Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
2000-10-20
2003-09-09
Nguyen, Lee (Department: 2682)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S433000
Reexamination Certificate
active
06618589
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates in general to the mobile communications field and, in particular, to a method for protecting cell and URA (Universal Mobile Telecommunications System Terrestrial Radio Access Network Registration Area) update message sequences.
2. Description of Related Art
The Universal Mobile Telecommunications System (UMTS) is the European version of the so-called third generation communication system, and is being developed under the auspices of the European Telecommunication Standards Institute (ETSI) The network component of the UMTS is referred to as the UMTS Terrestrial Radio Access Network (UTRAN).
FIG. 1
is a block diagram of an architecture that has been developed for the UTRAN.
Referring to
FIG. 1
, the UTRAN architecture
10
shown includes a Core Network
12
. A User Equipment (UE)
19
, which is typically a mobile terminal, is used by a subscriber to access the services offered by an operator through the Core Network
12
. The Core Network
12
is coupled to a Radio Network Controller (RNC)
16
a
, which controls radio resources and connectivity within a set of cells (e.g., cells
20
a-e
). Although only one RNC
16
a
is shown coupled via an interface to the Core Network
12
, this arrangement is for illustrative purposes only. It should be understood that more than one RNC (e.g.,
16
a-c
) can be coupled via an interface to the Core Network
12
.
A cell (e.g.,
20
a
) defines a geographical area where radio coverage is provided by radio transceiver equipment located at a radio base station site. Each such cell is identified with a unique identity, which is broadcast within that respective cell.
A URA (e.g.,
18
a
) defines a geographical area composed of one or more cells (e.g.,
20
a
and
20
b
). Each such URA is identified with a unique identity, which is broadcast within all cells belonging to that respective URA. As such, a URA can be composed of cells controlled by more than one RNC. A URA with cells controlled by more than one RNC can have an overlap between RNCs (i.e., an Overlapping URA).
A Signalling Network (e.g., Signalling System No.
7
)
14
is coupled to the RNCs
16
a-c
. The Signalling Network
14
enables the RNCs to perform the requisite RNC-to-RNC signalling, in order to maintain established connections when a UE is moving between cells controlled by different RNCs in the Radio Access Network.
For each Core Network-UE connection, the role of an RNC can be two-fold. One role of such an RNC is that of a Serving RNC (SRNC). In this role, the RNC is in charge of the connection with the UE. In other words, this RNC has full control of this connection within the Radio Access Network. As such, this RNC is connected to the Core Network
12
.
The second role of such an RNC is that of a Drift RNC (DRNC). In this role, the RNC supports the SRNC with radio resources for a connection with the UE, which needs radio resources in cells controlled by the DRNC.
Typically, the Radio Access Network
10
determines the role of an RNC (i.e., SRNC or DRNC) when the UE-Core Network connection is being established. Normally, the RNC that controls the cell where the connection to the UE is initially established, is assigned the SRNC role for this UE connection. As the UE moves, the connection is maintained by establishing radio communication branches via new cells, which can also involve cells controlled by other RNCs (e.g., DRNCs).
The above-described RNC roles are also relevant when a UE is using shared resources and experiencing at least some activity (i.e., some transfer of user data, or a CELL
13
FACH state). Furthermore, these RNC roles are also relevant when a UE is using shared resources and operating in a low activity state (i.e., no transfer of user data, or a CELL
13
PCH or URA
13
PCH state). In the CELL
13
FACH and CELL
13
DCH states, the UE reports its location on a cell basis (Cell Update). In the URA
13
PCH state, the UE only reports its location on a URA basis (URA Update). These RNC roles are relevant for all of the above-mentioned states, because control of the UEs in these states remains in the SRNC.
