WO2004112305A1

WO2004112305A1 - Method and apparatus for discarding the service data units in the acknowledgement mode of the rlc in the wireless communications system

Info

Publication number: WO2004112305A1
Application number: PCT/CN2003/000471
Authority: WO
Inventors: Sheng Liu; Baijun Zhao; Yulin Li
Original assignee: Utstarcom (China) Co. Ltd.
Priority date: 2003-06-18
Filing date: 2003-06-18
Publication date: 2004-12-23
Also published as: CN1771685A; CN100379192C; AU2003248218A1

Abstract

A method is provided for discarding the service data units in the acknowledgement mode of the radio link control (RLC) of the wireless communications systems, including the steps of, A) processing the SDU in the RLC layer from the higher protocol layer, the protocol data unit in each RLC layer then is formed; B) the PDU in each RLC layer corresponding to the SDU is primitively transmitted and/or retransmitted to the peer layer, and judged whether it meets the predetermined condition of discarding the SDU; C) if the said predetermined condition of discarding the SDU is satisfed, then the SDU is discarded; otherwise, the step B) is performed continuously by the step C); wherein, the said predetermined condition is that the total retransmission times exceeds a predetermined value, wherein n ≥2, amd less than or equal to the total of the PDU in the RLC layer of the said SDU. Corresponding device and system of the above mentioned method are also provided. Method and device of the invention can ensure that the channel rate doesn't influence the ratio of discarding SDU, and prevents the appearance of the too large delay changing.

Description

Method and device for discarding service data unit in radio link control protocol confirmation mode

The present invention generally relates to a related technology of a radio link control (RLC) protocol in a wireless communication system, and particularly relates to an improved service data unit (SDU) discarding method in a wireless communication system RLC protocol. Background technique

Figure 1 shows the WCDMA wireless interface protocol structure. As shown in the figure, the physical layer (PHY) is located at the bottom. On the control plane, above the physical layer are a media 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 transmission 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. Each RLC entity is configured by RRC into one of three modes: transparent mode (TM), unacknowledged mode (UM), and acknowledged mode (AM). Among them, TM mode and UM mode are mainly used for real-time services that are sensitive to delay, and AM mode is mainly used to transmit 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 the 3GPP (Third Generation Partnership Project) TS25.410, TS29.060, TS29.061 and other protocols, the SDU of the PDCP layer (the SDU of the RLC layer when there is no PDCP layer) is carried in GTP-U (user plane GPRS User Data Packets for External Packet Data Network (PDN) over Tunneling Protocol). Since PDCP is only used for IP (Internet Protocol), UDP ( User datagram protocol), TCP (Transmission Control Protocol) and other protocol headers are compressed. Therefore, regardless of the presence of the PDCP layer, 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 One IP packet.

In IP networks, the most widely used transport layer protocols are TCP and UDP, non-real-time applications of the interaction 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, the SDU at the RLC layer corresponds to a TCP / IP packet.

As shown in FIG. 2, the RLC SDU from the upper layer is segmented and / or cascaded into a fixed-length RLC load unit (PU) and an RLC protocol header is added, where the length of the PU is a semi-static parameter, which is Determined when a radio bearer is established or reconfigured. A typical example is that according to TS34.108, the typical PU length of a radio bearer for NRT services is 320 bits. If the MTU (Maximum Transmission Unit) of an IP packet is 576 bytes, each RLC layer SDU can be divided into approximately For 15 RLC layer PDUs, if the MTU of the IP packet is 1500 bytes, each RLC layer SDU can be divided into a maximum of about 38 RLC layer PDUs. 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 transmitted to

T¾J layer.

