CN101753277B - Method for transmitting message status report of radio link control layer - Google Patents

Abstract

The invention discloses a method for sending a wireless link control layer message status report, comprising: configuring a polling retransmission timer at an RLC sending end; and starting the polling retransmission timer after sending the polling message at the sending end, When the polling retransmission timer expires and the status report message is not received, the last sent message is retransmitted as a polling message; the RLC receiver configures a message reordering timer or/and a status report prohibition timer; The receiving end has been configured with a message reordering timer or/and status report prohibition timer. When receiving a polling message, determine whether to start the message reordering timer. If necessary, when the message reordering timer expires Construct the message status report, if it is not needed, construct the message status report immediately; after construction, judge whether the status report prohibition timer is started, if it is started, send the status report message when the status report prohibition timer times out, if not start, immediately Send a status report message. The invention improves the data transmission efficiency.

Description

Method for sending radio link control layer message status report

technical field

The present invention relates to a method for sending a message status report, in particular to a method for sending a radio link control layer message status report in a Long Term Evolution (LTE, Long Term Evolution) system.

Background technique

The Radio Link Control (RLC, Radio Link Control) protocol layer is a sublayer of Layer 2 (L2) in the wireless interface protocol stack of the LTE system, and is located above the Media Access Control (MAC, Media Access Control) layer. RLC The layer is mainly used to provide segmentation and retransmission services, such as link control, encapsulation and reassembly, concatenation, user data transmission, error correction, protocol error detection and repair, etc. Each RLC entity is configured by Radio Resource Control (RRC, Radio Resource Control) and operates in three modes, namely:

Transparent Mode (TM, Transparent Mode): After receiving the service data unit (SDU, Service Data Unit) from the upper layer, the sender forwards it directly without adding any additional control protocol overhead.

Unacknowledged Mode (UM, Unacknowledged Mode): The sending entity adds the necessary control protocol overhead to the high-level protocol data unit PDU (PDU, Protocol Data Unit) for forwarding, but does not guarantee delivery to the peer entity, and does not use retransmission protocol. Since the RLC PDU contains a sequence number, it is possible to check the integrity of the upper layer PDU.

Acknowledged Mode (AM, Acknowledged Mode): The sending side adds the necessary control protocol overhead to the high-level data and transmits it, and can guarantee delivery to the peer entity. Because of the automatic repeat request (ARQ, Automatic Repeat reQuest) capability, if the RLC receives an incorrect RLC PDU, it will notify the RLC entity at the opposite end to retransmit the PDU. Since the RLC PDU contains sequence number information, it supports sequential or out-of-order delivery of data to the upper layer. AM mode is the standard mode for packet data transmission.

The ARQ in the confirmation mode is to send a message status report (Status Report) to the sender through the RLC protocol entity receiver, and the RLC protocol entity sender confirms the sequence (ACK_SN) and sequence non-confirmation (NACK_SN) according to the message status report. To determine which PDUs have been confirmed by the receiving end, which PDUs or PDU fragments need to be retransmitted, so as to ensure the reliability of data transmission. In the 36.322 protocol, there are two types of triggering mechanisms for the receiving end of the RLC protocol entity to send a message status report:

The RLC protocol entity sender trigger mode: The RLC protocol entity sender sets the Polling bit of the RLC header of the PDU to "1". When the RLC protocol entity receiver receives a PDU, if the check finds that the Polling bit is "1", it is considered to be A polling message triggers a message status report. After the Hybrid Automatic Repeat reQuest (HARQ, Hybrid Automatic Repeat reQuest) reordering (Reordering) of the PDU is completed, the message status report is sent to the sender of the RLC protocol entity. There are three situations in which the sending end of the RLC protocol entity sends the polling message:

1) The PDU is the last message sent in the RLC protocol entity sender buffer;

2) The data payload sent by the sender of the RLC protocol entity reaches the upper limit of the polling (POLL_BYTE) configured by RRC, or the number of PDUs sent by the sender of the RLC protocol entity reaches the upper limit of the number of POLL_PDUs configured by RRC;

3) The polling retransmission timer (T_poll_restransmit) configured by the sending end of the RLC protocol entity times out.

The other type is triggered by the receiving end of the RLC protocol entity: after the packet reordering timer (T_reordering) of the receiving end of the RLC protocol entity expires.

