WO2006021159A1

WO2006021159A1 - Method for controlling transmission frequency of status reports

Info

Publication number: WO2006021159A1
Application number: PCT/CN2005/001331
Authority: WO
Inventors: Xuezhi Yang; Bing Xu; Bingyu Qu; Yingzhe Ding
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2004-08-26
Filing date: 2005-08-26
Publication date: 2006-03-02
Also published as: CN1741438A; CN100459483C

Abstract

A method for controlling transmission frequency of status reports can firstly set ACK transmission conditions for protocol data units(PDUs); decide whether it met said set ACK transmission conditions or not before reception entity transmits status reports to transmission entity; if not, ACK can not be involved in status reports; otherwise, ACK can be involved in status reports; said reception entity can transmit said status reports to said transmission entity. The present invention can be used to solve the occurrence of redundant PDU and the problem of status report transmission in prior art. By using the present invention, the frequency of ACK and NACK which are involved in status reports is different, and said ACK may be transmitted quickly, thereby can reduce the transmission of redundant status reports, and further reduce redundant retransmission PDU, thus enhance the efficiency of communication link.

Description

Method for controlling transmission frequency of status report

The present invention relates to the field of data unit status reporting techniques, and more particularly to a method of controlling a status to report a transmission frequency in an automatic repeat request mechanism of a wireless communication system. Background of the invention

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

The wireless interfaces of WCDMA are divided into a physical layer, a data link layer, and a network layer. Radio Link Control (RLC) in the data link layer supports three modes: transparent mode (TM), unacknowledged mode (UM), and acknowledge mode (AM) for segmentation, cascading, padding, error control, and flow control. , repeatability detection and other functions. 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 by the network layer, and then send the processed data unit to the network layer. The functional model of the RLC AM entity consisting of the sending entity and the receiving entity is shown in Figure 1, and the corresponding processing is shown in Figure 2. The sending entity performs data unit processing by the following steps:

Step 201: When receiving the RLC Service Data Unit (SDU) transmitted by the network layer, the sending entity first performs segmentation/cascading processing on the SDU.

The sending entity may also need to segment/cascade the processed RLC according to actual needs.

The PDU is filled.

Step 202: Send an entity assembly acknowledgement mode data (AMD) protocol data unit (PDU), and send the assembled AMD PDU to its own transmit buffer.

Step 203: The sending buffer in the sending entity performs the AMD PDU saved by itself. Scheduling.

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 to send to the receiving entity.

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

The receiving entity performs data unit processing by the following steps:

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

In step 206, the AMD PDU is parsed to determine whether the RLC SDU can be reassembled. If the complete RLC SDU can be reassembled, the reassembly operation is performed, and the reassembled RLC SDU is submitted to the upper layer.

In the foregoing step 206, before receiving the parsed AMD PDU, the receiving entity needs to determine whether the current AMD PDU is transmitted according to 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, determining whether the status report sent to the sending entity should include a NACK for retransmitting data or an ACK for determining that the AMD PDU is correctly received, and the receiving entity assembles a corresponding status report according to the judgment, and the status is assembled. 4 The advertisement is sent to the bottom layer, and the bottom layer sends the status report to the sending entity.

If the status report contains a NACK, the retransmission buffer in the sending entity reports the AMD PDU that needs to be retransmitted based on the received status report. In this case, the AMD PDU for transmitting the buffer scheduling in the above step 203 includes not only the newly assembled AMD PDU but also the AMD PDU stored in the retransmission buffer for retransmission. This mechanism of retransmitting data units is called an automatic repeat request (ARQ) mechanism. Of course, if the status report contains an ACK, the sending entity can confirm that the corresponding PDU has been correctly transmitted.

However, it is usually the case that the receiving entity sends multiple times to the same entity to the sending entity. The PDU and the acknowledgment information included are status reports of the NACK, and the transmitting entity retransmits the same PDU to the receiving entity multiple times. That is to say, it usually causes the system to transmit a lot of redundant data, which obviously wastes data transmission resources, and both the receiving entity and the transmitting entity waste more time transmitting redundant data.

