CN1667993A - A method for controlling transmit frequency of status report - Google Patents

Abstract

The invention discloses a method for controlling the sending frequency of a status report. The method sets sending conditions for status reports containing NACK sent from a receiving entity to a sending entity; before the receiving entity sends a status report including NACK to the sending entity, the Each PDU within the scope of this status report that has not been correctly received by the receiving entity is judged whether it meets the set NACK sending conditions. If not, the NACK of the PDU is not included in the status report; otherwise, it is allowed to A NACK for this PDU is included in the status report. The invention solves the problem of redundant PDU and status report transmission in the prior art. The present invention limits the sending of status reports including NACK without affecting the sending of status reports including ACK, reduces the sending of redundant status reports, further reduces redundant retransmission PDUs, and improves the reliability of communication links. utilization rate.

Description

A method of controlling the sending frequency of status reports

technical field

The present invention relates to the technical field of data unit status report, and more specifically relates to a method for controlling the sending frequency of a status report in an automatic repeat request mechanism of a wireless communication system.

Background technique

Universal Mobile Telecommunications System (UMTS) is a third-generation mobile communication system that adopts Wideband Code Division Multiple Access (WCDMA) air interface technology, and is also commonly referred to as a WCDMA system.

The wireless interface of WCDMA is divided into physical layer, data link layer and network layer. The radio link control (RLC) in the data link layer supports three modes: transparent mode (TM), unacknowledged mode (UM) and acknowledged mode (AM) to realize segmentation, concatenation, filling, error control, and flow control , Repeatability detection and other functions. Among them, the RLC AM entity includes a sending entity and a receiving entity, and the sending entity and the receiving entity process the data unit sent from the network layer, and then send the processed data unit to the network layer. The functional model of the RLC AM entity composed of the sending entity and the receiving entity is shown in Figure 1, and the corresponding processing process is shown in Figure 2. Among them, the sending entity performs data unit processing through the following steps:

Step 201. When the sending entity receives the RLC service data unit (SDU) transmitted from the network layer, it first performs segmentation/concatenation processing on the protocol processing unit (PDU).

According to actual needs, the sending entity may also need to fill the segmented/concatenated RLC PDUs.

Step 202: Assemble Acknowledged Mode Data (AMD) PDUs, and send the assembled AMD PDUs to the sending buffer.

Step 203, the sending buffer in the sending entity schedules the AMD PDUs stored by itself.

Step 204, if the scheduled PDU can be sent, set the query bit according to the rules configured by the network layer, and then submit the processed AMD PDU to the bottom layer and send it to the receiving entity.

In step 204, for the newly assembled AMD PDU, the serial number field is also set, and then the AMD PDU is encrypted.

The receiving entity proceeds with data unit processing through the following steps:

Step 205, the receiving entity decrypts the correctly received AMD PDU, and puts the decrypted data into the receiving buffer.

Step 206: Analyze the AMD PDU to determine whether the RLC SDU can be reassembled. If a complete RLC SDU can be reassembled, perform a reassembly operation and submit the reassembled RLC SDU to the upper layer.

In the above step 206, before the receiving entity parses the decrypted AMD PDU, it also needs to judge whether the current AMD PDU transmission is based on the value of the query bit in the AMD PDU and the status reporting mechanism configured by the network layer in the receiving entity. Accurate, that is, judge whether it is necessary to send a status report for retransmitting data to the sending entity, and if necessary, the receiving entity assembles a corresponding status report and sends the status report to the bottom layer. The bottom layer sends the status report to the retransmission buffer in the sending entity, and the retransmission buffer caches the AMD PDUs that need to be retransmitted according to the received status report. In this case, the AMD PDU dispatched by the sending buffer in the above step 203 not only has a newly assembled AMD PDU, but also includes an AMD PDU that is stored in the retransmission buffer and waits for retransmission. This mechanism for retransmitting data units is called an Automatic Repeat Request (ARQ) mechanism.

