U.S. patent application number 13/228257 was filed with the patent office on 2012-01-12 for apparatus and method for applying ciphering in a universal mobile telecommunications system.
This patent application is currently assigned to RESEARCH IN MOTION LIMITED. Invention is credited to Nicola Funnell.
Application Number | 20120009910 13/228257 |
Document ID | / |
Family ID | 35460541 |
Filed Date | 2012-01-12 |
United States Patent
Application |
20120009910 |
Kind Code |
A1 |
Funnell; Nicola |
January 12, 2012 |
APPARATUS AND METHOD FOR APPLYING CIPHERING IN A UNIVERSAL MOBILE
TELECOMMUNICATIONS SYSTEM
Abstract
Apparatus and a method for ciphering messages in mobile
telecommunications system user equipment and network are disclosed.
The apparatus is arranged to store a plurality of current ciphering
configurations and/or a plurality of old (previously applied)
ciphering configurations and/or a plurality of new (future)
ciphering configurations. Thus different ciphering configuration
may be applied at different times and for different radio
bearers.
Inventors: |
Funnell; Nicola; (Cumbria,
GB) |
Assignee: |
RESEARCH IN MOTION LIMITED
WATERLOO
CA
|
Family ID: |
35460541 |
Appl. No.: |
13/228257 |
Filed: |
September 8, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10864292 |
Jun 9, 2004 |
8036385 |
|
|
13228257 |
|
|
|
|
Current U.S.
Class: |
455/418 ;
455/552.1 |
Current CPC
Class: |
H04L 69/24 20130101;
H04W 8/205 20130101; H04L 69/18 20130101; H04W 12/037 20210101;
H04K 1/00 20130101; H04L 63/0428 20130101 |
Class at
Publication: |
455/418 ;
455/552.1 |
International
Class: |
H04W 88/02 20090101
H04W088/02; H04W 92/00 20090101 H04W092/00 |
Claims
1. A method for applying ciphering in a user equipment device (UE)
for use in a mobile telecommunications system, the method
comprising: selecting from a plurality of ciphering configurations
stored in the UE, a subset of a plurality of ciphering
configurations that may be used on a wireless communication;
determining which type of ciphering configuration to use on the
wireless communication; using one ciphering configuration from the
selected subset on the wireless communication to generate a
ciphered wireless communication; and transmitting the ciphered
wireless communication.
2. The method according to claim 1, further comprising: receiving
the wireless communication over a radio bearer (RB); and in which
selecting from the plurality of ciphering configuration comprises:
selecting, from the plurality of ciphering configurations stored in
the UE and based on the RB, the subset of the plurality of
ciphering configurations; and in which determining which type of
ciphering configuration to use is based on the RB and the wireless
communication.
3. The method according to claim 1, wherein the types of ciphering
configuration comprise at least one of the group comprising: new
ciphering configuration, old ciphering configuration and ciphering
configuration.
4. The method according to claim 1, wherein a maximum limit is
applied to the number of ciphering configuration of a given type
that are stored.
5. The method according to claim 1, further comprising determining
whether parameters of a ciphering configuration are required, and
removing parameters that are determined to be no longer
required.
6. The method according to claim 1, wherein the UE is capable of
communicating via a plurality of radio bearers, the method further
comprising storing parameters relating to a plurality of ciphering
configurations for a given type of ciphering configuration for each
RB.
7. The method according to claim 1, further comprising storing
parameters in a layer of a protocol stack which layer applies the
ciphering.
8. A mobile telecommunications device configured for use in a
mobile telecommunications system, the device comprising: a receiver
enabled to receive wireless communications; and a microprocessor,
memory, and software operable to select from a plurality of stored
ciphering configurations; a subset of a plurality of ciphering
configurations that may be used on a wireless communication; to
determine which type of ciphering configuration to use on the
wireless communication; to use one ciphering configuration from the
selected subset on the wireless communication to generate a
ciphered wireless communication; and to transmit the ciphered
wireless communication.
9. The device according to claim 8, in which: the wireless
communication is received over a radio bearer (RB); the subset is
selected based on the RB, and in which the software is operable to
determine which type of ciphering configuration to use based on the
RB and the wireless communication.
10. The device according to claim 8, stored ciphering
configurations including at least one of the group comprising: new
ciphering configuration, old ciphering configuration and ciphering
configuration.
11. The device according to claim 8, wherein a maximum limit is
applied to the number configurations of a given type that are
stored.
12. The device according to claim 8, further arranged to determine
whether parameters of a ciphering configuration are required, and
to delete parameters that are determined to be no longer
required.
