CN1771685A - Method and device for discarding service data unit in radio link control protocol acknowledgment mode - Google Patents

Abstract

There is provided a method for discarding service data units SDUs in a Radio Link Control (RLC) protocol acknowledged mode in a wireless communication system, comprising the steps of: A) processing RLC layer SDU from an upper layer protocol to form each RLC layer protocol data unit PDU corresponding to the SDU; B) initially transmitting and/or retransmitting each RLC layer PDU corresponding to the SDU to a peer layer, and judging whether a preset condition for discarding the SDU is met or not; C) if the preset discarding condition is met, discarding the SDU; otherwise, C) continuously and uninterruptedly executing the step B); the preset discarding condition is that the total weight transmission times of at most n RLC layer PDUs corresponding to the SDU exceed a preset threshold, wherein n is more than or equal to 2 but less than or equal to the total number of the RLC layer PDUs of the SDU. Corresponding equipment and a system for realizing the method are also provided. The method and the equipment can ensure that the SDU discarding rate is not influenced by the channel rate and prevent overlarge time delay change.

Description

Method and device for discarding service data units in radio link control protocol acknowledgment mode Technical field

The present invention generally relates to technologies related to the Radio Link Control (RLC) protocol in a wireless communication system, and in particular to an improved service data unit (SDU) discarding method in the RLC protocol of a wireless communication system. Background technique

Figure 1 shows the WCDMA radio interface protocol structure. As shown in the figure, the bottom layer is the physical layer (PHY). On the control plane, above the physical layer are respectively a medium access control layer (MAC), a radio link control layer (RLC) and a radio resource control (RRC) layer. In the user plane, in addition to the MAC layer and the RLC layer, it also includes a Packet Data Convergence Protocol (PDCP) layer and a Broadcast/Multicast Control (BMC) layer. The channel between the MAC layer and the physical layer is a transport channel, and the channel between the MAC layer and the RLC layer is a logical channel. For a specific end user equipment (UE), there may be multiple RLC entities, and different logical channels of the UE correspond to different RLC entities.

The RLC protocol provides segmentation and retransmission services for user and control data, and each RLC entity is configured by RRC in one of three modes: transparent mode (TM), unacknowledged mode (UM) and acknowledged mode (AM). Among them, the TM mode and the UM mode are mainly used for real-time services that are sensitive to delay, and the AM mode is mainly used for transmitting non-real-time packet-type services. For packet services, the PDCP layer can improve the spectrum utilization of wireless transmission through header compression. According to 3GPP (Third Generation Cooperation Project) TS25.410, TS29.060, TS29.061 and other agreements, the SDU of the PDCP layer (the SDU of the RLC layer when there is no PDCP layer) is carried on the GTP-U (user plane GPRS user data packets on an external packet data network (PDN) over a tunneling protocol. Since PDCP is only IP (Internet Protocol), UDP (using User Datagram Protocol), TCP (Transmission Control Protocol) and other protocol headers are compressed. Therefore, no matter whether there is a PDCP layer or not, the SDU of the RLC layer corresponds to a user data packet of an external PDN. When the external PDN is an IP network, it corresponds to An IP packet.

In IP networks, the most widely used transport layer protocols are TCP and UDP, non-real-time applications of interactive type and background type defined in 3GPP, such as WWW (web browsing), email, FTP (file transfer protocol), etc., typically Both use TCP as the transport layer protocol. As mentioned above, such services generally use RLC in AM mode in the radio bearer. In this case, an SDU at the RLC layer corresponds to a TCP/IP packet.

As shown in Figure 2, the RLC SDU from the upper layer is segmented and/or concatenated into a fixed-length RLC load unit (PU) and an RLC protocol header is added, wherein the length of the PU is a semi-static parameter, which is It is determined when the radio bearer is established or reconfigured. A typical example is that according to TS34.108, the typical PU length of the radio bearer of the NRT service is 320 bits, and if the MTU (Maximum Transmission Unit) of the IP packet is 576 bytes, then each RLC layer SDU can be divided into approximately 15 RLC layer PDUs, if the MTU of the IP packet is 1500 bytes, each RLC layer SDU can be divided into about 38 RLC layer PDUs at most. At the receiving end, when all RLC layer PDUs of an RLC layer SDU are received correctly, they will be reassembled into a complete SDU and sent to the

T¾J layer.