The status report assembled by the receiving entity contains positive acknowledgment (ACK) information and negative acknowledgment (NACK) information, the status report used to retransmit data contains NACK, and the status report used to determine that the AMD PDU is correctly received contains ACK. In the above-mentioned entire communication process from the sending entity to the receiving entity, if the sending entity receives a status report containing NACK, that is, a status report for retransmitting data, it will retransmit the PDU that has an error in the transmission or is discarded to ensure Correct transmission of data units. Of course, if the sending entity receives the status report including ACK, it can confirm that the corresponding PDU has been transmitted correctly.

However, at present, it usually occurs that the receiving entity sends multiple status reports for the same PDU to the sending entity and the confirmation information contained is NACK, and the sending entity retransmits the same PDU to the receiving entity multiple times. That is to say, at present, the system usually needs to transmit a lot of redundant data, which obviously wastes data transmission resources, and both the receiving entity and the sending entity both waste a lot of time in transmitting redundant data.

In addition, since the sending entity waits for the receiving entity to return a status report after sending the PDU to the receiving entity, if the status report returned by the receiving entity contains NACK, the sending entity should send the PDU to the receiving entity again. The waiting time of the sending entity in the whole process is the delay. If the sending entity receives multiple status reports containing NACK returned by the receiving entity, the sending entity is the delay for the PDU from the first sending of the PDU to the last retransmission of the PDU. Obviously, this period The time delay is long, which occupies the resources of the sending entity, and also has a certain impact on the work of the sending entity. The prior art does not solve this problem at present.

The above-mentioned problems not only appear in the ARQ mechanism of the WCDMA system, but also appear in the ARQ mechanisms of the Time Division Synchronous Code Division Multiple Access (TD-SCDMA) system and CDMA2000. For WCDMA and TD-SCDMA systems, the ARQ mechanism is in the Acknowledged Mode (AM) of the RLC protocol; for the CDMA2000 system, the ARQ mechanism is in the ARQ sublayer of the Link Access Control (LAC) protocol.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a method for controlling the sending frequency of the status report, so as to avoid the system from sending redundant status reports and data units.

In order to achieve the above purpose, the technical solution of the present invention is implemented as follows: a method for reporting the status of data units is applicable to a communication system including a sending entity and a receiving entity, and an automatic retransmission mechanism is used between the sending entity and the receiving entity. communication, the method includes the steps of:

a. Set a negative acknowledgment NACK sending condition for each protocol data unit PDU that is detected to be incorrectly received;

b. Before the receiving entity sends a status report to the sending entity each time, for each PDU within the scope of this status report that has not been correctly received by the receiving entity, determine whether it currently meets the NACK sending conditions set for the PDU, if not If it matches, the NACK of the PDU is not included in the status report; otherwise, the NACK of the PDU is allowed to be included in the status report;

c. The receiving entity sends the status report to the sending entity.

In the step a, the sending condition is set as follows: firstly, it is judged whether the NACK status report is sent for the first time for the PDU, if yes, the NACK sending condition is met; otherwise, it is further judged whether there is a corresponding PDU, and If the NACK timing device in normal working state exists, it does not meet the NACK sending condition, otherwise, it meets the NACK sending condition.

The step c may further include: the receiving entity respectively initializes the NACK sending condition of each PDU corresponding to the NACK in the status report.

In step c, the initial NACK sending condition is: if there is a NACK timing device corresponding to the PDU, start the timing device directly; otherwise, set a NACK timing device for the PDU and start the timing device.

In the step a, the NACK sending condition set for each detected PDU that is not correctly received is the same NACK sending condition;

In step a, the NACK sending condition is set as: judging whether there is a NACK timing device in a normal working state, if it exists, it does not meet the NACK sending condition; otherwise, it meets the NACK sending condition;

The step c further includes: initializing the NACK sending condition;

The initial NACK sending condition is: if the NACK timing device currently exists, start the timing device directly; otherwise, set a NACK timing device and start it.

The NACK timing device is a NACK timer;

In step a, the normal working state of the NACK timer means: the NACK timer has been started and has not timed out.

The NACK timing device is a counter;

In step a, when the NACK timing device is in a normal working state, the counter is in a counting state.