13. The device according to claim 8, further arranged to apply the
appropriate ciphering configuration according to parameters stored
with each ciphering configuration.
14. The device according to claim 8, wherein the device is further
arranged to store parameters associated with the ciphering
configurations in a layer of a protocol stack which applies
ciphering.
15. The device according to claim 13 wherein the device is operable
in a Universal Mobile Telecommunications System and the parameters
are stored in at least one of the Radio Link Control Layer and the
Medium Access Control (MAC) layer of the protocol stack of the
device.
16. A mobile communications network comprising a network of a
plurality of cells from a plurality of Node B transceivers and at
least one radio network controller (RNC), comprising: a
microprocessor, memory, and software operable to select, from a
plurality of stored ciphering configurations, a subset of a
plurality of ciphering configurations that may be used on a
wireless communication; to determine which type of ciphering
configuration to use on the wireless communication; to use one
ciphering configuration from the selected subset on the wireless
communication to generate a ciphered wireless communication; and to
transmit the ciphered wireless communication.
17. The device according to claim 16, in which: the wireless
communication is received over a radio bearer (RB); the subset is
selected based on the RB, and in which the software is operable to
determine which type of ciphering configuration to use based on the
RB and the wireless communication.
18. The network according to claim 16, the types of ciphering
configuration being at least one of the group comprising: new
ciphering configuration, old ciphering configuration and ciphering
configuration.
19. The network according to claim 16, wherein a maximum limit is
applied to the number of ciphering configurations of a given type
that are stored.
20. The network according to claim 16, further arranged to
determine whether parameters of a ciphering configuration are
required, and to delete parameters that are determined to be no
longer required.
21. The network according to claim 16, further arranged to apply
the appropriate ciphering configuration according to parameters
stored with each ciphering configuration.
22. The network according to claim 16, wherein the device is
further arranged to store parameters associated with the ciphering
configurations in a layer of a protocol stack which applies
ciphering.
23. The network according to claim 16, wherein the network is
operable in a Universal Mobile Telecommunications System and the
parameters are stored in at-least one of the Radio Link Control
Layer and the Medium Access Control (MAC) layer of the protocol
stack.
24. The network according to claim 16, wherein the microprocessor,
memory, and software reside on the NRC.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application is a continuation of co-pending U.S.
patent application Ser. No. 10/864,292 filed on Jun. 9, 2004, the
contents of which are incorporated herein by reference.
BACKGROUND
[0002] 1. Technical Field
[0003] This application relates to mobile telecommunications
systems in general, having particular application in UMTS
(Universal Mobile Telecommunications System) in general, and in
particular to an apparatus and method for applying ciphering in
universal mobile telecommunications system user equipment and
network.
[0004] 2. Description of the Related Art
[0005] The approaches described in this section could be pursued,
but are not necessarily approaches that have been previously
conceived or pursued. Therefore, unless otherwise indicated herein,
the approaches described in this section are not prior art to the
claims in this application and are not admitted to be prior art by
inclusion in this section.
[0006] In a typical cellular radio system, mobile user equipment
(UE) communicates via a radio access radio network (RAN) to one or
more core networks. User equipment (UE) comprises various types of
equipment such as mobile telephones (also known as cellular or cell
phones), lap tops with wireless communication capability, personal
digital assistants (PDAs) etc. These may be portable, hand held,
pocket sized, installed in a vehicle etc and communicate voice
and/or data signals with the radio access network.
[0007] The radio access network covers a geographical area divided
into a plurality of cell areas. Each cell area is served by at
least one base station, which may be referred to as a Node B. Each
cell is identified by a unique identifier which is broadcast in the
cell. The base stations communicate at radio frequencies over an
air interface with the UEs within range of the base station.
Several base stations may be connected to a radio network
controller (RNC) which controls various activities of the base
stations. The radio network controllers are typically connected to
a core network.
[0008] UMTS is a third generation public land mobile
telecommunication system. Various standardization bodies are known
to publish and set standards for UMTS, each in their respective
areas of competence. For instance, the 3GPP (Third Generation
Partnership Project) has been known to publish and set standards
for GSM (Global System for Mobile Communications) based UMTS, and
the 3GPP2 (Third Generation Partnership Project 2) has been known
to publish and set standards for CDMA (Code Division Multiple
Access) based UMTS. Within the scope of a particular
standardization body, specific partners publish and set standards
in their respective areas.