FIG. 2
is a diagram that illustrates state models for a UE. Referring to
FIG. 2
, a UE enters the Idle Mode
4
after power on. In this mode, the UE is not connected to the UTRAN. When a connection is established, the UE enters the Connected Mode
2
. As such, there are four states in the Connected Mode. Each such state reflects a certain level of activity.
The CELL_DCH state
7
is characterized by a dedicated channel (DCH) assigned to the UE. Macro-diversity can be used between DCHs of several cells.
In the CELL_FACH state
8
, no dedicated physical channel is assigned. However, the UE listens continuously to a common channel (the FACH) in the downlink belonging to the selected cell. In the uplink, the UE typically uses a random access channel (RACH). During each cell re-selection, the UE updates the network with the UE's current cell location.
In the CELL_PCH state
6
, the UE monitors a paging channel (PCH) of a selected cell. On the PCH, the UE uses discontinuous reception (DRX) to save power. The scheme about when the UE should listen is made in accordance with an agreement between the network and the UE, on a per UE basis. Also, at this point, the UE updates the network with the UE's current cell location at cell re-selection.
The URA_PCH state
5
is similar to the CELL_PCH state
6
. However, in the URA_PCH state
5
, the UE only updates the network about the UE's location after the UE has crossed a URA border. A URA is a group of cells. Consequently, in this state, the location of the UE is generally known only at the URA level.
FIG. 3
is a block diagram of the UTRAN architecture shown in
FIG. 1
, which further illustrates the RNCs′ roles. Referring to
FIG. 3
, RNC
1
16
a
functions as an SRNC for the connections to UE
1
19
, UE
2
27
and UE
3
28
. After successive Cell- or URA-Updates, the connection to UE
2
27
is now routed via a cell
25
and URA
23
a
controlled by RNC
2
16
b
, which functions as a DRNC for this connection. After successive Cell- or URA-Updates, the connection to UE
3
28
is now routed via a cell
26
and URA
23
a
controlled by RNC
3
16
c
, which functions as a DRNC for this connection.
FIG. 4
is a block diagram of the UTRAN architecture shown in
FIG. 1
, which illustrates how Cell-Update procedures are performed. As mentioned earlier, when a UE is in a CELL_PCH or CELL_FACH state, the UE reports a change in its location when it moves from one cell to another (Cell Update). Referring to
FIG. 4
, it can be seen that UE
1
19
performs a Cell-Update when moving from cell 1:2
20
b
to cell 1:3
20
c
, UE
2
27
performs a Cell-Update when moving from cell 2:5
25
a
to cell 3:1
25
b
, and UE
3
28
performs a Cell-Update when moving from cell 3:3
26
a
to cell 3:4
26
b
. When UE
3
28
performs a Cell-Update, the Cell-Update is conveyed to the SRNC for UE
3
(i.e., RNC
1
16
a
). The procedure used to convey the Cell Update to the SRNC is shown by the time-sequence diagram in FIG.
5
.
FIG. 5
shows an RNC-to-RNC signalling procedure used to support a Cell-Update from an RNC (the DRNC) other than the RNC where the connection with the network was established (the SRNC). As shown by the procedure
30
in
FIG. 5
, the DRNC sends a Cell Update Request message
32
to the SRNC. In response, the SRNC sends a Cell Update Response message
34
to the DRNC. A corresponding procedure for use on the radio air interface, which is also referred to as a Cell-Update procedure, is described with respect to FIG.
6
. As shown by the procedure
36
in
FIG. 6
, the UE sends a Cell Update Request message
37
to the RNC involved. In response, that RNC sends a Cell Update Response message
39
to that UE.
As mentioned above, when the UE involved is in a URA_PCH state (role), the UE only reports a change in its location when moving from one URA to another. This procedure is called a URA-Update. As such, the UE can remain in t
Lieshout Gert-Jan van
Maupin Alain
Rune Göran
Wallentin Pontus
Jenkens & Gilchrist P.C.
Nguyen Lee
Telefonaktiebolaget LM Ericsson (publ)
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