CN1275439C - A downlink data transmission assignment method in GPRS system - Google Patents

Abstract

The invention discloses a downlink data transmission assignment method in a GPRS system, comprising the following steps: (1) BSS receives downlink data from SGSN, and saves downlink data frames; (2) BSS tries to send a downlink assignment message on a packet channel, And set the response mark in this message; (3) BSS receives the downlink assignment response of mobile station on the specified uplink block, if received the response of mobile station, then perform step (5); (4) BSS in public control signal Resend the downlink assignment message on the channel; (5) After the assignment is successful, perform packet data transmission. Using the method for assigning downlink data transmission proposed by the invention can effectively reduce the discarding of downlink data packets caused by sending errors in assignment messages, and effectively improve the success rate of downlink data transmission assignment in the GPRS system.

Description

A Downlink Data Transmission Assignment Method in GPRS System

technical field

The present invention relates to a GPRS (General Packet Radio Service wireless packet data service) system, in particular, to a method for assigning downlink data transmission in the GPRS system.

Background technique

The downlink data transmission of the wireless port in the GPRS system is completed through the downlink temporary block flow (Temp Block Flow hereinafter referred to as TBF). There are three ways to establish the downlink temporary block flow: the downlink TBF establishment process on the CCCH (Common Control Channel) channel; the downlink TBF establishment process on the PCCCH (Packet Common Control Channel) channel and the PACCH (Packet Associated Control Channel) Packet-associated signaling channel) downlink TBF establishment process on the channel. The first two downlink TBF establishment procedures are collectively called the downlink TBF establishment procedure of the common control signaling channel, and the third downlink TBF establishment procedure is called the downlink TBF establishment procedure of the packet channel. Which establishment process to choose is determined by the channel monitored by the mobile station when the BSS (Base Station System, base station system) sends a packet downlink channel assignment message. If the mobile station does not monitor the channel and the BSS chooses to send the packet downlink channel assignment message, then the assignment process will fail. Since the establishment of the downlink TBF is completely triggered by the data packet issued by the SGSN (Serving GPRS Support Node, serving gateway support node), when the BSS sends a packet downlink channel assignment message, it is likely that it cannot know exactly what the mobile station is currently monitoring. channel, it is easy to cause the failure of the downlink assignment process, and then cause the result that the downlink data packet is discarded by the BSS. Especially when the TBF state of the mobile station is in the uplink release state or downlink release state, it is even more difficult for the BSS to know the channel that the mobile station is currently monitoring. Figures 1 and 2 illustrate this situation in detail.

The normal downlink TBF release process is shown in Figure 1. Point a in the figure represents the moment when the BSS sends a data block with FBI (Final Block Indication)=1 to the MS (MobileStation), that is, the moment of the last data block. Point b in the figure indicates the moment when the MS responds to the BSS with a downlink data response of FAI (Final Ack Indication)=1 after receiving the last data block sent by the BSS. From the moment indicated by point b, MS starts timer T3192. Point c in the figure indicates the moment when the BSS receives the downlink data response sent by the MS, and the BSS starts the timer T3193 from the moment indicated by point c. Point d in Figure 1 indicates that the timer T3193 on the BSS side expires, and the BSS releases the downlink TBF. The ETSI 0460740 protocol (section 13.2 on page 185) stipulates that T3193 must be greater than T3192, so the time when the BSS network side releases the downlink TBF is always later than the time when the MS side releases the downlink TBF. After the MS releases the downlink TBF, it no longer monitors the packet channel, but starts to monitor the common control signaling channel, so it cannot continue to receive messages on the packet channel. Δt1 in Figure 1 represents the time difference between the MS sending the downlink data response and starting the timer T3192 and the BSS receiving the downlink data response and starting the timer T3193. This time difference is related to the BSS system delay and the processing capabilities of MS and BSS. an indeterminate value. Due to the uncertain factor of Δt1, when the downlink data packet of the SGSN arrives at the BSS between points b and d, the BSS cannot accurately determine the channel that the MS is currently monitoring. Either the downlink assignment or the downlink assignment from the packet channel may fail.