In the 36.322 protocol, in order to avoid sending too frequent message status reports and occupying air interface resources, a message status report prohibition (T_status_prohibit) timer is set at the receiving end of the RLC protocol entity, and the timer is started every time a message status report is sent. During the running of the T_status_prohibit timer, it is forbidden to send the message status report. No matter how many times the message status report is triggered during this period, it is necessary to wait for the T_status_prohibit to expire before sending the next one.

In the 36.322 protocol, an optional length set is specified for the above T_poll_restransmit, T_reordering, and T_status_prohibit timers, but the relationship between these three timers is not determined. These three timers are responsible for the functions of "message status report trigger" and "message status report prohibition". If the duration is not configured properly, it may cause a large number of redundant The sending end of the entity sends repeatedly through the air interface; or the receiving end of the RLC protocol entity does not reply to the packet status report for a long time, and a large number of packets of the sending end remain in the buffer of the sending end of the RLC protocol entity and cannot be deleted, which may cause subsequent packet congestion.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a method for sending radio link control layer message status reports, which can suppress generation of invalid message status reports and improve data transmission efficiency.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

A method for sending radio link control layer message status reports,

The sending end of the radio link control protocol entity is configured with a polling retransmission timer; after the sending end of the radio link control protocol entity sends a polling message, the polling retransmission timer is started, and in the round If the status report message containing the response to the last sent message is not received before the query retransmission timer expires, the last sent message will be retransmitted as a polling message;

The receiving end of the radio link control protocol entity is configured with a message reordering timer, which can be configured with a status report prohibition timer; the receiving end of the radio link control protocol entity has been configured with a message reordering timer or/and status report prohibiting timing When receiving a polling message, judge whether to start the message reordering timer, if necessary, wait until the message reordering timer expires before constructing a message status report, if not, Then immediately construct the message status report; after the message status report is constructed, judge whether the status report prohibits the timer from starting, if it starts, then send the message status report of the latest generation when the status report prohibits the timer from overtime message, if it is not started, the message of the message status report will be sent immediately;

The sending end of the radio link control protocol entity retransmits redundant messages, and the length of the message reordering timer or/and the status report prohibiting timer of the receiving end of the radio link control protocol entity are set to be shorter than the length of the wireless link control protocol entity. The length of the polling retransmission timer at the sending end of the RCP entity.

Preferably, when the receiving end of the RLC protocol entity configures the packet reordering timer and the status report prohibition timer, the duration of the status report prohibition timer is shorter than the duration of the packet reordering timer.

Preferably, the method also includes:

The sending end of the radio link control protocol entity receives the message of the message status report, and judges whether the message of the message status report contains a response to the last sent message, and if so, stops responding to all The polling retransmission timer; if there is no, check whether there is a data message to be sent when the polling retransmission timer expires, and if there is, the message to be sent is sent to the said message as a polling message The receiving end of the RLC protocol entity, if not, retransmits the last sent message as a polling message to the receiving end of the RLC protocol entity.

Preferably, the status report prohibition timer is restarted after the receiving end of the RLC protocol entity sends a message status report.

Preferably, the packet reordering timer is started when the receiving end of the radio link control protocol entity forms a sliding window of packets.

Preferably, the sending end of the radio link control protocol entity determines the message not received by the receiving end of the radio link control protocol entity according to the received message status report, retransmits it, and deletes the message that has been deleted The packet received by the radio link control protocol entity receiving end.

Preferably, the message of the message status report includes the response information of the last polling message received by the receiver of the RLC protocol entity.

Preferably, the polling flag bit of the polling message is "1".

In the present invention, by setting the sending timing of the message status report, the mechanism of sending the message status report in the 36.322 protocol is rationally utilized, so that the receiving end of the RLC protocol entity can send the necessary status report as efficiently as possible, and restrains the communication between the RLC protocol entities. The redundant message transmission improves data transmission efficiency, especially for air interface transmission, which saves bandwidth and improves the resource utilization efficiency of air interface.

Description of drawings

FIG. 1 is a schematic flow diagram of a method for sending a radio link control layer message status report according to a first embodiment of the present invention;

2 is a schematic flow diagram of a method for sending a radio link control layer message status report according to a second embodiment of the present invention;

FIG. 3 is a schematic flowchart of a method for sending a radio link control layer message status report according to a third embodiment of the present invention.