RLC in AM mode uses Automatic Repeat Request (ARQ) to provide a low error rate radio bearer at the link layer, thereby improving the performance of the TCP protocol in a wireless network. The ARQ mechanism increases the transmission delay while ensuring a low error rate. Although this has a small impact on the quality of service (QoS) of non-real-time applications such as interaction types and background types, it has been caused by multiple retransmissions. A large delay will cause the retransmission timer of the TCP sender to time out, which will cause the TCP protocol to mistake the network for congestion and reduce the transmission rate through the flow control function, thereby causing problems such as a decrease in wireless link utilization and service throughput. On the other hand, when the sequential transmission function is enabled, Transmission also easily causes buffer overflow at the sender and receiver. Regarding the impact of wireless link layer technology on TCP performance, you can refer to RFC3481 TCP over Second and Third Generation Wireless Networks by 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 thereby reduce the 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 SDU transmission processing.

In the WCDMA wireless communication system, RLC in AM mode can use one of three SDU discarding methods: timer-based discarding method with explicit signaling, SDU discarding method after MaxDAT retransmissions, and MaxDAT secondary weighting. Do not discard after transmission. In the above three methods, the non-discard method after MaxDAT retransmissions will directly trigger the RLC layer reset process after the number of RLC layer PDU retransmissions in an AM mode reaches MaxDAT, so the application range is small. The timer-based discarding method with explicit signaling is as follows: For each SDU from a higher layer, a timer that monitors the transmission time of the SDU is started. If the SDU has not been successfully transmitted within a predetermined time, the sender will discard the SDU. And, if part of the SDU has been sent, the sender will use the in-band control command of the mobile receive window (MRW) to make the receive window and receive buffer of the receiver updated accordingly. The timer-based discard method with clear signaling due to the use of a fixed maximum delay constraint, although it is beneficial to improve the performance and QoS of higher-layer protocols such as TCP throughput, but this method is prone to cause more SDUs when the channel rate changes. thrown away. The SDU discarding method after MaxDAT retransmissions is the opposite of the timer-based discarding method with explicit signaling. It uses a fixed maximum number of retransmissions and guarantees a constant SDU at the cost of delay changes. Drop rate. According to the latest 3GPP specification TS25.322V5.4.0 (2003-03), in the SDU discard mode after MaxDAT retransmissions, once the number of RLC layer PDU retransmissions in an AM mode reaches MaxDAT, the sender will discard all The PDU has some segmented related SDUs, and all PDUs corresponding to these discarded SDUs in the sending window. At the same time, the sending end will use the MRW in-band control command to make the receiving window and receiving buffer of the receiving end corresponding. Update.

According to the foregoing description, it is known that in the current RLC protocol, the SDU discarding method after MaxDAT retransmissions is based on the judgment of whether the corresponding retransmission number of one PDU reaches the predetermined maximum number of MaxDATs to trigger the discarding of SDUs. As mentioned earlier, in practice, one SDU often corresponds to multiple PDUs, and the probability of unsuccessful MaxDAT retransmissions of one PDU will be much lower than the total number of retransmissions of each PDU corresponding to one SDU reaches MaxDAT. The probability. On the other hand, because the RLC receiver needs to wait for all RLC layer PDUs corresponding to an SDU to be completely successfully received, it can reassemble the SDU and submit it to the upper layer. In this way, the technology based on the current protocol specification is retransmitted after MaxDAT times. The SDU discarding method cannot effectively control the delay of SDU transmission, because once the total number of retransmissions of a PDU corresponding to an SDU is too high, but when the number of retransmissions of each PDU is lower than MaxDAT, a large delay will occur. It may cause the retransmission timer of the TCP sender to expire, thereby causing the TCP protocol to make incorrect control over the sending rate. Summary 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 confirmation mode of a wireless communication system is provided. The method includes the following steps: A) The RLC layer SDU from the upper layer protocol is segmented and concatenated 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 by the RLC layer sender functional entity one by one, and determines whether the predetermined condition for discarding the SDU is satisfied according to the status information from the peer layer;

C) if the predetermined discard condition is satisfied, discard the SDU; otherwise, step B) is performed continuously without interruption until all RLC layer PDUs corresponding to the SDU are successfully sent to the peer end receiving end;

Wherein, the predetermined discard condition in step B) is that the total number of retransmissions of a maximum of 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 value corresponds to the predetermined discard condition.

