CN101547473A

CN101547473A - Method for discarding service data unit (SDU) of link layer in TD-SCDMA system

Info

Publication number: CN101547473A
Application number: CN200910106348A
Authority: CN
Inventors: 潘磊
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2009-03-24
Filing date: 2009-03-24
Publication date: 2009-09-30

Abstract

The invention relates to a method for discarding service data units (SDU) of a link layer in a TD-SCDMA system. Radio link control layer RLC entities first create linked lists according to the survival time of the SDUs configured in a radio resource control layer before receiving the SDUs. When received, the SDUs are inserted into the linked lists one by one, and an RLC control module begins to periodically poll all the RLC entities of the current service after detecting that the RLC entities receive the SDUs, and discards overtime SDUs in the linked lists of the RLC entities. The method can allow the RLC entities to discard overtime SDUs more quickly without increasing expense caused with the increase of data quantity.

Description

Link layer abandons the method for service data unit in the TD-SCDMA standard

Technical field

The present invention relates to the communications field, relate in particular to the method that UE (subscriber equipment) sidelinks layer in a kind of TD-SCDMA (CDMA (Code Division Multiple Access) that the time-division is synchronous) standard abandons up service data unit (SDU).

Background technology

In the TD-SCDMA system, all corresponding RAB (RAB) of each business, and each RAB is made up of one or more RB.Each RB constitutes a link from the upper strata to the lower floor, the effect in its middle level two (comprising wireless chain control layer (RLC), media access control layer (MAC) etc.) is exactly to guarantee data transmission effectively reliably.For the UE side, at up direction, the effect of RLC is exactly that the top layer SDU that each is not of uniform size is carried out segmentation serial connection, forms of the same size and has the protocol Data Unit (PDU) of specification to wrap, and sends on the corresponding transmission channel through MAC; At down direction, the PDU bag that RLC then delivers MAC according to Length Indication (LI) SDU that the upper strata needs that recombinates out, and is delivered and is given the upper strata.

RLC is made up of a plurality of RLC entities, and each RLC entity is disposed and set up by radio resource control layer (RRC), and according to type of service three kinds of patterns is arranged: transparent mode (TM), Unacknowledged Mode (UM), affirmation mode (AM).The all corresponding radio bearer (RB) of each RLC entity, and in this RB, carry out the processing of data, do not interfere each other.The upper strata sends to corresponding RLC entity according to type of service with corresponding SDU.

No matter which kind of pattern the RLC entity is configured to, for the RLC entity, received the SDU that the upper strata issues after, if in setting-up time, there be not sending of success,, abandon this SDU then according to the rule of agreement.The time span that each SDU is dropped is to be determined by the configuration parameter that the upper strata issues.In addition, the AM pattern can also decide according to the maximum retransmission of PDU and abandon.

According to agreement, the RLC entity is whenever received a SDU, just opens a timer according to the time that abandons for it, if timer expiry, and SDU does not also send, and then abandons this SDU.If 32 RLC entities of current existence are carrying 5 SDU on each RLC entity, so, will drive 160 timers for it.Such expense obviously is difficult to accept.The resource of processor is limited, and when data volume was small, doing required expense like this can also guarantee; In case the data quantitative change is big, processor will go wrong because of inadequate resource.And doing the timer message queue like this can be very long, also is difficult on the efficient accept.Because it is passive that the RLC entity is received data, uncertain, also is very unsafe so do like this.

Summary of the invention

Technical problem to be solved by this invention is, provides link layer in a kind of TD-SCDMA standard to abandon the method for SDU, and the present invention can make the RLC entity abandon overtime SDU faster, and can be because of the change of data volume not big and increase expense.

The invention discloses the method that link layer in a kind of TD-SCDMA standard abandons SDU, described method is: the RLC entity is before receiving SDU, at first create a chained list according to the SDU time-to-live of RRC configuration, when receiving SDU, it is inserted in the described chained list successively, after the RLC control module has detected the RLC entity and has received SDU, all RLC entities of beginning periodic polls current business, and overtime SDU abandons in the chained list with described RLC entity.

When described RLC entity received SDU, at first recorder absolute time constantly was made into described SDU a node then, is inserted in the chained list of oneself.

Described node comprises the absolute time of memory address, top layer SDU sequence number, SDU time of reception of SDU.

Described RLC control module is poll RLC entity by the following method:

Steps A: start-up period timer;

Step B: wait for that described cycle timer is overtime, timer expiry, beginning poll;

Step C: whether the chained list of judging current RLC entity is empty, if, execution in step D then; Otherwise, travel through the chained list of current RLC entity;

Step D: judge whether this poll finishes, if, execution in step B then; Otherwise, the next RLC entity of poll.

The method that described RLC control module travels through described RLC entity chained list is as follows:

Whether the SDU that judges present node is overtime, if, then abandon described SDU, travel through the next node of described chained list; Otherwise, finish traversal.

Described RLC control module judges by the following method whether SDU is overtime:

Obtain the absolute time of current time, calculate the time difference of the absolute time and the absolute time of described SDU time of reception of described current time, the time-to-live of more described time difference and described SDU, if the described time difference is more than or equal to the time-to-live of described SDU, then described SDU is overtime, otherwise described SDU is not overtime.