[0009] Consider a wireless mobile device, generally referred to as
user equipment (UE), that complies with the 3GPP specifications for
the UMTS protocol. The 3GPP 25.331 specification, v.3.15.0,
referred to herein as the 25.331 specification, addresses the
subject of UMTS RRC (Radio Resource Control) protocol requirements
between the UMTS Terrestrial Radio Access Network (UTRAN) and the
UE.
[0010] In UMTS each radio bearer (including signalling radio
bearers) may be configured to apply ciphering to all data as part
of the security features of UMTS. Both the UE and the UTRAN store
ciphering configurations for applying ciphering. The 25.331
standard states in section 8.6.3.4 that, at any given time, the UE
needs to store at most two different ciphering configurations
(keyset and algorithm) per Core Network (CN) domain at any given
time in total for all radio bearers and three configurations in
total for all signalling radio bearers.
[0011] The ciphering configurations which are stored are: the
current ciphering configuration (the configuration which is
currently being applied to the data sent or received on the radio
bearer); a new ciphering configuration (if one exists); and an old
configuration.
[0012] As far as a new ciphering configuration is concerned, if the
UTRAN has decided to change the ciphering configuration, there is a
period of time after the new configuration has been sent to the UE
and before the new configuration is used. This period of time
allows the UTRAN and UE radio bearers to synchronise a move to the
new configuration at the same time and so no loss of data is
encountered. The time at which the new configuration becomes
current may be different for each radio bearer as it depends on
traffic flow in that radio bearer.
[0013] The old configuration is also stored because Packet Data
Units (PDUs) which have failed to be received correctly may be
retransmitted by the UTRAN and are ciphered using the configuration
which was current at the time they were first sent. It is therefore
possible that some PDUs which were originally sent before the new
ciphering configuration was activated are resent with the
previously used (old) ciphering configuration.
[0014] Parties may submit proposals to 3GPP and the agenda item
TSGR2#((99)K58 submitted to the TSG-RAN working group 2 of the 3GPP
(which may be found at
<http://www.3gpp.org/ftp/tsg_ran/WG2_RL2/TSGR2.sub.--09/Docs/Zips/R2-9-
9k58.doc>) relates to the activation time for new ciphering
configurations in Unacknowledged Mode (UM) and Acknowledged Mode
(AM).
[0015] There are proposed strategies for dealing with ciphering
configurations. A number of such strategies are detailed below.
[0016] Other aspects and features of the present invention will
become apparent to those ordinarily skilled in the art upon review
of the following description of specific embodiments of an
apparatus and method for applying ciphering in mobile
telecommunications system user equipment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Embodiments of the present invention will now be described,
by way of example only, with reference to the attached drawings, in
which:
[0018] FIG. 1 is an overview of a mobile telecommunications
system;
[0019] FIG. 2 is a block diagram illustrating an embodiment of a
protocol stack apparatus provided with a cell update handling RRC
block, in accordance with the present application;
[0020] FIG. 3 is a flow diagram illustrating storage of cipher
configurations in user equipment;
[0021] FIG. 4 is a flow diagram illustrating management of cipher
configurations in user equipment;
[0022] FIG. 5 is a block diagram illustrating a mobile device,
which can act as a UE and co-operate with the apparatus and methods
of FIGS. 1 to 4.
[0023] The same reference numerals are used in different figures to
denote similar elements.
DETAILED DESCRIPTION OF THE DRAWINGS
[0024] An apparatus and method for applying ciphering in universal
mobile telecommunications system user equipment is described. In
the following description, for the purposes of explanation,
numerous specific details are set forth in order to provide a
thorough understanding of the present invention. It will be
apparent, however, to one skilled in the art that the present
invention may be practised without these specific details. In other
instances, well-known structures and devices are shown in block
diagram form in order to avoid unnecessarily obscuring the present
invention.
[0025] The needs identified in the foregoing Background, and other
needs and objects that will become apparent from the following
description, are achieved by, in one aspect, a method for applying
ciphering in a mobile telecommunications system, the system
comprising a network of a plurality of cells and at least one user
equipment device, in which parameters relating to a plurality of
ciphering configurations for a given type of ciphering
configuration are stored. Thus, for instance, a plurality of new
ciphering configurations, old ciphering configurations or current
ciphering configurations may be stored.
[0026] In other aspects, the invention encompasses apparatus and a
computer-readable medium configured to carry out the foregoing
steps. In particular, the method may be implemented in a mobile
telecommunications device, with or without voice capabilities, or
other electronic devices such as handheld or portable devices.
[0027] Referring to the drawings, FIG. 1 shows an overview of a
network and a UE device. Clearly in practice there may be many UE
devices operating with the network but, for the sake of simplicity,
FIG. 1 only shows a single UE device 500. For the purposes of
illustration, FIG. 1 also shows a network 519 having a few
components. It will be clear to a person skilled in the art that in
practice a network will include far more components than those
shown.
