Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
2000-03-27
2003-06-17
Urban, Edward F. (Department: 2685)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C455S432300, C455S433000, C455S435100, C455S436000, C455S439000, C370S338000, C370S349000
Reexamination Certificate
active
06580699
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to telecommunication systems, and more particularly, to a system and method for updating an R-P connection when a mobile station roams from one radio network to another.
In a telecommunication system, as shown in
FIG. 1
, a packet data serving node (PDSN)
10
a
or
10
b
usually serves multiple radio networks (RNs), e.g.,
12
a,
12
b
and
12
c.
On the other hand, a single RN, e.g.
12
b,
can be in communication with more than one PDSN. When a mobile station (MS) roams from one RN to another, a RN-to-PDSN connection (R-P connection)
14
must be updated to maintain a smooth communication channel between the RN
12
and the PDSN
10
.
FIG. 2
shows a communication infrastructure describing the relationship among a PDSN
10
, base station controllers (BSCs)
16
,
18
, and
20
, Visitor's Location Registers (VLRs) or Mobile Service Centers (MSCs)
22
, representative cells of radio networks
24
a
and
24
b,
and a roaming MS
26
. For instance, when the MS
26
roams from one cell
28
, which is under the control of the BSC
16
, to another cell
30
controlled by the BSC
18
, an old R-P connection
32
between the BSC
16
and the PDSN
10
may have to be updated to reflect a new R-P connection
34
between the BSC
18
and the PDSN
10
. Furthermore, the MSC/VLR
22
may be in communication with both the BSC
16
and the BSC
18
without maintaining a communication channel with the PDSN
10
.
In one scenario, when the MS
26
roams to a new radio network, and if a BSC serving the new radio network is under a different PDSN
10
, the MS
26
may have to perform a mobile IP (M-IP) registration process. However, a race condition may happen during the M-IP registration when packets are still routed to the old network before the new M-IP registration has been completed. Hence, it is recommended by the Telecommunication Industry Association (TIA) to relay all these packets from the old radio network to the new radio network.
Although the TIA has dealt with the race condition during the M-IP registration, two other scenarios for switching the R-P connection are not contemplated by the TIA. In one scenario, the new BSC is under the same PDSN
10
, but relates to a different MSC/VLR
22
. As shown in
FIG. 2
, this could happen when the MS
26
roams into the territory of the BSC
20
from that of the BSC
16
. In another scenario, the new BSC
20
is under the same PDSN
10
and relates to the same MSC/VLR
22
. This occurs when the MS
26
moves from the control of the BSC
16
to the BSC
18
.
Therefore, an improved method is needed for timely switching or updating an R-P connection when a MS
26
roams into a new radio network.
SUMMARY OF THE INVENTION
A system and method is provided for timely maintaining or establishing an R-P connection after a mobile station (MS) roams from the control of an old base station controller (BSC) to that of a new BSC.
In one embodiment of the present invention, a Mobile Service Center (MSC) or Visitor's Location Register (VLR) stores packet data call status information including point to point protocol (PPP) session status information and configuration information about BSCs. The information may include related cells and pocket data service nodes (PDSNs) before the MS moves to a new radio network (RN). During a registration process of the MS
26
, once a Location Update Request is received from the MS
26
, the MSC/VLR
22
can check whether the MS
26
is in a PPP session and whether the MS
26
is moving to a new BSC but within the same packet zone. If so, the R-P connection can be switched over. In this case, the MSC/VLR
22
will inform the new BSC to establish the R-P connection with the PDSN
10
.
In another embodiment of the present invention, an R-P connection is maintained between the old BSC and the PDSN
10
during a registration process while a routing connection is made between the old BSC and the new BSC.
In another embodiment of the present invention, the MS
26
, instead of the MSC/VLR
22
, stores necessary information such as a PPP session indicator and a cell ID. During the registration process, the new BSC receives information about the R-P connection between the old BSC and the associated PDSN
10
from the MS
26
. Upon determining that a new R-P connection is needed, the PDSN
10
establishes the new R-P connection with the new BSC.
In another embodiment of the present invention, during an origination process, the MS
26
communicates directly with the new BSC. The new BSC subsequently communicates with the MSC/VLR
22
to obtain information about the old R-P connection. The new BSC establishes a new traffic channel with the MS
26
only if needed. The new BSC also checks the PPP session status information and triggers the construction of a new R-P connection.
In yet another embodiment of the present invention, if certain conditions require (e.g., the MS
26
is at an Inter-MSC
22
boundary cell), switching the R-P connection can be avoided. The packet traffic can be routed back to the old BSC via a base station to base station (BS—BS) link. Therefore there is no need to switch the R-P connection.
In another embodiment of the present invention, an R-P connection is initiated during a mobile termination process. Information about the old BSC and its link with the PDSN
10
is transferred to the new BSC.
In another embodiment of the present invention, an R-P connection is maintained during a mobile termination process by routing the packet traffic to the old BSC. A paging process is used for setting up a traffic channel between the new BSC and the MS
26
.
In yet another embodiment of the present invention, information about the old R-P connection and the associated PDSN
10
are given to the new BSC through a hard handoff process. A new R-P connection is then established.
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Jiang Jianping
Manning Serge
Haynes and Boone LLP
Nortel Networks Limited
Quach Henry M.
Urban Edward F.
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