The method may further include: setting the upper limit and the lower limit of the counting range of the counter, setting the initial value of the counter as the upper limit of the counting range, and setting the counter to: every certain time interval, the counter reduces the current counting value by one;

In step a, the counter is in the counting state: the current value of the counter is greater than the lower limit of the counting range;

In step c, the initializing the NACK sending condition further includes: setting the initial value of the counter as the upper limit of the counting range.

The counter decrements the current count value by one at regular time intervals: the counter decrements the current count value by one each time the MAC status indication primitive MAC_Status_Ind sent by the MAC is received.

The method may further include: setting the upper limit and the lower limit of the counting range of the counter, setting the initial value of the counter to the lower limit of the counting range, and setting the counter to: every certain time interval, the counter adds one to the current counting value;

In step a, the counter is in a counting state: the current value of the counter is less than the upper limit of the counting range of the counter;

In step c, the initializing the NACK sending condition further includes: setting the initial value of the counter as the lower limit of the counting range.

The counter adding one to the current count value at regular time intervals is as follows: each time the MAC_Status_Ind sent by the MAC is received, the counter adds one to the current count value.

The automatic repeat request mechanism can be located in the acknowledged mode AM of the radio link control RLC protocol in the wideband code division multiple access WCDMA or time division synchronous code division multiple access TD-SCDMA system.

The automatic repeat request mechanism may also be located in the automatic repeat request ARQ sublayer of the Link Access Control (LAC) protocol in the CDMA2000 system.

The solution of the present invention sets the conditions for sending status reports containing NACK, without affecting the sending of status reports containing ACK, limits the sending of status reports containing NACK, reduces the sending of redundant status reports, and further reduces the Redundant retransmission PDUs improve the utilization of communication links.

Description of drawings

Fig. 1 is the functional model schematic diagram of RLC AM entity in the prior art;

FIG. 2 is a schematic diagram of an implementation process in which a sending entity sends a PDU to a receiving entity in the prior art;

Fig. 3 is an implementation flowchart of an embodiment of the solution of the present invention.

Detailed ways

After analysis, there are two main reasons for the problem of redundant data transmission. On the one hand, because there is a delay in the transmission of PDUs and status reports in the communication system, after sending a PDU, the sending entity needs at least one round-trip time (RTT) to obtain information about whether the receiving entity has correctly received the PDU. Due to the existence of delay, the situation in the following steps will appear:

Step A, the sending entity sends a PDU for the first time, and the PDU has an error during transmission, that is, it is not sent to the receiving entity;

Step B, the receiving entity detects that the PDU is lost, and sends a status report including NACK to the sending entity;

Step C. After receiving the status report for the PDU, the sending entity transmits the PDU to the receiving entity for the second time, that is, retransmits the PDU;

Step D. Due to the delay, before receiving the PDU retransmitted by the sending entity, the receiving entity sends a status report containing NACK to the sender again;

Step E. After sending the status report again, the receiving entity receives the PDU retransmitted by the sending entity, and then sends a status report including ACK to the sending entity;

Step F, due to the delay, before receiving the status report including ACK sent by the receiving entity, the sending entity first receives the status report including NACK sent by the receiving entity in step D, so the third time transmits the status report to the receiving entity PDUs.

Apparently, the above process results in the transmission of redundant data.

Another reason for the occurrence of redundant data transmission is: in order to adapt to different service requirements, RLC supports multiple trigger mechanisms for status query and status report. The status query mechanism allows the receiving entity to flexibly perform status query according to different mechanisms. The trigger mechanism of the status report allows the receiving entity to flexibly configure the status report according to different mechanisms. For the sending entity, it only needs to select the required information according to the information in the status report Retransmitted PDUs are sufficient. However, if the receiving entity sends status reports for the same PDU according to several different mechanisms, it may happen that the receiving entity sends status reports consecutively within a short time interval, which results in the frequency of status reports arriving at the sending entity High, so redundant PDUs may be retransmitted, thereby wasting air interface resources.

