CN1697556A

CN1697556A - Method for transferring status report

Info

Publication number: CN1697556A
Application number: CN 200410034760
Authority: CN
Inventors: 杨学志
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2004-05-12
Filing date: 2004-05-12
Publication date: 2005-11-16
Anticipated expiration: 2024-05-12
Also published as: WO2005109817A1; CN100512506C

Abstract

The method is suitable for communication system under AM entity including acknowledgement mode. Procedure of sending status report includes steps: in time of determined to need to send out status report, if further determining that current RLC SDU to be packed and transmitted by AMD PDU is not a tail data of RLC SDU, current AM entity inserts status report and LI special value into AMD PDU; the said LI special value indicates following meanings: transmitted RLC SDU data are not ended; RLC SDU data length contained in current AMD PDU is LI; current AMD PDU contains LI specific data of status report; then, AM entity sends the AMD PDU out. Procedure of receiving status report includes steps: in time of receiving AMD PDU, and determining that LI special value is contained in AMD PDU, AM entity picks up RLC SDU data from current AMD PDU, and status report; receiving next part of RLC SDU. The invention can transmits status report in concatenation when RLC SDU transmission is not ended.

Description

Transmission method of status report

Technical Field

The present invention relates to information transmission technology, and more particularly, to a method for transmitting status reports in acknowledged mode in a mobile communication system.

Background

Radio transmission techniques of the Universal Mobile Telecommunications System (UMTS) include Frequency Division Duplex (FDD) and Time Division Duplex (TDD), with FDD being currently used for WCDMA and TDD being currently used for TD-CDMA and TD-SCDMA. TD-CDMA and TD-SCDMA are also referred to as 3.84McpsTDD and 1.28McpsTDD, respectively, based on the difference in chip rate. The UMTS system comprises a Radio Access Network (RAN) for handling all radio related functions and a Core Network (CN) part which is responsible for handling all voice calls and data connections within the UMTS system and implementing switching and routing functions with external networks.

In the UMTS system, a radio interface protocol is divided into a physical layer, a data link layer, and a network layer. The Radio Link Control (RLC) in the data link layer supports three modes, namely a Transparent Mode (TM), an Unacknowledged Mode (UM) and an Acknowledged Mode (AM), and realizes functions of segmentation, concatenation, filling, error control, flow control, repeatability detection and the like. Among them, the AM mode has an automatic repeat request (ARQ) mechanism, and the RLC AM mode may employ a sliding window protocol.

As shown in fig. 1, each RLC AM entity includes a transmitting side and a receiving side, the transmitting side is used for scheduling and transmitting data units, and transmitting the data units to an opposite RLC AM entity; the receiving side is responsible for receiving the data unit and sending to the high level, and produce the status report, convey the receiving state of the data unit to the sending side, send to the RLC AM entity of opposite terminal, the status report is used for functions such as window control, etc. The specific implementation process is shown in fig. 1, and includes:

the RLC AM entity sending side receives an RLC Service Data Unit (SDU) sent by a higher layer, carries out segmentation/cascade processing on the received RLC SDU so as to realize that the RLC SDU is put into one or more PDU (protocol data unit) with Acknowledged Mode Data (AMD) for transmission, and can also carry out filling processing according to actual needs; then, assembling AMD PDU, encrypting the assembled AMD PDU and sending the encrypted AMD PDU to a sending buffer; a sending buffer in a sending side schedules the AMD PDU stored by the sending side, if the scheduled PDU allows sending, a polling bit and a Piggybacked STATUS protocol data unit (Piggybacked PDU) are set according to a rule configured by a high layer, and if the PDU is a newly assembled AMD PDU, a sequence number field is also set; and then submitting the scheduled AMD PDU to an AM entity which is sent to the opposite end by the bottom layer.