RLC in AM mode adopts automatic repeat request (ARQ) to provide a radio bearer with a low error rate at the link layer, thereby improving the performance of the TCP protocol in the wireless network. While the ARQ mechanism ensures a low error rate, it also increases the transmission delay. Although this has little impact on the quality of service (QoS) of non-real-time applications such as interactive types and background types, the excessive time caused by multiple retransmissions A large delay will cause the retransmission timer of the TCP sender to expire, so that the TCP protocol will mistakenly believe that the network is congested and reduce the sending rate through the flow control function, resulting in the problem of decreased wireless link utilization and service throughput. On the other hand, when the sequential transmission function is enabled, multiple retransmissions at the RLC layer may easily cause buffer overflows at the sending end and the receiving end. For the impact of wireless link layer technology on TCP performance, you can refer to RFC3481 TCP over Second and Third Generation Wireless Networks " of IETF (Internet Engineering Task Force), "Comparison of Mechanisms for Improving TCP Performance over Wireless Links" by Hari Balakrishnan et al. , IEEE/ACM Transactions on Networking, Vol.5, No.6,

In order to reduce the above-mentioned excessive delay caused by multiple retransmissions, and the resulting problem of decreased radio link utilization and service throughput, the service data unit in the radio link control (RLC) protocol is generally used (SDU) discard method to complete the SDU transmission processing.

In a WCDMA wireless communication system, RLC in AM mode can adopt one of three SDU discarding methods: timer-based discarding with explicit signaling, SDU discarding after MaxDAT times of retransmission, MaxDAT times of retransmission Do not discard after transmission. Among the above three methods, the method of not discarding after MaxDAT retransmissions will directly trigger the reset process of the RLC layer after the number of retransmissions of the RLC layer PDU in AM mode reaches MaxDAT, so the application range is relatively small. The timer-based discarding method with clear signaling is as follows: for each SDU from the upper layer, start a timer to monitor the transmission time of the SDU, if the SDU has not been successfully transmitted within the predetermined time, the sender will discard the SDU , and, if some segments of the SDU have been sent, the sending end will use the in-band control command of the mobile receiving window (MRW), so that the receiving window and the receiving buffer of the receiving end are updated accordingly. The timer-based discarding method with explicit signaling uses a fixed maximum delay constraint. Although it is beneficial to improve the throughput and QoS of high-level protocols such as TCP, this method tends to cause more SDUs when the channel rate changes thrown away. The SDU discarding method after MaxDAT retransmissions is contrary to the timer-based discarding method with explicit signaling. It uses a fixed maximum number of retransmissions to ensure a constant SDU at the cost of delay changes. discard rate. According to the latest 3GPP specification TS25.322V5.4.0 (2003-03), in the SDU discarding method after MaxDAT retransmissions, once the number of retransmissions of an RLC layer PDU in AM mode reaches MaxDAT, the sender will discard all The relevant SDUs with partial fragments in the PDU, and all the PDUs corresponding to these discarded SDUs in the sending window, and the sending end will use the MRW in-band control command to make the receiving window and receiving buffer of the receiving end corresponding renew.

According to the above description, in the current RLC protocol, the SDU discarding method after MaxDAT times of retransmission is based on the judgment of whether the corresponding number of retransmissions of a PDU reaches the predetermined maximum number of MaxDAT to trigger the discarding of the SDU. As mentioned above, in practical applications, one SDU often corresponds to multiple PDUs, and the probability of unsuccessful retransmissions of up to MaxDAT times for one PDU will be much lower than the total number of retransmissions of each PDU corresponding to one SDU reaching MaxDAT The probability. On the other hand, since the RLC receiving end needs to wait for all the RLC layer PDUs corresponding to an SDU to be completely and successfully received, it can reassemble the SDU and submit it to the upper layer. The SDU discarding method will not be able to effectively control the SDU transmission delay, because once the total number of retransmissions of the PDU corresponding to a certain SDU is too high, but the respective retransmission times of each PDU are lower than MaxDAT, a large delay will be generated. It may cause the retransmission timer of the TCP sending end to time out, so that the TCP protocol makes wrong control on the sending rate. Contents of the invention

In order to solve the above problems in the prior art, the present invention provides an improved SDU discarding method in the RLC protocol of a wireless communication system, a device for implementing the discarding method, and a wireless communication system using the device.