Detailed ways

The basic idea of the present invention is: by setting the sending timing of the message status report, rationally utilizing the mechanism about the sending of the message status report in the 36.322 agreement, the RLC protocol entity receiving end can send the status report as efficiently as possible, and suppress the problem in the RLC Redundant message transmission between protocol entities improves data transmission efficiency, especially for air interface transmission, which saves bandwidth and improves air interface resource utilization efficiency.

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail by citing the following embodiments and referring to the accompanying drawings.

Fig. 1 is a schematic flow chart of the sending method of the radio link control layer message status report of the first embodiment of the present invention. In this embodiment, the receiving end of the RLC protocol entity is only provided with a message reordering timer, as shown in Fig. 1 As shown, the sending method of the radio link control layer message status report in the embodiment of the present invention includes the following steps:

Step 101: Set the duration of the packet reordering timer at the receiving end of the RLC protocol entity to be shorter than the duration of the polling retransmission timer at the sending end of the RLC protocol entity.

This step is the basic step of message status report suppression in the present invention, which needs to be set in the transmission system in advance. The reason why the duration of the message reordering timer is set to a smaller value is based on the consideration of the sending mechanism of the message status report in the radio link control protocol entity: the sender of the RLC protocol entity sends a Polling bit "1" After the polling message, start the polling retransmission timer to start timing, that is, start T_poll_restranmit; after the RLC protocol entity receiving end receives the polling message, it determines that its Polling bit is "1", then it needs to report to the RLC protocol entity The sending end sends the message of the message status report, but the timing of sending the message of the message status report has certain requirements: when the receiving end of the RLC protocol entity receives the data message, if the sequence number of the received message is not continuous , the sliding window of the message is generated, and T_reordering will be started at this time. Generally, after the sliding window disappears, the message of the message status report will be sent to the sending end of the RLC protocol entity. In order to enable the receiving end of the RLC protocol entity to report the receiving status of the message in time, but not to report too frequently, T_reordering is set. Only when T_reordering times out, the receiving end of the RLC protocol entity sends a message to the sending end of the RLC protocol entity. The message of the message status report, the message of the message status report includes the response information of the last sent message received before, of course, also includes the status response messages of some unreceived data messages. After receiving the message of the message status report, the sender of the RLC protocol entity confirms that it contains the response information of the last sent message, and stops T_poll_restranmit. Certainly, if the sending end of the RLC protocol entity sends a polling message but the receiving end of the RLC protocol entity does not start T_reordering, the receiving end of the RLC protocol entity will immediately send a message of message status report.

Step 102: When the sending end of the RLC protocol entity receives the message of the message status report before the polling retransmission timer expires, stop timing the polling retransmission timer; After receiving the message of the message status report, the polling message will be retransmitted to the receiving end of the RLC protocol entity.

Before T_poll_restransmit times out, the sender of the RLC protocol entity receives the message of the message status report, and confirms whether it contains the response information of the last sent message. If so, it means that the last sent polling message has been received. If it is received correctly, turn off T_poll_restransmit. If not, it means that the polling message sent last time was not sent successfully. When T_poll_restransmit times out, judge whether there is currently any data to be sent by the upper layer or a retransmission message of this protocol layer. If so, Send the next data message to be sent as a polling message, and send it to the RLC protocol entity receiving end after the Polling position of the data message to be sent is "1". If there is no data message to be sent, then Retransmit the last sent message as a polling message to the receiving end of the RLC protocol entity.

When the duration of T_poll_restransmit is longer than the duration of T_reordering, even if the receiving end of the RLC protocol entity generates a packet status report message, it will not be sent to the sending end of the RLC protocol entity immediately before T_reordering expires. Only when T_reordering expires will the latest The generated message of the message status report is sent to the sending end of the RLC protocol entity, which prevents the receiving end of the RLC protocol entity from sending the message of the message status report too frequently. The duration of T_poll_restransmit is set to be greater than the duration of T_reordering, thereby avoiding the possibility that the sender of the RLC protocol entity may generate redundant polling messages, thus not causing data congestion, saving the processing resources of the sender of the RLC protocol entity, and improving the RLC Efficiency of effective data processing between protocol entities.

