WO2005104413A1

WO2005104413A1 - Method for transmitting adjustment information of transmitting window size by the receiving end in radio link data transmission

Info

Publication number: WO2005104413A1
Application number: PCT/CN2005/000517
Authority: WO
Inventors: Bing Xu
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2004-04-19
Filing date: 2005-04-18
Publication date: 2005-11-03
Also published as: CN1319316C; CN1691590A

Abstract

The invention discloses a method for transmitting adjustment information of transmitting window size (Window Size SUFI) by the receiving end in radio link data transmission. Setting a buffer threshold for adjusting the transmitting window at the receiving end, in the process of data transmission, that the receiving end transmits Window Size SUFI includes the following steps: (1) the receiving end checks whether the occupancy of receiving buffer reaches the buffer threshold, if so, performs step (2), other wise returns to step (1); (2) calculates the transmitting window size number (WSN) in Window Size SUFI, and then fills the calculated WSN into the Windows Size SUFI; (3)transmits the Windows Size SUFI to the transmitting end, and returns to step (1). The application of the invention effectively resolves the problem of losing Window Size SUFI, implements the flow control better, as well as reduces the waste of idle port resource.

Description

Method for receiving window size adjustment information at receiving end in wireless link data transmission TECHNICAL FIELD

The present invention relates to wireless link data transmission technology in a wideband code division multiple access (WCDMA) system, and in particular, to a method for receiving window size adjustment information (Window Size SUFI) at a receiving end in wireless link data transmission. Background of the invention

The radio link control protocol (RLC) in the WCDMA system controls the transmission of radio link data packets. The RLC protocol is a sliding window-based control protocol. See Figure 1, which is a schematic diagram of the RLC protocol sliding window. Among them, the block with crossed slashes at the RLC sender refers to the peer confirming that it has not received the data packet that needs to be resent. The shaded block indicates the data packet waiting for confirmation by the peer. The blank block indicates that the buffer is not occupied. The RLC receiving end has a crossed diagonal line to indicate that the peer sends data packets that need to be re-received, a shaded square to indicate a received packet, and a blank square to indicate that no buffer is occupied. The basic variables of the RLC protocol are described as follows:

Configured_Tx_Window_Size: The initial value of the send window configured by the upper protocol layer to the RLC sender is also the maximum send window size. The unit is expressed by the number of protocol data units (PDUs). The RLC sender requests a send buffer according to this variable.

Configured— Rx— Window— Size: The size of the initial receive window configured by the upper protocol layer to the RLC receiver. The unit is expressed by the number of PDUs. The RLC receiver edits this variable in the receive buffer.

VT (S): Send status variable. Indicates the sequence number of the next PDU to be sent (excluding retransmitted PDUs).

VT (A): Confirm state variable. Represents the next consecutive PDU waiting to be acknowledged by the receiver Serial number.

V (R): Receive status variable. Indicates the sequence number of the next consecutive PDU to be received. VR (H): Highest expected reception state variable. Indicates the sequence number of the highest PDU expected to be received.

VT (MS): Maximum transmission state variable. PDU sequence numbers greater than or equal to this value will not allow transmission.

VT (MS) = VT (A) + VT (WS) o

VT (WS): the size of the transmission window. The initial value is also Configured— Tx_Window_Size, the minimum value is 1 (or other upper-level configuration value), and VT (WS) changes within this range.

VR (MR): The maximum allowed state variable. The PDU sequence number is greater than or equal to this value and will be rejected by the RLC receiver. VR (MR) = VR (R) + Configured— Rx— Window—Size.

The RLC receiver informs the RLC sender through the status PDU (Status PDU) that some packets have been received and some packets have not been received. After receiving these status PDUs, the RLC sender changes the value of VT (A), thus Push the VT (MS) forward to ensure that data is continuously sent. When the RLC sender detects that a certain PDU has not been received by the receiver, as shown in Figure 1, the RLC sender has a cross-hatched block. That will cause the VT (S) to continue to increase until the VT (MS), and no longer send data with a serial number greater than or equal to the VT (MS). When the RLC receiver detects that a certain PDU has not been received, as shown in Figure 1, the RLC receiver has a crossed diagonal block. Then VR (H) will continue to increase until VR (MR), and no longer receive data with a serial number greater than or equal to VR (MR).