The normal uplink TBF release process is shown in Figure 2. Point a in the figure indicates the time when the MS sends a data block with FBI=1 to the BSS, that is, the time when the last uplink data block is sent. Point b in the figure indicates the moment when the BSS sends an uplink data response with FAI=1 to the MS. Point c in the figure indicates the moment when the MS sends a packet control confirmation to the BSS. From the moment indicated by point c, the MS releases the uplink TBF, no longer monitors the packet channel, and starts to monitor the public control signaling channel, so it cannot continue to receive Messages on packet channels. Point d in the figure indicates the moment when the BSS receives the packet control acknowledgment sent by the MS, and the BSS releases the uplink TBF. It can be seen from Figure 2 that the time when the BSS network side releases the uplink TBF is always later than the time when the MS side releases the uplink TBF, and Δt2 and Δt3 in the figure are related to the system delay, the processing capabilities of the MS and BSS, and the wireless environment. are two indeterminate values. Therefore, when the downlink data packet of the SGSN arrives at the BSS between point a and point d, the BSS cannot accurately determine the channel that the MS is currently monitoring. Channel sending packet downlink channel assignment may fail.

For the situation shown in Figure 1, the ETSI 0460740 protocol (section 9.3.2.5 on page 72) points out that the downlink assignment at the BSS side should be sent from the packet channel during the operation of T3193. However, it can be clearly seen from the above analysis process that this assignment method has obvious defects. As shown in Figure 1, when the timer T3192 on the MS side overflows, the timer T3193 on the BSS side has not yet overflowed. From the packet channel, since the MS does not monitor the packet channel, it cannot receive the downlink assignment message sent by the network side, and the downlink assignment must fail. For the situation shown in Figure 2, the ETSI 0460740 protocol does not clearly describe this. So far, no relevant public technical information has been found that can effectively solve the above-mentioned downlink assignment problem.

Contents of the invention

The technical problem to be solved by the present invention is the low success rate of assignment of downlink data transmission in the above-mentioned GPRS system, and a method for assigning downlink data transmission that can effectively improve the assignment success rate is proposed.

The core idea of the present invention is that when the BSS receives the downlink data from the SGSN, but cannot confirm the channel currently monitored by the mobile station, it first attempts to assign a packet channel, and if successful, enters the normal downlink data transmission process; Then assign the common control signaling channel again. The two assignment processes ensure that the mobile station correctly receives the downlink assignment message sent by the network side.

The technical scheme that the present invention proposes is: a kind of downlink data transmission assignment method in GPRS system, comprises the following steps:

(1) The BSS receives the downlink data from the SGSN and saves the downlink data frame;

(2) The BSS attempts to send a downlink assignment message on the packet channel, and sets an acknowledgment flag in the message;

(3) The BSS receives the downlink assignment response of the mobile station on the specified uplink block, and if the response of the mobile station is received, step (5) is performed;

(4) The BSS resends the downlink assignment message on the common control signaling channel;

(5) After the assignment is successful, packet data transmission is performed.

or:

(1) The BSS receives the downlink data from the SGSN and saves the downlink data frame;

(2) The BSS attempts to send a downlink assignment message on the common control signaling channel, and sets a response flag in the message;

(3) The BSS receives the downlink assignment response of the mobile station on the specified uplink block, and if the response of the mobile station is received, step (5) is performed;

(4) The BSS resends the downlink assignment message on the packet channel;

(5) After the assignment is successful, packet data transmission is performed.

In the above step (2), the method for setting the response flag in the downlink assignment message is to set the uplink reserved block flag in the downlink assignment message, indicating that the message needs to be answered by the mobile station.

Using the method for assigning downlink data transmission proposed by the present invention can effectively reduce the phenomenon of discarding downlink data packets caused by sending errors in the assignment message in the aforementioned two cases, and effectively improve the success of assignment of downlink data transmission in the GPRS system Rate.

Description of drawings

Figure 1 is a schematic diagram of the normal downlink TBF release process of the BSS and MS.

Fig. 2 is a schematic diagram of the normal uplink TBF release process of the BSS and the MS.

Fig. 3 is a specific flowchart of the assignment method proposed by the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

Fig. 1 and Fig. 2 have been explained in the background art.

Fig. 3 is a specific flowchart of the assignment method proposed by the present invention. As shown in the figure, the method proposed by the present invention includes the following steps:

Step (1): The BSS receives the downlink data from the SGSN, saves the downlink data frame, and prolongs the life cycle of the downlink data frame.