[0028] FIG. 1 shows an overview of the radio access network 519
(UTRAN) used in a UMTS system. The network 519 as shown in FIG. 1
comprises three Radio Network Subsystems (RNS) 2. Each RNS has a
Radio Network Controller (RNC) 4. Each RNS 2 has one or more Node B
6 which are similar in function to a Base Transmitter Station of a
GSM radio access network. User Equipment UE 500 may be mobile
within the radio access network. Radio connections (indicated by
the straight dotted lines in FIG. 1) are established between the UE
and one or more of the Node Bs in the UTRAN.
[0029] The radio network controller controls the use and
reliability of the radio resources within the RNS 2. Each RNC may
also be connected to a 3G mobile switching centre 10 (3G MSC) and a
3G serving GPRS support node 12 (3G SGSN).
[0030] An RNC 4 controls one or more Node B's. An RNC plus its Node
B's together make up an RNS 2. A Node B controls one or more cells.
Each cell is uniquely identified by a frequency and a primary
scrambling code (primary CPICH in FDD, primary CCPCH in TDD).
[0031] Generally in UMTS a cell refers to a radio network object
that can be uniquely identified by a UE from a cell identifier that
is broadcast over geographical areas from a UTRAN access point. A
UTRAN access point is a conceptual point within the UTRAN
performing radio transmission and reception. A UTRAN access point
is associated with one specific cell i.e., there exists one UTRAN
access point for each cell. It is the UTRAN-side end point of a
radio link. A single physical Node B 6 may operate as more than one
cell since it may operate at multiple frequencies and/or with
multiple scrambling codes.
[0032] The UE 500 is configured to store more than one ciphering
configuration of a given type (current, old, new) such that a
plurality of current ciphering configurations are stored and/or a
plurality of old (previously applied) ciphering configurations are
stored and/or a plurality of new (future) ciphering configurations
are stored.
[0033] The UTRAN 519 may also be configured to store more than one
ciphering configuration of a given type (current, old, new) for
each Radio Bearer such that a plurality of current ciphering
configurations are stored and/or a plurality of old (previously
applied) ciphering configurations are stored and/or a plurality of
new (future) ciphering configurations are stored.
[0034] For instance, a plurality of old ciphering configurations
may be stored. If the transmit window for a radio bearer is large
then it is possible that the ciphering configuration may be changed
more than once between the first transmission of a PDU and its
retransmission.
[0035] Additionally or alternatively a plurality of pending new
configurations may be stored. For instance, according to clause
8.1.12.4b of the 25.331 standard, if a cell update procedure is
initiated during the change in security configuration, then the
configuration should be aborted and the UE should resume to the
state it was in before it attempted the change. Storing a plurality
of pending new configurations enables a UE to also revert to using
a pending new configuration which was the pending new configuration
at the time the change was attempted.
[0036] Therefore if the UE had previously been storing a pending
configuration, and a new configuration was received, the UE stores
both pending future configurations until the configuration is
complete so that it may restore the original pending configuration
if the change is aborted. The UTRAN may also store both pending
future configurations until the configuration is complete.
[0037] The size of the transmission window is different for each
radio bearer. This means that the number of old configurations
which are required may be different for each radio bearer. Also
each radio bearer will not necessarily have the same old or current
ciphering configurations as other radio bearers. Since the
activation time for each radio bearer is dependant on traffic flow,
the new configuration may become the current configuration at
different times on different radio bearers. So at any given time
some radio bearers may be using the newest ciphering configuration,
while others may be using the previous one as the new has not
activated yet. Thus the UE and/or network may store more than one
current configuration so that the RBs may have a different current
configuration depending on the activation time for each RB.
[0038] The configurations may activate at different times in
different Radio Bearers. Allowing the storage of a plurality of
configurations for a given type of ciphering configuration means
that it is possible to store new, old and current configurations
for each Radio Bearer, each of which may be different from each
other. Thus configurations relevant for each Radio Bearer may be
stored, rather than only storing three configurations per CN
domain.
[0039] In this way it is easier for the UE and network to determine
which ciphering configuration should be used for each PDU to be
transmitted or retransmitted on a Radio Bearer. If the UE or
network was limited to storing only one new, one current and one
old configuration for all Radio Bearers, the UE or network may
simply not have the required configuration and so it would be
unable to cipher or decipher the data.