The timer status prohibition timer (Timer_Status_Prohibit) and query prohibition timer (Timer_Poll_Prohibit) defined in the current protocol can limit the sending frequency of the status report within a certain range by setting a specific time period. Taking Timer_Status_Prohibit as an example, the timer is started only when the status report prohibition function is used. If the Timer_Status_Prohibit is in the normal working state, the receiving entity cannot send a status report containing NACK or ACK. This timer is started when the receiving entity sends a status report for the STATUS PDU, and a new status report of NACK or ACK cannot be sent before the timer expires. Although the sending frequency of the status report can be limited to a certain range by setting a specific time period, or in other words, the sending frequency of the status report can be controlled by setting a larger Timer_Status_Prohibit and Timer_Poll_Prohibit, and the transmission of redundant data can be reduced or eliminated , however, this approach has flaws. This is because the ARQ mechanism has different requirements for the sending frequency of ACK and NACK: the higher the frequency of ACK, the sending entity can clear the PDUs buffered in the sending buffer in time, thereby reducing the blocking probability of the sending window and improving the link efficiency. The utilization rate and reduce the demand for memory; due to the problem of redundant data unit transmission, the frequency of sending NACK should not be too high. That is to say, the existing technical solutions cannot meet the requirements of ACK and NACK at the same time, and cannot well eliminate the problem of redundant data unit transmission.

In order not to affect the sending frequency of the status report containing ACK as far as possible, and to reduce the sending frequency of the status report containing NACK, the solution of the present invention is mainly based on the prior art, setting A NACK sending condition. In this way, before sending the status report, the receiving entity first judges whether the PDU that is not correctly received by the receiving entity meets the NACK sending condition set for the PDU. If not, it will not be included in the status report Include the NACK for the PDU; otherwise, allow the NACK for the PDU to be included in the status report, and reset the NACK sending condition for the PDU.

In the solution of the present invention, the NACK sending condition can be set for each PDU that is detected not to be received correctly. Of course, the NACK sending conditions for different PDUs may be different; the same NACK can also be set for all PDUs that are detected not to be received correctly The sending condition, that is, all detected PDUs that are not received correctly correspond to the same NACK sending condition.

In the following, firstly, a detailed description will be given to the situation where the NACK sending condition is set for each PDU that is detected not to be received correctly. Referring to Fig. 3, the present embodiment takes setting PDU(n) as an example, and the set timing device is a timer, and the corresponding solution includes the following steps:

Step 301, setting a NACK sending condition for each detected PDU that is not received correctly.

The set NACK sending condition is: if the NACK status report is sent for the first time for a certain PDU, the NACK for the PDU can be set in the status report; if the NACK status report has been sent for the PDU before, or , the current NACK status report that needs to be sent is not the first time, it is also necessary to determine whether there is a NACK timing device corresponding to the PDU and in a normal working state. If there is such a timing device, it cannot be set in the status report. NACK for the PDU; otherwise, a NACK for this PDU can be set in the status report.

In this embodiment, the timing device is a timer, and when the timing device is in a working state, it means that the timer has been started and has not timed out.

Steps 302 - 303 , when the receiving entity needs to send a status report, it first judges whether it needs to send a NACK for PDU(n), if yes, go to step 304 , otherwise, go to step 307 .

Step 304 , the receiving entity further judges whether the NACK is sent for the first time, and if so, determines that the NACK sending condition is met, and proceeds to step 306 ; otherwise, proceeds to step 305 .

Step 305. The receiving entity judges whether there is a NACK timer corresponding to the PDU and in a normal working state. If it exists, determine that the NACK sending condition is not met, and enter step 307; otherwise, determine that the NACK sending condition is met, and enter Step 306.

Step 306 , add a NACK for the PDU(n) in the status report, and then go to step 307 .

Step 307, the receiving entity processes the next PDU.

In step 307, if the receiving entity determines that the status report may also contain NACKs for other PDUs, it continues to process the next PDU; otherwise, the receiving entity sends the current status report to the sending entity.

Through the above steps, the purpose of the present invention can be achieved.

