U.S. patent application number 12/312699 was filed with the patent office on 2011-10-27 for telecommunications networks and devices.
Invention is credited to Jonathon Batkin, Jose-Luis Carrizo Martinez, David Fox, Timothy Frost, Gavin Wong.
Application Number | 20110263274 12/312699 |
Document ID | / |
Family ID | 40853867 |
Filed Date | 2011-10-27 |
United States Patent
Application |
20110263274 |
Kind Code |
A1 |
Fox; David ; et al. |
October 27, 2011 |
TELECOMMUNICATIONS NETWORKS AND DEVICES
Abstract
A GSM, UMTS or LTE mobile telecommunications network includes a
radio access network comprising base stations, and further includes
one or more additional access points. An access point may be
connected to the network core by an IP transport broadband
connection. The access point is configured to appear to the mobile
terminal as a base station. Arrangements are disclosed which allow
the network to restrict access to the network via these access
points whilst also minimizing signaling requirements. The access
points may be excluded from traditional Tracking Areas, but
associated therewith by a network controller in a mapping in order
to notify authorized mobile terminals of the Access Point's
existence.
Inventors: |
Fox; David; (Reading,
GB) ; Frost; Timothy; (Madrid, ES) ; Wong;
Gavin; (Surrey, GB) ; Carrizo Martinez;
Jose-Luis; (Berkshire, GB) ; Batkin; Jonathon;
(Wiltshire, GB) |
Family ID: |
40853867 |
Appl. No.: |
12/312699 |
Filed: |
November 22, 2007 |
PCT Filed: |
November 22, 2007 |
PCT NO: |
PCT/GB2007/004471 |
371 Date: |
February 16, 2011 |
Current U.S.
Class: |
455/456.2 |
Current CPC
Class: |
H04W 60/00 20130101;
H04W 84/045 20130101; H04W 48/02 20130101; H04W 68/12 20130101;
H04W 12/08 20130101; H04W 92/24 20130101; H04W 68/04 20130101; H04W
36/14 20130101 |
Class at
Publication: |
455/456.2 |
International
Class: |
H04W 4/02 20090101
H04W004/02; H04W 24/00 20090101 H04W024/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 22, 2006 |
GB |
0623321.7 |
Jan 30, 2007 |
GB |
0701759.3 |
Sep 18, 2007 |
GB |
0718152.2 |
Claims
1. A network controller for use in a telecommunications network
including a radio access network comprising a plurality of base
stations, each defining a cell and being configured to wirelessly
transmit data that is receivable by one or more mobile terminals,
with at least one of the base stations being an Access Point (AP);
and wherein the network controller is configured to: receive a
paging request relating to a given mobile terminal; access first
data indicating the last known location of the given mobile
terminal; access second data indicating any Access Points
associated with the last known location; and where one or more
Access Points are associated with the last known location, paging
those Access Points, in addition to any macro base stations within
the last known location.
2. The network controller of claim 1 wherein the second data the
network controller is configured to access only indicates any
Access Points associated with the last known location that the
given mobile terminal is authorised to access.
3. The network controller of claim 1, further configured to page
one or more default Access Points associated with the given
terminal.
4. (canceled)
5. The network controller of claim 1, wherein the network
controller is further configured to only page a subset of the
Access Points indicated in the second data where the number of
Access Points indicated in the second data is greater than a
predetermined threshold.
6. In a telecommunications network including a radio access network
comprising a plurality of base stations, each defining a cell, and
being configured to wirelessly transit data that is receivable by
one or more mobile terminals, with at least one of the base
stations being an Access Point (AP), a method of paging a given
mobile terminal within the network, the method comprising:
receiving a paging request relating to a given mobile terminal;
accessing first data indicating the last known location of the
given mobile terminal; accessing second data indicating any Access
Points associated with the last known location; and where one or
more Access Points are associated with the last known location,
paging those Access Points, in addition to any macro base stations
within the last known location.
7. The method of claim 6 wherein the second data accessed only
indicates any Access Points associated with the last known location
that the given mobile terminal is authorised to access.
8. The method of claim 6, further comprising: additionally paging
one or more default Access Points associated with the given
terminal.
9. The method of claim 8 wherein the one or more default Access
Points which are additionally paged are one or more Access Points
for which the given mobile terminal is registered as being
authorised to access.
10. (canceled)
11. In a telecommunications network including a radio access
network comprising a plurality of base stations, each defining a
cell, for wirelessly transmitting data that is receivable by one or
more mobile terminals, wherein at least one of the base stations is
an Access Point (AP), a method of controlling access to the
telecommunications network via the at least one Access Point, the
method comprising: defining tracking areas in the network covering
one or more base station cells but which exclude the at least one
Access Point cells.
12. The method of claim 11, further comprising: creating a mapping
associating one or more of the at least one Access Points with one
and more Tracking Areas; and using the mapping to perform at least
one of the following: a) notify an idle mobile terminal that it is
authorised to select the one or more Access Points when in the one
or more Tracking Areas; b) trigger the establishment of a transport
network connection between a base station and each of the one or
more Access Points. c) trigger the establishment of a transport
network connection between a network controller and each of the one
or more Access Points. d) page a mobile terminal within the one or
more tracking areas and at the one or more Access Points where one
of the one or more Tracking Areas was the last Tracking Area
recorded for the mobile terminal; e) where an Access Point is
mapped to a first Tracking Area, notify an idle mobile terminal
that it is authorised to move from the Access Point to another base
station within the first Tracking Area without performing a
Tracking Area update; f) notify a mobile terminal that it is
authorised to access the one or more Access Points and that it
should undertake a search for transmissions by the one or more
Access Points; g) notify a mobile terminal that it should undertake
measurements of transmission received from the one or more Access
Points; and h) notify a base station controlling handover of a
mobile terminal that the mobile terminal is authorised to be handed
over to the one or more Access Points.
13. The method of claim 11, further including comprising: a mobile
terminal transmitting a Tracking Area update request to a network
controller; the network controller determining whether any Access
Points exist, in the vicinity of the mobile terminal's new Tracking
Area; where one or more Access Points exist, creating a mapping
associating the new Tracking Area with the one or more Access
Points; and transmitting the mapping to the mobile terminal.
14-20. (canceled)
21. A telecommunications network, comprising: a radio access
network comprising a plurality of base stations, each defining a
cell, and being configured to wirelessly transmit data that is
receivable by one or more mobile terminals, with at least one of
the base stations being an Access Point (AP), wherein the radio
access network is arranged in a plurality of tracking areas with
each tracking areas covering one or more cells but excluding the
cells of the at least one Access Point.
22. (canceled)
23. A micro base station configured for use in a telecommunications
network including a radio access network comprising one or more
macro base stations configured to wirelessly transmit data that is
receivable by one or more mobile terminals, the micro base station
having a smaller coverage area than the one or more macro base
stations, and wherein the micro base station is configured to
broadcast information from which the at least one mobile terminal
is able to determine if it has access rights to the micro base
station.
24-26. (canceled)
27. The micro base station of claim 23, wherein the micro base
station is configured to additionally broadcast encrypted
authorisation data for use by the one or more mobile terminals to
decrypt with a previously obtained decryption key, if applicable to
each mobile terminal.
28. A mobile terminal configured for use in a telecommunications
network including a radio access network comprising a plurality of
base stations, each defining a cell, and being configured to
wirelessly transmit data that is receivable by the mobile terminal,
with at least one of the base stations being an Access Point (AP);
and wherein the mobile terminal is further configured to: receive
data transmitted by one or more proximate base stations; determine
if the received data includes an Access Indicator Field, being data
that may be transmitted by the one or more Access Points to
restrict access; and using the Access Indicator field to determine
if the mobile terminal is entitled to utilise the Access Point, and
only attempting to utilise the Access Point if the mobile terminal
is entitled to do so.
29. In a telecommunications network including a radio access
network comprising a plurality of base stations configured to
wirelessly transmitting data that is receivable by one or more
mobile terminals, wherein at least one of the base stations is an
Access Point (AP), a method of restricting access to the at least
one Access Point, the method comprising: transmitting information
from each Access Point from which mobile terminals are able to
determine their ability to access the given base station.
30-31. (canceled)
32. A network controller for use in a telecommunications network
including a radio access network comprising a plurality of base
stations, each defining a cell and being configured to wirelessly
transmit data that is receivable by one or more mobile terminals,
with at least one of the base stations being an Access Point (AP);
and wherein the network controller is configured to: receive a
paging request relating to a given mobile terminal; where one or
more Access Points are defined as default locations for the given
mobile terminal, paging those Access Points, in addition to any
macro base stations within the last known location.