Fig. 2 is the schematic flow chart of the sending method of the radio link control layer message status report of the second embodiment of the present invention, in this embodiment, the RLC protocol entity receiving terminal is only provided with message status report prohibition timer, as shown in Fig. 2, the sending method of the radio link control layer message status report in the embodiment of the present invention comprises the following steps:

Step 201: Set the duration of the packet status report prohibition timer at the receiving end of the RLC protocol entity to be shorter than the polling retransmission timer at the sending end of the RLC protocol entity.

Similar to step 101, step 201 is the basic step of message status report suppression in the present invention. The reason why the duration of the message status report prohibiting timer is set to a smaller value is also to enable the RLC protocol entity receiving end to report the receiving state of the message in time, so as to prevent the RLC protocol entity sending end from failing to report for a long time. T_poll_restransmit times out and retransmits the poll message. After the receiving end of the RLC protocol entity sets T_status_prohibit, when the receiving end of the RLC protocol entity receives the polling message, it will not report the status report of the message immediately, but will send the latest generated message to the sending end of the RLC protocol entity when T_status_prohibit times out The message of the message status report, the message of the message status report includes the response information of the last sent message received before, of course, also includes the status response messages of some unreceived data messages. After sending the message of message status report, restart T_status_prohibit.

Step 202: When the sending end of the RLC protocol entity receives the message of the message status report before the polling retransmission timer expires, stop timing the polling retransmission timer; After receiving the message of the message status report, the polling message will be retransmitted to the receiving end of the RLC protocol entity.

The processing manner of step 202 is exactly the same as that of step 102, and will not be repeated here.

When the duration of T_poll_restransmit is longer than the duration of T_status_prohibit, even if the receiving end of the RLC protocol entity receives the polling message, it will not send a packet status report message to the sending end of the RLC protocol entity before T_status_prohibit times out, and only when T_status_prohibit times out The newly generated packet status report message is sent, thereby preventing the receiving end of the RLC protocol entity from sending the message status report message too frequently. The duration of T_poll_restransmit is set to be greater than the duration of T_status_prohibit, thereby avoiding the possibility that the sender of the RLC protocol entity may generate redundant polling messages, thus not causing data congestion, saving the processing resources of the sender of the RLC protocol entity, and improving the RLC Efficiency of effective data processing between protocol entities.

Fig. 3 is the schematic flow chart of the sending method of the radio link control layer message status report of the third embodiment of the present invention, in this embodiment, the receiving end of RLC protocol entity is provided with message reordering timer and message status at the same time Report prohibition timer, as shown in Figure 3, the sending method of the radio link control layer message state report of the embodiment of the present invention comprises the following steps:

Step 301: Set the duration of the packet reordering timer and packet status report prohibition timer at the receiving end of the RLC protocol entity to be less than the duration of the polling retransmission timer at the sending end of the RLC protocol entity.

Similar to step 101, step 301 is the basic step of message status report suppression in the present invention. Setting the duration of the message reordering timer and the message status report prohibition timer to be less than the duration of the polling retransmission timer is also to enable the receiving end of the RLC protocol entity to report the receiving status of the message in time, but not It is too frequent to ensure that the sender of the RLC protocol entity will not send redundant polling messages.

The receiving end of the RLC protocol entity receives the polling message and determines the receiving status of the message that needs to be sent. However, since T_status_prohibit and T_reordering are set, the receiving end of the RLC protocol entity needs to determine whether T_status_prohibit is enabled. If it is enabled, it will be when T_status_prohibit times out If T_status_prohibit is not activated, the newly generated message for sending message status report will be sent when T_reordering times out. When T_status_prohibit and T_reordering are started at the same time, even if T_reordering times out, it will still be sent when T_status_prohibit is not timed out. The message of the message status report will not be sent, that is to say, in this case, the message status report that needs to be reported due to T_reordering timeout is suppressed. If neither T_status_prohibit nor T_reordering is started, the receiving end of the RLC protocol entity will report the message status report after receiving the polling message.

As a preferred solution, the duration of the packet status report prohibition timer is set to be shorter than the duration of the packet reordering timer. When the message status report prohibition timer is set for a long time, the report of the message status is not timely enough, which may affect the deletion processing of the transmitted message by the sending end of the RLC protocol entity, resulting in the increase of redundant messages and affecting its processing speed.

Those skilled in the art should understand that it is better to configure the packet reordering timer, the packet reordering timer, and the packet status report prohibition timer's duration relationship in the RLC protocol entity of the same system according to the aforementioned requirements. Of course, for different message status reporting methods, the timer duration setting methods in the foregoing embodiments can be used.