According to a first aspect of the present invention, a method for discarding a service data unit (SDU) in a radio link control (RLC) protocol acknowledgment mode of a wireless communication system is provided, and the method includes the following steps: A) Segmenting and concatenating the RLC layer SDUs from the upper layer protocol to form each RLC layer protocol data unit (PDU) corresponding to the SDU;

B) each RLC layer PDU corresponding to the SDU is initially transmitted and/or retransmitted to the peer layer one by one through the RLC layer sender functional entity, and judges whether the predetermined condition for discarding the SDU is met according to the state information from the peer layer;

C) If the predetermined discarding condition is met, discard the SDU; otherwise, perform step B) continuously and without interruption, until all RLC layer PDUs corresponding to the SDU are successfully sent to the receiving end of the peer layer;

Wherein, the predetermined discarding condition in step B) is that the total number of retransmissions of up to n RLC layer PDUs corresponding to the SDU exceeds a predetermined threshold, where n>2 but less than or equal to the total number of RLC layer PDUs of the SDU , and wherein the predetermined threshold corresponds to the predetermined discarding condition.

According to a second aspect of the present invention, there is provided a device in a wireless communication system for implementing a function of discarding a service data unit (SDU) in a radio link control (RLC) protocol, the device comprising:

Segmentation and concatenation processing means for processing the RLC layer SDU from the upper layer protocol to form each RLC layer protocol data unit (PDU) corresponding to the SDU; sending means for each RLC layer PDU corresponding to the SDU Initially transmit and/or retransmit to the peer layer one by one through the functional entity of the sending end of the RLC layer;

judging means, configured to judge whether the predetermined condition for discarding the SDU is met according to the status information from the peer layer;

discarding means, configured to discard the SDU when the predetermined discarding condition is met, otherwise, the sending means continuously and uninterruptedly perform initial transmission and/or retransmission of each RLC layer PDU corresponding to the SDU until the SDU All corresponding RLC layer PDUs are successfully sent to the receiving end of the peer layer;

Wherein, the predetermined discarding condition is that the total number of retransmissions of up to n RLC layer PDUs corresponding to the SDU exceeds a predetermined threshold, where n > 2 but less than or equal to the The total number of RLC layer PDUs of the SDU, and the predetermined threshold corresponds to the predetermined discarding condition.

According to a third aspect of the present invention, a wireless communication system is provided, including a core network (CN), a radio access network (UTRAN), an end user equipment (UE), and a radio link control (RLC) protocol for A device for discarding a service data unit (SDU) when a predetermined condition for discarding a service data unit (SDU) is met, wherein the device for implementing the function of discarding an SDU is a radio link control (RLC) as provided in the second aspect of the present invention. ) A device that implements the function of discarding a service data unit (SDU) in the protocol.

According to a preferred embodiment of the present invention, the total number of retransmissions of all PDUs corresponding to the SDU from the upper layer is counted at the sending end of the RLC layer. Once the total number of retransmissions reaches a predetermined threshold, the sending end will discard the SDU and For all PDUs corresponding to the SDU within the sending window, the sending end will use the same method as the prior art to update the receiving window and receiving buffer of the receiving end through the MRW in-band control command.

According to another preferred embodiment of the present invention, when counting the sum of the retransmission times of each PDU corresponding to an SDU, the retransmission times of PDUs that include other SDU partial segments in addition to the SDU partial segments should also be counted.

Compared with the prior art, the present invention can not only ensure that the SDU discarding rate is not affected by the channel rate, but also prevent excessive time delay changes to a certain extent. Description of drawings

The purpose, features and benefits of the present invention will become more apparent by describing the specific embodiments of the present invention in detail in conjunction with the accompanying drawings. in:

Fig. 1 is a schematic diagram of a wireless interface protocol structure in a WCDMA wireless communication system; Figure 2 is a schematic diagram of the segmentation and concatenation of RLC layer SDUs in the RLC wireless protocol confirmation mode (AM mode);

FIG. 3 is a flowchart of a specific embodiment of the SDU discarding method according to the present invention;

FIG. 4 is a detailed flowchart of step S40 in the flowchart shown in FIG. 3. Detailed ways

A specific embodiment of the present invention, that is, a specific embodiment of the SDU discarding method after retransmission of each RLC layer PDU corresponding to an SDU for a predetermined number of times (TotalMaxDAT times in this embodiment) will be described in detail below with reference to the accompanying drawings. .