33. In a telecommunications network including a radio access
network comprising a plurality of base stations, each defining a
cell, and being configured to wirelessly transit data that is
receivable by one or more mobile terminals, with at least one of
the base stations being an Access Point (AP), a method of paging a
given mobile terminal within the network, the method comprising:
paging the given mobile terminal, at one or more default Access
Points, in addition to any macro base stations within a last known
location area.
34. A base station configured for use in a telecommunications
network including a radio access network comprising a plurality of
base stations, each defining a cell, and being configured to
wirelessly transit data that is receivable by one or more mobile
terminals, with at least one of the base stations being an Access
Point (AP), wherein the base station is configured to: broadcast a
first tracking area intended for use by mobile terminals that are
stationary or travelling at a speed up to and including a threshold
speed; and broadcast a second tracking area intended for use by
mobile terminals that are travelling at a speed greater than the
threshold speed.
35. In a telecommunications network including a radio access
network comprising a plurality of base stations, each defining a
cell, and being configured to wirelessly transit data that is
receivable by one or more mobile terminals, with at least one of
the base stations being an Access Point (AP), a method of tracking
mobile terminals, comprising: broadcasting a first tracking area
intended for use by mobile terminals that are stationary or
travelling at a speed up to and including a threshold speed; and
broadcasting a second tracking area intended for use by mobile
terminals that are travelling at a speed greater than the threshold
speed.
36-39. (canceled)
Description
TECHNICAL FIELD
[0001] This application relates to a telecommunications network
including a radio access network for wirelessly transmitting
between a mobile telecommunications device and a base station. This
application also relates to a method and arrangement for
controlling communication access of a mobile device to one or more
base stations, and further relates to a system and method for
reducing paging in a mobile telecommunications network and in
particular to a system and method for reducing the paging of a
mobile terminal with the mobile is camped on an access
point/femto-cell.
BACKGROUND
[0002] When a calling party (whether a subscriber within the mobile
telecommunications network or outside it) attempts to call a mobile
terminal within the network, that mobile terminal must be paged.
Paging is a process of broadcasting a message which alerts a
specific mobile terminal to take some action, such as to notify the
terminal that there is an incoming call to be received.
[0003] The architecture and steps taken when an incoming call is
directed to a mobile communication device across a GSM/UMTS macro
network are shown in FIGS. 1 and 2. [0004] 1. At step 100, a call
is initiated for a target mobile subscriber B. The call may have
been initiated by another mobile or from a fixed line device.
Typically, this call is initiated by entering the unique contact
number (for example MSISDN) of subscriber B. [0005] 2. The carrier
from where the call is initiated, or an interconnecting carrier,
identifies a particular mobile operator that the contact number for
subscriber B is assigned to (step 110). The carrier identifies a
Gateway Mobile Switching Centre (GMSC) 210 associated with that
mobile operator within the core network 12 and contacts that GMSC
210 (step 120). Gateway MSC 210 then takes on responsibility for
routing the call to the target subscriber. [0006] 3. If the GMSC
210 does not know the subscriber, which is typically the case, it
queries the Home Location Register (HLR) 10 associated with the
mobile operator to which B is a subscriber to determine the Mobile
Switching Centre (MSC), in this case MSC 2, which is currently
handling incoming and outgoing communication for subscriber B and
to which subscriber B is currently registered (step 130). HLR 10
stores the details of the MSCs which are currently handling
communications for each of its subscribers. [0007] 4. At 140 GMSC
210 forwards the call to MSC 2 which is currently handling
communications to and from target subscriber B. The control of the
call is passed to the MSC. [0008] 5. At 150 the MSC identifies the
target subscriber and determines from its Visitor Location Register
(VLR) 14 in which Location Area (LA) subscriber B is located. A
location area is a geographic area covered by at least one cell. A
MSC covers at least one location area. [0009] 6. At 160, MSC 2
instructs the BSC(s) and/or RNC(s) parenting cells belonging to
that LA to page the subscriber on all cells within the location
area in which the subscriber is located. [0010] 7. Paging messages
are then transmitted on the paging channels of all the cells of the
LA in which the customer is located. [0011] 8. The target
subscriber receives and reads the paging message and responds at
170, setting up a radio signalling channel and progressing with the
call control. [0012] 9. The call is established at 180 and a radio
voice channel is established.
[0013] Typically there are tens of MSCs in each country, each being
responsible for several cells in at least one LA. Thus when an
incoming call is directed to a mobile subscriber, only a fraction
of the total number of cells in the network are paged (i.e. those
in the relevant LA under control of the relevant MSC). In this way,
pages for a particular subscriber are not transmitted in cells
under MSCs which do not contain the subscriber.
[0014] There have recently been proposals to allow access to the
features and services provided by GSM and UMTS networks other than
by accessing those networks in the conventional manner described
above. It has been proposed to increase network capacity by
providing additional special base stations (micro base stations),
variously referred to as access points (APs), home access points
(HAPs) or femto-cells, amongst others. These APs are typically
located at a subscriber's home. It has also been proposed to use
APs in the Long Term Evolution (LTE) telecommunications network
currently being developed, but not yet implemented. LTE is likely
to be the next network implementation after 3G.
[0015] APs connect to the core network of a mobile communication
network via IP networks. Typically, APs will be available to mobile
subscribers to plug into their home DSL connection and network
signals are carried to and from the AP via the IP network. The AP
will, typically, provide mobile network coverage throughout the
home, but will have a small coverage area. Thus subscribers will
camp on their AP only when in their home.
[0016] An advantage of using an access point connected to the core
network via an IP network is that existing broadband DSL
connections can be used to link mobile terminals with the network
core without using the capacity of the radio access network or
transmission network of a mobile telecommunications network, or
they are able to provide mobile network access where there is no
conventional radio access network coverage. For example, UMTS
coverage could be provided by an access point where there is no
conventional UMTS coverage (perhaps only GSM coverage).
[0017] Since these access points are not conventional base
stations, however, additional challenges arise. In particular,
communications between the access point and the network are IP
based communications, and may be, for example, transmitted via an
ADSL backhaul connection to an IP network, such as the Internet.
However, the capacity of such ADSL backhauls are limited, and not
under the control of the telecommunications network provider, so
there needs to be restrictions put in place on which user terminals
(UEs) are able to access each AP in order to maintain an acceptable
degree of service quality.
[0018] A problem that arises because of the need of such access
restrictions is that UEs will be split into those which are
authorised to access each AP and those which are not authorised to.
Nevertheless all UEs would attempt to access an AP once it became
available as a preferred base station.
[0019] For instance, considering a UE in a connected state, when an
AP provides the UE with the best signal strength in a given region,
the UE's current Node B/base station will attempt to hand the UE
over to the AP. If the UE is one of the UEs which is not supposed
to use the AP, the handover procedure will be initiated and the
core network or the AP will have to reject the handover. Similarly,
considering a UE in an idle state, when the UE receives the
Location Area broadcast by the AP, and notes it to be different
from its previous Location Area, the UE will look to camp on the AP
and request a Location Area update from the network. If the UE is
not authorized to camp on the AP the update will be rejected by the
core network.
[0020] These access rejections are a waste of signalling resources.
This is particularly a problem where an AP exists in an area of
high traffic or high penetration of APs, as there is likely to be
an unacceptable level of access attempts by UEs, many of which will
result in unnecessary signalling. There therefore needs to be a
better balance between restricting access to APs and limiting the
use of signalling resources in doing so.
[0021] A further problem faced by mobile communication networks is
how to handle paging through APs.
[0022] By definition, the location of mobiles on idle mode is only
known with the resolution of the LA. When a mobile moves between
LAs, i.e. when it reselects a cell belonging to a different LA to
that where it is registered, it initiates a LA update procedure to
inform the network about such a move.
[0023] Therefore, when a call has to be terminated towards a mobile
in idle mode, the phone needs to be paged on all cells of the LA.
The load of the paging channels in any given cell is proportional
to the number of cells in the location area, so when numerous APs
are added to the network, the network load naturally increases.
However, if this load becomes too high, the LA would need to be
split or cells re-parented into another LA.
[0024] Due to the limitations of the network and to the expectation
that each RNC concentrator will control in the order of hundreds of
thousands of APs, it is likely that a high number of APs may belong
to the same LA. Mobile terminal traffic will therefore create a
considerable paging load on the femto-layer.
[0025] Accordingly, it would be desirable to provide a system that
addresses these problems.
