Source: https://patents.google.com/patent/WO2006083149A1/en
Timestamp: 2019-07-19 09:14:41
Document Index: 236501410

Matched Legal Cases: ['art 310', 'art 405', 'art 410', 'art 405', 'art 405', 'art 410', 'art 405']

WO2006083149A1 - Method and apparatus for requesting/transmitting status report of a mobile communication system - Google Patents
WO2006083149A1
WO2006083149A1 PCT/KR2006/000442 KR2006000442W WO2006083149A1 WO 2006083149 A1 WO2006083149 A1 WO 2006083149A1 KR 2006000442 W KR2006000442 W KR 2006000442W WO 2006083149 A1 WO2006083149 A1 WO 2006083149A1
PCT/KR2006/000442
2006-02-07 Application filed by Samsung Electronics Co., Ltd. filed Critical Samsung Electronics Co., Ltd.
2006-08-10 Publication of WO2006083149A1 publication Critical patent/WO2006083149A1/en
METHOD AND APPARATUS FOR REQUESTING/TRANSMITTING STATUS REPORT OFA MOBILE COMMUNICATION SYSTEM
Referring to FIG. 1, the UMTS system comprises a Core Network (CN) 100 and a plurality of Radio. Network Subsystems (RNSs) 110 and 120. The RNSs 110 and 120 constitute a UMTS Terrestrial Radio Access Network (UTRAN). In order to connect the UTRAN with a packet data network such as the Internet, the CN 100 comprises a Serving GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN).
The RNSs 110 and 120 comprise Radio Network Controllers (RNCs) 111 and 112, and a plurality of Node Bs 115, 113, 114, and 116. Specifically, the RNS
110 comprises the RNC 111 and Node Bs 115 and 113, and the RNS 120 comprises the RNC 112 and Node Bs 114 and 116. The RNCs 111 and 112 can be classifϊed as a serving RNC, a drift RNC, and a control RNC, according to their roles. The serving RNC controls communication information of a User Equipment (UE) 130 and exchanges data with the CN 100. The drift RNC directly connects with the UE 130 by wireless communication, and the control RNC controls radio resources of each Node B.
The RNCs 111 and 112, and the Node Bs 115, 113, 114, and 116 are interconnected through interfaces labeled "lub," and the RNCs 111 and 112 are interconnected through an interface labeled "lur." Although not shown in FIG. 1, the UE 130 and the UTRAN are interconnected through an interface "Uu." Each of the RNCs 111 and 112 allocate radio resources to the multiple Node Bs 115 and 113 or 114 and 116, which are controlled by the RNC itself. Each of the Node Bs 115, 113, 114, and 116, provide the allocated radio resources to the UE 130. The radio resources are arranged according to each cell, and the radio resources provided by each Node B corresponds to radio resources for a specific cell. The UE 130 sets radio channels by using the radio resources for specific cells controlled by the Node Bs 115, 113, 114, and 116, and transmits/receives data through the setup radio channels. The UE 130 identifies the physical channels only based on the cells. Therefore, it is of little significance to distinguish between the Node B and the cell, and the Node B and the cell will be used without distinction between them in the following description.
The physical layer 214 is a layer for providing an information transmission service using a radio transmission technology, and corresponds to the first layer (Ll) from among the seven Open System Inter- working (OSI) layers. The physical layer 214 is connected through transport channels to the MAC layer 212. Through the transport channels, data is exchanged between the MAC layer 212 and the physical layer 214. A transport Format (TF) of the transport channels is defined by a scheme according to which specific data is processed in the physical layer 214.
The RLC layer 210 takes charge of setup and release of the logical channels. Each entity of the RLC layer 210 may operate in one of an Acknowledged Mode (AM), Unacknowledged Mode (UM), and a Transparent Mode (TM). The three operation modes are distinguished by differences in the functions which they provide. The RLC AM entity of the sender performs segmentation, concatenation, or padding of data from the higher layer, i.e. RLC Service Data Unit (RLC SDU), thereby generating segments, each of which having a size that is proper for transmission through a radio channel. Then, the RLC AM entity inserts information about the segmentation/concatenation/padding to the segments, generates Protocol Data Units (PDUs) by inserting sequence numbers to the segments, and then transmits the RLC PDUs to the lower layer, the MAC layer 212. The RLC AM entity of the receiver checks the sequence numbers of the RLC PDUs transmitted from the sender in order to determine if there is any RLC PDU which the entity failed to receive, and requests retransmission of such an RLC PDU. As noted, an important characteristic of the RLC AM entity is that it supports retransmission of the RLC PDU. Especially, the RLC PDU used by the RLC AM is called "AMD PDU (AM Data PDU)."