In addition, since the sending entity waits for the receiving entity to return a status report after transmitting the PDU to the receiving entity, if the status report returned by the receiving entity includes an ACK, the sending entity does not need to send the PDU to the receiving entity again. If the NACK is included, the transmitting entity should also send the PDU to the receiving entity again. The sending entity waits for the entire process as a delay. If the sending entity receives multiple status reports including NACKs returned by the receiving entity, the sending entity sends the PDUs from the time of sending the PDU to the last time the PDU is retransmitted, which is the delay for the PDU. Obviously, this time The delay is longer, occupies the resources of the sending entity, and also has a certain impact on the work of the sending entity. Existing technology does not currently address this issue.

The above problems are not only found in the ARQ mechanism of the WCDMA system, but also in the Time Division Synchronous Code Division Multiple Access (TD-SCDMA) system and the CDMA 2000 ARQ mechanism. For WCDMA and TD-SCDMA systems, the ARQ mechanism is in the acknowledgment mode (AM) of the RLC protocol; for the CDMA 2000 system, the ARQ mechanism is in the ARQ sublayer of the Link Access Control (LAC) protocol. . Summary of the invention

In view of this, it is a primary object of the present invention to provide a method of controlling the transmission frequency of a status report to prevent the system from transmitting redundant status reports and data units.

To achieve the above objective, the technical solution of the present invention is implemented as follows: A method for controlling a status report transmission frequency, which is applicable to a communication system including a transmitting entity and a receiving entity, and an automatic retransmission mechanism is adopted between the transmitting entity and the receiving entity. To communicate, the method includes the following 05 001331 Steps:

a. Set a positive acknowledgement ACK transmission condition for the protocol data unit PDU;

b. Before receiving the status report to the sending entity, the receiving entity determines whether the ACK condition is currently met. If not, the ACK is not included in the status report; otherwise, the ACK is allowed in the status report;

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

The step c may further include: initializing an ACK transmission condition set for the PDU. In the step a, the ACK sending condition set for the PDU is: determining whether there is an ACK timing device in a normal working state, if yes, not meeting the ACK sending condition; otherwise, conforming to the ACK sending condition.

The step c may further include: initializing the ACK transmission condition; the initializing ACK transmission condition is: determining whether there is an ACK timing device for the PDU, if yes, directly initializing the ACK timing device; otherwise, setting an ACK timing device And start.

The method may further comprise: setting a negative acknowledgement NACK transmission condition for each PDU that is detected to have not been correctly received;

The step c further includes: determining, in the scope of the status report, each PDU that is not correctly received by the receiving entity, determining whether the current NACK transmission condition set for the PDU is met, and if not, in the status report. The NACK of the PDU is not included; otherwise, the NACK of the PDU is allowed to be included in the status report.

The sending condition is set to: first determine whether the NACK transmission status report is sent for the first time for the PDU, and if the first transmission, the NACK transmission condition is met; if it is not the first time, it is further determined whether the The NACK timing device corresponding to the PDU and in a normal working state, if yes, does not meet the NACK transmission condition, and if not, the NACK transmission condition is met; Step C of T/CN2005/001331 further includes: each of the receiving entities respectively initializing the status report

The NACK corresponds to the NACK transmission condition of the PDU; 'the initial NACK transmission condition is: if the NACK timing device corresponding to the PDU currently exists, the timing device is directly activated; otherwise, a NACK timing device is set for the PDU and started .

The NACK transmission condition set for each PDU that is detected to be not correctly received is the same NACK transmission condition;

The NACK transmission condition is set to: determine whether there is a NACK timing device in a normal working state, if yes, the NACK transmission condition is not met; otherwise, the NACK transmission condition is met;

The step c further includes: initializing a NACK transmission condition; the initial NACK transmission condition is: if the NACK timing device is currently present, directly starting the timing device; otherwise, setting a NACK timing device, and starting the timing device .

