CN101146339B - Cross-SGSN handover method and mobile communication network - Google Patents

Abstract

The invention relates to the field of mobile communication, and discloses a cross-SGSN switching method and a mobile communication network. In the present invention, when a terminal is handed over across SGSNs, the network side keeps the bearer between the original SGSN and GGSN unchanged, creates a new bearer between the original SGSN and the target SGSN, and transfers The service data packet of the terminal. Because the data packets buffered by the original SGSN for the terminal can be sent to the target SGSN through the newly created bearer, and then sent to the terminal by the target SGSN, the loss of service data packets can be reduced or avoided.

Description

Cross-SGSN handover method and mobile communication network

technical field

The invention relates to the field of mobile communication, in particular to the handover technology across SGSNs.

Background technique

General Packet Radio Service ("GPRS") is a new packet data bearer service developed on the existing Global System for Mobile communication ("GSM"). GPRS provides end-to-end, wide-area wireless IP connection.

As a transitional technology for the evolution from GSM to the third-generation mobile communication, GPRS integrates mobile communication and data network into one, and enables IP services to be introduced into the vast mobile market. The fundamental difference between GPRS and GSM is that GSM is a circuit switching system with a rate of 9.6Kbps per second, while GPRS uses packet switching.

GPRS business will bring users and operators better services and greater opportunities: provide users with third-generation services for market development, and prolong the life cycle of GSM at the same time.

GPRS has the following main features:

Provide users with access rates from 9kbps to more than 171.2kbps. More effective use of wireless resources, can dynamically allocate 1 to 8 time slots located on the same carrier frequency to a single user. Radio interface resources can be shared between voice and data traffic based on traffic flow and operator choice.

Supporting uplink and downlink asymmetric transmission enables more effective intercommunication with IP networks. GPRS provides intercommunication with IP network and X.25 network from the protocol structure.

It can provide users with all the functions that the Internet can provide. A user will have a fixed or dynamically assigned IP address while having a phone number. GPRS users have shorter setup times.

The operator can use the user's business traffic as the charging standard.

Provide users with richer data services than GSM data services (including supplementary services and short message services), and support four types of QoS.

In other words, GPRS is a packet-mode wireless network superimposed on GSM, which can upgrade any GSM network, so that the GSM network can evolve from the second-generation mobile communication network to the third-generation (3G) network, known as It is system of the 2.5th generation. It maximizes the use of existing wireless network infrastructure and improves the utilization of wireless resources.

Figure 1 shows the GPRS standard framework.

GPRS superimposes a layer of network on the basis of the original GSM network to form a GSM/GPRS network. On the basis of the GSM network, GPRS adds ServingGPRS Support Node (SGSN for short), gateway general packet Wireless service support node (Gateway GPRS Support Node, "GGSN" for short), billing gateway (optional), edge gateway (optional) and other entities. At the same time, the connection between entities is realized through the GPRS backbone network.

Among them, the SGSN is a basic constituent network element of a packet switching (Packet Switching, "PS" for short) network. Its main function is to forward the input/output IP packets for the user equipment (User Equipment, referred to as "UE") in the service area of the SGSN, and its status is similar to the access mobile service in the circuit switching (Circuit Switching, referred to as "CS") domain Switching Center (Visitor Mobileservices Switching Center, referred to as "VMSC").

The functions provided by the SGSN include: routing and forwarding of packet data packets in the local SGSN area, providing services for all PS users in the local SGSN area, encryption and authentication functions, session management functions, mobility management functions, and common Mobile communication system terrestrial radio access network (UMTSTerrestrial Radio Access Network, referred to as "UTRAN"), GGSN, home location register (Home Location Register, referred to as "HLR"), mobile switching center (Mobile Switching Center, referred to as "MSC"), short Interface functions such as Short Message Service-Gateway Mobile Switching Center (Short Message Service-Gateway Mobile Switching Center, referred to as "SMS-GMSC"), Short Message Service Interworking MSC (MSC Short Message Service Interworking MSC, referred to as "SMS-IWMSC").

The SGSN also integrates a function similar to the Visitor Location Register (VLR) in the CS network. When the user is in the Attached (attached) state, the SGSN stores the user information and location information related to the group. Similar to VLR, most of the user information in SGSN is obtained from HLR during location update.

In addition, the GGSN is also a network element functional entity introduced to provide PS service functions in the UMTS network, providing routing and encapsulation of data packets between the PS network and the external data network. Which GGSN the user chooses as the gateway is determined according to the subscription information of the user and the access point name (APN) requested by the user during the activation process of the packet data protocol (Packet Data Protocol, referred to as "PDP") context.