As described above, when the RLC operates in the Acknowledged Mode (AM), the receiver requests retransmission of the packet which has not been received, and the retransmission request is transferred through the transmission of a message named "status report." However, when the receiver fails to receive the final packet, the receiver side cannot recognize the fact that it is necessary to request the retransmission, so that too much delay occurs for the retransmission request.
Accordingly, embodiments of the present invention have been made to solve the above-mentioned and other problems occurring in the prior art, and an object of embodiments of the present invention is to provide a method and apparatus for reducing excessive retransmission delay which may occur due to the loss of the last packet of a transmission buffer in a Radio Link Control (RLC) layer of a mobile communication system. It is another object of embodiments of the present invention to provide a method and apparatus for repeatedly transmitting the last packet of a transmission buffer several times, regardless of a retransmission request of a receiver in a Radio Link Control (RLC) layer of a mobile communication system.
In accordance with another aspect of embodiments of the present invention, an apparatus is provided for requesting a status report for retransmission control in a Radio Link Control (RLC) layer of a mobile communication system, the apparatus comprising a Packet Data Unit (PDU) construction block for receiving a Service Data Unit (SDU) from a higher layer and dividing the SDU into a plurality of PDUs, a transmission buffer for storing the PDUs in a buffer, a poll bit setting block for setting a poll bit for a last PDU from among the PDUs stored in the buffer, the poll bit requesting a status report, and a ciphering block for ciphering the last PDU having the setup poll bit and transmitting the last PDU to a receiver, wherein the last PDU is repeatedly transmitted at least twice from a sender to the receiver regardless of whether there is a request for retransmission of the last PDU. In accordance with another aspect of embodiments of the present invention, a method is provided for transmitting a status report for retransmission control in a mobile communication system, the method comprising the steps of (1) receiving a PDU through a lower layer from a sender, the received PDU having a setup poll bit which requests a status report, (2) determining if the received PDU is a retransmitted PDU, (3) ignoring the poll bit of the received PDU without transmitting the status report when the received PDU is a retransmitted PDU, and (4) transmitting the status report in response to the poll bit when the received PDU is not a retransmitted PDU.
FIG. 4 is a block diagram for illustrating a structure of an exemplary RLC AM entity according to an embodiment of the present invention; FIG. 5 is a flowchart for illustrating an exemplary operation of an RLC
AM entity according to an embodiment of the present invention;
FIG. 9 is a flowchart for illustrating an exemplary operation of a receiver according to the first embodiment of the present invention; FIG. 10 is a block diagram for illustrating an exemplary method for processing RLC PDUs according to a second embodiment of the present invention;
Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention unclear. Further, various specific definitions found in the following description are provided to help in the general understanding of embodiments of the present invention, and it is apparent to those skilled in the art that the present invention can be implemented without such definitions. Embodiments of the present invention reduce retransmission delay by determining if there is an error in sequence numbers of received packets or loss of a packet among the packets in an RLC layer of a mobile communication system supporting retransmission of the packets. As a basis for the description of exemplary embodiments of the present invention, operations of RLC AM entities will be described in detail.
A Data/Control (D/C) bit field 320 is a one bit flag which indicates if the RLC PDU includes data (i.e. RLC SDU) or only a status report. As used herein, an RLC PDU including data (i.e. RLC SDU) is called "AMD PDU." A sequence number of 12 bits is inserted in a Sequence Number (SN) field 325. The sequence number is an integer between 0 and 4095, which monotonically increases for each AMD PDU. A poll bit 330 is a field used in order to request the receiver to transmit a status report. When the poll bit 330 is set to "1," it implies that the receiver is requested to transmit a status report. The HE 335 is a two bit field which represents if the field following the HE 335 is the length indicator part 310 or the payload 315.