[0040] The UE or UTRAN may be arranged to store ciphering
configurations in the layer of the protocol stack that applies the
ciphering. Thus, for instance, the UE may store ciphering
configurations in the Radio Resource Control (RRC), a sublayer of
Layer 3 on the UMTS radio interface. Alternatively the UE may store
the ciphering configurations in the Radio Link Control (RLC) layer,
a sublayer of the radio interface. This latter implementation has
the advantage in Unacknowledged Mode (UM) and Acknowledged Mode
(AM), as in these modes it is the RLC layer that applies the
ciphering to the data and thus less signalling will be required to
determine the ciphering configuration to be applied. In Transparent
Mode (TM), the UE may be arranged to store the ciphering
configurations in the MAC layer as in TM the ciphering is applied
in the MAC layer. The UTRAN also includes a similar protocol stack
with the RLC and the MAC generally being stored in a RNC.
[0041] An example will now be considered of the operation of a UE
which stores parameters relating to more than one instance of a
ciphering configuration of a given type. Consider two radio bearers
RB1 and RB2. At time t=0, each radio bearer has the same old,
current and new configurations (C1, C2 and C3 respectively) with C2
activating at time t=0, but C3 activates at time t2 in RB1 and t4
in RB2. So at time t=0 the UF, is configured as follows:
TABLE-US-00001 RB1 RB2 Time t Old Current New Old Current New 0 C1
C2 C3.sub.t2 C1 C2 C3.sub.t4
[0042] At time t=1 the UE is configured as follows:
TABLE-US-00002 RB1 RB2 Time t Old Current New Old Current New 0 C1
C2 C3.sub.t2 C1 C2 C3.sub.t4 1 C1 C2 C3.sub.t2 C1 C2 C3.sub.t4
[0043] At time t=2:
TABLE-US-00003 RB1 RB2 Time t Old Current New Old Current New 0 C1
C2 C3.sub.t2 C1 C2 C3.sub.t4 1 C1 C2 C3.sub.t2 C1 C2 C3.sub.t4 2
C1.sub.<t0/ C3 -- C1 C2 C3.sub.t4 C2.sub..gtoreq.t0, <t2
[0044] At time t=2, RB1 has two Old ciphering configurations C1 and
C2. C1 will be applied to any PDUs that are subsequently received
but which were transmitted prior to t=0 and C2 will be applied to
any PDUs that are subsequently received but which were transmitted
on or after t=0 and before t=2. C3 is applied to PDUs with a
sequence number representing time after t=2. RB2 has a single old,
new and current configuration.
[0045] At time t=4 the new cipher configuration C.sub.3 will
activate for RB2 and the following cipher configurations are
stored:
TABLE-US-00004 RB1 RB2 Time t Old Current New Old Current New 0 C1
C2 C3.sub.t2 C1 C2 C3.sub.t4 1 C1 C2 C3.sub.t2 C1 C2 C3.sub.t4 2
C1.sub.<t0/ C3 -- C1 C2 C3.sub.t4 C2.sub..gtoreq.t0, <t2 3
C1.sub.<t0/ C3 -- C1 C2 C3.sub.t4 C2.sub..gtoreq.t0, <t2 4
C1.sub.<t0/ C3 -- C1.sub.<t0/ C3 C2.sub..gtoreq.t0, <t2
C2.sub..gtoreq.t0, <t4
[0046] Old ciphering configurations may be discarded as soon as all
PDUs transmitted with that ciphering configuration have been
received by the UE. Thus in the above example, the old ciphering
configuration C1 may be deleted for RB1 once all PDUs transmitted
prior to t=0 have been received. This may be determined by
examining the sequence number of each PDU.
[0047] Now consider the situation in which at time t=3 the UTRAN
changes the new ciphering configuration to C4 with activation times
in each RB as follows:
TABLE-US-00005 RB1 RB2 Time t Old Current New Old Current New 0 C1
C2 C3.sub.t2 C1 C2 C3.sub.t4 1 C1 C2 C3.sub.t2 C1 C2 C3.sub.t4 2
C1.sub.<t0/ C3 -- C1 C2 C3.sub.t4 C2.sub..gtoreq.t0, <t2 3
C1.sub.<t0/ C3 C4.sub.t5 C1 C2 C4.sub.t4 C2.sub..gtoreq.t0,
<t2
[0048] According to the 25.331 standard, if a UTRAN sends a new
configuration (e.g. C4) before a previous one has activated (e.g.
C3), then the UTRAN must use the same activation time. So
therefore, as shown above, the new configuration C4 has an
activation time t4, the same as the previous new configuration C3.
C3 may therefore be deleted from the configurations for RB2 as
being redundant.