In addition, when the receiving entity finishes processing the status report and sends the status report to the sending entity, it should also re-initialize the timer for the PDU(n) and the PDUs corresponding to other NACKs in the status report. Of course, the receiving entity can also re-initialize the corresponding timer immediately after adding these NACKs to the status report. For the initialization timer, if there is currently a NACK timer corresponding to the PDU, the timer can be started directly; otherwise, a NACK timer is set for the PDU and the timer is started.

That is to say, the above scheme first sets the NACK sending condition for the PDU that has detected a problem. When the receiving entity sends a status report to the sending entity, it first judges whether the PDU that is detected to be received incorrectly satisfies the set NACK condition. If the sending condition is satisfied, the NACK for the PDU is allowed to be added in the status report; otherwise, the NACK for the PDU is not included in the status report. That is to say, if the receiving entity has started a timer for a certain PDU, within the timer time, even if the receiving entity triggers a NACK for the PDU again, it cannot send the NACK to the sending entity. Only when there is no timer corresponding to the PDU, and there is a timer corresponding to the PDU, but the timer is not started or the timer expires, the receiving entity can include the NACK for the PDU in the status report and send the A status report is sent to the sending entity.

Of course, the timing device can also be set as a counter, and the counter can be set to count according to a certain time interval. Since the MAC sends to the RLC at a fixed time interval to inform the RLC of the data rate that the RLC can send to the MAC, that is, the number of PDUs that the RLC can send to the MAC within a certain period of time, the counter can be set to be sent according to the MAC Incoming MAC status indication primitives (MAC_Status_Ind) are counted. The upper and lower limits of the count range of the counter are also set, wherein the initial value of the counter is set as the upper limit of the count range. And after the counter is started, it will decrease its own count value by one every certain time interval. For the case of counting according to the MAC_Status_Ind, each time the MAC_Status_Ind sent by the MAC is received, the own count value is decremented by one.

Through such a setting, when the receiving entity sends a status report, if it detects that there is a counter corresponding to a certain PDU, it also needs to judge whether the counter corresponding to the PDU is the lower limit of the counting range, and if so, then in this state The NACK for the PDU is included in the report, otherwise, the NACK for the PDU is not included in the status report.

The above is to set the initial value of the counting range of the counter as the upper limit of the counting range. Similarly, the initial value can also be set as the lower limit of the counting range. After the counter starts, every time it receives the MAC_Status_Ind sent by the MAC, it will set the current The count value of is incremented by one. In this way, when the receiving entity sends a status report, if it detects that there is a counter corresponding to a certain PDU, it also needs to judge whether the counter corresponding to a certain PDU that is detected to be received incorrectly is the upper limit of the counting range set, if If yes, include the NACK for the PDU in the status report, otherwise, do not include the NACK for the PDU in the status report.

For the case where the timing means is a counter, similarly, the reinitialization of the counter may be when the status report is sent to the sending entity, or when a NACK is included in the status report. Also, reinitializing the counter resets the initial value of the counter. For the initialization counter, if there is a counter corresponding to the PDU, the counter can be started directly; otherwise, a counter is set for the PDU and the counter is started.

The above is to set the NACK sending condition for each PDU that is detected not to be received correctly, and to set the NACK sending condition for all PDUs that are detected not to be received correctly, that is, the second processing method of the present invention, which is the same as the above The main differences in processing are the following:

1) This process is to set the NACK sending condition for all detected PDUs that are not received correctly. The set NACK sending condition is: judging whether there is a NACK timing device in a normal working state, if yes, the NACK sending condition is not met; otherwise, the NACK sending condition is met.

2) In this process, when the receiving entity determines that it is necessary to send a NACK for PDU(n), it directly judges whether there is a NACK timing device in a normal working state. If it is, it is determined that it does not meet the NACK sending condition; condition.

Through the above-mentioned second method, if the receiving entity has started the timing device for all PDUs that have been detected not to be received correctly, within the timing device time, even if the receiving entity triggers a NACK for one of the PDUs, it cannot Send a NACK for the PDU to the sending entity. Only when the NACK timing device is not set, and there is a corresponding NACK timing device, but the timing device is not started or the timer expires, the receiving entity can include the NACK for the PDU in the status report and send the status report to the sending entity. Of course, the timing device in this processing method can also be a timer, a counter, or other devices capable of realizing timing.

