Completely solves the problem of GPRS routing detour

With the development of wireless routing technology, it has also promoted the upgrade of GPRS routing technology, but there are still many problems. Here we mainly analyze the problem of GPRS routing. As an extension of gsm in the field of group switching, GPRS provides efficient bandwidth for sudden applications such as Internet access on mobile terminals, therefore, the current GPRS wireless routing scheme is mainly designed for the terminal to access the external group switching network at high speed.

However, in the traditional GPRS routing scheme, group data is encapsulated and forwarded by the GGSN node regardless of whether the mobile terminal accesses the external data network or communicates with other mobile terminals. When grouped data is transmitted in the GPRS route group data network, in some cases, for example, when two interactive terminals are in the same GGSN, this encapsulation Forwarding is not necessary, therefore, the traditional GPRS routing scheme has the problem of GPRS routing loose when dealing with terminal-to-terminal communication.

In addition, with the rapid development of wireless communication and network services, information exchange between mobile stations becomes more and more frequent, and the amount of data exchanged increases rapidly. The data communication between GPRS terminals becomes more and more important, GPRS routing is also becoming an important factor affecting information communication efficiency. Therefore, in order to avoid GPRS routing and make information interaction between mobile stations more efficient and fast, we need to optimize the GPRS routing scheme for data transmission between mobile stations.

Based on GSM, GPRS introduces a GPRS network based on IP packet switching, and nodes in the network are interconnected by IP. GPRS provides high-speed Interconnection Between the terminal and the external data network. The terminal accesses the external group data network through the GGSN. When the Internet sends the group to the GPRS terminal, the destination address is a PDP address at the network layer, the grouped data can be delivered to mobile terminals only after the address is forwarded by GGSN. Therefore, the signaling path is consistent with the data path. For information interaction between mobile stations, the existing Protocol process is also maintained in the same way as above. For two GPRS terminals under the same GGSN, the communication between them does not involve the external grouping network, and the data stream does not need to obtain the GGSN. The two data encapsulation and forwarding processes between SGSN and GGSN undoubtedly increase the latency of group data waiting in the network queue. In addition, GPRS introduces an error correction and re-transmission mechanism to reduce the error probability, when the error rate is high, the queuing latency will be longer, and the data load of the GGSN node will also increase.

Therefore, the optimization scheme is mainly to transform the routing process between traditional GPRS mobile stations, that is, to carry out some transformation based on the original protocol process: one SGSN can simulate information interaction between GGSN and other SGSN and even HLR. Because the GPRS Core network is secure, this added interface function is not restricted by the security verification program and is not difficult to implement. At the same time, this simulation does not need to change the existing interfaces and protocols, and is transparent to the transformation of SGSN and HLR for interaction with it.

Therefore, a GPRS route can be directly established between SGSN to transmit grouped data packets, so that the data does not need to return to GGSN. In addition, by adding this simulation interface function, SGSN can also directly obtain necessary data from HLR without additional overhead; GGSN still retains part of PDP context information; the SGSN status machine should make more detailed plans for various statuses and add necessary judgment mechanisms to determine the changes of data flows under different circumstances, at the same time, the establishment of the route when the terminal visits the external network will not be affected. The information interaction between SGSN and HLR and SGSN must only increase by 1 ~ The expenditure of two messages has almost no impact on the complexity of the entire process. SGSN maintains a simple route table, which is part of session management and is allocated by the system, the table stores information about the next secondary node of the recently established MS-MS data route. The content of the route table should be updated regularly to ensure the validity and accuracy of the index. Because the number of communications between the mobile stations in the same core network is limited, the amount of data to be maintained is not large. Therefore, the establishment and maintenance of the SGSN route table will not impose a heavy burden on the nodes.

The above optimization scheme is implemented through necessary transformation of SGSN, which is transparent to the traditional SGSN node, the GPRS route creation process and the grouped data path of the terminal accessing the external data network are not changed. The SGSN performs more detailed status analysis and complex processing when processing the communication process between mobile stations in the backbone network, but it does not greatly increase the complexity of the SGSN software. The simulation of GGSN can fully utilize the existing Protocol basis and interface, without adding a new module. Because one GGSN can serve multiple sgsns, the processing burden of GGSN is reasonably distributed to each SGSN, which is conducive to the improvement of the overall system efficiency. At the same time, the transformation of the GPRS group data transmission does not affect the normal delivery of the GPRS voice service.