The RLC AM entity receives at least one RLC SDU from a higher layer, divides/concatenates/pads the RLC SDU, generates an RLC PDU by inserting an
AMD PDU header 305 and one or more length indicators, and then transmits the RLC PDU to a lower layer. Thereafter, the RLC PDU is transmitted through lower layers and a radio channel to a counterpart RLC AM entity.
FIG. 4 is a block diagram illustrating an exemplary structure of an RLC AM entity according to an embodiment of the present invention. The RLC AM entity performs bi-directional communication, so one RLC AM entity 400 comprises both a transmitting part 405 and a receiving part 410.
Referring to FIG. 4, the transmitting part 405 generates an AMD PDU 420a by using an RLC SDU 415 which is data of a higher layer, and then transmits the generated AMD PDU 420a to a receiving part of a counterpart RLC AM entity. Further, if necessary, the transmitting part 405 transmits a status report 420b to the receiving part of a counterpart RLC AM entity. The receiving part 410 receives an AMD PDU 425a and a status report 425b from a transmitting part of a counterpart RLC AM entity, performs the retransmission if necessary, reconstructs the RLC SDU 430 by using the AMD PDU 425 a, and transmits the RLC SDU 430 to a higher layer. Specifically, the transmitting part 405 of the RLC AM entity 400 comprises a segmentation/concatenation block 435, an RLC header adding block 440, a retransmission buffer 445, a transmission buffer 450, a poll bit setting block 455, and a ciphering block 460.
The MAC layer (not shown) determines whether to transmit the AMD PDUs stored in the transmission buffer 450 or not. At each transmission period, the MAC layer determines the number of AMD PDUs to be transmitted. Then, the AMD PDUs stored in the transmission buffer 450 are output to the poll bit setting block 455 according to the command of the MAC layer. The poll bit setting block 455 sets P bits of the output AMD PDUs. If polling is necessary, the P bit is set to "1." Otherwise, the P bit is set to "0." Upon receiving the AMD PDU from the poll bit setting block 455, the ciphering block 460 ciphers and transmits the AMD PDU with the exception of the AMD PDU header, thereby preventing a third party from interpreting the AMD PDU 420a.
In exemplary embodiments of the present specification, the sender refers to an RLC AM entity which mainly transmits the RLC SDU at a corresponding time point, and the receiver transmits an RLC AM entity which mainly transmits the status report at the corresponding time point. For example, in a downlink service such as a File Transfer Protocol (FTP), a user serves as the receiver because the user receives data and transmits a status report in response to the data reception, and a network serves as the sender because it transmits the data, receives the status report, and then performs the retransmission. That is, the RLC AM entity serving as the sender transmits the RLC SDU through its transmitting part and receives the status report through its receiving part, and the RLC AM entity serving as the receiver receives the RLC SDU through its receiving part and transmits the status report through its transmitting part. As described above, the RLC AM entity supports Automatic
Retransmission Request (ARQ) operation. The receiver checks sequence numbers of the received AMD PDUs, and transmits a status report reporting failure in receiving any PDU. Based on the status report, the sender performs retransmission of the non-received PDU. The status report may be transmitted either according to a command of the sender or based on the determination by the receiver itself.
- When a PDU remaining in the transmission buffer is the last PDU, the poll bits of the AMD PDUs can be set up;
- When a PDU remaining in the retransmission buffer is the last PDU, the poll bits of the AMD PDUs can be set up;
- Whenever a predetermined number of AMD PDUs are transmitted, the poll bit can be set up; and - At each predetermined period, the poll bit can be set up.
The sender may include more than one poll trigger. Then, when one of the poll triggers occurs, the sender sets the poll bits. Upon receiving an AMD PDU having a setup poll bit, the receiver 510 generates and transmits a status report to the sender 505 in step 525. In this step, an RLC PDU including the status report is called "status PDU." For example, the status report comprises information of both sequence numbers of PDUs received up to the current time point and sequence numbers of PDUs which have not yet been received.