SUMMARY OF THE INVENTION
[0026] According to the system described herein, in a
telecommunications network including a radio access network
comprising a plurality of base stations, each defining a cell, for
wirelessly transmitting data that is receivable by one or more
mobile terminals, wherein at least one of the base stations is an
Access Point (AP), a method of controlling access to the
telecommunications network via the at least one Access Point
includes: defining tracking areas in the network covering one or
more base station cells but excluding the at least one Access Point
cells.
[0027] The method may include: creating a mapping associating one
of the at least one Access Points with one and more Tracking Areas,
and using the mapping to perform at least one of the following:
[0028] a) notify an idle mobile terminal that it is authorised to
select the one Access Point when in the one or more Tracking Areas;
[0029] b) trigger the establishment of a transport network
connection between a base station and one of the at least one
Access Points. [0030] c) trigger the establishment of a transport
network connection between an MME and one of the at least one
Access Points. [0031] d) page a mobile terminal where one of the
one or more Tracking Areas was the last Tracking Area recorded for
the mobile terminal; [0032] e) notify an idle mobile terminal that
it is authorised to move about the mapping without performing a
Tracking Area update; [0033] f) notify a mobile terminal that it
should undertake a search for transmissions by the one Access
Point; [0034] g) notify a mobile terminal that it should undertake
measurements of transmission received from the one Access Point;
and [0035] h) notify a base station controlling handover of a
mobile terminal that the mobile terminal is authorised to be handed
over to the one Access Point.
[0036] According further to the system described herein, in a
telecommunications network including a radio access network
comprising a plurality of base stations configured to wirelessly
transmitting data that is receivable by one or more mobile
terminals, wherein at least one of the base stations is an Access
Point (AP), a method of restricting access to the at least one
Access Point includes: transmitting information from each Access
Point from which mobile terminals are able to determine their
ability to access the given base station.
[0037] The information transmitted may be an Access Indicator
Field. It may also be provided that unless it is determined that
the mobile terminal has a right of access to the base station, the
mobile terminal does not attempt to access the base station.
[0038] The Access Indicator Field can be used by the mobile
terminal to determine if it is authorised to use the Access Point
without the need for the mobile terminal signalling an intent to
use the AP and determining its authorisation status from the core
network. The system described herein therefore reduces the use of
signalling resources.
[0039] According further to the system described herein, a
telecommunications network includes a radio access network
comprising a plurality of base stations, each defining a cell, and
being configured to wirelessly transmit data that is receivable by
one or more mobile terminals, with at least one of the base
stations being an Access Point (AP), and wherein the radio access
network is arranged in a plurality of tracking areas with each
tracking areas covering one or more cells but excluding the cells
of the at least one Access Point.
[0040] Each Access Point may be a base station connected by IP
transport to the network.
[0041] According further to the system described herein, a
telecommunications network includes a radio access network
comprising a plurality of base stations configured to wirelessly
transmit data that is receivable by one or more mobile terminals,
with at least one of the base stations being an Access Point (AP),
and wherein the least one Access Point is configured to broadcast
information from which the at least one mobile terminal is able to
determine if it has access rights to each of the at least one
Access Points.
[0042] The Access Point may be configured to broadcast an Access
Indicator Field from which the one or more mobile terminal is able
to determine if it has access rights.
BRIEF DESCRIPTION OF THE FIGURES
[0043] Embodiments of the system described herein will be explained
by way of example with reference to the accompanying drawings, in
which:
[0044] FIG. 1 is a flowchart showing the steps taken when an
incoming call is direct to a mobile terminal across a macro network
according to the prior art;
[0045] FIG. 2 is a simplified macro network useful in explaining
the operation of the flowchart of FIG. 1;
[0046] FIG. 3 is a diagrammatic drawing of elements of a mobile
telecommunications network for use in explaining the operation of
such a network;
[0047] FIG. 4 shows a modified mobile telecommunications network
for receiving IP based communications from an access point in
addition to communications from a conventional base station;
[0048] FIG. 5 shows an exemplary signalling diagram in relation to
an UE in an idle state moving into the tracking area of a new base
station;
[0049] FIG. 6 shows an exemplary signalling diagram in relation to
a UE in an active state moving into the tracking area of a new base
station;
[0050] FIG. 7 shows the network architecture of a mobile
communication network incorporating APs and the paging path to
subscribers who are camped on those APs; and
[0051] FIG. 8 illustrates a flowchart setting out the steps taken
during the paging process for a subscriber camped on an AP
according to an embodiment.
[0052] In the drawings like elements are generally designated with
the same reference sign.
DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS
[0053] Certain elements of a mobile telecommunications network, and
its operation, will now briefly be described with reference to FIG.
3.
[0054] Each base station (BS) corresponds to a respective cell of
its cellular or mobile telecommunications network and receives
calls from and transmits calls to a mobile terminal in that cell by
wireless radio communication in one or both of the circuit switched
or packet switched domains. Such a subscriber's mobile terminal
(UE) is shown at 1. The mobile terminal may be any portable device
with networking capabilities, such as a handheld mobile telephone,
a personal digital assistance (PDA) or a laptop computer equipped
with a datacard.
[0055] In a GSM mobile telecommunications network, each macro base
station comprises a base transceiver station (BTS) and a base
station controller (BSC). A BSC may control more than one BTS. The
BTSs and BSCs comprise the radio access network.
[0056] In a UMTS mobile telecommunications network, each macro base
station comprises a node B and a radio network controller (RNC). An
RNC may control more than one node B. The node Bs and RNCs comprise
the radio access network.
[0057] In the proposed LTE mobile telecommunications network, each
macro base station comprises an eNode B. The macro base stations
are arranged in groups and each group of macro base stations is
controlled by one or more core network management entities, such as
a Mobility Management Entity (MME) and possibly a User Plane Entity
(UPE).
[0058] Conventionally, in a GSM/UMTS network, the base stations are
arranged in groups and each group of base stations is controlled by
one mobile switching centre (MSC), such as MSC 2 for base stations
3, 4 and 5. As shown in FIG. 1, the network has another MSC 6,
which is controlling a further three base stations 7, 8 and 9. In
practice, the network will incorporate many more MSCs and base
stations than shown in FIG. 1. The base stations 3, 4, 5, 7, 8 and
9 each have dedicated (not shared) connection to their MSC2 or
MSC6--typically a cable connection. This prevents transmission
speeds being reduced due to congestion caused by other traffic.
[0059] Each subscriber to the network is provided with a smart card
or SIM which, when associated with the user's mobile terminal,
identifies the subscriber to the network. The SIM card is
pre-programmed with a unique identification number, the
"International Mobile Subscriber Identity" (IMSI) which is not
visible on the card and is not known to the subscriber. The
subscriber is issued with a publicly known number, that is, the
subscriber's telephone number, by means of which calls to the
subscriber are initiated by callers. This number is the MSISDN.
[0060] The network includes a home location register (HLR) 10
which, for each subscriber to the network, stores the IMSI and the
corresponding MSISDN together with other subscriber data, such as
the current or last known MSC or SGSN of the subscriber's mobile
terminal.
[0061] When the subscriber wishes to activate their mobile terminal
in a network (so that it may make or receive calls subsequently),
the subscriber places their SIM card in a card reader associated
with the mobile terminal (terminal 1 in this example). The mobile
terminal 1 then transmits the IMSI (read from the card) to the base
station 3 associated with the particular cell in which the terminal
1 is located. In a traditional network, the base station 3 then
transmits this IMSI to the MSC 2 with which the BS 3 is registered.
In a network using the functionality described in 3GPP TS 23.236,
the base station follows prescribed rules to select which MSC to
use, and then transmits this IMSI to the selected MSC.
[0062] MSC 2 then accesses the appropriate storage location in the
HLR 10 present in the network core 12 and extracts the
corresponding subscriber MSISDN and other subscriber data from the
appropriate storage location, and stores it temporarily in a
storage location in a visitor location register (VLR) 14. In this
way, therefore the particular subscriber is effectively registered
with a particular MSC (MSC 2), and the subscriber's information is
temporarily stored in the VLR (VLR 14) associated with that
MSC.
[0063] When the HLR 10 is interrogated by the MSC 2 in the manner
described above, the HLR 10 additionally performs an authentication
procedure for the mobile terminal 1. The HLR 10 transmits
authentication data to the MSC 2 in "challenge" and "response"
forms. Using this data, MSC 2 passes a "challenge" to the mobile
terminal 1 through base station 3. Upon receipt of this data, the
mobile terminal 1 passes this data to its SIM and produces a
"response". This response is generated using an encryption
algorithm on the SIM and a unique Ki on the SIM. The response is
transmitted back to the MSC 2 which checks it against its own
information for the subscriber which checks it against information
that it has obtained for that subscriber from the HLR 10 in order
to complete the authentication process. If the response from the
mobile terminal 1 is as expected, the mobile terminal 1 is deemed
authenticated. At this point the MSC 2 requests subscription data
from the HLR 10. The HLR 10 then passes the subscription data to
the VLR 14.