FIG. 3 shows a flow chart of a specific embodiment of the SDU discarding method of the present invention, taking the sending process of an SDU as an example. As shown in FIG. 3, in step S20, the RLC layer SDU from the upper layer protocol first enters the segmentation and concatenation processing unit of the AM mode RLC layer sending end, and after being processed by this unit, each RLC layer PDU corresponding to the SDU is formed. In step S30, the counter Counter_ReTrans that counts the total number of retransmissions of each RLC layer PDU corresponding to the SDU is cleared. In step S40, the SDIJ discarding method of the invention is used to complete the sending process of the SDU. In step S50, the sending process of the SDU ends, and the result may be that the SDU is discarded, or the SDU is successfully sent to the receiving end of the peer layer.

FIG. 4 describes the processing performed in step S40 of FIG. 3 in more detail. As shown in Figure 4, in step S100, the sender of the RLC layer PDU judges whether there is an RLC layer PDU corresponding to the SDU that needs to be retransmitted according to the status information from the peer layer generated during the transmission of the SDU? If retransmission is not required, then in step S160 it is judged whether all the RLC layer PDUs corresponding to the SDU have been successfully sent to the receiving end of the peer layer? If the judgment result is "yes", then end the sending process of the SDU (step S50), otherwise, continue to wait for the next transmission from the peer layer The status information is judged. If it is determined in step S100 that there are RLC layer PDUs that need to be retransmitted, the retransmission counter Counter—ReTrans is updated in step S110, that is, Coimter ReTrans—Counter—ReTrans+k, where k is the number of RLC layer PDUs that need to be retransmitted. Then, in step S120, it is judged whether the value of the counter Counter_ReTrans exceeds a predetermined value TotalMaxDAT? The predetermined threshold is the maximum total number of retransmissions allowed for each RLC layer PDU corresponding to the SDU corresponding to the SDU discarding condition. If the value of the counter Counter_ReTrans exceeds the predetermined threshold, the SDU is discarded in steps S130 and S140, and the sending end uses the MRW in-band control command to make the receiving window and the receiving buffer of the receiving end of the peer layer correspondingly renew. And the sending end discards the SDU, including discarding the backup of the SDU retained at the sending end and all PDUs corresponding to the SDU within the sending window. If it is determined in step S120 that the value of the counter Counter_ReTrans does not exceed the predetermined threshold TotalMaxDAT, then retransmission processing is performed in step S170, that is, the sender retransmits the RLC layer PDU indicated in the status information that needs to be retransmitted.

The predetermined threshold TotalMaxDAT in this embodiment is pre-determined according to the required SDU discard rate and the requirement to prevent excessive delay changes, so it can be easily changed according to actual needs.

Please note that although for the sake of clarity, the flowchart in FIG. 4 draws the retransmission processing of the corresponding RLC layer PDU in a separate box (S170), but those skilled in the art should understand that in actual implementation, the The retransmission of the RLC layer PDU corresponding to the SDU that needs to be retransmitted according to a certain state information judgment, and the initial transmission and/or retransmission of other RLC layer PDUs corresponding to the SDU are performed simultaneously. That is to say, the other RLC layer PDU may only include the RCL layer PDU of the SDU that needs to be transmitted initially, and may be a combination of the RCL layer PDU to be transmitted initially and the RLC layer PDU that needs to be retransmitted in the previous processing . Of course, it is also possible that the other RLC layer PDUs have been successfully sent to the receiving end of the peer layer, and in this case only the The RLC layer PDU that needs to be retransmitted after the second judgment can be retransmitted. Moreover, among the above-mentioned RLC layer PDUs determined to be retransmitted, some may even be RLC layer PDUs that have been retransmitted many times. Unless it is judged that the condition of discarding the SDU is satisfied, the sending of the RLC layer PDUs corresponding to the SDU (including the initial transmission and the RLC layer PDUs that need to be retransmitted) will be continuously and uninterrupted, even when step S100 is executed , S110, S120, S160 and S170 are not interrupted at the same time. In addition, the status information from the peer layer mentioned in step S100 is transmitted from the peer layer to the sender. And the transmission of the status information can be started in a variety of ways, for example, when the polling bit of the data PDU (AMD PDU) is 1"; or the timer-based status PDU transmission function is used, and the timer Timer_Status—Periodic times out, etc. Etc. The transmission of status information may also be delayed, for example, when the status PDU prohibition function is used. What kind of status information transmission mechanism is used depends on the specific implementation of the system. Thus, the counter mentioned in step S110 The update step of Counter—ReTrans may be 1" (transmit status information whenever it is determined that an RLC layer PDU needs to be retransmitted), or any integer greater than 1 but less than or equal to the total number of RLC layer PDUs corresponding to the SDU (depending on Based on the time interval of status information transmission and the number of RLC layer PDUs that need to be retransmitted during this time interval). It should be noted here that the content described in this paragraph is well known in the communication field, and is not critical to the implementation of the SDU discarding method of the present invention.