If SDU is overtime, then before abandoning described SDU, also carry out following steps:

Judge the pattern of described RLC entity, if transparent mode or Unacknowledged Mode then directly abandon described SDU; If affirmation mode then sends to the opposite end and abandons report, obtain abandoning described SDU after the affirmation of opposite end.

When described service ending, described RRC discharges all RLC entities, deletes described cycle timer simultaneously.

It is the timer that all RLC entities of a business are opened one-periods that the present invention only needs, and whether the SDU of active poll RLC entity is overtime, and when judging that SDU is whether overtime, adopting absolute time difference and time-to-live to compare locatees, if it is overtime, then focus on, do not only having promoted performance like this, saved resource.

Description of drawings

Fig. 1 is the flow chart of the method for the invention.

Embodiment

Below in conjunction with the drawings and specific embodiments the method for the invention is done and to be described in further detail.

As shown in Figure 1, be the flow chart of the method for the invention, specifically comprise the steps:

Step 101:RRC is that described business is set up required RLC entity according to the configuration parameter that type of service and upper strata issue;

The configuration parameter that the upper strata issues comprises the time-to-live of SDU: DisTime.

Step 102: each RLC entity is that oneself creates a doubly linked list according to the DisTime of RRC configuration, is used for storing the SDU that receives;

Whether step 103:RLC control module detects has the RLC entity to receive SDU; If then execution in step 104; Otherwise, continue execution in step 103;

Step 104:RLC control module start-up period timer, the absolute time of the time of reception of the SDU that the RLC entity record receives: Tik_sdu is made into described SDU a node then, is inserted in the chained list of oneself;

After the RLC entity is made into node with the SDU that receives, insert chained list successively to the order of afterbody according to head from chained list;

The memory address, top layer SDU sequence number, the Tik that comprise SDU in the node;

Step 105:RLC control module waiting timer is overtime;

Step 106: timer expiry, RLC control module begin the RLC entity of poll current business;

Step 107:RLC control module travels through the chained list of current RLC entity;

Step 108: whether the SDU that judges present node is overtime, if then execution in step 109; Otherwise, execution in step 113;

Determination methods is: obtain the absolute time Tik_current of current time, calculate the time difference of Tik_current and Tik_sdu, more described time difference and DisTime, if the described time difference is more than or equal to DisTime, then described SDU is overtime, otherwise described SDU is not overtime.

Step 109: judge the pattern of current RLC entity, if TM or UM, then execution in step 110; If AM, then execution in step 111;

Step 110: directly abandon described SDU, execution in step 112;

Step 111: send to the opposite end and to abandon report, obtain abandoning described SDU, execution in step 112 after the affirmation of opposite end;

Step 112: travel through the next node of described chained list, execution in step 108;

Step 113: finish traversal;

Step 114: judge whether this poll finishes, if then execution in step 116; Otherwise, execution in step 115;

Step 115: inquire about next RLC entity, execution in step 107;

Step 116: judge whether current business finishes, if then execution in step 117; Otherwise, continue poll, execution in step 105;

Step 117:RRC discharges all RLC entities, the deletion cycle timer, and abandon all SDU.

Should be understood that though the present invention is suitable equally for network side at the UE side, just up-downgoing changes.Concerning the those of ordinary skill in field, the technology of the present invention place, can be equal to accordingly according to technical scheme of the present invention and design thereof and change or replace, and all these changes or replacement, all should belong to the protection range of claims of the present invention.

Claims

1, link layer abandons the method for service data unit SDU in a kind of TD-SCDMA standard, it is characterized in that, wireless chain control layer RLC entity is before receiving SDU, at first create a chained list according to the SDU time-to-live of radio resource control layer RRC configuration, when receiving SDU, it is inserted in the described chained list successively, after the RLC control module has detected the RLC entity and has received SDU, all RLC entities of beginning periodic polls current business, and overtime SDU abandons in the chained list with described RLC entity.

2, link layer abandons the method for SDU in the TD-SCDMA standard as claimed in claim 1, it is characterized in that, when described RLC entity receives SDU, recorder absolute time constantly at first, then described SDU is made into a node, is inserted in the chained list of oneself.

3, link layer abandons the method for SDU in the TD-SCDMA standard as claimed in claim 2, it is characterized in that, described node comprises the absolute time of memory address, top layer SDU sequence number, SDU time of reception of SDU.

4, link layer abandons the method for SDU in the TD-SCDMA standard as claimed in claim 1, it is characterized in that described RLC control module is poll RLC entity by the following method:

Steps A: start-up period timer;

5, link layer abandons the method for SDU in the TD-SCDMA standard as claimed in claim 4, it is characterized in that the method that described RLC control module travels through described RLC entity chained list is as follows:

6, abandon the method for SDU as link layer in claim 1 or the 5 described TD-SCDMA standards, it is characterized in that described RLC control module judges by the following method whether SDU is overtime:

7, link layer abandons the method for SDU in the TD-SCDMA standard as claimed in claim 5, it is characterized in that, if SDU is overtime, then also carries out following steps before abandoning described SDU:

8, link layer abandons the method for SDU in the TD-SCDMA standard as claimed in claim 1, it is characterized in that when described service ending, described RRC discharges all RLC entities, deletes described cycle timer simultaneously.