[0064] The authentication process will typically be repeated at
regular intervals while the mobile terminal 1 remains activated and
can also be repeated each time the mobile terminal makes or
receives a call, if required.
[0065] Each of the MSCs of the network (MSC 2 and MSC 6) has a
respective VLR (14 and 11) associated with it and operates in the
same way as already described when a subscriber activates a mobile
terminal in one of the cells corresponding to one of the base
stations controlled by that MSC.
[0066] When the subscriber using mobile terminal 1 wishes to make a
call, having already inserted the SIM card into the reader
associated with this mobile terminal and the SIM has been
authenticated in the manner described, a call may be made by
entering the telephone number of the called party in the usual way.
This information is received by the base station 3 and passed on to
MSC 2. MSC 2 routes the call towards the called party. By means of
the information held in the VLR 14, MSC 2 can associate the call
with a particular subscriber and thus record information for
charging purposes.
[0067] The MSCs 2 and 6 support communications in the circuit
switched domain--typically voice calls. Corresponding SGSNs 16 and
18 are provided to support communications in the packet switched
domain--such as GPRS data transmissions. The SGSNs 16 and 18
function in an analogous way to the MSCs 2 and 6. The SGSNs 16, 18
are equipped with an equivalent to the VLR for the packet switched
domain.
[0068] A known paging process in a UMTS/GSM network was describe in
relation to FIGS. 1 and 2. If the network knows in which cell the
mobile terminal is located, it is only necessary to page in that
cell. However, if the mobile terminal is moving within the network,
the precise cell in which the mobile terminal is located may not be
known. It may therefore be necessary to perform paging in a number
of cells. The greater the number of cells in which paging occurs,
the greater the waste of valuable signalling capacity within the
network.
[0069] In a UMTS/GSM network, the problems of excessive use of
signalling capacity is addressed in a known manner by dividing the
coverage area of the mobile telecommunications network into a
plurality of location areas (LAs) and into a plurality of routing
areas (RAs). The equivalent areas in the proposed LTE network are
described as tracking areas (TAs).
[0070] A location area in a UMTS/GSM network relates to a
particular geographical area for communications in the
circuit-switched domain. Typically, although not necessarily, a
location area is larger than the area of a single cell but is
smaller than the area covered by one MSC. Each cell within the
network broadcasts data indicative of the identity of its location
area. The mobile terminal uses this data to determine when it has
moved into a new location area. The terminal stores its last known
location area on its SIM. This information stored on the SIM is
compared with the location area information broadcast by the local
cell. The identities of the two location areas are compared. If
they are different, the mobile terminal determines that it has
entered a new location area. The mobile terminal then gains access
to a radio channel and requests a location update. If the MSC/VLR
is the same for the new and old location areas, the network can
immediately authenticate the mobile terminal and note the change of
location area. However, if the mobile terminal is moved to a
different MSC/VLR, the MSC/VLR addresses a message to the HLR. The
HLR notes the new location and downloads security parameters to
allow the network to authenticate the mobile. It also passes on
subscription details of the user to the new VLR and informs the old
VLR to delete its records.
[0071] A routing area in a UMTS/GSM network relates to a particular
geographical area for communications in the packet-switched domain.
Typically, although not necessarily, a routing area is larger than
the area of a single cell but is smaller than the area covered by
one SGSN. A routing area is typically, although not necessarily,
smaller than a location area. There may be many routing areas
within one location area. Each cell within the network broadcasts
data indicative of its routing area (in addition to the data
mentioned above indicative of the identity of its location area).
The mobile terminal uses this received data to determine when it
has moved to a new routing area. The terminal stores the last known
routing area on its SIM. The information stored on the SIM is
compared with the routing area information broadcast by the local
cell. The identities of the two routing areas are compared. If they
are different, the mobile terminal determines that it has entered a
new routing area. The mobile terminal then gains access to a radio
channel and requests a routing area update.
[0072] The functionality just described may also apply to the
proposed LTE mobile telecommunications network, with its eNode Bs
performing the functionality of the base stations and the MME/UPE
performing the functionality of the MSCs/VLRs. It is also to be
appreciated that the functionality just described is one example of
a network in which the embodiments of the invention may be
implemented.
[0073] The expression "Tracking Area" will be used as a general
term to encompass LAs and RAs in a GSM/UNITS network, as well as
the corresponding areas in an LTE network.
[0074] FIG. 4 shows elements for providing access to a GSM or UNITS
network by both a conventional macro base station 3 and a micro
base station (AP 20). The Access Point, AP 20 provides a radio link
21 to mobile terminal 1.
[0075] The radio link 21 from the AP 20 to the mobile terminal 1
uses the same cellular telecommunication transport protocols as the
conventional base station 3 but with a smaller range--for example
25m. The AP 20 appears to the mobile terminal 1 as a conventional
base station, and, on a general level, no modification to the
mobile terminal 1 is required in order for it to operate with the
AP 20. The AP 20 performs a role corresponding to that of a GSM BTS
22 and BSC 26 and/or UMTS Node B and RNC and/or an LTE Node B.
[0076] Communications between the access point 20 and the core
network 12 are IP based communications, and may be, for example,
transmitted over a broadband IP network (and routed via the
Internet). The communications are routed via MSC 32 or SGSN 34. The
access point 20 converts the cellular telecommunications transport
protocols used between the mobile terminal 1 and the AP 20 to IP
based signalling.
[0077] The connection 23 between the access point 20 and the core
network 12 may use the PSTN telephone network. Typically a DSL
cable connection connects the access point 20 to the PSTN network.
The data is transmitted between the access point 20 and the core
network 12 by IP transport/DSL transport (a backhaul connection).
The bandwidth of the cable connection between the access point and
the telephone exchange is shared with multiple other users
(typically between 20 and 50 other users). This means that the
speed of transmission of data between the access point 20 and the
telephone exchange varies significantly in dependence upon the
activities of the other access point devices sharing the
connection.
[0078] The access point 20 may be connected to the core network 12
by means other than a DSL cable and the PSTN network. For example,
the access point 20 may be connected to the core network 12 by a
dedicated cable connection that is independent of the PSTN, or by a
satellite connection between the access point 20 and the network
core 12.
[0079] A conventional macro base station is connected by an
exclusive, dedicated connection to the MSC 2/SGSN 16/MME (not
shown) and network core 12. The connection is not shared with other
base stations, and therefore its speed will not depend upon other
traffic of other devices.
[0080] AP 20 would typically be configured to serve a Wireless
Local Area Network (WLAN) located in a home or office, in addition
to GSM/UMTS/LTE networks. The WLAN could belong to the subscriber
of the mobile terminal 1, or be an independently operated WLAN. The
owner of AP 20 can prescribe whether the AP is either open or
closed, whereby an open AP is able to carry communications from any
mobile device in the GSM/UMTS/LTE network, and a closed AP is only
able to carry communications from specific pre-designated mobile
devices.
[0081] With this background in mind, an implementation of the first
embodiment of the invention will now be described, which seeks to
minimise unnecessary signalling in regard to closed APs.
[0082] Conventionally, when a mobile terminal is in idle mode and
moves from a first location area to a second location area, the
mobile terminal detects that a different Location Area identity (LA
ID) (from that stored in the mobile terminal) is being broadcast by
the local base station/AP. The mobile terminal then sends a
location area update request to the core network 12/MME. The
request includes the first (current) LA ID and the mobile
terminal's current Temporary Mobile Subscriber Identity (TMSI). The
MSC/MME with which the mobile terminal is currently registered then
sends a new TMSI to the mobile terminal 1. When the mobile terminal
moves from a first (current) location area to a second location
area, and the second location area is administered by a different
MSC/MIME, similar steps occur and in addition the different MSC/MME
requests user profile information from the, original MSC/MME.
[0083] Each cell provided by the core network has a unique cell
global identity (CGI), whereby the CGI is typically a concatenation
of the Location Area ID and a Cell ID and uniquely identifies a
given cell. Traditionally, each AP has its own cell and also has
its own unique Tracking Area identifier, which is broadcast (along
with its cell ID), so that all passing mobile terminals are able to
identify the AP and to attempt to access the network via the AP
when proximate to it. In other words, the APs are traditionally
treated the same as the Node Bs.
[0084] For instance, in idle mode, the UEs traditionally monitor
the system information broadcast by the APs and the eNode Bs, so
that the UEs are able to assess the network conditions and be ready
to access the network by the most appropriate route. UEs are often
described as "camping" on an AP or Node B when that AP or Node B
provides the most suitable prospective access point.