The functions provided by the GGSN include: the interface function with the external IP packet network. Specifically, the GGSN needs to provide the gateway function for the UE to access the external packet network. From the perspective of the external network, the GGSN is like an addressable PS network All user IP routers in the network need to exchange routing information with the external network; session management, that is, complete the communication establishment process between the UE and the external network; and the function of sending the packet data of the mobile user to the correct SGSN.

When the terminal moves into a new cell in the READY (service ongoing) state, and the new cell belongs to another SGSN (GPRS Serving Node), the terminal must update its location and switch from the original cell to the new cell. Update the routing area between SGSNs.

The status before the update of the SGSN routing area is shown in Figure 2, where the thick solid line is the bearer of the transmission terminal service data packet. It can be seen that the bearer path is "GGSN—original SGSN—source BSC—source base station—terminal".

The updated state of the SGSN routing area is shown in Figure 3, where the thick solid line is the bearer of the transmission terminal service data packet. It can be seen that the bearer path is "GGSN—target SGSN—target BSC—target base station—terminal".

During the handover, the original SGSN caches data from the GGSN that needs to be sent to the terminal, and the GGSN may no longer retain these data. After the handover occurs, the new bearer path has been switched to the target SGSN and no longer passes through the original SGSN, so the data in the original SGSN will be discarded, resulting in data loss. When the terminal fails to receive the expected data within a predetermined period of time, it will trigger the retransmission of the upper layer, resulting in jitter and delay of service data packets.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a cross-SGSN handover method and a mobile communication network, so that the loss of service data packets can be reduced when a terminal is handed over across SGSNs.

To achieve the above object, the present invention provides a handover method across SGSN, comprising the following steps:

When the terminal switches from the routing area of the original SGSN to the routing area of the target SGSN, the network side maintains the first bearer between the original SGSN and the GGSN, establishes a second bearer between the original SGSN and the target SGSN, and passes the first and second Carrying the service data packets of the transmission terminal.

Wherein, the terminal is a terminal using packet switching domain services.

Furthermore, in the method, the services include streaming media and conversational services.

In addition, in the method, after the second bearer is established, the original SGSN sends the buffered data of the terminal to the terminal through the target SGSN.

The present invention also provides a mobile communication network, which includes at least one GGSN and at least two SGSNs. The SGSN where the terminal is originally located is used to establish a connection with the target SGSN for the terminal when the terminal in its routing area switches to the routing area of the target SGSN. The second bearer between the SGSNs, and maintain the first bearer with the GGSN;

The GGSN is used for maintaining the first bearer between the terminal and the original SGSN where the terminal is located when switching between different SGSN routing intervals.

Wherein, the terminal is a terminal using packet switching domain services.

In addition, the services include streaming media and conversational services.

In addition, the original SGSN where the terminal is located is also used to send the cached service data packet of the terminal to the terminal through the target SGSN after the second bearer is established.

Through comparison, it can be found that the main difference between the technical solution of the present invention and the prior art is that when a terminal is handed over across SGSNs, the network side keeps the bearer between the original SGSN and the GGSN unchanged, and creates a new bearer between the original SGSN and the target SGSN. The service data packet of the terminal is transmitted through the bearer of the three nodes of the GGSN, the original SGSN and the target SGSN. Since the data packets buffered by the original SGSN for the terminal can be sent to the target SGSN through the newly created bearer, and then sent to the terminal by the target SGSN, the loss of service data packets can be reduced or avoided. The loss of business data packets is less, the chance of retransmission will be smaller, and the jitter and delay of business data packets will be improved accordingly.

Description of drawings

Fig. 1 is the framework diagram of GPRS in the prior art;

FIG. 2 is a schematic diagram of a network state before inter-SGSN routing update in the prior art;

Fig. 3 is a schematic diagram of the network state after the routing update between SGSNs in the prior art;

Fig. 4 is a schematic diagram of the network status after the inter-SGSN routing is updated according to the embodiment of the present invention;

Fig. 5 is a flow chart of cross-SGSN handover according to an embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.

The flow chart of the embodiment of the method of the present invention is shown in FIG. 5 .

In step 510, the terminal that is using the packet switching (Packet Switching, "PS" for short) domain service initiates a handover from the routing area of the original SGSN to the routing area of the target SGSN. The PS domain services used by the terminal may be streaming media, conversational services, and the like. The data of the PS domain service must pass through the GGSN.

Then enter step 520, the first bearer established for the terminal between the GGSN and the original SGSN remains unchanged. The GGSN continues to send the service data packets that need to be sent to the terminal to the original SGSN, and the original SGSN caches these data.