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

A segmentation and cascade processing device is configured to process an RLC layer SDU from an upper layer protocol to form each RLC layer protocol data unit (PDU) corresponding to the SDU; a sending device is configured to each RLC layer PDU corresponding to the SDU Initial transmission and / or retransmission to the peer layer by the RLC layer sender functional entity one by one;

A determining device, configured to determine whether a predetermined condition for discarding the SDU is satisfied according to status information from a peer layer;

The discarding device is configured to discard the SDU when the predetermined discarding condition is satisfied; otherwise, the sending device performs initial and / or retransmission of each RLC layer PDU corresponding to the SDU without interruption until the SDU All corresponding RLC layer PDUs are successfully sent to the peer end.

The predetermined discard condition is that the total number of retransmissions of a maximum of 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 wherein the predetermined threshold value corresponds to the predetermined discarding condition.

According to a third aspect of the present invention, a wireless communication system is provided, which includes a core network (CN), a radio access network (UTRAN), a terminal user equipment (UE), and is used in a radio link control (RLC) protocol. A device that discards an SDU when a predetermined condition for discarding a service data unit (SDU) is satisfied, wherein the device for implementing the function of discarding the SDU is the radio link control (RLC) provided by the second aspect of the present invention. ) A device in the protocol that implements the function of discarding service data units (SDUs).

According to a preferred embodiment of the present invention, the sender of the RLC layer counts the total number of retransmission times of all PDUs corresponding to the upper-layer SDU. Once the total number of retransmission times reaches a predetermined threshold, the sender will discard the SDU and For all PDUs corresponding to the SDU in the sending window, at the same time, the sending end will update the receiving window and receiving buffer of the receiving end by using the MRW in-band control command in the same manner as in the prior art.

According to another preferred embodiment of the present invention, when the total number of retransmission times of each PDU corresponding to an SDU is counted, the number of retransmission times of those PDUs that include other SDU partial segments in addition to the partial segment containing the SDU It 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, and can prevent excessive delay variation to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

Through the detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, the objects, features, and benefits of the present invention will become more apparent. among them:

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

3 is a flowchart of a specific embodiment of an 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 description

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

FIG. 3 shows a flowchart of a specific embodiment of the SDU discarding method according to the present invention by using an SDU sending process as an example. As shown in FIG. 3, in step S20, the RLC layer SDU from the upper layer protocol first enters the segment and cascade processing unit of the AM mode RLC layer sender, and after processing by this unit, each RLC layer PDU corresponding to the SDU is formed. In step S30, the counter Counter_ReTrans, which counts the total number of retransmission times of each RLC layer PDU corresponding to the SDU, is cleared. In step S40, the SDIJ discard method is used to complete the sending process of the SDU. In step S50, the sending process of the SDU ends, and as a result, the SDU may be discarded, or the SDU may be successfully sent to the peer end.

FIG. 4 describes the processing performed in step S40 of FIG. 3 in more detail. As shown in FIG. 4, in step S100, the sender of the RLC layer PDU determines 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 it is determined in step S160 whether all RLC layer PDUs corresponding to the SDU have been successfully transmitted to the peer end. If the determination result is "Yes", then the sending process of the SDU is ended (step S50), otherwise, it continues to wait for the next transmission from the peer layer Status information. If it is determined in step S100 that there are RLC layer PDUs that need to be retransmitted, then in step S110, the retransmission counter Counter_ReTrans, that is, Coimter ReTrans_Counter_ReTrans + k is updated, where k is the number of RLC layer PDUs that need to be retransmitted. Then, in step S120, it is determined whether the value of the counter Counter_ReTrans exceeds a predetermined threshold 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 discard condition. If the value of the counter Counter_ReTrans exceeds the predetermined threshold, the SDU is discarded in steps S130 and S140, and the sender uses the MRW in-band control command to make the receive window and receive buffer of the peer end corresponding. Update. And the sender discards the SDU, including discarding the backup of the SDU retained at the sender and all PDUs corresponding to the SDU in 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 transmitting end retransmits the RLC layer PDU in the status information indicating that retransmission is required.