In the current version of the RLC protocol, the RLC receiver is required to control the size of the send window of the RLC sender based on its own reception conditions, most of which are receiving buffer conditions, so as to control the bandwidth usage of the wireless link. The protocol uses a status PDU that contains Window Size SUFI. Line flow control to adapt to changes in the wireless environment and improve the efficiency of wireless link bandwidth usage. According to the protocol, the usual method is that the receiving end includes Window Size SUFI information in the Status PDU and sends it to the sending end of the RLC. The composition of Window Size SUFI is shown in Table 1:

TYPE WSN Table 1

Among them, TYPE: information type parameter. The length is 4 bits and the value is: 0001, which means that it is WINDOW SUFI information. WSN: Send window size parameter. The length is 12 bits, and the value is: The size of the window filled by the RLC receiver according to its receiving conditions. When the RLC sender receives a Status PDU containing Window Size SUFI information, it changes the VT (WS) to the WSN in the Window Size SUFI information. If WSN = 0, the SUFI is discarded. If WSN> Configured_Tx— Window— Size, Then VT (WS) is taken.

Configured—Tx— Window—Size. In this way, the size of the sending window can be changed to avoid the decrease in bandwidth utilization efficiency of the data link and data congestion.

See Figure 2 and Figure 2 for a schematic diagram of the receiving end notifying the sending end of the change of the sending window through the Window Size SUFI message. As shown in FIG. 2, when the RLC receiver detects that the available buffer space of the receiving buffer is increasing and reaches certain thresholds, for example, all retransmitted packets in FIG. 2 have been received, and the RLC receiver does not occupy a buffer. when. The RLC receiver sends a Status PDU containing Window Size SUFI information to the RLC sender. The WSN in the Window Size SUFI information is greater than the current sender's VT (WS), and the window size SUFI is used to notify. The RLC sender adds VT (WS).

After the RLC sender receives the Status PDU, it changes the VT (WS) to the WSN in the Window Size SUFI message, and increases the sending window to prevent the bandwidth utilization efficiency of the data link from decreasing.

When the wireless link is degraded, there will be data loss, resulting in available free space in the RLC receiver's buffer. At this time, the RLC receiving end uses Window Size SUFI to reduce the data sending of the RLC sending end, and notifies the RLC sending end to reduce VT (WS), thereby reducing the sending window and avoiding data congestion.

According to the protocol, the sender does not monitor the wireless link bandwidth usage. Only when receiving the Window Size SUFI information from the receiver, the window size is adjusted according to the information requirements. In this way, if the Window Size SUFI sent by the receiver is lost, the sender It will not take the initiative to make window adjustments. When the link changes from a bad state to a good state, once the RLC receiver requests the RLC sender to increase the sending window Window Size SUFI information is lost, the sender does not perform window adjustments, and the window size SUFI trigger is not uniform in the RLC protocol. Standard, after a trigger, it may take a long time to trigger, especially in the case of wireless quality. When the packet loss rate decreases, the trigger will not even trigger. During this time, even if the wireless link is good, the wireless link may Sending data at a very low rate will cause a serious decrease in the speed of the wireless link.

According to the actual measurement of different services, the PDU drop rate of some non-real-time data services can be tolerated to 10%. In a good wireless environment, the drop rate specified by the protocol does not exceed 0.7%, so in comparison, Window Size SUFI The probability of loss is high.

According to the above description, if the Window Size SUPI information that informs the RLC sender to adjust the send window is lost during wireless transmission, it will cause data congestion or the rate of the wireless link to drop.

At present, there are two main methods for the receiver to send Window Size SUFI information:

(1) A method of periodically sending Window Size SUFI information. At present, this method is generally adopted. This method sends Window Size SUFI according to the timer T period throughout the running time of the RLC receiving entity, until the RLC receiving entity dies. This can basically ensure that the RLC sender receives Window Size SUFI information and performs flow control normally. The second method: The Status Report must include Window Size SUFI information. This method must include Window Size SUFI information of TYPE 0001 in the Status Report. Because the Status Report is sent more frequently, it can also ensure that the RLC sender receives Window Size SUFI information and performs flow control normally.

Although the above two methods can perform normal flow control, in both methods the receiving end blindly and repeatedly sends the Window Size SUFI information multiple times. In fact, in some cases, the sending window does not need to be adjusted. The Window Size SUFI information sent many times is unnecessary, which wastes valuable air interface resources.

It can be seen that, because the window size SUFI triggering and application discussion is relatively simple in the protocol, no related protection measures are proposed. As a result, the air interface resources are wasted in the actual application process, the utilization efficiency of the wireless link bandwidth is reduced, and even the RLC protocol is degraded to a one-stop protocol, which greatly affects the application of data transmission. Summary of the invention

In view of this, the main object of the present invention is to provide a method for the receiver to send Window Size SUFI during wireless link data transmission, solve the problem caused by the lost Window Size SUFI, and reduce the waste of air interface resources.