Then enter step 530, the original SGSN interacts with the target SGSN when the terminal initiates handover, and creates a second bearer between the original SGSN and the target SGSN. The second bearer is used to transmit service data packets of the terminal between the two SGSNs.

Then enter step 540, after the second bearer is established, the original SGSN will send the downlink service data packet buffered for the terminal to the target SGSN, and the target SGSN will deliver it to the terminal through the target BSC and target base station. Because the data packets buffered by the original SGSN for the terminal can be smoothly sent to the terminal, the loss of service data packets can be reduced or avoided. The loss of business data packets is less, the chance of retransmission will be smaller, and the jitter and delay of business data packets will be improved accordingly.

After switching to the target base station subordinate to the target SGSN, the terminal returns data to the network side according to the path of the target base station, target BSC, target SGSN, original SGSN, and GGSN.

Thereafter, if the terminal switches back to the base station of the original SGSN in the next handover, the second bearer is released and the state shown in FIG. 2 is restored.

If the terminal switches to the base station of another target SGSN (herein referred to as the second target SGSN) in the next handover, the second bearer between the original SGSN and the target SGSN is released, and a new third bearer is created between the original SGSN and the second target SGSN. Bearer and network status are similar to those in Figure 4, except that the target SGSN is changed to the second target SGSN. Of course, since one SGSN can manage many base stations, the probability of continuous switching between multiple SGSNs is relatively small.

The network structure in the network embodiment of the present invention is shown in FIG. 4 . The network mainly involves one GGSN and two SGSNs. These two SGSNs are the original SGSN that provides services for the terminal before the terminal switches between SGSNs, and the target SGSN that provides services for the terminal after the terminal switches between SGSNs. The functions of these three network side devices during the handover process of the terminal across SGSNs are different from those in the prior art. Instructions are given below:

The GGSN is used to maintain the first bearer between the terminal and the original SGSN when switching between different SGSN routing intervals. However, in the prior art, the GGSN deletes the bearer with the original SGSN, and creates a new bearer with the target SGSN.

The original SGSN is used to create a second bearer with the target SGSN and keep the first bearer with the GGSN when the terminal switches to the target SGSN. However, in the prior art, the original SGSN deletes the bearer between the GGSN and the GGSN. The original SGSN is also used to send the buffered terminal service data packet to the terminal through the target SGSN after the second bearer is established. However, in the prior art, the original SGSN discards the service data packets buffered for the terminal.

The target SGSN is used to create a second bearer with the original SGSN when the terminal is handed over from the original SGSN. However, in the prior art, the target SGSN is a new bearer between the target SGSN and the GGSN.

The network state formed after the cross-SGSN handover is shown in Figure 4, where the thick solid line is the bearer path serving the terminal. It can be seen that the bearer path formed by the solution of the present invention is: GGSN——Original SGSN——Target SGSN - target BSC - target base station - terminal. GGSN can also be connected with other networks, such as the Internet, to provide services for terminals. Because the original SGSN remains in the newly formed bearer path, the buffered service data packets of the original SGSN will not be lost, and the jitter and delay of the service data packets caused by cross-SGSN handover are correspondingly improved.

Although the present invention has been illustrated and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the present invention. The spirit and scope of the invention.

Claims (6)

1. the changing method of a SGSN-spanning is characterized in that, comprises following steps:

Terminal is when the route district of former SGSN switches to the route district of target SGSN, network side keeps the carrying of first between former SGSN and the GGSN, between former SGSN and target SGSN, set up second carrying, by the business data packet of the described first and second carrying transmission terminals;

Former SGSN sends to this terminal with the data of the described terminal of institute's buffer memory by target SGSN after second carrying is set up.

2. the changing method of SGSN-spanning according to claim 1 is characterized in that, described terminal is for using the terminal of grouping commutative field service.

3. the changing method of SGSN-spanning according to claim 2 is characterized in that, described business comprises Streaming Media and session service.

4. mobile communications network, comprise at least one GGSN and at least two SGSN, it is characterized in that, when the SGSN at the original place of terminal is used for terminal in its route district and switches to the route district of target SGSN, be second carrying between this terminal foundation and the target SGSN, and the carrying of first between maintenance and the GGSN;

GGSN is used for terminal when the interval switching of different SGSN routes, first carrying between maintenance and the original place SGSN of this terminal;

The original place SGSN of terminal also is used for after second carrying is set up, and the business data packet of this terminal of institute's buffer memory is sent to this terminal by target SGSN.

5. mobile communications network according to claim 4 is characterized in that, described terminal is for using the terminal of grouping commutative field service.

6. mobile communications network according to claim 4 is characterized in that described business comprises Streaming Media and session service.

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