The predetermined threshold TotalMaxDAT in this embodiment is determined in advance according to the requirements of the SDU discarding rate to be met and the requirement to prevent excessive delay changes, so it can be easily changed according to actual needs.

Please note that although the flowchart of FIG. 4 draws the retransmission processing of the corresponding RLC layer PDUs in a separate box (S170) for the sake of clarity, those skilled in the art should understand that in actual implementation, The retransmission of the RLC layer PDU corresponding to the SDU that needs to be retransmitted at a certain state information, and the initial transmission and / or retransmission of other RLC layer PDUs corresponding to the SDU are performed simultaneously. That is, the other RLC layer PDUs may only include the RCL layer PDUs of the SDU that need to be transmitted initially, and may be a combination of the RCL layer PDUs to be transmitted initially and the RLC layer PDUs that are determined to need retransmission in the previous processing. . Of course, it may also be that the other RLC layer PDUs have been successfully sent to the receiving end of the peer layer. In this case, only the Only the RLC layer PDUs that need to be retransmitted for re-transmission processing are needed. In addition, among the RLC layer PDUs that are determined to be retransmitted as described above, some may even be RLC layer PDUs that have been retransmitted multiple times. Unless it is judged that the condition for discarding the SDU is satisfied, the sending of each RLC layer PDU (including the initial transmission and the RLC layer PDU that needs to be retransmitted) corresponding to the SDU will be performed continuously without interruption, even if step S100 is performed , S110, S120, S160 and S170 without interruption. In addition, the status information from the peer layer mentioned in step S100 is transmitted from the peer layer to the transmitting end. And the transmission of status information can be started in multiple 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 timeout, etc. Etc. The transmission of status information may also be delayed, for example when the status PDU disable function is used. The specific form of status information transmission mechanism used depends on the specific implementation of the system. Therefore, the counter mentioned in step S110 Counter- ReTrans update step 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 and less than or equal to the total number of RLC layer PDUs corresponding to the SDU (depending on For the time interval of status information transmission and the number of RLC layer PDUs determined to be retransmitted in the time interval). It should be noted here that the content described in the text of this paragraph is well known in the communication field, and is not critical for implementing the SDU discarding method of the present invention.

It should be emphasized that the specific implementation method of the SDU discarding method after TotalMaxDAT retransmission of the present invention described above is only described for the sending process of an SLC at the RLC layer. In specific implementation, due to the AM mode The RLC sender sends based on a transmission window with a certain width. Due to the impact of retransmission, there may be cases where multiple SDUs at the RLC layer are not successfully sent to the receiver at the peer layer. Therefore, in specific implementation, For each of these SDUs, a separate retransmission counter, Counter_ReTrans, should be used. It is easy to understand that the SDU discarding method of the present invention counts the total number of retransmissions of a maximum of 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 certain predetermined threshold, so as to determine whether a condition for discarding the SDU is satisfied. In the above-mentioned preferred embodiments of the present invention described with reference to FIGS. 3 and 4, n takes an integer corresponding to the number of all RLC layer PDUs corresponding to the SDU, which is equivalent to the total number of retransmissions of all RLC layer PDUs corresponding to the SDU. Count and judge. However, the selection of the n RLC layer PDUs may be various. For example, the corresponding at least n RLC layer PDUs may be either consecutive n PDTJs or spaced n PDUs. Count and judge the retransmission times of the n corresponding RLC layer PDUs with even or odd bits, and so on.