[0085] In idle mode, the UE may be stationary, or be moving
throughout the network. In whatever location the UE is, the UE will
be able to receive system information broadcast from Node Bs and
APs that are in range.
[0086] According to this first embodiment of the invention, APs are
configured to broadcast an indication in the downlink from which
each UE is able to determine if they have the right to access the
network via the AP or not. According to this first embodiment of
the invention, the information which the APs broadcast includes an
Access Indicator Field, which is broadcast in addition to the AP's
cell ID and TA ID. Other information, such as a Neighbouring Cell
List may also be broadcast.
[0087] This Access Indicator Field serves to prevent the UEs from
treating the AP in the same manner as an eNode B. In this regard
the UEs are configured, upon receiving the Access Indicator Field,
to determine if they are authorised to access the network via the
AP before attempting to do so.
[0088] Considering a UE in idle mode detecting the signal broadcast
by the AP, the UE will note the different Tracking Area from its
previously recorded position. Rather than immediately requesting a
TA area update, however, the UE will note the Access Indicator
Field and determine from this field and the CGI field if it is
authorised by the network to access the network via this AP.
[0089] For example, the Access Indicator Field may be a simple
password which the UE needs to match with a pre-stored password to
determine if access to the network via the AP has previously been
granted.
[0090] Alternatively, from the Access Indicator Field, the UE may
simply be notified that the transmitting Base Station is a
micro-base station or AP. It may then use the broadcast information
to determine if it is authorised to utilise the AP, such as by
using the CGI field. In this regard, the UE could compare the CGI
field or a component of the CGI field, such as its Cell ID
component, to a list relating to any APs that the UE is authorised
to access. This Access list may be stored on the UE itself, or
remotely so that the UE queries a remote network entity to
determine if it is authorised to use the AP.
[0091] Where the Access list is stored on the network, subscribers
are mapped to appropriate APs, typically by storing each
subscriber's MSISDN with an appropriate identifier of all APs with
which it is registered (such as the AP ID).
[0092] In addition, the Access Indicator Field may include a
decryption key that the UE uses to decrypt an access password
previously stored on the UE, to determine if the user has
previously been authorised to use this AP, or it may be an
encrypted password code which the UE needs to use its own
previously stored decryption key to decode.
[0093] If the UE determines that it is not authorised to use this
AP, the UE will simply treat the AP as a cell from a forbidden TA
(i.e. it will not perform future measurements of the AP) and
maintain its existing Tracking Area record. If it is authorised,
however, then the UE may request a TA update from the core
network/MME. Therefore it is apparent that the broadcast Access
Indicator Field can be used by the UE to determine if it is
authorised to use the AP without the need for the UE signalling an
intent to use the AP and determining its authorisation status from
the core network/MME.
[0094] When a UE is authorised to camp on an AP, and a TA update is
performed, an entity managing the UE, such as the GMSC/MME may also
create a mapping between the AP and the UE's last recorded Cell's
Tracking Area and provide a copy of this mapping to the UE. This
mapping associates the AP with the TA, and effectively indicates
that the UE's present AP is in or adjacent the TA of its last
recorded cell, and can then be used by the UE to restrict the
number of TA updates that it performs, by not requiring a TA update
to occur when the UE moves between the AP and the UE's last
recorded TA. This mapping is recognition of the fact that the range
of the AP is typically small, so the likelihood of the UE moving
out of the range of the UE and back into the range of the
previously recorded Cell is high. The mapping can therefore be used
to further minimise signalling between the UE and the MME.
[0095] This Tracking Area mapping may be stored alongside the AP
Access list, on the UE itself and/or within the network. That is,
in addition to the AP access list associating a UE/subscriber ID
with an AP ID, the list can associate each AP ID with one or more
TAs. This Access list would typically be updated whenever the
network receives new AP authorisation data or tracking information,
as applicable.
[0096] According to a second embodiment of the invention, APs are
excluded from the predefined location areas/tracking areas
(LAs/TAs) configured by the operator. By excluding the APs from the
TAs it is possible to control a UE's ability to access the APs. The
Tracking Areas are hence restricted to base stations in the
macro-layer.
[0097] Therefore according to this second embodiment of the
invention, the APs are not given a LA ID/TA ID or their LA ID/TA ID
is set to "null". Each AP in this embodiment only broadcasts its
Cell ID, and not a unique LA/TA ID. Since the APs only have a
unique cell global identity, the UEs do not consider them to be
accessible merely by virtue of the information broadcast.
Therefore, by virtue of not broadcasting a TA ID, the UEs will not
consider the AP as a possible point of access; further information
needs to be acquired by the UE before the AP will be considered a
possible point of access. In other words, since there is no unique
LA/TA ID information, the UE will initially treat the AP as if it
belonged to a Forbidden LA/TA.
[0098] An example of the signalling that may occur in the idle
state situation for this second embodiment of the invention is
illustrated in FIG. 5 in relation to the UE moving into the TA of a
new base station/eNode B of a telecommunications network. This
Figure illustrates how the UE is made aware of the AP if it is a
possible point of access to the network.
[0099] The eNode B broadcasts system information which includes the
eNode B's Cell ID and Location Area/Tracking Area ID, as well as
possibly a "Neighbour Cell List" in the system information. The UE
uses the broadcasted system information to know which cells to
monitor, such as by keeping a record of signal strength and/or
interference parameters. This system information only includes
information about neighbouring eNode B's and perhaps nearby open
APs; nearby closed APs are excluded. It is however preferable that
all nearby APs are excluded, due to their more limited capacity, so
the rest of this embodiment will be described with this
presumption.
[0100] The UE will know that it has moved to a new TA, as the TA
broadcast by the eNode B will be different to its last recorded
eNode B. The UE will therefore perform a Mobility Management (MM)
Procedure, such as a location area/tracking area update, so that
the network knows the new location of the UE, for future paging
requirements. With reference to FIG. 5, to perform the Tracking
Area Update, the UE transmits a "Tracking Area Update" request
message to the eNode B to which it has moved.
[0101] Once received, the eNode B forwards the "Tracking Area
Update" message to a core network component, such as the MME. The
MME stores a record of the new TA, and also refers to a list of APs
accessible to the UE from the new location (if any). In this regard
the MME preferably has a list of all APs accessible in each of its
location areas/tracking areas, and all UEs that are authorised to
access each of those APs. The MME will create a mapping between the
new Tracking Area of the UE and the accessible APs associated with
that TA, and include the mapping in the UE context. The UE context
will be stored at the MME and a copy forwarded to the eNode B in
the "Tracking Area Accept" update message. The mapping is stored at
the MME for future use, and can be updated as new information is
received. For instance, the stored UE context can be used during
handover to selectively download information to the new eNode B/AP
for use in subsequent handovers.
[0102] In the FIG. 5 example, the UE is allowed to access the Home
AP, and so the MME will map an association between the Home AP and
the UE's current macro-layer TA. Therefore, when the MME transmits
the "Tracking Area Accept" update message back to the UE, via the
eNode B, this message includes the UE context, as well as the Cell
ID of the Home AP, being Cell ID#2, and the associated macro-layer
Tracking Area, being TA ID#1. The inclusion of the AP's cell ID in
this message is used to inform the UE that an AP cell is available
and that it should look for that AP in addition to the cells
controlled by neighbouring eNode Bs identified in the system
information. This therefore induces the UE to do a search for the
AP in order to detect its broadcast signal.
[0103] Therefore, in this way the network notifies the UE as to
which APs it is able to access. By doing so, the typical "trial and
error" signalling approach is avoided, as the UEs will not try to
access an AP until they have been notified that they can access the
AP. A further advantage of excluding the APs from the Tracking
Areas, is that more efficient searching can be achieved, as the UEs
do not consider APs as possible points of access until told by the
network.
[0104] When the UE is notified of the existence of an AP, and that
it is an AP that the UE is allowed to access, the UE adds the Home
AP to its list of entities on which it keeps a measurement report.
The UE also utilises the mapping between the Home AP and the
Tracking Area of the Node B to restrict the number of TA updates
that it performs, by not requiring a TA update to occur when the UE
reselects between the Home AP and the last recorded Cell's Tracking
Area. This mapping is recognition of the fact that the range of the
AP is typically small, so the likelihood of the UE moving out of
the range of the UE and back into the range of the previously
recorded Cell is large. The mapping can therefore be used to
further minimise signalling between the UE and the MME.
