Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
2001-04-30
2003-04-08
Kizou, Hassan (Department: 2662)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C370S342000
Reexamination Certificate
active
06545992
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to mobile communications and, more particularly, to the selection of a GGSN to aggregate data calls in a mobile communication network.
2. Discussion of Related Art
Current digital wireless or mobile communication networks are predominantly second generation (“2G”) networks. The dominant protocols are TDMA, GSM, and CDMA. These networks have limited capability in servicing data (as opposed to voice) calls. Typical bandwidth is about 9.6 Kbits/second.
Third generation (“3G”) networks have been proposed. CDMA2000 and UMTS are two of the more popular proposed 3G networks. These proposals are intended to serve more voice users on a given network and to support higher data rates (e.g., greater than 144 Kbits/second) to a mobile station, such as a “cell phone.”
FIG. 1
shows an exemplary arrangement of a UMTS network
100
. A geographical “coverage area” is partitioned into a number of smaller geographical areas called “cells” (not shown.) Mobile stations (MSs)
101
powered on in the coverage area communicate via a radio channel to a corresponding node
102
. A plurality of nodes
102
a-n
communicate via links
103
a-n
with a corresponding Radio Network Controller (RNC)
104
. The RNC
104
aggregates the communication traffic from the nodes and provides functionality, such as detecting the service options activated by the MS
101
. The combination of nodes
102
and RNC
104
is called a Universal Terrestrial Radio Access Network (UTRAN)
105
. There are potentially many UTRANs in a network.
Each UTRAN
105
communicates with a call server
108
(also called a MSC server or a session control manager) via signaling links
106
and bearer trunks
107
and communicates with a SGSN
111
via IP link
110
. The traffic between the UTRAN and the call server, i.e., voice calls, may be ATM-based, and the interface is defined by the Iu-cs interface. The call server has control logic for managing the voice calls and a bearer plane for switching the incoming voice traffic.
The traffic between a UTRAN and an SGSN is packet-based. The ingress to the SGSN are GTP (GPRS Tunneling Protocol) tunnels, and the SGSN switches these tunnels based on instructions from the control logic in the call server. These instructions are contained in IP packets and sent from the SGSN to the call server via link
120
to the IP network
118
, from which the call server receives them. Analogously, the UTRAN may communicate IP traffic to the call server via the SGSN and IP network
118
,
120
. The traffic in the GTP tunnels may be data traffic, e.g., traffic to a web site, or it may be packetized voice in which case the control logic would be required to give special management to such traffic, e.g., QoS considerations. (SGSN is the industry acronym for “Serving GPRS Support Node”.) A call server
108
and an SGSN
111
may each handle a (potentially different) plurality of UTRANs
105
a-n.
The call server
108
is responsible for handling circuit based voice calls if the Iu-CS interface is implemented. The UTRAN
105
is responsible for detecting the activation of such calls and, in response to such activation, cooperates with the call server to establish the necessary signaling links
106
and bearer circuits
107
to the call server
108
. The call server, in addition to cooperating with the UTRAN, establishes corresponding signaling links
112
and bearer circuits
114
to the voice network. More specifically, the call server establishes signaling links with the SS
7
signaling network
113
and bearer circuits with the PSTN bearer circuit network
115
. Voice calls may thus be routed to a called party using conventional signaling and switching and using circuit based techniques.
A SGSN
111
is responsible for handling data calls—both conventional data calls such as Internet requests and voice calls over the data network. The UTRAN
105
is responsible for detecting the activation of such calls and, in response to such activation, cooperates with the SGSN
111
to establish the necessary data paths via IP link
109
to the SGSN
111
. The SGSN then helps establish a GTP tunnel starting from the UTRAN and extending to a GGSN
119
to set up a virtual private network, or “VPN.” The control logic for this switching behavior can reside in the call server. (GGSN is the industry acronym for “Gateway GPRS Supporting Node”.) The SGSN then processes the received information and forms it into IP packets that may be carried on the tunnel in the private IP network
118
. The GGSN receives IP packets from potentially many SGSNs
111
j-l
and aggregates such traffic in addition to providing other services, such as security. The aggregated IP traffic may then be communicated on to a public IP network
120
such as the Internet
121
.
Mobility management needs to be performed for both voice and data calls. For circuit-switched voice calls, the call server
108
is responsible for managing mobile terminals. Control logic in the call server accesses a Visiting Location Register (VLR)
116
typically co-located with the call server to carry out this function. The VLR holds subscriber information that is typically a subset of the information stored in the Home Location Register (HLR)
117
. The HLR is updated to handle mobility management for both voice and data calls. As a subscriber roams while making a circuit-switched voice call, circuit connections to the appropriate UTRAN from the call server have to be maintained. For data calls (including packetized voice calls) the call server is also responsible for mobility management. In this case the GTP tunnel from the appropriate SGSN to the appropriate UTRAN needs to be maintained as the subscriber roams in the network. Mobility management in the case of data calls involves the selection and maintenance of such tunnels. The logic to carry out this function resides in the call server and accesses the HLR and VLR to perform this function.
When a MS
101
makes a data call (i.e., when it initiates a packet session), the UTRAN
105
receives signaling information, detects that a data call is forthcoming and begins to receive packets from the MS
101
. Upon detecting that a data call is forthcoming, agent software executing in the call server mobility management module access the HLR
117
using the subscriber ID of the MS, the MS number (MSN), the terminal identification code, or the like, as a key to obtain certain subscriber profile information including the “home” GGSN for that subscriber. As the data call continues, the SSGN which receives the data packets from the UTRAN sends the data packets over IP network
118
to the home GGSN which aggregates the packets for subsequent transmission to the public IP network
121
,
122
.
The inventors believe that static assignment of a GGSNs causes certain inefficiencies and disadvantages. For example, if a user is roaming, the GGSN at the end of the tunnel may be far away from the user. Not only is this inefficient use of the network (as the IP packets may have to encounter many hops in the network) but performance will suffer. This performance disadvantage may make the approach less suitable for using the data side of the network for voice over IP calls and for certain multimedia traffic.
SUMMARY
In accordance with the present invention, a method and system of determining a GGSN to serve data calls in a mobile communications network is provided. Messages are received from the control logic in the call server, and analyzed to determine if the message is requesting the identity of a GGSN. If the received message is requesting the identity of a GGSN, a GGSN selection algorithm is executed to identify a GGSN to serve data calls from a specified MS. A reply is then constructed and sent to the SGSN identifying the selected GGSN.
According to one aspect of the invention, the GGSN that is closest to the SGSN is selected. According to another aspect of the invention a GGSN that has the capacity to serve data calls from the specified MS is selected. According to yet anot
Aravamudan Murali
Naqvi Shamim A.
Sundar Rangamani
Vishwanathan Kumar K.
Hale and Dorr LLP
Kizou Hassan
Odland David
Winphoria Networks, Inc.
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