The timing device is a timer; the timing device is in a normal working state as: the timer has been started and has not timed out. ·

The timing device is a counter; the timing device is in a normal working state as: the counter is in a counting state.

The method may further include: setting an upper limit and a lower limit of the counter count range, setting an initial value of the counter to an upper limit of the count range, and setting the counter to: the counter increments the current count value by one every certain time interval;

The counter is in the counting state as: The current value of the counter is greater than the lower limit of the counter counting range.

The method may further comprise: setting an upper limit and a lower limit of the counter count range, setting an initial value of the counter to a lower limit of the count range, and setting the counter to: at regular intervals, the counter increments the current count value by one; PT/CN2005/001331 The counter is in the counting state: The current value of the counter is less than the upper limit of the counter counting range.

The counter counts according to the number of times the MAC sends the MAC status indication primitive. The automatic repeat request mechanism is located in the acknowledgment mode AM of the radio link control LC protocol in the wideband code division multiple access WCDMA or the time division synchronous code division multiple access TD-SCDMA system; or the link access control LAC protocol in the CDMA2000 system The automatic retransmission requests the ARQ sublayer.

The present invention sets the transmission condition for the status report including the ACK so that the ACK and the NACK allowed in the status report are different, so that the ACK can be transmitted faster, and the NACK can be transmitted slowly, thereby reducing the redundancy state. The transmission of the report, and thus the redundant retransmission PDU, reduces the utilization of the communication link, and also ensures timely positive confirmation, avoiding congestion in the transmission window. BRIEF DESCRIPTION OF THE DRAWINGS

1 is a schematic diagram of a functional model of an RLC AM entity in the prior art;

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

3 is a flowchart of an implementation of an embodiment of the solution of the present invention;

FIG. 4 is a flowchart of an implementation of another embodiment of the solution of the present invention. Mode for carrying out the invention

After analysis, there are two main reasons for the problem of redundant data transmission. On the one hand, there is a delay in the transmission of PDUs and status reports in the communication system. After transmitting a PDU, the transmitting entity needs at least one loop time (RTT) to obtain information about whether the receiving entity correctly receives the PDU. Due to the existence of the delay, The situation in the following steps will occur:

Step A: The sending entity sends the PDU for the first time, and the PDU has an error during the 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 a 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: Because there is a delay, before receiving the PDU retransmitted by the sending entity, the receiving entity sends a status report including the NACK to the sender again;

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

Step F: Because there is a delay, before receiving the status report including the ACK sent by the receiving entity, the sending entity first receives the status report containing the NACK sent by the receiving entity in step D, so the third time is transmitted to the receiving entity. PDU.

Obviously, the above process causes the transmission of redundant data.

Another reason for the emergence of redundant data transmission is that RLC supports a variety of status queries and status triggering mechanisms to accommodate different business requirements. 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, only the information in the status report needs to be selected according to the information in the status report. The retransmitted PDU is sufficient. However, if the receiving entity sends status reports for the same PDU according to a number of different mechanisms, there may be cases where the receiving entity continuously sends status reports within a short time interval, which causes the status report to reach the sending entity. It is higher, so redundant PDUs may be retransmitted, which wastes air interface resources.

Timer state inhibit timer defined in the current protocol (Timer Status - Prohibit) And the query prohibit timer (Timer JPoll_Prohibit), can set the specific time period to limit the transmission frequency of the status report to a certain range. Taking Timer_Status_Prohibit as an example, the timer is only started when the status report inhibit function is used. If Timer_Status_Prohibit is in normal working condition, the receiving entity cannot send a status report containing NACK or ACK. The timer is started after the notification is sent by the receiving entity for the status of the STATUS PDU, and a new status report of NACK or ACK cannot be sent until the timer expires.