The receiving side of the RLC AM entity puts the received AMD PDU into a receiving buffer; then, decrypting and analyzing the data obtained by decryption; and then judging whether the analyzed PDU can recombine the RLC SDU, if the analyzed PDU can recombine the complete RLC SDU, carrying out recombination operation, and submitting the RLC SDU obtained by the recombination to a high layer. The method comprises the steps that an RLC control unit, a receiving buffer of a receiving side and a retransmission management module judge whether current AMD PDU transmission is accurate or not and whether a corresponding STATUS report needs to be sent back or not, if the STATUS report needs to be sent back and can be Piggybacked by the AMD PDU, an AM entity sending side sets a field in an RLC header, places the STATUS report in a Piggybacked STATUS PDU, and sends the STATUS report to an AM entity of an opposite end through the AMD PDU; and if the STATUS report cannot be piggybacked by the AMD PDU currently, the transmitting side independently constructs a STATUS protocol data unit (STATUS PDU), and transmits the STATUS report to the opposite terminal AM entity through the STATUS PDU.

Fig. 2 shows the format of AMD PDU, wherein a Length Indicator (LI) is used to indicate the RLC header end position in AMD PDU to the byte number of the last byte of RLC SDU in this PDU, i.e. the Length of Data (Data), and can also be understood as identifying the position where the RLC SDU Data ends in this PDU. For an AMD PDU, when the AMD PDU length is not greater than 126 bytes, a 7-bit LI is used; other cases use 15-bit LI. LI is used to indicate some meaning in addition to length. As shown below, table 1 indicates the meaning of the 7-bit LI special value, and table 2 indicates the meaning of the 15-bit LI special value.

Bits (Bit)	Description (Description)
Bits (Bit)	Description (Description)	0000000	The previous RLC PDU is filled with exactly one RLC SDU, and the absence of an LI in the previous RLC PDU marks the end of that SDU
1111100	UMD PDU: the first byte of this RLC PDU is the first byte of an RLC PDU; AMD PDU: retention (in the current version, PDU with this value is discarded)	0000000
1111100		1111101	Retention (in the current version, PDU with this value is discarded)
1111110	AMD PDU: the remainder of the PDU includes a Piggybacked STATUS protocol data unit (Piggybacked PDU); UMD PDU: retention (in the current version, PDU with this value is discarded)	1111101
1111110		1111111	The remainder of the RLC PDU is padding bits, which may be zero in length

TABLE 1

Bits (Bit)	Description (Description)
Bits (Bit)	Description (Description)	000000000000000	The previous RLC PDU is filled with exactly one RLC SDU, and the absence of an LI in the previous RLC PDU marks the end of that SDU
111111111111011	The last segment of an RLC SDU remains one byte after filling the previous RLC PDU, the absence of an LI in the previous RLC PDU marks the end of the RLC SDU, and the last byte in the previous PDU is ignored	000000000000000
111111111111011		111111111111100	UMD PDU: the first byte of this RLC PDU is the first byte of an RLC SDU; AMD PDU: retention (in the eye)In the former version, the PDU with this value is discarded)
111111111111101	Retention (in the current version, PDU with this value is discarded)	111111111111100
111111111111101		111111111111110	AMD PDU: the remainder of the PDU includes a Piggybacked STATUS protocol data unit (Piggybacked PDU); UMD PDU: retention (in the current version, PDU with this value is discarded)
111111111111111	The remainder of the RLC PDU is padding bits, which may be zero in length	111111111111110

TABLE 2

Referring to fig. 2 and table 1, the following table 3 shows the format of Piggybacked STATUS PDU Piggybacked AMD PDU, where LI is 1111110 to indicate that the rest of the PDU contains a Piggybacked STATUS PDU.

RLC head (first byte)
RLC head (first byte)	RLC head (second byte)
LI ═ bbbbbbb, denotes length indication	RLC head (second byte)
LI ═ bbbbbbb, denotes length indication	LI 1111110, indicating that the rest of the PDU contains a piggybacked status protocol data unit
Data of
Data of	Piggybacked STATUS protocol data unit (Piggybacked STATUS PDU)

TABLE 3

As already explained above, in the RLC protocol of the UMTS system, the AM entity may use a STATUS protocol data unit (STATUS PDU) or a piggybacked STATUS PDU to send a STATUS report to the peer AM entity. At present, when a STATUS report is sent, before the current RLC SDU transmission is not finished, only a single STATUS PDU can be constructed to transmit the STATUS report, and the method for constructing the STATUS PDU introduces many padding bits and occupies bandwidth.