[0105] In an alternative, it is to be appreciated that the UE may
have access to a list of APs that it is allowed to use, so that the
UE is notified by the core network of all APs in the UE's vicinity,
and it is the responsibility of the UE to determine its eligibility
to access each AP, such as was illustrated in the first embodiment
of the invention. This list may be stored on the UE itself, or be
remotely available to the UE, such as securely located on a remote
server. It is, however, preferred that the information on
accessible APs comes from the network, rather than the UE
determining this itself, as this ensures signalling is kept to a
minimum.
[0106] Where the core network performs the access determination,
the UE will still typically have a list relating to the accessible
APs, although this list will essentially be used for keeping a
record of access passwords and the like.
[0107] The mapping between the Home AP and the Tracking Area of the
eNode B has an additional advantage from the MME's perspective. In
this regard, if a communication arrives for the UE, the MME will
send a paging message in both the last recorded Tracking Area for
the UE, being TA ID#1, and to any APs mapped to that Tracking Area,
which in this case will be the Home AP (as referenced in FIG. 5).
This allows the MME to trace the UE if it has camped on the AP,
despite the AP being not part of a Tracking Area. The mapping
therefore effectively creates a new Tracking Area, encompassing
nearby APs which are accessible by the UE, which is unique to the
UE.
[0108] Therefore, in general, when the UE, in idle mode, moves to a
geographical location where the UE could reselect to the Home AP,
the MME is responsible for ensuring that the necessary association
between the new geographic location and the Home AP exists.
[0109] In a further variation, the size of the Macro-layer Tracking
Area may be varied by the MME, depending upon the number of APs
which the UE is allowed to access in that area. For instance, if
the number of accessible APs mapped to a given Tracking Area is
large, then the core network may decide to split that Tracking Area
into two or more sections, or move some of the macro base stations
within that Tracking Area to an alternative Tracking Area.
[0110] In a related variation, the physical size of a Tracking Area
is typically decreased in urban areas in order to maintain a
similar level of paging load to less-populated areas, as the
concentration of UEs in urban areas is dramatically increased. One
problem that arises from smaller Tracking Areas, however, is that
for fast moving UEs, a higher signalling load on the core network
results. Therefore, alternatively, or in addition, Tracking Areas
for a UE can be determined based upon its speed, so that the faster
the UE is travelling, the larger the physical Tracking Area
allocated to the UE. In an implementation of this, eNode Bs will
broadcast a number of different sizes of Tracking Areas, such as a
smaller one for low mobility UEs and a larger one for higher
mobility UEs.
[0111] For instance, a first Tracking area could be defined for use
by terminals that are stationary or travelling at a speed up to and
including a threshold speed, say of 20 kmh. A second Tracking Area
could also be defined for use by terminals that are travelling at a
speed greater than this threshold speed.
[0112] The speed of the terminal could be determined and
communicated to the terminal by any appropriate means. For
instance, the core network could determine the terminal's speed and
notify it of such, such as via an OTA communication, so that the
terminal could then determine the applicable Tracking Area.
Alternatively, the terminal itself may be installed with a suitable
application for determining its speed.
[0113] In a still further variation, which is particularly
applicable in the situation of a UE being permanently associated
with a Home AP, rather than the core network notifying the UE of
the mapping between the Home AP and a proximate Tracking Area, in
the interests of efficiency, this information may be provisioned to
the UE by utilising an Over-The-Air (OTA) upload to the UE's
SIM.
[0114] So far, this description of the embodiments of the
invention, with the UE operating in Idle mode, has assumed that the
UE is only associated with a single Tracking Area at any one time.
However it is possible that the UE is associated with more than one
Tracking Area. In this implementation, the identifiers of multiple
Tracking Areas are broadcast in the system information of a cell.
When the UE performs a Mobility Management (MM) procedure, such as
a Tracking Area Update, the UE may become associated with more than
one TA within which the idle mode UE is free to move within without
contacting the network. When the UE is allocated multiple Tracking
Areas, the MME needs to maintain a list of which TA IDs have been
allocated to the UE. This is because, when it becomes necessary for
the MME to page the UE, the MME would look up which eNode Bs form
part of the Tracking Areas allocated to the UE in order to page
them. The paging message would be passed to all the applicable
eNode Bs in order to locate the UE.
[0115] Once the UE is in a connected state, the mobility of the UE
is managed by the network, and so there are different
considerations in regard to how the APs with no allocated Tracking
Area ID, are managed. In this regard, in a connected state, the UE
will be connected to the network via an eNode B or AP which
provides the best signal. When the signal falls below a certain
threshold, the UE will handover its connection to an alternative
eNode B or AP.
[0116] With reference to FIG. 6, the eNode B provides the UE with
the best signal in this instance, and so has been handed over to
it. Upon handover, the MME provides the eNode B with a "UE
context", which contains information about the UE and neighbouring
cells.
[0117] Since APs are not included in the Tracking Area associated
with the eNode B, this UE context also contains information about
any nearby APs that the UE is allowed to be connected to, which in
this instance is only the Home AP.
[0118] The eNode B will provide the UE with an updated Neighbour
Cell List, which includes the identities of any accessible APs,
being the Home AP in this example. The UE can then provide a
measurement report to the eNode B about the Home AP when it is
discovered. During its idle time slots, a connected UE scans the
Broadcast Control Channel (BCCH) of all the cells in its unique
neighbouring cell list.
[0119] This neighbour cell list can be used to filter the UE's
measurement reports--in that it only keeps reports on entities
included in this cell list. These measurement reports are provided
to the eNode B, as when the UE is in a connected state, it is the
job of the eNode B to monitor the measurement reports and decide
when handover is necessary.
[0120] It is to be appreciated that the identity details of all the
accessible APs is preferably only provided to the UE when the
amount of APs that the UE can access is small. If however, there
are a large number of APs to which the UE can connect to, then a
filtering mechanism is preferably used, whereby the MME, for
instance, filters which AP details will be downloaded to the UE.
One approach for doing this is to build a table of Tracking
Areas/eNode Bs for each AP location, which is used to control from
which cells it is possible to perform a handover to the AP. This
table could also be used to provide the UE with information as to
which subset of APs for which it should be scanning the network.
This would therefore minimise wastage of the UE's battery, as less
scanning would be required.
[0121] This list may also be used by the eNodeB to trigger the
establishment of the X2 interface between the eNodeB and the AP.
The X2 interface is the transport network connection between eNode
Bs. It is also used for APs to communicate with eNode Bs. As APs
are added to the network, the relationship between these APs and
their neighbouring base stations needs to be established, and the
table is a mechanism for notifying the eNode B of the existence of
the AP, and enables the X2 interface to be established between the
two of them, if it has not already been done.
[0122] Since the eNode B is responsible for initiating handover
when the UE is an active state, the eNode B uses the AP information
stored in the UE context to ensure that the UE is only handed over
to an AP where the network has approved the association. In other
words, the UE can only be handed over to APs that are listed in
this "UE context".
[0123] The eNode B will trigger a handover when its broadcast
system information signal, as received by the UE, falls below a
predetermined quality received threshold, and where a better
quality signal is available from a neighbouring base
station/AP.
[0124] The base stations/Node Bs therefore rely on the MME to
provide them with information on the APs that the UE can utilise,
since the APs are not included in the Tracking Areas in this
embodiment of the invention. The MME accordingly needs to have
up-to-date subscription information on the authorised APs for each
UE.
[0125] Therefore, it is to be appreciated that in order for a UE to
be able to access one or more APs, the UE's subscription
information may provide the necessary authorisation. This can be
done in non-real time using written subscription information
provided when the Access Point is registered (i.e. a Home AP is
registered, and the occupants of that home list their mobile
terminals as being authorised to access the telecommunications
network via that AP).
[0126] Alternatively, this could be achieved by a UE owner
purchasing the right to gain access, such through a web application
or by SMS. Once this purchase is completed, the MME is notified of
such, and so updates its relevant list, and the UE also stores a
record of the relevant AP's details, including, for example, as
access password.
[0127] Alternatively, the owner of an AP may wish to reserve access
to their AP for exclusive use of friends (e.g. for a home-located
AP) or customers (e.g. for a business-located AP). A real-time
registration process is preferable for this approach. The
registration can be achieved by the AP "registered owner" inviting
a person to use the AP by sending a specially formulated SMS to the
network, such as "Grant Access to [telephone number]". Upon
receiving this request, the MME would proceed to add the person's
UE identity to its list of UE's authorised to access the particular
AP.