It should be emphasized that in the specific implementation method of the SDU discarding method after TotalMaxDAT retransmissions of the present invention described above, only the sending process of an RLC layer SDU is described. In the specific implementation, due to the AM mode The RLC sending end sends based on a sending window of a certain width. Due to the influence of retransmission, there may be a situation where multiple RLC layer SDUs are not successfully sent to the receiving end of the peer layer. Therefore, in specific implementation, For each of these SDUs, an independent retransmission counter Counter—ReTrans shall be used respectively. It is easy to understand that the SDU discarding method of the present invention counts the total number of retransmissions of up to n RLC layer PDUs of the SDU, where n is greater than or equal to 2 and less than or equal to the total number of RLC layer PDUs corresponding to the SDU. Then it is judged whether the obtained value of the total number of retransmissions exceeds a predetermined threshold, so as to judge whether the condition for discarding the SDU is satisfied. In the above-mentioned preferred embodiment of the present invention described with reference to Fig. 3 and Fig. 4, n takes the integer corresponding to the number of all RLC layer PDUs corresponding to SDU, which is equivalent to the total number of retransmissions of all RLC layer PDUs corresponding to SDU Count and judge. However, the selection of the n RLC layer PDUs can be various, for example, the corresponding at least n RLC layer PDUs can be either consecutive n PDTJs, or n intervals of PDUs, such as for The retransmission times of n corresponding RLC layer PDUs with even or odd bits are counted and judged, and so on.

According to the description of the above embodiments, those skilled in the art can easily think of other selection methods of RLC layer PDUs for counting the number of retransmissions other than the examples listed above, and these selection methods should be considered to belong to the protection scope of the present invention .

In addition, in other embodiments of the present invention, the aforementioned SDU discarding method in the prior art based on the number of retransmissions of a single RLC layer PDU based on the SDU and the above-mentioned corresponding maximum n RLC layers based on the SDU in the present invention can also be combined. The SDU drop method is applied in combination with the total number of retransmissions of the PDU. As long as the SDU discarding condition in any discarding method is satisfied, the corresponding SDIL is discarded

According to other specific embodiments of the present invention, when counting the number of retransmissions of each PDXJ corresponding to an SDU, those PDUs that include partial segments of other SDUs in addition to the partial segments of the SDU should also be included in the statistics . When it is determined that an SDU is to be discarded and the RLC layer PDU corresponding to the SDU is discarded within the sending window, those PDUs that contain not only the partial segments of the SDU but also the partial segments of other SDUs should not be discarded.

In each of the above embodiments, for the concatenation and segmentation processing of the SDU, the SDU is discarded after it is determined that the predetermined discarding condition of the SDU is met, and the predetermined discarding condition of the SDU is determined not to be met. The steps of continuously and uninterrupted initial transmission and/or retransmission of each RLC layer PDU of the SDU when setting the discarding condition are the same as the corresponding steps described above with reference to FIG. 3 and FIG. 4 , so they will not be repeated here.

It should be understood that although the above description of the specific embodiments of the present invention is implemented in the context of a WCDMA (Wideband CDMA) wireless communication system, the method of the present invention can also be used to implement SDU discarding in other similar wireless communication systems .

In addition, the SDU discarding method of the present invention described in the above specific embodiments is implemented by corresponding control software, however, various hardware devices known in the art can also be used to implement the functions of each step, so as to provide The device and system of the SDU discarding method of the present invention.