Although it is possible to limit the transmission frequency of the status report to a certain range by setting a specific time period, or by setting a larger Timer-Status-Prohibit and Timer- Poll-Prohibit, the transmission frequency of the status report can be controlled, and Reduce or eliminate the transmission of redundant data, but this method has drawbacks. This is because the ARQ mechanism requires different transmission frequencies for ACK and NACK: The higher the frequency of ACK, the higher the ACK of the ACK can be cleared in the transmission buffer, which can reduce the blocking probability of the transmission window and improve the chain. The utilization of the road and the reduction of the memory requirement; due to the problem of redundant data unit transmission, the frequency of sending the NACK cannot be too high. That is to say, the existing technical solutions cannot meet the requirements of ACK and NACK at the same time, and the problem of redundant data unit transmission cannot be well eliminated.

Since the sending entity needs to confirm the data according to the ACK, in order to maximize the sending frequency of the status report including the ACK, the sending entity can clear the PDU buffered in the sending buffer in time, and minimize the transmission of the redundant data unit. The inventive solution mainly sets the ACK transmission condition for the PDU based on the prior art. In fact, the same ACK transmission condition is set for all PDUs. In this way, before receiving the status report, the receiving entity first determines whether the PDU sent by the receiving entity correctly meets the ACK sending condition set for the PDU, and if not, does not include an ACK for the PDU in the status report; , Allows ACKs for this PDU to be included in this status report.

The case where the ACK transmission condition is set for the PDU will be described in detail below. See picture 3, the corresponding solution includes the following steps:

Step 301: Set an ACK sending condition for the PDU.

The set ACK transmission condition is: determining whether there is an ACK timing device in a normal working state, if it is, that is, the transmission condition is not met, the ACK cannot be included in the status report; otherwise, the transmission condition is met, so The status report contains an ACK.

In this embodiment, the timing device is a timer, and the timer device is in an active state, that is, the timer is started and has not timed out. Of course, for ease of processing, the timing device is adapted to be placed in the receiving entity.

Step 302: The receiving entity determines whether there is an ACK timing device in a normal working state when the status report needs to be sent. If not, the process proceeds to step 305; otherwise, the process flow ends.

Step 305: The receiving entity includes an ACK in the status report.

Since the status report sent by the receiving entity includes the corresponding information of the PDU that has been correctly received in the scope of the investigation and can send the ACK, after receiving the status report, the sending entity can determine that the information has been correctly determined according to the information. Received PDU.

Through the above steps, the transmission frequency of the status report containing ACK can be controlled.

Of course, when the receiving entity processes the status report and sends the status report to the transmitting entity, the ACK sending condition should also be initialized in order to facilitate the determination of the ACK when the status report is sent next time. Specifically, when the ACK transmission condition is initialized, it is first determined whether there is currently an ACK timing device for the PDU, and if so, the ACK timing device is directly initialized, otherwise, the ACK timing device is set, and the timing device is activated. Of course, the initializing the ACK timing device may specifically be when the receiving entity sends a status report to the transmitting entity, or when the ACK is set to the status report.

In addition, the set timing device can also be a counter and set the counter as a root Counting is performed according to a certain time interval. Since the MAC sends a data rate to the RLC for notifying that the RLC can transmit to the MAC at a fixed time interval, that is, the number of PDUs that the RLC can transmit to the MAC within a certain time, therefore, the counter can be set to be sent according to the MAC. The incoming MAC status indication primitive (MAC_Status_Ind) counts. Also set the upper and lower limits of the counter count range, where the initial value of the counter is set to the upper limit of the count range. And after the counter is started, it will decrement its own count value by one every certain time interval. For the case of counting according to MAC_Status_Ind, it is the MAC-Status-Ind-time sent every time the MAC is sent, and the count value of itself is decremented by one.

With such a setting, when the receiving entity reports that there is a counter corresponding to a certain PDU, it is also necessary to determine whether the counter corresponding to the PDU is the lower limit of the counting range, and if so, in the state The report contains an ACK for the PDU, otherwise the ACK for the PDU is not included in the status report.