[0128] In a further alternative, the registered owner of an AP has
an access password that they are able to provide to a person to
allow them to use their UE to access the AP. To effect this, the UE
owner would enter the password into a third party's UE, and the UE
would transmit a "Tracking Area Update" request message to the
network, together with a field identifying the AP, and the AP
password. This would force a Tracking Area Update in relation to
the AP. The MME, upon receiving the Tracking Area Update request
(via the nearest Node B) would note the inclusion of the AP and its
password, verify the password and update its AP table to include
the UE as an authorised user of the AP. The MME would also
preferably create a mapping between the Tracking Area of the Node B
that forwarded the TA update, and the AP. The UE would then be able
to utilise the AP to access the network.
[0129] The mapping of APs to tracking areas is an important
component of these embodiments of the invention. It is to be
appreciated that since an AP can be located in every house in a
certain region, and that new APs can be added to the network at any
time, the network needs to keep updating its associations between
tracking areas and APs to ensure that best use of APs can be made
by those UEs authorised to use them. In particular, transport
network connections need to be established between the new APs and
other Node Bs (the X2 interface) as well as between the new APs and
the controlling MME (the S1 interface). The mappings can be used to
establish these connections.
[0130] The X2 interfaces can be established by the eNode Bs, when
they are passed the mapping information from the MME. This
typically occurs when the UE is in active mode, and the eNode B's
are responsible for controlling the mobility of the UE.
[0131] An S1 interface will need to be established to make an MME a
controlling MME in the situation of a Home AP being newly added to
the network. This AP will have one or more different Tracking Areas
that overlap it, or which are adjacent to it. The network will
therefore need to create mappings for each of the different
Tracking Areas and the AP, so that an authorised UE in any of the
different Tracking Areas is notified of the existence of the Home
AP.
[0132] In other words, considering the authorised UE in idle mode
moving into TA#1, which is adjacent to the AP, when the UE performs
a Tracking Area Update, the UE will be informed of the existence of
the Home AP, and the MME will create a mapping between TA#1 and the
AP. The MME will also create the S1 interface between itself and
the AP, if one has not already been created.
[0133] Should the UE then move into another Tracking Area, such as
TA#2, then the AP will again perform a Tracking Area Update and
also create a mapping between TA#2 and the AP in view of their
geographical proximity. At this point, the MME may also create a
mapping or link between TA#1, TA#2 and the AP, so that the UE is
free to move in the area covered by both Tracking Areas and the AP
without the need for a Tracking Area update. Once the process has
been performed for each TA, it need not be repeated, as the MME
will save the mappings for future reference.
[0134] If an access point is physically moved (e.g. when someone
moves home), it may be necessary to cancel the mappings recorded
for the AP, and to register the new location in the network, by
updating the mapping between the AP location and the terrestrial
cells/tracking areas.
[0135] A further embodiment of the invention will now be described,
which also seeks to minimise unnecessary signalling in closed APs.
In this embodiment, paging is sought to be minimised when the core
network pages the UE, which is labelled Subscriber C in FIG. 7. In
this embodiment, each AP is assigned to a location area which is
handled by an MSC and paging and calls are routed to the APs via
the core network. For a target subscriber C who is camped on AP
370, the initial steps of call and paging routing are the same as
those followed when a subscriber is camped on a macro base station
as discussed with reference to FIGS. 1 and 2.
[0136] Specifically, with reference to the flowchart in FIG. 8, the
GMSC/MME 310 responsible for the target subscriber is identified
(step 410), and the call is routed to the GMSC 310 of the
subscriber (step 420). The GMSC 310 then contacts HLR 320 to
identify the MSC/eNode B which is currently responsible for
subscriber C (step 420). The GMSC 310 passes control of the call to
the MSC/eNode B (step 440).
[0137] On receiving control of the call, MSC 330 identifies the
last cell/location area in which subscriber C was located. If the
subscriber C is camped on an AP the MSC will identify the LA
associated with that AP. Where a mapping exists associating an AP
with one or more location areas, about which the terminal can move
without performing a location area update, it may be necessary to
page the terminal in: [0138] any macro-network cells of those one
or more location areas; [0139] the AP the terminal was last camped
on; [0140] as well as any other APs in those one or more location
areas that the terminal is authorised to use.
[0141] For any macro-network cells in that LA, the process
continues as described in FIGS. 1 and 2 in relation to the macro
layer for those macro cells.
[0142] At step 450, the MSC 330 passes the paging instruction to an
RNC concentrator(s) 340 parenting the AP belonging to the relevant
location area to page the subscriber C on the cells within the
location area.
[0143] To determine if any other APs in the one or more LAs exist
which the terminal is authorised to access, the network will hold
an access list 360 in an Access Point Database 350 which maps
subscribers to APs. Typically, each subscriber's MSISDN will be
stored with an appropriate identifier (such as the Access Point ID,
which is a unique identifier associated with the AP/femto-cell) of
all APs with which it is registered.
[0144] This AP database 350 has a number of potential uses,
including: [0145] For controlling the access to any given AP when a
closed system is implemented; and [0146] For the implementation of
Vodafone's "Homezone".TM. which differentiates between owners and
members who receive preferential tariffs and, potentially,
treatment, and guests, who have access to the network via the AP,
but at the normal tariff (i.e. same as through the
macro-network).
[0147] On receiving the instruction to page subscriber C, the RNC
concentrator(s) 340 queries the AP database 360 to retrieve the AP
IDs of the APs which are within the LA and to which the subscriber
being paged is registered, whether as an owner, member or guest at
460.
[0148] In the example of FIG. 7, subscriber C is registered to use
three separate APs, namely 370, 380 and 390. Since these are the
only three APs on which the target subscriber could be camped
(since they are the only APs to which the subscriber is registered)
these are the only APs which need to page the subscriber. At 470,
the AP RNC 340 then instructs paging messages to be transmitted on
the paging channels of all the femto-cells of the LA in which the
target subscriber is registered, namely 370,380 and 390. These
pages are transmitted from APs 370, 380 and 390 at 480.
[0149] In the situation where the LA includes a macro cell, the
page will also be sent out on that macro cell, since, typically,
macro cells are open.
[0150] At the time the page is transmitted, subscriber C is located
in a cell provided by AP 370. On receiving the page from the
network via AP 370, subscriber C reads the paging message and
responds at 490, setting up a radio signalling channel and
progressing with the call control. The call is then established and
a radio channel is established at 500.
[0151] This embodiment of the invention therefore helps to reduce
the paging load to APs through to the femto-layer and potentially
eliminates restrictions on the allocation of femto cells to
LAs.
[0152] According to an alternative embodiment, the network has a
default position whereby it always pages the UE in one or more
default "Home APs" as well as the Tracking Area where the UE was
last registered. This embodiment of the invention is particular
useful where the number of APs with which the UE can associate is
small (i.e. one or two), or where a single AP is seen as the
default home AP.
[0153] Alternatively, if there are a large of APs with which the UE
is registered in a given area, then the MME can page the UE in its
current Tracking Area and a subset of the applicable APs. This will
again help to minimise the paging load.
[0154] In the embodiments described above, the AP is configured to
appear to the UE as a conventional base station that communicates
with the UE using GSM/UMTS/LTE protocols in accordance with the
Standards (where they exist) and the licensed radio spectrum.
Alternatively, the AP could communicate with the UE by any other
suitable technology--for example, by a Bluetooth (RTM) connection,
WiFi or another unlicensed mobile access (UMA) protocol, which
allows the GSM/UMTS/LTE features to be provided using a
non-GSM/UMTS/LTE bearer technology.
[0155] The above described embodiments have also assumed that all
APs in the network require access to them to be controlled, however
it is also within the scope of this invention that only a subset of
all the APs are controlled. For example, it is within the scope the
present invention that some APs are given Tracking Area IDs,
whereas others in the network are not.
[0156] In another embodiment of the system described herein, a
network controller is provided for use in a telecommunications
network including a radio access network comprising a plurality of
base stations, each defining a cell and being configured to
wirelessly transmit data that is receivable by one or more mobile
terminals, with at least one of the base stations being an Access
Point (AP). The network controller may be configured to: receive a
paging request relating to a given mobile terminal; access first
data indicating the last known location of the given mobile
terminal; access second data indicating any Access Points
associated with the last known location; and where one or more
Access Points are associated with the last known location, paging
those Access Points, in addition to any macro base stations within
the last known location. The second data the network controller is
configured to access may only indicate any Access Points associated
with the last known location that the given mobile terminal is
authorised to access. The network controller of may be further
configured to page one or more default Access Points associated
with the given terminal and to determine the one or more default
Access Points from a list of Access Points the given mobile
terminal is registered as being authorised to access. The network
controller may be further configured to only page a subset of the
Access Points indicated in the second data where the number of
Access Points indicated in the second data is greater than a
predetermined threshold.