To achieve the above object, the present invention provides a method for transmitting window size adjustment information Window Size SUFI at a receiving end during wireless link data transmission. The method sets a buffer threshold for adjusting a sending window at a receiving end, and receives data during data transmission. The process of sending Window Size SUFI by the client includes the following steps:

1) The receiving end checks the receiving buffer occupancy during the data transmission process. If the result of the check reaches the receiving buffer occupancy threshold, then step 2) is performed, otherwise it returns to step 1);

2) Calculate the window size parameter WSN in the Window Size SUFI, and fill the calculated WSN in the Window Size SUFI; 3) Send the Window Size SUFI to the sending end, and return to step 1).

Wherein, the step 3) may be: sending the Window Size SU I to the sending end, and starting a timer;

When the timer expires, the receiving end checks the receiving buffer occupancy, and if the receiving result still reaches the buffer threshold, it returns to step 2);-If the check result does not reach the buffer threshold, return to step 1).

The predetermined time of the timer may be flexibly set according to a specific service or application scenario. The method for setting a buffer threshold for adjusting a sending window may be: preset a first buffer threshold for reducing a sending window and a second buffer threshold for increasing a sending window according to a specific service or application scenario;

The step 1) may be: the receiving end checks the receiving buffer occupancy rate, and if the checking result indicates that the buffer occupancy rate exceeds the first buffering threshold; or the buffering occupancy rate is lower than the second buffering threshold, step 2) is performed, otherwise returns step 1 ).

Step 1) The method for the receiving end to check the receiving buffer occupancy may be: receiving. After the receiving end creates the receiving entity, it checks the receiving buffer occupancy in real time or periodically checks the receiving buffer occupancy.

Step 2) The method for calculating the WSN in Window Size SUFI may be: if the check result cache occupancy is greater than or equal to the first cache threshold, then decrease the WSN; if the cache occupancy is less than or equal to the second cache threshold, then Increase WSN.

Step 3) The method for sending the Window Size SUFI to the sending end may be: adding the Window Size SUFI to the status data unit, and sending the status data unit to the sending end.

As can be seen from the above technical solution, in the wireless link data transmission method of the present invention, the receiving end sends a Window Size SUFI method. The receiving end sets a buffer threshold for adjusting the sending window, repeatedly checks the receiving buffer occupancy rate, and according to the receiving Cache occupancy to trigger send Window Size SU L Since the present invention is directed to the actual situation of the receiving buffer of the receiving end, sending Window Size SUFI is triggered only when the sending window needs to be adjusted, which avoids blindly and repeatedly sending Window Size SUFI information multiple times, thereby saving valuable air interface resources . Even if the Window Size SUFI is lost, because the receiver is still checking the occupancy of the receiving buffer, it can also send Window Size SUFI again according to the current occupancy of the receiving buffer. window. Brief description of the drawings

Figure 1 is a schematic diagram of the sliding window of the RLC protocol;

FIG. 2 is a schematic diagram of a receiving end notifying a sending end to change a sending window through a Window Size SUFI message;

FIG. 3 is a flowchart of sending Window Size SUFI information by a data receiving end according to a preferred embodiment of the present invention. Mode of Carrying Out the Invention

In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

In the wireless link data transmission method of the present invention, the method for sending Window Size SUFI at the receiving end sets a buffer threshold for adjusting the sending window at the receiving end, repeatedly checks the occupancy rate of the receiving buffer, and triggers transmission according to the occupancy rate of the receiving buffer. Window Size SUFI.

The following describes a preferred embodiment of the present invention.

Referring to FIG. 3, FIG. 3 is a flowchart of sending Window Size SUFI information by a data receiving end according to a preferred embodiment of the present invention. In this implementation, a specific service or application scenario at the receiving end is preset to set a first buffer threshold for reducing the sending window and a second buffer threshold for increasing the sending window. These two thresholds are the occupancy of the receiving buffer, which The first cache threshold is 70%, and the second cache threshold is 30%. The process includes the following steps:

Step 301: The receiving end checks the occupancy rate of the receiving buffer. After the receiving end creates the receiving entity, the receiving buffer occupancy rate can be checked in real time, or the receiving buffer occupancy rate can be checked periodically.

In step 302, it is determined whether the receiving buffer occupancy rate is greater than or equal to the first buffer threshold, and if yes, step 303 is performed; otherwise, step 308 is performed.