And when the Piggybacked STATUS PDU is adopted, the transmission state report of one PDU unit can be prevented from being independently constructed, so that a plurality of filling bits are avoided, and the bandwidth is saved. However, since the LI is used to indicate the end of an RLC SDU, it is only after the current SDU ends in an AMD PDU that the Piggybacked STATUS PDU can be concatenated at the tail of the ADM PDU for transmission, that is, if an RLC SDU occupies multiple AMDPDUs during the transmission of the RLC SDU, the LI can only appear in the last AMD PDU, and the Piggybacked STATUS PDU can only be placed at the tail of the last AMD PDU for transmission of a STATUS report; if the STATUS report is transmitted before the current rlc PDU transmission is not finished, the transmission of the STATUS report can be achieved only by constructing a STATUS PDU.

Disclosure of Invention

In view of the above, a primary objective of the present invention is to provide a STATUS report transmission method, so that a Piggybacked STATUS PDU can be used to transmit a STATUS report when RLC SDU transmission is not finished, thereby avoiding constructing a separate STATUS PDU, avoiding introducing too many padding bits, and saving bandwidth.

In order to achieve the above purpose, the technical scheme of the invention is realized as follows:

the sending process including status report: the current AM entity judges whether a state report needs to be sent or not, exits the current flow if not, further judges whether RLC SDU to be packaged and transmitted by the current AMD PDU is tail data of the RLC SDU if the current AM entity needs to send the state report, exits the current flow if the current AMD PDU needs to be packaged and transmitted, inserts the state report into the AMD PDU, inserts an LI special value indicating that the data transmission of the RLC SDU is not finished, an LI indicating the data length of the RLC SDU contained in the current AMD PDU and an LI specific value indicating that the current AMD PDU contains the state report, and then sends the AMD PDU out;

the method also comprises a status report receiving process: when the AM entity receives the AMD PDU, judging whether the LI special value is contained, if not, exiting the current flow, if so, taking RLC SDU data and a status report out of the current AMD PDU; and continues reception of the subsequent portion of the RLC SDU.

Wherein, the status report is carried by Piggybacked status protocol data unit Piggybacked data unit; the LI indicating that the current AMD PDU contains the status report is a specific value indicating that the rest of the AMD PDU contains a piggybacked status protocol data unit.

Wherein, in the AMD PDU, the LI which represents the RLC SDU data length in the current AMD PDU is positioned behind an LI special value which represents the RLC SDU data length LI in the current AMD PDU; the piggybacked status PDU is located behind the RLC SDU data in the current AMD PDU.

Wherein, the LI special value adopts a reserved field of LI in an AM mode of a UMTS RLC protocol. When the length of the AMD PDU is not more than 126 bytes, the LI is 7 bits, otherwise, the LI is 15 bits.

The communication system is a Universal Mobile Telecommunications System (UMTS).

It can be seen from the above that, the method for transmitting a STATUS report according to the present invention can insert a piggybacked STATUS protocol data unit after an AMD PDU to transmit the STATUS report without transmission completion in the transmission process of an RLC PDU, and does not affect the transmission process of the current RLC SDU, thereby avoiding separately constructing a STATUS PDU, further avoiding introducing many padding bits, saving bandwidth, and improving link transmission efficiency.

Drawings

Fig. 1 is a model diagram of an RLC AM entity.

FIG. 2 is a diagram of AMD PDU format in UMTS.

Fig. 3 is a flow chart of status report transmission according to the present invention.

Fig. 4 is a flow chart of status report reception according to the present invention.

Detailed Description

When the RLC SDU is not transmitted, the method inserts the Piggybacked PDU transmission state report under the condition of not influencing the transmission of the RLC SDU so as to avoid independently constructing the STATUS PDU. The following is a detailed description of the implementation of the present invention.

The present invention uses at least 3 LI in the LI field of the AMD PDU format. Wherein, a special value LI is used to indicate that the RLC SDU data transmission in the current AMD PDU is not finished, and the special value is set by the invention; using one LI to indicate the length of the RLC SDU data contained in the current AMD PDU; and using an LI specific value to indicate that the current AMDPDU contains a Piggybacked STATUS PDU, wherein the Piggybacked STATUS PDU contains a STATUS report.

