selection by a user device in limited service mode and in the shared network
environment for IMS emergency call services.
CLAIMS
1. A method of assisting selection by a mobile radio communications
device of a desired network from a plurality of networks in a multi-network
environment, the method including creating a structured representation of network
identifiers for the said plurality of networks respectively, and locating the identifier
of the said desired network at a predetermined position within the said structured
representation.
2. The method according to Claim 1, wherein the said multi-network
environment comprises a shared network environment.
3. The method according to Claim 1 or 2, wherein the said structured
representation comprise at least one of a list, matrix and/or any required bit-map
representation of the network identifiers.
4. The method according to Claim 3, wherein the said predetermined
position in the said structured representation comprises the first position within a
network list.
5. The method according to Claim 3, wherein said predetermined
position comprises a particular specified position within the list, matrix or bitmap
representation.
6. The method according to any one of Claims 1 to 5, further including
the step of varying the position of at least two of the network identifiers within the
structured representation so as to change the network identifier found at the said
predetermined position.
7. The method according to Claim 6, further including periodically
varying the position of the said at least two network identifiers.
8. The method according to any one of Claims 1 to 7, for assisting with
the selection of a desired network by a mobile radio communications device
operating in a limited service mode and/or seeking emergency bearer services from
one, or more, of the plurality of networks.
9. A mobile radio communications network device arranged to operate
in a multi-network environment and for assisting selection by a mobile radio
communications device of a desired network from a plurality of networks, the
device further being arranged to create a structured representation of network
identifiers for the said plurality of networks respectively, and to locate the identifier
of the said desired network at a predetermined position within the said structured
representation.
10. The device according to Claim 9, wherein the said multi-network
environment comprises a shared network environment.
11. The device according to Claim 10, wherein the said structured
representation comprises at least one of a list, matrix and/or any required bit-map
representation of the network identifiers.
12. The device according to Claim 11, wherein the said predetermined
position in the said structured representation comprises the first position within a
network list or a particular specified position within the list or matrix or as
identified by way of a bitmap representation.
13. The device according to any one of Claims 9 to 12, arranged to vary
the position of at least two of the network identifiers within the structured
representation so as to change the network identifier found at the said
predetermined position.
14. The device according to Claim 13, further arranged to periodically
vary the position of the said at least two network identifiers.
15. The device according to any one of Claims 9 to 14, arranged for the
selection of a desired network by a mobile radio communications device operating
in limited service mode and/or seeking emergency bearer services from one of the
plurality of networks.
16. A mobile radio communications device arranged for selecting a
desired network from a plurality of networks within a multi-network environment,
the device being arranged to receive a structured representation of network
identifiers for the said plurality of networks and to select the said network by means
of the network identifier located at a predetermined position within the said
structured representation.
17. The device according to Claim 16, wherein the said multi—network
environment comprises a shared network environment.
18. The device according to Claim 16 or 17, wherein the said structured
representation comprises at least one of a list, matrix and/or any required bit map
representation of the network identifiers.
19. The device according to Claim 18, wherein the said predetermined
position in the said structured representation can comprise the first position within a
list, or a particular specified position within the list, matrix or bitmap
representation.
20. The device according to any one of Claims 16 to 19, arranged for the
selection of a desired network when operating in a limited service mode and/or
seeking emergency bearer services from one, or more, of the plurality of networks.
21. A computer program, computer program product or computer readable
medium comprising instructions for carrying out a method has defined in any one
of Claims 1 to 8.
22. A method of selection by a User Device of a desired PLMN offering
emergency bearer services from a list of PLMNs within a shared network
environment, the method including creating a list of network identifiers for the said
plurality of PLMNs respectively, and locating the identifier of the said desired
PLMN at a predetermined position within the said list.
23. A network node device arranged to operate in a shared network
environment and for assisting selection by a User Device of a desired PLMN
offering emergency bearer services from a plurality of PLMNs, the node device
further being arranged to create a list of network identifiers for the said plurality of
PLMNs respectively, and to locate the identifier of the said desired PLMN at a
predetermined position within the list.
24. A user device arranged for selecting a desired PLMN offering
emergency bearer services from any plurality of PLMNs within a shared network
environment, the device being arranged to receive a list of network identifiers for
the said plurality of the PLMNs and to select the said desired network by means of
the network identifier located at a predetermined position within the list.
25. A method of assisting selection by a mobile communications device
of a desired network and substantially as hereinbefore described with reference to
the accompanying drawings.
26. The device according to Claim 9, further including:
transmission and reception circuitry which is associated with memory
functionality; and
processor functionality which includes ordering functionality serving to
locate the network identifier of a network having a predetermined desired
characteristic such as an emergency bearer service at a predetermined position in
the PLMN listing to be transmitted from the device within the SI.
27. The device according to Claim 16, further including:
transmission and reception circuitry and associated storage media; and
processor functionality which includes selection functionality which serves
to identify the PLMN associated with the PLMN identifier found at a
predetermined location within the shared PLMN list received within the IS
broadcast from a mobile radio communication network device.