According to the description of the foregoing embodiments, those skilled in the art can easily think of other RLC layer PDU selection methods that count the number of retransmission times except the examples listed above. 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 foregoing prior art SDU discarding method based on the number of retransmissions of a single RLC layer PDU of the SDU and the foregoing maximum of n RLC layers corresponding to the SDU in the present invention may also be used. The SDU discard method of the total retransmission times of PDUs is applied in combination. As long as the SDU discard condition in any discard method is met, the corresponding SDIL is discarded

According to other specific embodiments of the present invention, when counting the retransmission times of each PDXJ corresponding to an SDU, PDUs that include other SDU partial segments in addition to the partial segment containing the SDU should also be counted. . When it is determined that an SDU is to be discarded and the RLC layer PDU corresponding to the SDU is discarded within the transmission window, those PDUs that contain other SDU partial segments in addition to the partial segments containing the SDU should not be dropped.

In the above-mentioned embodiments, for the concatenation and segmentation processing of the SDU, it is determined that the SDU is discarded after meeting the predetermined discarding conditions of the SDU, and it is determined that the preemption of the SDU is not satisfied. The steps of initially transmitting and / or retransmitting each RLC layer PDU of the SDU without discontinuity when determining the discarding conditions are the same as the corresponding steps described above with reference to FIG. 3 and FIG. 4, and therefore are not 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 similar other 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, but various hardware devices known in the art may also be used to implement the functions of each of the steps, so as to provide for implementation Apparatus and system for 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 specific embodiments described above, but is defined by the appended claims.

Claims

Rights request

1. A method for discarding a service data unit (SDU) in a radio link control (RLC) protocol confirmation mode of a wireless communication system, the method includes the following steps:

A) The RLC layer SDU from the upper layer protocol is segmented and cascaded to form each RLC layer protocol data unit (PDU) corresponding to the SDU;

It is characterized in that the predetermined discard condition in step B) is that the total number of retransmissions of a maximum of n RLC layer PDUs corresponding to the SDU exceeds a predetermined threshold, where n> 2 but less than or equal to the RLC layer of the SDU The total number of PDUs, and wherein the predetermined threshold value corresponds to the predetermined drop condition.

2. The method for discarding SDUs in the RLC protocol confirmation mode of the wireless communication system according to claim 1, characterized in that: the n RLC layer PDUs are n consecutive PDILs

3. The method for discarding SDUs in the RLC protocol confirmation mode of the wireless communication system according to claim 2, characterized in that: said consecutive n RLC layer PDUs are all RLC layer PDUs corresponding to said SDUs.

4. The method for discarding the SDU in the RLC protocol confirmation mode of the wireless communication system according to claim 1, wherein the n RLC layer PDUs are discontinuous n PDUs.

5. The method for discarding the SDU in the RLC protocol confirmation mode of the wireless communication system according to any one of claims 1-4, characterized in that: when determining the SDU pair Whether the total number of retransmissions of the maximum n RLC layer PDUs exceeds the predetermined threshold value, and also determines the number of retransmissions of each RLC layer PDU of the SDU. When the number of retransmissions exceeds the predetermined threshold, or the number of retransmissions of a certain RLC layer PDU exceeds another predetermined threshold, the SDU is discarded, where the another predetermined threshold is based on an RLC layer PDU with the SDU. The predetermined discard condition corresponding to the number of retransmissions is determined.

6. The method for discarding the SDU in the RLC protocol confirmation mode of the wireless communication system according to any one of claims 1-5, characterized in that: for a partially segmented RLC layer containing other SDUs different from the SDU The number of PDU retransmissions is also counted.

7. The method for discarding the SDU in the RLC protocol confirmation mode of the wireless communication system according to any one of claims 1-5, characterized in that: when it is determined that the SDU needs to be discarded, discarding the corresponding SDU in the sending window. All RLC layer PDUs that contain only the partial segment of the SDIJ, and do not discard PDILs that contain other SDU partial segments in addition to the partial segment containing the SDU

8. A device for implementing a function of discarding a service data unit (SDU) in a radio link control (RLC) protocol in a wireless communication system, the device including:

The discarding device is configured to discard the SDU when the predetermined discarding condition is satisfied; otherwise, the sending device performs initial transmission and / or retransmission of each RLC layer PDU corresponding to the SDU without interruption until All RLC-layer PDUs corresponding to the SDU are successfully sent to the receiving end of the peer layer; It is characterized in that the predetermined discard condition is that the total number of retransmissions of a maximum of 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 value corresponds to the predetermined discard condition.