The above is to set the initial value of the counter counting range to 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 is started, the MAC-Status-Ind is sent every time the MAC is sent. Once, the current count value is incremented by one. In this way, when the receiving entity sends a status report, if it is detected that there is a counter corresponding to a certain PDU, it is also required to determine whether the counter corresponding to a certain PDU that is not correctly received is determined to be the upper limit of the set range. Yes, the ACK for the PDU is included in the status report, otherwise the ACK for the PDU is not included in the status report.

When the ACK transmission condition is initialized, if the timing device is a counter, the reinitialization counter is the initial value of the reset counter. For the initialization counter, if there is currently a counter corresponding to the PDU, the counter can be directly started; otherwise, a counter is set for the .PDU, and the counter is started.

Through the above scheme, if the receiving entity has activated the ACK timing device for the PDU, the receiving entity may send the PDU to the transmitting entity if the timing device times out. ACK. That is, the receiving entity sends a status report including the ACK according to the timing device dedicated to determining the ACK transmission, so that when the status report including the ACK is sent, the transmission condition of the NACK is not considered, so that the sending entity can learn as early as possible. The PDU has been received correctly.

The foregoing is to set an ACK transmission condition for the PDU. In fact, the NACK transmission condition may be further set for each PDU that is detected to be incorrectly received. Of course, the same NACK transmission condition may be set for all PDUs that are not correctly received. Thereby the receiving entity is able to control the transmission frequency of the status report containing the NACK.

The following is a detailed description of the case where the ACK transmission condition is set for the PDU and the NACK transmission condition is set for each PDU that is detected to have not been correctly received. Referring to FIG. 4, this embodiment takes the setting of the PDU (n) as an example, and the set timing device is a timer. The corresponding solution includes the following steps:

Step 401: Set a NACK transmission condition for each PDU that is detected to be not correctly received, and set an ACK transmission condition for all PDUs.

The set ACK transmission condition is: Determine whether there is an ACK timing device in a normal working state, and if so, cannot include an ACK in the status report; otherwise, it is allowed to include an ACK in the status report.

The set NACK transmission condition is: If the NACK status report is currently sent for a certain PDU for the first time, the NACK for the PDU may be set in the status report; if the NACK status report has been previously sent for the PDU, or If the 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 such a timing device exists, the status report cannot be set in the status report. NACK of the PDU; otherwise, a NACK for the PDU can be set in the status report.

Of course, if it is the same for all PDUs that are detected that they were not received correctly The NACK transmission condition is: the NACK transmission condition is: determining whether there is a NACK timing device in a normal working state, and if so, not conforming to the NACK transmission condition; otherwise, conforming to the NACK transmission condition.

In this embodiment, the timing device is also a timer, and the timing device is in an active state, that is, the timer is started and has not timed out.

Step 402 403: The receiving entity first determines whether the ACK timing device is in a normal working state when the status report needs to be sent, and if not in the normal working state, proceeds to step 404; otherwise, proceeds to step 405.

Step 404: The receiving entity includes an ACK in the status report, and then proceeds to step 405. Step 405: The receiving entity determines whether it is necessary to send a NACK for the PDU (n), and if yes, proceeds to step 406; otherwise, proceeds to step 408.

Step 406: The receiving entity determines whether there is a NACK timing device for the current PDU (n) and is in a normal working state. If yes, it determines that the NACK transmission condition is not met, and then proceeds to step 408; otherwise, determines that the NACK transmission condition is met, and then Proceed to step 408.

Step 407: Add a NACK for the PDU (n) in the status report, and then proceed to step 408.

Step 408: The receiving entity determines whether the next PDU needs to send a NACK.

Through the above steps, the control of the status report transmission frequency including ACK and NACK can be realized.

In addition, when the receiving entity processes the status report and sends the status report to the sending entity, if the status includes an ACK, the ACK timing device should be reinitialized; if the status report includes a NACK, The timer for the PDU ( n ) and the PDU corresponding to the other NACKs in the status report should be reinitialized. Of course, the receiving entity may also reinitialize the corresponding timer immediately after adding the ACK or NACK to the status report. For the initialization timer, if there is currently an ACK timer and ' The NACK timer corresponding to the PDU can directly start the timer; otherwise, an ACK timer needs to be set, and a NACK timer is set for the PDU, and the set timer is started.