Whenever receiving an AMD PDU, the receiver 510 confirms a sequence number of the received AMD PDU and manages parameters named VR(R) and VR(H). The parameter VR(R) stores a value obtained by adding "1" to a sequence number of an AMD PDU which has been received most recently from among the AMD PDUs arranged in sequence. The sequential arrangement of AMD PDUs implies that there has been no failure in reception of the PDUs. When PDU[x] is defined as an AMD PDU having a sequence number of x, if the receiver 510 is, for example, receiving and buffering PDU[I], PDU[2], PDU[3], and PDU[5], the PDU[I], PDU[2], and PDU[3] are in a state in which they have been arranged in sequence and the parameter VR(R) has a value of 4. That is to say, VR(R) represents a sequence number of an AMD PDU which is expected to be received. When the receiver 510 has received an AMD PDU having the same sequence number as VR(R), the receiver 510 updates the VR(R) according to the received AMD PDU. In the above example, when PDU[4] has been received, the VR(R) is updated to 6.
The parameter VR(H) stores a value obtained by adding "1" to the highest sequence number from among the sequence numbers of the AMD PDUs received and buffered up to the current time point. The parameter VR(H) is used to identify the non-received PDU. When an AMD PDU has been received and a sequence number of the received AMD PDU is larger than or equal to the current value of the VR(H), the parameter VR(H) is updated.
The status report comprises the value of the VR(R), which reports the AMD PDUs received up to the current time point to the sender. Further, the status report comprises sequence numbers of the AMD PDUs which have not been received up to the current time point. Upon receiving the status report, the sender 505 discards from the retransmission buffer the AMD PDUs which are identified to have been received by the receiver 510, and retransmits the AMD PDUs which are identified to have not been received by the receiver 510. In step 530, the sender 505 transmits a new or retransmission AMD PDU to the receiver 510. When a predetermined condition is satisfied, the receiver 510 generates and transmits a status report to the receiver 510 in step 540. As used herein, it is said that a status report is triggered, when requirements for transmission of a status report are satisfied. The status trigger can be defined as follows, but is not limited thereto.
- When a non-received PDU is detected, the status report can be transmitted. That is, when a sequence number of a received AMD PDU is larger than VR(H), it is determined that there is a non-received PDU. For example, when the VR(H) is 10 and PDU[Il] is received, it is determined that PDU[IO] is not received;
- When an AMD PDU having a setup poll bit is received, the status report can be transmitted; and
- At each predetermined period, the status report can be transmitted.
Referring to FIG. 6, the sender 605 set a poll bit for the last AMD PDU remaining in the transmission buffer. The sender 605 receives an RLC SDU 610 from a higher layer and divides the RLC SDU 610 into three RLC PDUs 615, 620, and 625. The RLC PDU 615 has a sequence number of x, the RLC PDU 620 has a sequence number of (x+1), and the RLC PDU 625 has a sequence number of (x+2). After transmitting the RLC PDU[x] 615 and the RLC PDU[x+l] 620, the sender 605 set a poll bit for the RLC PDU[x+2] and transmits the RLC PDU[x+2]. It is assumed, for example, that the receiver 630 has received the RLC
PDU[x] 615 and the RLC PDU[x+l] 620, but has not received the RLC
PDU[x+2] 625. However, there is no more RLC PDUs to be received after the
RLC PDU[x+2] 625, and the receiver 630 cannot recognize the failure in reception of the RLC PDU[x+2] 625.
More specifically, upon receiving the RLC PDU[x+l] 620, the receiver 630 updates the VR(H) to (x+2). Thereafter, only when the receiver 630 receives a next RLC PDU (not shown) having a sequence number of (x+3), can the receiver 630 recognize that the RLC PDU[x+2] 625 having the sequence number (x+2) has not been received. However, because the RLC PDU[x+2] 625 having the sequence number (x+2) is the final PDU to be transmitted, the receiver 630 cannot recognize that there is a PDU which has not been received. Therefore, the status report is not triggered in spite of the fact that there is a PDU which has not been received. Further, because the RLC PDU[x+2] 625 having a setup poll bit is lost during its transmission, there is no triggering of the status report by the poll bit.
Usually, an RRC message including control information of an RRC layer is divided into a plurality of RLC PDUs by an RLC AM entity. Therefore, it is necessary to rapidly transmit the RRC message to the counterpart, because the RRC message may include various control information in relation to the RRC connection during a call processing procedure. Further, only after it is confirmed that one RRC message is completely received, does the RRC layer transmit the next RRC message. Therefore, delay in retransmission of the RRC messages may be a cause which significantly increases the delay in the call processing. In the above-mentioned situation, the sender 605 cannot recognize the failure in the reception of the RLC PDU [x+2] 625 and does not perform the retransmission. Even when the receiver 630 has been set to periodically transmit a status report, the failure in the reception of the RLC PDU[x+2] 625 is not recognized before the next period for the periodic transmission of the status report, so the retransmission is delayed as much. When there is no setup for periodic transmission of the status report by the receiver 630, the receiver 630 cannot require retransmission of the RLC PDU[x+2] 625 before it receives an RLC PDU by the next RLC SDU.