In use, the set LI special value is placed at the first LI position of the 3 LI in the AMD PDU, the second LI is used to indicate the data length of the RLC SDU carried by the PDU, and the third LI is used to indicate that a Piggybacked STATUS PDU is concatenated at the end of the PDU. Thus, after receiving the AMD PDU and detecting the first LI special value, the receiving party knows that the RLC SDU after the position specified by the second LI in the PDU is not completely transmitted, and will continue to receive the RLC SDU data in the subsequent AMDPDU to complete the reception of the RLC SDU; and on the other hand, reading out a Piggybacked STATUS PDU from the AMD PDU according to a third LI special value, and realizing the transmission of the STATUS report. The LI specific value set as described above is placed in the first position of the 3 LI, but it is understood that the LI specific value set may be placed in the second or third position in the AMD PDU.

As can be seen from tables 1 and 2, in the current RLC release LI special value, 1111100 and 1111101 of 7 bits, and 111111111111100 and 111111111111101 of 15 bits are reserved fields in the AMD PDU, and can be set to indicate that the next RLC SDU indicated by LI does not end up in the present PDU.

In this example, for LI of 7 bits and 15 bits, setting 1111100 and 111111111111100 respectively indicates that the next LI-indicated RLC SDU has not ended within the current AMD PDU. In the following, taking 7-bit LI as an example, and referring to fig. 2, and the status report sending procedure shown in fig. 3 and the status report receiving procedure shown in fig. 4, a detailed description is made of a method for sending a status report when the transmission of the current RLC SDU is not finished, including:

the current AM entity judges whether a state report needs to be sent or not, if not, the current flow is exited, otherwise, the current flow is further judged, whether RLC SDU to be packaged and transmitted by the current AMD PDU is tail data of the RLC SDU or not is judged, namely, whether the transmission of the RLC SDU is finished or not is judged, if yes, the current flow is exited, the state report is incidentally carried when the RLC SDU is transmitted according to the method shown in the table 3, otherwise, the AMD PDU carrying the RLC SDU and the state report is constructed by using the method disclosed by the invention; and then, sending the RLC SDU with the piggybacked status report.

When the STATUS report is Piggybacked, the STATUS report is carried by using a Piggybacked STATUS PDU, the Piggybacked STATUS PDU is concatenated at the tail of the current AMD PDU, and the configuration is performed according to the AMD PDU structure shown in table 4. Wherein the first LI-1111100 denotes: the RLC SDU indicated by the next LI in the AMD PDU does not end within the PDU, i.e. it means that the next LI ═ bbbbbbbb does not indicate the end of RLC SDU transmission; the next LI, i.e. the second LI, is used to indicate the number of bytes occupied by the RLC SDU in the current AMD PDU, or the length of RLC SDU data in the AMD PDU; the next LI, 1111110, described in table 1, indicates that the remainder of the current AMD PDU contains a concatenation status protocol data unit; the next data is the RLC SDU data encapsulated by the AMD PDU, and the tail of the AMDPDU is the Piggybacked STATUS PDU. After the AM entity constructs the PDU, the transmitting side transmits the AMD PDU to the opposite-end AM entity.

RLC head (first byte)
RLC head (first byte)	RLC head (second byte)
LI ═ 1111100, meaning: the next LI indicates that the SDU is not over within this PDU	RLC head (second byte)
	LI ═ bbbbbbb, denotes length indication
LI 1111110, indicating that the remainder of the PDU contains a concatenation status protocol data unit	LI ═ bbbbbbb, denotes length indication
	Data of
Piggybacked STATUS protocol data unit (Piggybacked STATUS PDU)	Data of

TABLE 4

After the opposite terminal AM entity receiving side receives the AMD PDU, the receiving side judges the encapsulated RLC SDU data by LI 1111100 and the second LI bbbbbb, and reads the encapsulated RLC SDU data, and knows that the RLC SDU data in the subsequent AMD PDU still belongs to the current RLC SDU, and continues to receive the subsequent part of the current RLC SDU, so as to complete the reception and reassembly of the RLC SDU. On the other hand, the receiving side knows the position of the Piggybacked STATUS PDU in the AMD PDU from LI bbbbbb and LI 1111110, and reads out the Piggybacked STATUS PDU, thereby completing the transmission of the STATUS report.