The above descriptions are only preferred embodiments of the solutions of the present invention, and are not intended to limit the protection scope of the present invention.

Claims (10)

1. A method for controlling the sending frequency of a status report, applicable to a communication system comprising a sending entity and a receiving entity, and an automatic retransmission mechanism is used for communication between the sending entity and the receiving entity, wherein the method comprises the following steps: a. Set a negative acknowledgment NACK sending condition for each protocol data unit PDU that is detected to be incorrectly received; b. Before the receiving entity sends a status report to the sending entity each time, for each PDU within the scope of this status report that has not been correctly received by the receiving entity, determine whether it currently meets the NACK sending conditions set for the PDU, if not If it matches, the NACK of the PDU is not included in the status report; otherwise, the NACK of the PDU is allowed to be included in the status report; c. The receiving entity sends the status report to the sending entity. 2. The method according to claim 1, characterized in that in the step a, the sending condition is set as follows: first judge whether it is the first time to send a NACK status report for the PDU, if yes, it is in line with the NACK sending condition; otherwise, further judge whether there is a NACK timing device corresponding to the PDU and in a normal working state, if it exists, it does not meet the NACK sending condition, otherwise, it meets the NACK sending condition; The step c further includes: the receiving entity respectively initializes the NACK sending conditions of the PDU corresponding to each NACK in the status report; The initial NACK sending condition is: if there is a NACK timing device corresponding to the PDU, start the timing device directly; otherwise, set a NACK timing device for the PDU and start it. 3. The method according to claim 1, characterized in that in the step a, the NACK sending condition set for each detected PDU that is not correctly received is the same NACK sending condition; In step a, the NACK sending condition is set as: judging whether there is a NACK timing device in a normal working state, if it exists, it does not meet the NACK sending condition; otherwise, it meets the NACK sending condition; The step c further includes: initializing the NACK sending condition; The initial NACK sending condition is: if the NACK timing device currently exists, start the timing device directly; otherwise, set a NACK timing device and start it. 4. The method according to claim 2 or 3, wherein the NACK timing device is a NACK timer; In step a, the normal working state of the NACK timer means: the NACK timer has been started and has not timed out. 5. The method according to claim 2 or 3, wherein the NACK timing device is a counter; In step a, when the NACK timing device is in a normal working state, the counter is in a counting state. 6. The method according to claim 5, further comprising: setting the upper limit and lower limit of the counting range of the counter, setting the initial value of the counter to the upper limit of the counting range, and setting the counter to: every certain time interval, the counter will decrement the current count value by one; In step a, the counter is in the counting state: the current value of the counter is greater than the lower limit of the counting range; In step c, the initializing the NACK sending condition further includes: setting the initial value of the counter as the upper limit of the counting range. 7. The method according to claim 6, characterized in that the counter reduces the current count value by one every time a certain time interval is received: each time a MAC status indication primitive sent by the medium access control MAC is received MAC_Status_Ind once, the counter will decrement the current count value by one. 8. The method according to claim 5, further comprising: setting the upper limit and the lower limit of the counting range of the counter, setting the initial value of the counter to the lower limit of the counting range, and setting the counter to: every certain Time interval, the counter adds one to the current count value; In step a, the counter is in a counting state: the current value of the counter is less than the upper limit of the counting range of the counter; In step c, the initializing the NACK sending condition further includes: setting the initial value of the counter as the lower limit of the counting range. 9. The method according to claim 8, wherein the counter adds one to the current count value at regular intervals: each time the MAC_Status_Ind sent by the MAC is received, the counter counts the current count value plus one. 10. The method according to claim 1, wherein the automatic repeat request mechanism is located in the confirmation mode of the Radio Link Control (RLC) protocol in WCDMA or Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems AM; or located in the automatic repeat request ARQ sublayer of the link access control LAC protocol in the CDMA 2000 system.

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