First Exemplary Embodiment According to a first exemplary embodiment of the present invention, in order to solve the above-mentioned and other problems, when a poll bit of an AMD PDU to be transmitted has been set up and the AMD PDU is the last PDU stored in the buffer, that is, when there is no AMD PDU to be transmitted after the last AMD PDU, the last AMD PDU having the setup poll bit is repeatedly transmitted several times. At this time, the last AMD PDU having the setup poll bit is repeatedly transmitted a predetermined number of times, regardless of whether there is a retransmission request from the receiver.
Referring to FIG. 7, the sender 705 receives the RLC SDU 710, divides the RLC SDU 710 into three RLC PDUs 715, 720, and 725, and stores the three divided RLC PDUs 715, 720, and 725 in a buffer. For example, the RLC PDU
715 has a sequence number of x, the RLC PDU 720 has a sequence number of (x+1), and the RLC PDU 725 has a sequence number of (x+2). After transmitting the RLC PDU[x] 715 and the RLC PDU[x+l] 720, the sender 705 sets a poll bit for the RLC PDU[x+2] 725 and then transmits the RLC PDU[x+2] 725. At this time, because the RLC PDU[x+2] 725 is the last PDU stored in the buffer, the RLC PDU[x+2] 725 is retransmitted several times as indicated by reference numerals 730 and 735.
Upon receiving at least one of the RLC PDUs 725, 730, and 735 having the setup poll bit, the receiver 740 transmits a status report. Preferably, the receiver 740 transmits the status report only one time even when it receives more than one of the RLC PDUs 725, 730, and 735 having the setup poll bit. FIG. 8 is a flowchart of an exemplary transmission operation according to the first embodiment of the present invention. The transmission operation is started just before the initially transmitted AMD PDU reaches the lower layer.
Referring to FIG. 8, the AMD PDU to be transmitted is submitted to the lower layer at step 805, and the sender determines if the AMD PDU to be transmitted is the last PDU from among the scheduled PDUs at step 810. The scheduled PDUs refer to PDUs which are in a state in which the PDUs can be transmitted at any time, that is, in a state in which the PDUs are stored in the transmission buffer and the transmission of the PDUs is not inhibited due to a window operation, and so forth. Since the RLC AM entity performs a flow control through a window, the sender cannot transmit PDUs outside of the window. For example, if PDU[IO] through PDU[IOO] are stored in a transmission buffer of an RLC AM entity and the window is formed over PDU[IO] through PDU[73], the last PDU from among the scheduled PDUs is PDU[73].
Then, the sender sets the poll bit for the AMD PDU at step 815, and then transmits the AMD PDU at step 820. In step 825, the sender retransmits the AMD PDU at one or more predetermined next transmission periods. The retransmission is performed after the sender receives the status report from the receiver. However, the retransmission in step 825 can be performed regardless of the reception of the status report about the AMD PDU. This is because the receiver cannot recognize the loss of the AMD PDU as described above. Because the sender retransmits the last AMD PDU having the setup poll bit several times, the receiver can receive the AMD PDU having the setup poll bit several times. However, because it is preferable to transmit the status report only one time, the receiver transmits the status report only one time when it has received the same AMD PDU having the setup poll bit several times in a relatively short time.
FIG. 9 is a flowchart of an exemplary operation of a receiver according to the first embodiment of the present invention. As described below, a control unit of the receiver monitors the received AMD PDUs in order to determine if a status report trigger by the poll bit has occurred. When the receiver receives an AMD PDU having a setup poll bit at step
905, the receiver determines if the received AMD PDU is a retransmitted AMD PDU at step 910. This determination can be achieved through a comparison between the sequence number of the currently received AMD PDU and the sequence number of the most recently received AMD PDU. A more detailed description is provided below.