[0049] Now after t4 and t5 have passed the stored cipher
configurations are as follows:
TABLE-US-00006 RB1 RB2 Time t Old Current New Old Current New 0 C1
C2 C3.sub.t2 C1 C2 C3.sub.t4 1 C1 C2 C3.sub.t2 C1 C2 C3.sub.t4 2
C1.sub.<t0/ C3 -- C1 C2 C3.sub.t4 C2.sub..gtoreq.t0, <t2 3
C1.sub.<t0/ C3 C4.sub.t5 C1 C2 C4.sub.t4 C2.sub..gtoreq.t0,
<t2 4 C1.sub.<t0/ C3 C4.sub.t5 C1 C4 -- C2.sub..gtoreq.t0,
<t2 C2.sub..gtoreq.t0, <t4 5 C1.sub.<t0/ C4 --
C1.sub.<t0/ C4 -- C2.sub..gtoreq.t0, <t2/ C2.sub..gtoreq.t0,
<t4 C3.sub..gtoreq.t2, t5
[0050] If a PDU which was originally transmitted just after t2 is
retransmitted after t5, C3 will be used if the PDU was transmitted
on RB1 and C2 if the PDU was transmitted on RB2. As shown above, at
t=3 there are two new configurations shown with the same activation
time. The two new ciphering configurations C3 and C4 only exist
whilst the configurations procedure occurs. If the ciphering
configuration C4 is successfully implemented, then C3 is discarded.
If the configuration procedure implementing ciphering configuration
C4 fails, then C4 may be discarded and C3 implemented as the new
ciphering configuration.
[0051] The situation may be similar when implemented in the
network.
[0052] Messages from between the UTRAN and the UE include a
sequence number that is sequential. The time indications given
above may be considered equivalent to the sequence number included
in messages sent by the UTRAN to the UE. As the sequence numbers
are sequential, the UE may determine whether a PDU has been missed
by virtue of this sequence number. When a UE determines from the
sequence number that all messages ciphered with a given cipher
configuration Cn have been received, then the UE may discard the
old ciphering configuration Cn as it is no longer applicable.
[0053] Referring to the drawings, FIG. 2 is a block diagram
illustrating an embodiment of a device's protocol stack provided
with a RRC block, in accordance with the present application.
[0054] The RRC block 200 is a sub layer of Layer 3 130 of a UMTS
protocol stack 100. The RRC 200 exists in the control plane only
and provides an information transfer service to the non-access
stratum NAS 134. The RRC 200 is responsible for controlling the
configuration of radio interface Layer 1 110 and Layer 2 120. When
the UTRAN wishes to change the UE configuration it will issue a
message to the UE containing a command to invoke a specific RRC
procedure. The RRC 200 layer of the UE decodes this message and
initiates the appropriate RRC procedure. When the procedure has
been completed (either successfully or not) then the RRC may send a
response message to the UTRAN (via the lower layers) informing the
UTRAN of the outcome. However, in many cases the RRC need not and
does not reply.
[0055] The RRC block 200 can implement several different behaviour
strategies for implementing ciphering of messages. The number of
ciphering configurations of a given type (current, new, old) may be
limitless or a maximum limit (e.g. 20) may be applied. The UE may
be arranged to delete any old ciphering configurations that are no
longer applicable for any radio bearer in use by the UE on a CN
domain.
[0056] The operation of a UE having the capability to store
ciphering parameters relating to a plurality of ciphering
configurations of a given type (e.g. current, new, old) will now be
described with reference to the drawings.
[0057] FIG. 3 is a flow chart illustrating the operation of a UE
according to one embodiment of handling of cipher configurations by
the UE. At step 302, the UE receives cipher configuration
parameters (for instance according to clause 8.1.12.3 of the 25.331
standard these parameters are contained in the field "Ciphering
mode Info"). At step 304, the ciphering configuration information
is stored in a memory of the UE.
[0058] Periodically, the UE carries out an audit of the stored
cipher configurations. As illustrated in FIG. 4, at step 402 the UE
determines whether each of the stored cipher configurations is
still applicable. As mentioned above, this determination may be
based on the sequence numbers of messages sent and received by the
UE. The UE then, at step 404, removes from the store any ciphering
configurations that are deemed no longer to be applicable.
[0059] Thus the UE may store all the ciphering configurations that
it receives for a given Core Network, but manages the storage so
that ciphering configurations are deleted when it is determined
that they are no longer applicable to messages sent and received by
the UE.