[0157] In another embodiment of the system described herein, in a
telecommunications network including a radio access network
comprising a plurality of base stations, each defining a cell, and
being configured to wirelessly transit data that is receivable by
one or more mobile terminals, with at least one of the base
stations being an Access Point (AP), a method of paging a given
mobile terminal within the network is provided. The method
includes: receiving a paging request relating to a given mobile
terminal, accessing first data indicating the last known location
of the given mobile terminal, accessing second data indicating any
Access Points associated with the last known location, and where
one or more Access Points are associated with the last known
location, paging those Access Points, in addition to any macro base
stations within the last known location. The second data accessed
may only indicate any Access Points associated with the last known
location that the given mobile terminal is authorised to access.
The method may further include additionally paging one or more
default Access Points associated with the given terminal. The one
or more default Access Points which are additionally paged may be
one or more Access Points for which the given mobile terminal is
registered as being authorised to access. The method may further
include only paging a subset of the Access Points indicated in the
second data where the number of Access Points indicated in the
second data is greater than a predetermined threshold.
[0158] In another embodiment of the system described herein, in a
telecommunications network including a radio access network
comprising a plurality of base stations, each defining a cell, for
wirelessly transmitting data that is receivable by one or more
mobile terminals, wherein at least one of the base stations is an
Access Point (AP), a method of controlling access to the
telecommunications network via the at least one Access Point is
provided. The method includes defining tracking areas in the
network covering one or more base station cells but which exclude
the at least one Access Point cells. The method may further
include: creating a mapping associating one or more of the at least
one Access Points with one and more Tracking Areas, and using the
mapping to perform at least one of the following: [0159] a) notify
an idle mobile terminal that it is authorised to select the one or
more Access Points when in the one or more Tracking Areas; [0160]
b) trigger the establishment of a transport network connection
between a base station and each of the one or more Access Points.
[0161] c) trigger the establishment of a transport network
connection between a network controller and each of the one or more
Access Points. [0162] d) page a mobile terminal within the one or
more tracking areas and at the one or more Access Points where one
of the one or more Tracking Areas was the last Tracking Area
recorded for the mobile terminal; [0163] e) where an Access Point
is mapped to a first Tracking Area, notify an idle mobile terminal
that it is authorised to move from the Access Point to another base
station within the first Tracking Area without performing a
Tracking Area update; [0164] f) notify a mobile terminal that it is
authorised to access the one or more Access Points and that it
should undertake a search for transmissions by the one or more
Access Points; [0165] g) notify a mobile terminal that it should
undertake measurements of transmission received from the one or
more Access Points; and [0166] h) notify a base station controlling
handover of a mobile terminal that the mobile terminal is
authorised to be handed over to the one or more Access Points.
[0167] In another embodiment, the system described herein may
further include a mobile terminal transmitting a Tracking Area
update request to a network controller, the network controller
determining whether any Access Points exist, in the vicinity of the
mobile terminal's new Tracking Area, and where one or more Access
Points exist, creating a mapping associating the new Tracking Area
with the one or more Access Points, and transmitting the mapping to
the mobile terminal. The network controller may only create the
mapping in respect of the one or more Access Points which the
mobile terminal is authorised to access. The mapping may be
established for a particular mobile terminal based upon one or more
Access Points which exist in or in the vicinity of the one or more
Tracking Areas. Subscription data relating to the one or more
Access Points a particular mobile terminal is authorised to use,
may be utilised to determine which of the at least one Access
Points is included in the mapping. The subscription data may be
managed by a network controller and the subscription data is
updatable from the particular mobile terminal for a given Access
Point by: including authorisation data and an identify of the
Access Point in a Tracking Area update message; and transmitting
the message to the network controller, which defines the given
Access Point in the subscription data upon verifying the
authorisation data. The mapping may be used to notify a mobile
terminal that it should undertake measurements of transmissions
received from the one or more Access Points, the method further
comprising using a filtering mechanism to restrict the number of
Access Points which the mobile terminal monitors. When the mapping
is used to establish the transport network connection between the
base station and one of the at least one Access Points, the
transport network connection established is the X2 interface. When
the mapping is used to establish the transport network connection
between the network controller and one of the at least one Access
Points, the transport network connection established is the S1
interface.
[0168] In another embodiment of the system described herein, a
telecommunications network includes a radio access network
comprising a plurality of base stations, each defining a cell, and
being configured to wirelessly transmit data that is receivable by
one or more mobile terminals, with at least one of the base
stations being an Access Point (AP), and where the radio access
network is arranged in a plurality of tracking areas with each
tracking areas covering one or more cells but excluding the cells
of the at least one Access Point. Each Access Point may be a micro
base station having a smaller coverage area than the other base
stations, being macro base stations. A micro base station may be
configured for use in a telecommunications network including a
radio access network comprising one or more macro base stations
configured to wirelessly transmit data that is receivable by one or
more mobile terminals. The micro base station may have a smaller
coverage area than the one or more macro base stations, and the
micro base station may be configured to broadcast information from
which the at least one mobile terminal is able to determine if it
has access rights to the micro base station. The micro base station
may be configured to broadcast an Access Indicator Field from which
the one or more mobile terminal is able to determine if it has
access rights. The Access Indicator Field may be a password for use
by the mobile terminal to compare with a previously obtained
password to determine if access to the micro base station is
permitted. The micro base station may be configured to additionally
broadcast a decryption key for use by the one or more mobile
terminals to decrypt authorisation data, if applicable to each
mobile terminal, and may be configured to additionally broadcast
encrypted authorisation data for use by the one or more mobile
terminals to decrypt with a previously obtained decryption key, if
applicable to each mobile terminal.
[0169] In another embodiment of the system described herein, a
mobile terminal is configured for use in a telecommunications
network including a radio access network comprising a plurality of
base stations, each defining a cell, and being configured to
wirelessly transmit data that is receivable by the mobile terminal,
with at least one of the base stations being an Access Point (AP).
The mobile terminal is further configured to: receive data
transmitted by one or more proximate base stations; determine if
the received data includes an Access Indicator Field, being data
that may be transmitted by the one or more Access Points to
restrict access; and using the Access Indicator field to determine
if the mobile terminal is entitled to utilise the Access Point, and
only attempting to utilise the Access Point if the mobile terminal
is entitled to do so.
[0170] In another embodiment of the system described herein, in a
telecommunications network including a radio access network
comprising a plurality of base stations configured to wirelessly
transmitting data that is receivable by one or more mobile
terminals, where at least one of the base stations is an Access
Point (AP), a method of restricting access to the at least one
Access Point is provided. The method includes transmitting
information from each Access Point from which mobile terminals are
able to determine their ability to access the given base station.
The information transmitted may be an Access Indicator Field. The
method may further include that, unless it is determined that the
mobile terminal has a right of access to the base station, the
mobile terminal does not attempt to access the base station.
[0171] In another embodiment of the system described herein, a
network controller is provided for use in a telecommunications
network including a radio access network comprising a plurality of
base stations, each defining a cell and being configured to
wirelessly transmit data that is receivable by one or more mobile
terminals, with at least one of the base stations being an Access
Point (AP). The network controller may be configured to receive a
paging request relating to a given mobile terminal, where one or
more Access Points are defined as default locations for the given
mobile terminal, paging those Access Points, in addition to any
macro base stations within the last known location.
[0172] In another embodiment of the system described herein, in a
telecommunications network including a radio access network
comprising a plurality of base stations, each defining a cell, and
being configured to wirelessly transit data that is receivable by
one or more mobile terminals, with at least one of the base
stations being an Access Point (AP), a method of paging a given
mobile terminal within the network is provided. The method includes
paging the given mobile terminal, at one or more default Access
Points, in addition to any macro base stations within a last known
location area.
[0173] In another embodiment of the system described herein, a base
station is configured for use in a telecommunications network
including a radio access network comprising a plurality of base
stations, each defining a cell, and being configured to wirelessly
transit data that is receivable by one or more mobile terminals,
with at least one of the base stations being an Access Point (AP).
The base station is configured to broadcast a first tracking area
intended for use by mobile terminals that are stationary or
travelling at a speed up to and including a threshold speed, and
broadcast a second tracking area intended for use by mobile
terminals that are travelling at a speed greater than the threshold
speed.
[0174] In various embodiments, a system according to that described
herein may be provided for performing any of the above-noted
methods.
[0175] Other embodiments of the invention will be apparent to those
skilled in the art from a consideration of the specification or
practice of the invention disclosed herein. It is intended that the
specification and examples be considered as exemplary only, with
the true scope and spirit of the invention being indicated by the
following claims.
* * * * *