In step 303, the size parameter WSN of the sending window in the Window Size SUFI is calculated, and the calculated WSN is filled in the Window Size SUFL. At this time, the check result cache occupancy is greater than or equal to the first cache threshold, so the WSN is reduced.

Step 304: Add Window Size SUFI to the status data unit, send the status data unit to the sender, and start timer 1;

In step 305, it is determined whether timer 1 has reached a predetermined time, and if so, step 306 is performed; otherwise, return to execute this step.

Step 306: The receiving end checks the occupancy rate of the receiving buffer.

Step 307: Determine whether the receiving buffer occupancy ratio is still greater than or equal to the first buffer threshold, and if yes, return to step 303; otherwise, return to step 301.

Step 308: Determine whether the receiving buffer occupancy is less than or equal to the second buffer threshold, and if yes, go to step 309; otherwise, go back to step 301.

In step 309, the size parameter WSN of the sending window in the Window Size SUFI is calculated, and the calculated WSN is filled in the Window Size SUFL. At this time, the buffer occupancy is less than or equal to the first buffer threshold, so the WSN is increased.

Step 310: Add Window Size SUFI to the status data unit, send the status data unit to the sender, and start timer 2;

Step 311, determine whether the timer 2 has reached a predetermined time, and if so, perform step 306; Otherwise, return to this step.

Step 312: The receiving end checks the occupancy rate of the receiving buffer.

In step 313, it is determined whether the occupancy rate of the receiving buffer is still less than or equal to the second buffer threshold, and if yes, return to step 309; otherwise, return to step 301.

Both the timer 1 started in step 304 and the timer 2 started in step 311 in this embodiment can be flexibly set according to specific services or application scenarios.

In addition, in this embodiment, the checking of the receiving buffer occupancy rate is implemented by using a query mode. In actual applications, it may also be implemented by using other methods such as interrupts.

It can be seen from the foregoing embodiments that the method for sending the Window Size SUFI by the receiving end in the wireless link data transmission of the present invention sends the Window Size SUFI information only when necessary. Even if the Window Size SUFI is lost, because the receiving end is still checking the occupancy of the receiving buffer, it can also send Window Size SUFI again according to the current occupancy of the receiving buffer. Good flow control, and reduce the waste of air interface resources.

Claims

Claim

1. A method of receiving window size adjustment information Window Size SUFI at the receiving end during wireless link data transmission, characterized in that the method sets a buffer threshold for adjusting the sending window at the receiving end, and the receiving end sends Window during data transmission The size SUFI process includes the following steps:

2) Calculate the size parameter WSN of the sending window in Window Size SUFI, and fill the calculation. Fill out the WSN into the Window Size SUFI;

3) Send the Window Size SUFI to the sending end, and return to step 1).

2. The method according to claim 1, wherein the step 3) is: sending the Window Size SUFI to the sender, and starting a timer;

When the timer reaches the predetermined time, the receiving end checks the receiving buffer occupation rate. If the receiving result still reaches the buffer threshold, it returns to step 2); if the check result does not reach the buffer threshold, it returns to step 1).

3. The method according to claim 2, wherein: the predetermined time of the timer is set according to a specific service or application scenario.

4. The method according to claim 1, wherein the method for setting a buffer threshold for adjusting a sending window is: presetting a first buffer threshold for reducing a sending window according to a specific service or application scenario And a second buffer threshold for increasing the sending window;

The step 1) is as follows: the receiving end checks the receiving buffer occupancy rate, and if the checking result indicates that the buffer occupancy rate exceeds the first buffering threshold; or the buffering occupancy rate is lower than the second buffering threshold, step 2) is performed; otherwise, the process returns to step 1 ).

5. The method according to claim 1 or 4, characterized in that step 1) said receiving. The method for the receiving end to check the receiving buffer occupancy is: After the receiving end creates the receiving entity, it checks the receiving buffer occupancy in real time.

6. The method according to claim 1 or 4, characterized in that, in step 1), the method for the receiving end to check the receiving buffer occupancy is: after the receiving end creates the receiving entity, the receiving buffer occupancy is periodically checked. Check.

7. The method according to claim 4, characterized in that, in step 2), the method for calculating the Window Size SUFI. The method of WSN is: if the check result cache occupancy is greater than or equal to the first 'cache threshold, then decrease the WSN ; If the cache occupancy is less than or equal to the second cache threshold, increase the WSN.

.

8. The method according to claim 1, wherein, in step 3), the method for sending Window Size SUFI to the sending end is: adding Window Size SUFI to the status data unit, and sending the status data unit to the sending end .