If the status report needs to be transmitted when the RLC SDU transmission is not finished, the status report is transmitted using the AMD PDU structure shown in table 4. If the status report is not required to be transmitted, the subsequent rlc SDU data continues to be transmitted using the AMD PDU structure provided in the prior art, as shown in the following table, where table 5 is the subsequent PDU containing SDU data, and table 6 is the PDU containing SDU tail data. The RLC SDU data in the AMD PDU shown in table 5, table 6 and table 4 all belong to one RLC SDU.

RLC head (first byte)
RLC head (first byte)	RLC head (second byte)
Data of	RLC head (second byte)

TABLE 5

The data contained in the AMD PDU shown in table 5 is part of the RLC SDU which is not transmitted. There is no LI byte in the AMD PDU, indicating that there is RLC presentData for the subsequent portion of the SDU continues to be transmitted in the subsequent AMD PDU.

RLC head (first byte)
RLC head (first byte)	RLC head (second byte)
LI ═ bbbbbbb, denotes length indication	RLC head (second byte)
LI ═ bbbbbbb, denotes length indication	LI 1111111, which indicates that the remaining part is the padding bit
Data of
Data of	Stuffing bits

TABLE 6

Table 6 shows AMD PDU in which RLC SDU ends, i.e. the data in AMD PDU is the tail data of RLC SDU. The first LI ═ bbbbbb indicates the byte length of the RLC SDU in the current PDU, i.e., the end position, and indicates the end of the RLC SDU transmission; the second LI 1111111 indicates that the rest of the AMD PDU is padding bits.

After the opposite terminal AM entity continues to receive the AMD PDUs shown in tables 5 and 6 according to the existing method, the RLC SDUs in these AMD PDUs are reassembled and then delivered to the upper layer, and the transmission of the RLC SDUs is completed.

It can be seen that, by the scheme of the present invention, in the transmission process of an RLC SDU, the insertion of Piggybacked STATUS PDU transmission STATUS report is implemented, thereby avoiding the separate construction of STATUS protocol data unit for transmitting STATUS report, further avoiding the introduction of padding bit, saving bandwidth, and improving link transmission efficiency.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A transmission method of status report is suitable for the communication system under the entity containing acknowledged mode AM, characterized by that, the method includes the sending process of the status report and receiving process of the status report; wherein,

the sending process of the status report comprises the following steps:

the current AM entity judges whether a state report needs to be sent or not, exits the current flow if not, further judges whether RLC SDU to be packaged and transmitted by the current AMD PDU is tail data of the RLC SDU if the current AM entity needs to send the state report, exits the current flow if the current AMD PDU needs to be packaged and transmitted, inserts the state report into the AMD PDU, inserts an LI special value indicating that the data transmission of the RLC SDU is not finished, an LI indicating the data length of the RLC SDU in the current AMD PDU and an LI specific value indicating that the current AMD PDU contains the state report, and then sends the AMD PDU out;

the receiving process of the status report comprises the following steps:

when the AM entity receives the AMD PDU, judging whether the LI special value is contained, if not, exiting the current flow, if so, taking RLC SDU data and a status report out of the current AMD PDU; and continues reception of the subsequent portion of the RLC SDU.

2. The method of claim 1, wherein the STATUS report is carried by a Piggybacked STATUS protocol data unit (Piggybacked STATUS PDU); the LI indicating that the current AMD PDU contains the status report is a specific value indicating that the rest of the AMD PDU contains a piggybacked status protocol data unit.

3. The method of claim 2 wherein the AMD PDU wherein the LI indicating the RLC SDU data length in the current AMD PDU is preceded by an LI specific value, the LI specific value is preceded by an LI indicating the RLC SDU data length in the current AMD PDU; the piggybacked status PDU is located behind the RLC SDU data in the current AMD PDU.

4. A method according to claim 1 or 3, characterized in that the LI-specific value is the reserved field for LI in the AM mode of the UMTS RLC protocol.

5. The method of claim 4 wherein the length of the AMD PDU is not greater than 126 bytes, the LI is 7 bits, otherwise it is 15 bits.

6. The method of claim 1 wherein the communication system is a Universal Mobile Telecommunications System (UMTS).