Step 302: When the sending end of the RLC protocol entity receives the message of the message status report before the polling retransmission timer expires, stop timing the polling retransmission timer; After receiving the message of the message status report, the polling message will be retransmitted to the receiving end of the RLC protocol entity.

The processing manner of step 302 is exactly the same as that of step 102, and will not be repeated here.

When the duration of T_poll_restransmit is longer than the duration of T_status_prohibit and T_reordering, even if the receiving end of the RLC protocol entity receives the polling message, it will not send a packet status report message to the sending end of the RLC protocol entity before T_status_prohibit or T_reordering times out, while T_status_prohibit The setting ensures that as long as the conditions for constructing a message status report message are met during the T_status_prohibit timing process, even if the RLC protocol entity receiving end does not generate a message sliding window and starts T_reordering, it will report to the RLC protocol entity when T_status_prohibit times out. The sender sends the message of the message status report. It avoids the fact that the receiving end of the RLC protocol entity sends the message status report at too low frequency, and it will not be too frequent; it also avoids the possibility of redundant polling messages being generated at the sending end of the RLC protocol entity, so that data blocking will not be caused. The processing resource of the sending end of the RLC protocol entity is saved, and the efficiency of valid data processing between the RLC protocol entities is improved.

Considering the general system data transmission rate and the message sending mechanism in the 36.322 protocol, the time reference values of T_status_prohibit, T_status_prohibit and T_reordering are 300ms, 100ms and 200ms respectively, and the specific values can be set according to the specific system transmission rate and system requirements. As long as the above-mentioned setting conditions of the timer duration are satisfied.

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

Claims (8)

1. A sending method of radio link control layer message status report, is characterized in that, comprises: The sending end of the radio link control protocol entity is configured with a polling retransmission timer; after the sending end of the radio link control protocol entity sends a polling message, the polling retransmission timer is started, and in the round If the status report message containing the response to the last sent message is not received before the query retransmission timer expires, the last sent message will be retransmitted as a polling message; The receiving end of the radio link control protocol entity is configured with a message reordering timer, which can configure a status report prohibition timer; the receiving end of the radio link control protocol entity has been configured with a message reordering timer or/and status report prohibiting timing When receiving a polling message, judge whether to start the message reordering timer, if necessary, wait until the message reordering timer expires before constructing a message status report, if not, Then immediately construct the message status report; after the message status report is constructed, judge whether the status report prohibits the timer from starting, if it starts, then send the message status report of the latest generation when the status report prohibits the timer from overtime message, if it is not started, the message of the message status report will be sent immediately; The sending end of the RLC protocol entity retransmits the redundant message, and sets the duration of the message reordering timer or/and the duration of the status report prohibiting timer of the receiving end of the RLC protocol entity to be shorter than the duration of the wireless link control protocol entity. The length of the polling retransmission timer at the sending end of the link control protocol entity. 2. The method according to claim 1, wherein when the receiving end of the radio link control protocol entity configures the packet reordering timer and the status report prohibition timer, the duration of the state report prohibition timer is less than the report period. The duration of the file reordering timer. 3. The method according to claim 1 or 2, characterized in that the method further comprises: The sending end of the radio link control protocol entity receives the message of the message status report, judges whether the message of the message status report contains a response to the last sent message, and if so, stops the Polling retransmission timer; if there is no, check whether there is a data message to be sent when the polling retransmission timer expires, and if there is, the message to be sent is sent to the wireless network as a polling message The receiving end of the link control protocol entity, if not, retransmits the last message sent as a polling message to the receiving end of the radio link control protocol entity. 4. The method according to claim 3, wherein the status report prohibition timer is restarted after the receiving end of the radio link control protocol entity sends a message status report. 5. The method according to claim 3, wherein the packet reordering timer is started when the receiving end of the radio link control protocol entity forms a sliding window of packets. 6. The method according to claim 3, wherein the RLC protocol entity sending end determines the message not received by the RLC protocol entity receiving end according to the received message status report. The message is retransmitted, and the message that has been received by the receiver of the RLC protocol entity is deleted. 7. The method according to claim 4, wherein the message of the message status report includes response information of the last message received by the receiving end of the RLC protocol entity. 8. The method according to claim 4, wherein the polling flag bit of the polling message is "1".

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