Although the present invention has been described above in conjunction with some specific embodiments, those skilled in the art should understand that various modifications can be made to the present invention without departing from the basic principle and spirit of the present invention. Therefore, the protection scope of the present invention is not limited to the above specific embodiments, but is defined by the appended claims.

Claims (1)

1. Claim

   1st, a kind of wireless communication system wireless spread-spectrum technology（RLC) service data unit in protocol validation pattern（SDU discarding method), this method comprises the following steps：

   A) will the rlc layer SDU from upper-layer protocol be segmented forms corresponding each rlc layer protocol Data Unit of the SDU with cascade after processing（ PDU ) ；

   B corresponding each rlc layer PDU of the SDU just) are passed and/or be retransmitted to one by one peer layer through rlc layer transmitting terminal functional entity, and determine whether that satisfaction abandons the predetermined condition of the SDU according to the status information from peer layer；

   C condition) is abandoned if meeting the Yu and Dinging Lost, the SDU is abandoned;Otherwise, step B is continuously performed without interruption), until the corresponding all rlc layer PDU of the SDU are successfully transmitted to peer layer receiving terminal；

   It is characterized in that：In step B) in described pre- to determine the Lost conditions of abandoning be the corresponding most n rlc layer PDU of the SDU total number of retransmissions more than a predetermined threshold, wherein n>2 but rlc layer PDU less than or equal to SDU sum, and wherein the predetermined threshold is corresponding with the predetermined discarding condition.

   2nd, in wireless communication system rlc protocol affirmation mode as claimed in claim 1 SDU discarding method, it is characterised in that：The n rlc layer PDU is continuous n PDIL

   3rd, in wireless communication system rlc protocol affirmation mode as claimed in claim 2 SDU discarding method, it is characterised in that：The continuous n rlc layer PDU is the corresponding all rlc layer PDU of the SDU.

   4th, SDU Lost digging soil methods in wireless communication system rlc protocol affirmation mode as claimed in claim 1, it is characterised in that：The n rlc layer PDU is discontinuous n PDU.

   5th, in the wireless communication system rlc protocol affirmation mode as any one of claim 1-4 SDU discarding method, it is characterised in that：Judging described SDU pairs While whether the most n rlc layer PDU answered total number of retransmissions exceedes the predetermined threshold, also each rlc layer PDU of SDU number of retransmissions is judged, when total number of retransmissions of most n rlc layer PDU exceedes the predetermined threshold, or some rlc layer PDU number of retransmissions exceed another predetermined threshold when, then abandon the SDU, wherein, another predetermined threshold is the predetermined discarding condition according to corresponding to the number of retransmissions of a rlc layer PDU with the SDU to determine.

   6th, in the wireless communication system rlc protocol affirmation mode as any one of claim 1-5 SDU discarding method, it is characterised in that：Also counted for the rlc layer PDU of the partial segments containing other SDUs different from described SDU number of retransmissions.

   7th, in the wireless communication system rlc protocol affirmation mode as any one of claim 1-5 SDU discarding method, it is characterised in that：When judging to need to abandon the SDU, all rlc layer PDU of the corresponding only partial segments comprising the SDIJ of the SDU are abandoned in transmission window, without abandoning those PDIL that other SDU partial segments are further comprises in addition to the partial segments comprising the SDU

   8th, it is used to realize wireless spread-spectrum technology in a kind of wireless communication system（RLC) service data unit is abandoned in agreement（SDU the equipment of function), the equipment includes：

   Segmentation and cascade processing unit, for the rlc layer SDU from upper-layer protocol to be formed into each corresponding rlc layer protocol Data Unit of the SDU after processing（ PDU )；Dispensing device, for just passing and/or being retransmitted to peer layer one by one through RLC layers of transmitting terminal functional entity by corresponding each rlc layer PDU of the SDU；

   Decision maker, for being determined whether to meet the predetermined condition for abandoning the SDU according to the status information from peer layer；

   Lost abandons device, for abandoning Tiao Jian Shi Lost and abandoning the SDU meeting the Yu and Ding Lost, otherwise, by continuous each rlc layer PDU corresponding to the SDU without interruption of the dispensing device just pass and/or retransmit, until the corresponding all rlc layer PDU of the SDU are successfully transmitted to peer layer receiving terminal； It is characterized in that：It is described that pre- to determine the Lost conditions of abandoning be the corresponding most n rlc layer PDU of the SDU total number of retransmissions more than a predetermined threshold, wherein n>2 but rlc layer PDU less than or equal to SDU sum, and wherein the predetermined threshold is corresponding be confused predetermined discarding condition.