Step (2): The BSS tries to send a downlink assignment message on the packet channel, and sets an acknowledgment flag in the message. In one embodiment of the present invention, the method of setting the response flag in the downlink assignment message is to set the uplink reserved block flag in the downlink assignment message, indicating that the message needs to be answered by the mobile station.

Step (3): The BSS receives the downlink assignment response from the mobile station on the specified uplink block. If the response from the mobile station is received, it means that the downlink assignment is successful, and then step (5) is executed. If the BSS does not receive the response from the mobile station on the specified uplink block, it means that the downlink assignment on the packet channel is unsuccessful, and it goes to step (4).

Step (4): The BSS resends the downlink assignment message on the common control signaling channel.

Step (5): After the assignment is successful, perform packet data transmission.

The present invention also has an equivalent technical solution, that is, first try to send the downlink assignment message on the public control signaling channel, and if unsuccessful, then send the downlink assignment message on the packet channel. The specific process is similar to the above-mentioned flow, and will not be repeated. .

Use the technical scheme that the present invention proposes, for situation shown in Fig. 1, when the downlink data packet of SGSN arrives BSS between b point and c point, through steps (1), (2), (3) in the present invention, (5) The normal packet downlink data transmission process can be entered. When the downlink data packet of SGSN arrives at SGSN between point c and d, the normal downlink data transmission can be entered through steps (1), (2), (3), (4), and (5) in the present invention process. For the situation shown in Figure 2, when the SGSN downlink packet data packet arrives at the BSS between point a and point b, it can carry out normal operation through steps (1), (2), (3) and (5) in the present invention Packet downlink data transmission process, when the downlink data packet of SGSN arrives at SGSN between c point and d point, get final product through steps (1), (2), (3), (4), (5) in the present invention Enter the normal downlink data transmission process.

The following table carries out comparative experiments with 2 mobile phones respectively carrying out 100 FTP data transmission business processes (the data volume size of each data transmission is 90Kbps), and tests the influence of the present invention on the packet loss rate of downlink data transmission before and after the implementation of the present invention. cellphone type The packet loss rate of the downlink packet channel assignment message sent directly from the packet-associated signaling control channel when the BSS is in the downlink or uplink release state The packet loss rate of sending downlink packet channel assignment messages directly from the common control signaling channel when the BSS is in the downlink or uplink release state Packet loss rate after adopting the present invention OT96MGPRS 25% 25% 5% Erisson T39MC 20% twenty two% 6%

The experimental results shown in the above table have fully demonstrated that after adopting the technical solution proposed by the present invention, the assignment success rate of downlink data transmission in the GPRS system is effectively improved, and then the downlink data packet loss caused by assignment message sending errors is reduced. packet rate.

Claims (3)

1, a kind of downlink data transmission assigning method in the gprs system is characterized in that comprising the steps:

(1) BSS receives the downlink data of service gateway support node, preserves downlink data frame;

(2) BSS attempts sending downstream assigned message on grouped channels, and in this message respond flag is set;

(3) downstream assigned of BSS receiving mobile on up of appointment is replied, if received replying of travelling carriage, and execution in step (5) then, if do not received replying of travelling carriage, execution in step (4) then;

(4) BSS resends downstream assigned message on public control signaling channel;

(5) after assigning successfully, carry out packet data transmission.

2, a kind of downlink data transmission assigning method in the gprs system is characterized in that comprising the steps:

(1) BSS receives the downlink data of service gateway support node, preserves downlink data frame;

(2) BSS attempts sending downstream assigned message on the public control signaling channel, and in this message respond flag is set;

(3) downstream assigned of BSS receiving mobile on up of appointment is replied, if received replying of travelling carriage, and execution in step (5) then, if do not received replying of travelling carriage, execution in step (4) then;

(4) BSS resends downstream assigned message at grouped channels;

(5) after assigning successfully, carry out packet data transmission.

3, a kind of downlink data transmission assigning method in the gprs system according to claim 1 and 2, it is characterized in that in the described step (2), the method that respond flag is set in downstream assigned message is at the mid-up reserved block mark of downstream assigned message, and this message of indication travelling carriage need be replied.

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