Referring to FIG. 10, the sender 1005 receives the RLC SDU 1010 from a higher layer, divides the RLC SDU 1010 into three RLC PDUs 1015, 1020, and 1025, and stores them in a buffer. For example, the RLC PDU 1015 has a sequence number of x, the RLC PDU 1020 has a sequence number of (x+1), and the RLC PDU 1025 has a sequence number of (x+2). After transmitting the RLC PDU[x] 1015 and the RLC PDU[x+l] 1020, the sender 1005 sets a poll bit for the RLC PDU[x+2] 1025 and then transmits the RLC PDU[x+2] 1025. It is assumed, for example, that the RLC PDU[x+2] 1025 which is the last PDU stored in the buffer, is lost during its transmission.
The receiver 1040 receives the RLC PDU[x] 1017 and the RLC PDU[x+l] 1022. When the receiver 1040 has received the RLC PDU[x] 1017, the receiver 1040 starts a timer for generating a status report trigger. Thereafter, when the receiver 1040 has received the RLC PDU[x+l] 1022, the receiver 1040 restarts the timer. Specifically, the restarting of the timer comprises the steps of stopping the operating timer, initializing the timer, and then operating the timer again. When a next RLC PDU having a sequence number of (x+2) is not received before the expiration of the time which was started when the RLC PDU[x+l] 1022 was received, the receiver 1040 constructs and transmits a status report 1030. The status report 1030 comprises information reporting the reception of PDUs up to the RLC PDU 1022 having the sequence number (x+1). Upon receiving the status report, the sender 1005 recognizes the loss of the RLC PDU 1025 having the sequence number (x+2) and retransmits the RLC PDU 1035 having the sequence number (x+2). FIG. 11 is a flowchart for illustrating an exemplary timer control operation of a receiver RLC AM entity according to the second embodiment of the present invention. As described below, the control unit of the receiver monitors received AMD PDUs, manages the VR(H) and VR(R), and controls the timer. Referring to FIG. 11 , an AMD PDU is received in step 1105. In step 1110, the receiver determines if the sequence number of the received AMD PDU is smaller than the VR(H). When the sequence number of the received AMD PDU is smaller than the VR(H), the receiver proceeds to step 1115. When the sequence number of the received AMD PDU is larger than or equal to the VR(H), the receiver proceeds to step 1130.
'In step 1115, the receiver stores the AMD PDU at a proper location in the buffer, so that the received AMD PDU and already stored AMD PDUs can be stored according to an order of their sequence numbers. In step 1120, if it is possible to reconstruct the RLC SDU by using the AMD PDUs stored in the reception buffer, the receiver reconstructs the RLC SDU and transmits the reconstructed RLC SDU to a higher layer. Then, in step 1125, the receiver waits for the reception of a next AMD PDU. At this time, the timer is neither stopped nor restarted.
As noted from FIG. 11, the receiver starts or stops the timer whenever receiving an AMD PDU, and transmits a status report at the time point when the timer expires. FIG. 12 is a block diagram for illustrating an exemplary operation according to the second embodiment of the present invention.
Referring to FIG. 12, the sender 1205 has two RLC SDUs to be transmitted, including RLC SDU[x] 1215 and RLC SDU[y] 1220, which are divided into six AMD PDUs 1225, 1230, 1235, 1240, 1245, and 1250 having sequence numbers from 1 to 6, respectively. It is assumed, for example, that from among the six AMD PDUs 1225 through 1250, the AMD PDUs 1235 and 1250 having the sequence numbers of 3 and 6 failed to reach the receiver 1210 and are lost. The VR(H) is 1 at the time point when the receiver 1210 receives AMD PDU[I]. Upon receiving AMD PDU[I] 1225, the receiver 1210 starts the timer and updates the VR(H) to 2. Wlien receiving AMD PDU[2] 1230 which has a sequence number equal to the VR(H), the receiver 1210 updates the VR(H) to 3, stops the timer, and determines if there is a reconstructable RLC SDU, as performed in steps 1130 and
1135 of FIG. 11. Because there is no reconstructable RLC SDU, the receiver 1210 restarts the timer and waits for the arrival of a next AMD PDU.