Similarly, the above timer may also be a counter, and the corresponding processing is the same as the foregoing, and therefore will not be described again.

The above description is only a preferred embodiment of the solution of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

Claim

A method for controlling a transmission frequency of a status report, which is applicable to a communication system including a transmitting entity and a receiving entity, and the transmitting entity and the receiving entity communicate by using an automatic retransmission mechanism, wherein the method comprises the following steps:

b. The receiving entity determines whether the ACK transmission condition is currently met before sending the status report to the sending entity. If not, the ACK is not included in the status report; otherwise, the status report is allowed to include the ACK;

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

The method according to claim 1, wherein the step c further comprises: initializing an ACK transmission condition set for the PDU.

The method according to claim 1, wherein in the step a, the ACK sending condition set for the PDU is: determining whether there is an ACK timing device in a normal working state, if not, not meeting the condition ACK transmission condition; otherwise, ACK transmission condition is met.

The method according to claim 3, wherein the step c further comprises: initializing the ACK transmission condition; the initializing ACK transmission condition is: determining whether there is an ACK timing device for the PDU, if yes, The ACK timing device is initialized directly; otherwise, the ACK timing device is set and started.

The method according to claim 1, 2, 3 or 4, characterized in that the method further comprises: setting a negative acknowledgement NACK transmission condition for each PDU that is detected to have not been correctly received;

Before the step c, the method further includes: determining, by the status report, each PDU that is not correctly received by the receiving entity, and determining whether the current PDU is set for the PDU. The NAC transmission condition, if not met, does not include the NACK of the PDU in the status report; otherwise, the NACK of the PDU is allowed to be included in the status report.

The method according to claim 5, wherein the NACK transmission condition is set to: first determine whether the NACK transmission status report is currently sent for the PDU for the first time, and if the first transmission is performed, the NACK transmission is met. If the condition is not the first time, it is further determined whether there is a NACK timing device corresponding to the PDU and in a normal working state, if not, the NACK transmission condition is not met, and if not, the NACK transmission condition is met;

The step c further includes: receiving, by the entity, a NACK transmission condition of each NACK corresponding PDU in the status report, respectively; the initial NACK transmission condition is: if the NACK timing device corresponding to the PDU currently exists, directly starting the Timing device; otherwise, a NACK timing device is set for the PDU and started.

The method according to claim 5, wherein the NACK transmission condition set for each PDU that is detected to be incorrectly received is the same NACK transmission condition; and the NACK transmission condition is set to: Determining whether there is a NACK timing device in a normal working state, if not, not meeting the NACK transmission condition; otherwise, conforming to the NACK transmission condition;

The method according to claim 3, 6 or 7, wherein the timing device is a timer; and the timing device is in a normal working state: the timer has been started and has not timed out.

9. The method according to claim 3, 6 or 7, wherein the timing device is a counter; and the timing device is in a normal working state: the counter is in a counting state.

10. The method according to claim 9, wherein the method further comprises: setting an upper limit and a lower limit of the counter count range, setting an initial value of the counter to an upper limit of the count range, and setting the counter to: Time interval counter decrements the current count value by one;

11. The method according to claim 9, wherein the method further comprises: setting an upper limit and a lower limit of the counter count range, setting an initial value of the counter to a lower limit of the count range, and setting the counter to: every certain Time interval, the counter will force the current count value;

The counter is in the counting state: the counter current value 'J, the upper limit of the counter counting range.

The method according to claim 10 or 11, wherein the counter counts according to the number of times the MAC sends the MAC status indication primitive.

13. The method according to claim 1, wherein the automatic repeat request mechanism is located in an acknowledge mode of a radio link control RLC protocol in a wideband code division multiple access (WCDMA) or a time division synchronous code division multiple access (TD-SCDMA) system. AM; or the automatic retransmission request ARQ sublayer of the Link Access Control LAC protocol located in the CDMA2000 system.