[0060] When this technique is implemented in the network, the
operation of the network may be similar. Thus a network device in
the UTRAN (for instance, the RNC) maintains a protocol stack for a
given device similar to that shown in FIG. 2 and the UTRAN has the
capability to store ciphering parameters relating to a plurality of
ciphering configurations of a given type (e.g. current, new, old).
The UTRAN stores different configurations for different RB's,
domains and UEs. For each RB for each UE the UTRAN may store a
plurality of different ciphering configurations of a given
type.
[0061] Turning now to FIG. 5, FIG. 5 is a block diagram
illustrating a mobile device, which can act as a UE and co-operate
with the apparatus and methods of FIGS. 1 to 9, and which is an
exemplary wireless communication device. Mobile station 500 is
preferably a two-way wireless communication device having at least
voice and data communication capabilities. Mobile station 500
preferably has the capability to communicate with other computer
systems on the Internet. Depending on the exact functionality
provided, the wireless device may be referred to as a data
messaging device, a two-way pager, a wireless e-mail device, a
cellular telephone with data messaging capabilities, a wireless
Internet appliance, or a data communication device, as
examples.
[0062] Where mobile station 500 is enabled for two-way
communication, it will incorporate a communication subsystem 511,
including both a receiver 512 and a transmitter 514, as well as
associated components such as one or more, preferably embedded or
internal, antenna elements 516 and 518, local oscillators (LOs)
513, and a processing module such as a digital signal processor
(DSP) 520. As will be apparent to those skilled in the field of
communications, the particular design of the communication
subsystem 511 will be dependent upon the communication network in
which the device is intended to operate. For example, mobile
station 500 may include a communication subsystem 511 designed to
operate within the Mobitex.TM. mobile communication system, the
DataTAC.TM. mobile communication system, GPRS network, UMTS
network, or EDGE network.
[0063] Network access requirements will also vary depending upon
the type of network 502. For example, in the Mobitex and DataTAC
networks, mobile station 500 is registered on the network using a
unique identification number associated with each mobile station.
In UMTS and GPRS networks, however, network access is associated
with a subscriber or user of mobile station 500. A GPRS mobile
station therefore requires a subscriber identity module (SIM) card
in order to operate on a GPRS network. Without a valid SIM card, a
GPRS mobile station will not be fully functional. Local or
non-network communication functions, as well as legally required
functions (if any) such as "911" emergency calling, may be
available, but mobile station 500 will be unable to carry out any
other functions involving communications over the network 502. The
SIM interface 544 is normally similar to a card-slot into which a
SIM card can be inserted and ejected like a diskette or PCMCIA
card. The SIM card can have approximately 64K of memory and hold
many key configuration 551, and other information 553 such as
identification, and subscriber related information.
[0064] When required network registration or activation procedures
have been completed, mobile station 500 may send and receive
communication signals over the network 502. Signals received by
antenna 516 through communication network 502 are input to receiver
512, which may perform such common receiver functions as signal
amplification, frequency down conversion, filtering, channel
selection and the like, and in the example system shown in FIG. 5,
analog to digital (A/D) conversion. A/D conversion of a received
signal allows more complex communication functions such as
demodulation and decoding to be performed in the DSP 520. In a
similar manner, signals to be transmitted are processed, including
modulation and encoding for example, by DSP 520 and input to
transmitter 514 for digital to analog conversion, frequency up
conversion, filtering, amplification and transmission over the
communication network 502 via antenna 518. DSP 520 not only
processes communication signals, but also provides for receiver and
transmitter control. For example, the gains applied to
communication signals in receiver 512 and transmitter 514 may be
adaptively controlled through automatic gain control algorithms
implemented in DSP 520.
[0065] Mobile station 500 preferably includes a microprocessor 538
which controls the overall operation of the device. Communication
functions, including at least data and voice communications, are
performed through communication subsystem 511. Microprocessor 538
also interacts with further device subsystems such as the display
522, flash memory 524, random access memory (RAM) 526, auxiliary
input/output (I/O) subsystems 528, serial port 530, keyboard 532,
speaker 534, microphone 536, a short-range communications subsystem
540 and any other device subsystems generally designated as
542.
[0066] Some of the subsystems shown in FIG. 5 perform
communication-related functions, whereas other subsystems may
provide "resident" or on-device functions. Notably, some
subsystems, such as keyboard 532 and display 522, for example, may
be used for both communication-related functions, such as entering
a text message for transmission over a communication network, and
device-resident functions such as a calculator or task list.
[0067] Operating system software used by the microprocessor 538 is
preferably stored in a persistent store such as flash memory 524,
which may instead be a read-only memory (ROM) or similar storage
element (not shown). Those skilled in the art will appreciate that
the operating system, specific device applications, or parts
thereof, may be temporarily loaded into a volatile memory such as
RAM 526. Received communication signals may also be stored in RAM
526.