   9th, as being used to realize wireless spread-spectrum technology in wireless communication system that claim 8 is confused（RLC) service data unit is abandoned in agreement（SDU the equipment of function), it is characterised in that：The n rlc layer PDU is continuous n PDU.

   10th, it is used to realize wireless spread-spectrum technology in wireless communication system as claimed in claim 9（RLC) service data unit is abandoned in agreement（SDU the equipment of function), it is characterised in that：The continuous n rlc layer PDU is the corresponding all rlc layer PDIL of the SDU

   11st, it is used to realize wireless spread-spectrum technology in wireless communication system as claimed in claim 8（RLC) service data unit is abandoned in agreement（SDU the equipment of function), it is characterised in that：The n rlc layer PDU is discontinuous n PDIL

   12nd, it is used to realize wireless spread-spectrum technology in the wireless communication system as any one of claim 8-11（RLC the equipment that the apple of service data one fills the function of (SDU)) is abandoned in agreement, it is characterised in that：While whether the total number of retransmissions for judging the corresponding most n RLC layers of PDU of the SDU exceedes the predetermined threshold, also each rlc layer PDU of SDU number of retransmissions is judged, when total number of retransmissions of most n RLC layers of PDU exceedes the predetermined threshold, or some RLC layers of PDU number of retransmissions exceed another predetermined threshold when, then abandon the SDU, wherein, another predetermined threshold is that Yu according to corresponding to the number of retransmissions of a rlc layer PDU with the SDU Dings Lost and abandons condition to determine.

   13rd, it is used to realize wireless spread-spectrum technology in the wireless communication system as any one of claim 8-11（RLC) service data unit is abandoned in agreement（SDU the equipment of function), it is characterised in that：Also counted for the rlc layer PDU of the partial segments containing other SDUs different from described SDU number of retransmissions. 14th, it is used to realize wireless spread-spectrum technology in the wireless communication system as any one of claim 8-11（RLC) service data unit is abandoned in agreement（SDU the equipment of function), it is characterised in that：When judging to need to abandon the SDU, all rlc layer PDU of the corresponding only partial segments comprising the SDU of the SDU are abandoned in transmission window, without abandoning those PDU that other SDU partial segments are further comprises in addition to the partial segments comprising the SDU.

   15th, a kind of wireless communication system, including core net（), CN wireless access network (UTRAN), end user device（), UE and in wireless spread-spectrum technology (RLC) agreement when meeting predetermined discarding service data unit（The SDU is abandoned during condition SDU), it is characterised in that：The equipment that SDU functions are abandoned for Shi Xian Lost is wireless spread-spectrum technology as claimed in claim 8（RLC) realized in agreement and abandon service data unit（SDU the equipment of function).

   16th, wireless communication system as claimed in claim 15, it is characterised in that：The n rlc layer PDU is continuous n PDU.

   17th, wireless communication system as claimed in claim 16, it is characterised in that：It is described

   18th, wireless communication system as claimed in claim 15, it is characterised in that：Be confused n rlc layer PDU is discontinuous n PDU.

   19th, the wireless communication system as any one of claim 15-18, it is characterised in that：While whether the total number of retransmissions for judging the corresponding most n rlc layer PDU of the SDU exceedes the predetermined threshold, also each rlc layer of SDU PDU number of retransmissions is judged, when total number of retransmissions of most n rlc layer PDU exceedes the predetermined threshold, or some rlc layer PDU number of retransmissions exceed another predetermined threshold when, then abandon the SDU, wherein, another predetermined threshold is that Yu according to corresponding to the number of retransmissions of a rlc layer PDU with the SDU Dings Lost and abandons condition to determine.

   20th, the wireless communication system as any one of claim 15-18, it is special Levy and be：Also counted for the rlc layer PDU of the partial segments containing different other SDU of the SDU from being confused number of retransmissions.

   21st, the wireless communication system as any one of claim 15-18, it is characterised in that：When judging to need to abandon the SDU, all rlc layer PDU, the PDIL without abandoning those partial segments that other SDU are further comprises in addition to the partial segments comprising the SDU of the corresponding only partial segments comprising the SDU of the SDU are abandoned in transmission window