9. The device for implementing a function of discarding a service data unit (SDU) in a radio link control (RLC) protocol in a wireless communication system according to claim 8, characterized in that the n RLC layer PDUs are continuous N PDUs.

10. The device for implementing a function of discarding a service data unit (SDU) in a radio link control (RLC) protocol in a wireless communication system according to claim 9, characterized in that: the n consecutive RLC layer PDUs Are all RLC layer PDILs corresponding to the SDU

11. The device for implementing a function of discarding a service data unit (SDU) in a radio link control (RLC) protocol in a wireless communication system according to claim 8, wherein the n RLC layer PDUs are not N consecutive PDILs

12. The device for implementing the function of discarding service data-Apple Charger (SDU) in a radio link control (RLC) protocol in a wireless communication system according to any one of claims 8-11, wherein: When determining whether the total number of retransmissions of the maximum n RLC layer PDUs corresponding to the SDU exceeds the predetermined threshold, the number of retransmissions of each RLC layer PDU of the SDU is also determined. When the total number of retransmissions of a layer PDU exceeds the predetermined threshold, or when the number of retransmissions of a certain RLC layer PDU exceeds another predetermined threshold, the SDU is discarded, where the another predetermined threshold is based on one of the SDUs. The predetermined discard condition corresponding to the number of RLC layer PDU retransmissions is determined.

13. The device for implementing a function of discarding a service data unit (SDU) in a radio link control (RLC) protocol in a wireless communication system according to any one of claims 8-11, wherein: The number of retransmissions of the RLC layer PDUs of the partial segments of other SDUs with different SDUs is also counted.

14. The device for implementing a function of discarding a service data unit (SDU) in a radio link control (RLC) protocol in a wireless communication system according to any one of claims 8 to 11, wherein: When the SDU is discarded, all RLC layer PDUs corresponding to the SDU and including only partial segments of the SDU are discarded in the sending window without discarding those SDU partial segments that include other SDU segments PDU.

15. A wireless communication system, including a core network (CN), a radio access network (UTRAN), an end user equipment (UE), and a service for discarding service data in a radio link control (RLC) protocol when meeting a predetermined requirement The SDU is discarded when the conditions of the unit (SDU) are discarded, characterized in that: the device for implementing the function of discarding the SDU is the implementation of the discard service data unit (SDU) in the radio link control (RLC) protocol according to claim 8. ) Functioning device.

16. The wireless communication system according to claim 15, wherein the n RLC layer PDUs are consecutive n PDUs.

17. The wireless communication system according to claim 16, wherein:

18. The wireless communication system according to claim 15, wherein: the n RLC layer PDUs are discontinuous n PDUs.

19. The wireless communication system according to any one of claims 15-18, characterized in that: while determining whether the total number of retransmissions of a maximum of n RLC layer PDUs corresponding to the SDU exceeds the predetermined threshold, The number of retransmissions of each RLC layer PDU of the SDU is also determined. When the total number of retransmissions of the maximum n RLC layer PDUs exceeds the predetermined threshold, or the number of retransmissions of one RLC layer PDU exceeds another predetermined number When the threshold is reached, the SDU is discarded, where the another predetermined threshold is determined according to a predetermined discarding condition corresponding to the number of retransmissions of an RLC layer PDU of the SDU.

20. The wireless communication system according to any one of claims 15 to 18, wherein The characteristic is that the number of retransmissions of the RLC layer PDUs containing partial segments of other SDUs different from the fanned SDU is also counted.

21. The wireless communication system according to any one of claims 15-18, wherein: when it is determined that the SDU needs to be discarded, the SDU corresponding to the SDU that contains only a partial segment of the SDU is discarded in the sending window. All RLC layer PDUs without discarding PDILs that contain partial segments of other SDUs in addition to the partial segments of the SDU