[0068] As shown, flash memory 524 can be segregated into different
areas for both computer programs 558 and program data storage 550,
552, 554 and 556. These different storage types indicate that each
program can allocate a portion of flash memory 524 for their own
data storage requirements. Microprocessor 538, in addition to its
operating system functions, preferably enables execution of
software applications on the mobile station. A predetermined set of
applications that control basic operations, including at least data
and voice communication applications for example, will normally be
installed on mobile station 500 during manufacturing. A preferred
software application may be a personal information manager (PIM)
application having the ability to organize and manage data items
relating to the user of the mobile station such as, but not limited
to, e-mail, calendar events, voice mails, appointments, and task
items. Naturally, one or more memory stores would be available on
the mobile station to facilitate storage of PIM data items. Such
PIM application would preferably have the ability to send and
receive data items, via the wireless network 502. In a preferred
embodiment, the PIM data items are seamlessly integrated,
synchronized and updated, via the wireless network 502, with the
mobile station user's corresponding data items stored or associated
with a host computer system. Further applications may also be
loaded onto the mobile station 500 through the network 502, an
auxiliary I/O subsystem 528, serial port 530, short-range
communications subsystem 540 or any other suitable subsystem 542,
and installed by a user in the RAM 526 or preferably a non-volatile
store (not shown) for execution by the microprocessor 538. Such
flexibility in application installation increases the functionality
of the device and may provide enhanced on-device functions,
communication-related functions, or both. For example, secure
communication applications may enable electronic commerce functions
and other such financial transactions to be performed using the
mobile station 500.
[0069] In a data communication mode, a received signal such as a
text message or web page download will be processed by the
communication subsystem 511 and input to the microprocessor 538,
which preferably further processes the received signal for output
to the display 522, or alternatively to an auxiliary I/O device
528. A user of mobile station 500 may also compose data items such
as email messages for example, using the keyboard 532, which is
preferably a complete alphanumeric keyboard or telephone-type
keypad, in conjunction with the display 522 and possibly an
auxiliary I/O device 528. Such composed items may then be
transmitted over a communication network through the communication
subsystem 511.
[0070] For voice communications, overall operation of mobile
station 500 is similar, except that received signals would
preferably be output to a speaker 534 and signals for transmission
would be generated by a microphone 536. Alternative voice or audio
I/O subsystems, such as a voice message recording subsystem, may
also be implemented on mobile station 500. Although voice or audio
signal output is preferably accomplished primarily through the
speaker 534, display 522 may also be used to provide an indication
of the identity of a calling party, the duration of a voice call,
or other voice call related information for example.
[0071] Serial port 530 in FIG. 5, would normally be implemented in
a personal digital assistant (PDA)-type mobile station for which
synchronization with a user's desktop computer (not shown) may be
desirable, but is an optional device component. Such a port 530
would enable a user to set preferences through an external device
or software application and would extend the capabilities of mobile
station 500 by providing for information or software downloads to
mobile station 500 other than through a wireless communication
network. The alternate download path may for example be used to
load an encryption key onto the device through a direct and thus
reliable and trusted connection to thereby enable secure device
communication.
[0072] Other communications subsystems 540, such as a short-range
communications subsystem, is a further optional component which may
provide for communication between mobile station 500 and different
systems or devices, which need not necessarily be similar devices.
For example, the subsystem 540 may include an infrared device and
associated circuits and components or a Bluetooth.TM. communication
module to provide for communication with similarly enabled systems
and devices.
[0073] When mobile device 500 is used as a UE, protocol stacks 546
include apparatus and a method for handling messages that relate to
a cell other than the currently operating cell in universal mobile
telecommunications system user equipment.
Extensions and Alternatives
[0074] In the foregoing specification, the invention has been
described with reference to specific embodiments thereof. It will,
however, be evident that various modifications and changes may be
made thereto without departing from the scope of the technique. The
specification and drawings are, accordingly, to be regarded in an
illustrative rather than a restrictive sense.
[0075] It is to be noted that the methods as described have shown
steps being carried out in a particular order. However, it would be
clear to a person skilled in the art that the order of the
evaluation is immaterial with respect to the operation of the
method. The ordering of the steps as described herein is not
intended to be limiting.
[0076] It is also to be noted that where a method has been
described it is also intended that protection is also sought for a
device arranged to carry out the method and where features have
been claimed independently of each other these may be used together
with other claimed features.
* * * * *
References