When receiving AMD PDU[4] 1240 which has a sequence number larger than the VR(H), the receiver 1210 determines that there is a non-received PDU, and transmits a status report (not shown). Based on AMD PDU[4] 1240, the VR(H) is updated to 5. The transmitted status report contains information reporting the failure in the reception of AMD PDU[3]. Further, because this case corresponds to a case in which the sequence number is larger than or equal to the VR(H), the receiver 1210 stops the timer and determines if there is a reconstructable RLC SDU, as performed in steps 1130 and 1135 of FIG. 11. Because there is no reconstructable RLC SDU, the receiver 1210 restarts the timer. When receiving AMD PDU[5] which has a sequence number equal to the
VR(H), the receiver 1210 stops the timer and determines if there is a reconstructable RLC SDU, as performed in steps 1130 and 1135 of FIG. 11. Because there is no reconstructable RLC SDU, the receiver 1210 restarts the timer and waits for arrival of a next AMD PDU. The receiver 1210 updates the VR(H) to 6.
In response to the status report, the sender 1205 retransmits the AMD PDU[3] 1255. Then, the receiver 1210 receives the AMD PDU[3] 1255 which has a sequence number smaller than the VR(H), and then performs the operations steps 1115 through 1125 of FIG. 11. At this time, because it is possible to reconstruct the RLC SDU[x] by using the RLC PDU[I], the RLC PDU[2], and the RLC PDU[3], the receiver 1210 transmits the reconstructed RLC SDU[x] to a higher layer and waits for arrival of a next AMD PDU.
1. A method for requesting a status report for retransmission control in a mobile communication system, the method comprising the steps of: (1) receiving a Service Data Unit (SDU) from a higher layer, dividing the
SDU into a plurality of Packet Data Units (PDUs);
4. The method as claimed in claim 1, wherein the status report comprises: a sequence number of a PDU which is expected to be received at a time point when the status report is transmitted; and a sequence number of a PDU which has been identified as being a non- received unit at the time point when the status report is transmitted.
5. The method as claimed in claim 1, wherein step (1) comprises the steps of: segmenting, concatenating, or padding the SDU into data having a predetermined size; and adding at least one of a data/control bit field, a sequence number field, a poll bit field for indicating whether to request a status report or not, and a length indicator indicating a location of an end of an SDU included in a coiτesponding
PDU to the data having the predetermined size, thereby constructing the corresponding PDU.
8. An apparatus for requesting a status report for retransmission control in a Radio Link Control (RLC) layer of a mobile communication system, the apparatus comprising: a Packet Data Unit (PDU) construction block for receiving a Service Data
Unit (SDU) from a higher layer and dividing the SDU into a plurality of PDUs; a transmission buffer for storing the PDUs in a buffer; a poll bit setting block for setting a poll bit for a last PDU from among the PDUs stored in the buffer, the poll bit requesting a status report; and a ciphering block for ciphering the last PDU having the setup poll bit and transmitting the last PDU to a receiver, wherein the last PDU is repeatedly transmitted from a sender to the receiver regardless of whether there is a request for retransmission of the last PDU.
11. The apparatus as claimed in claim 8, wherein the status report comprises: a sequence number of a PDU which is expected to be received at a time point when the status report is transmitted; and a sequence number of a PDU which has been identified as being a non- received unit at the time point when the status report is transmitted.
12. The apparatus as claimed in claim 8, wherein the PDU constmction block comprises: a segmentation/concatenation block for segmenting, concatenating, or padding the SDU into data having a predetermined size; and an RLC header adding block for adding at least one of a data/control bit field, a sequence number field, a poll bit field for indicating whether to request a status report or not, and a length indicator indicating a location of an end of an
SDU included in a corresponding PDU to the data having the predetermined size, thereby constructing the corresponding PDU.
(1) receiving a PDU through a lower layer from a sender, the received PDU having a setup poll bit which requests a status report; (2) determining if the received PDU is a retransmitted PDU;
16. The method as claimed in claim 15, wherein the status report comprises: a sequence number of a PDU which is expected to be received at a time point when the status report is transmitted; and a sequence number of a PDU which has been identified as being a non- received unit at the time point when the status report is transmitted.
20. The apparatus as claimed in claim 19, wherein the status report comprises: a sequence number of a PDU which is expected to be received at a time point when the status report is transmitted; and a sequence number of a PDU which has been identified as being a non- received unit at the time point when the status report is transmitted.
24. The method as claimed in claim 23, wherein the status report comprises: a sequence number of a PDU which is expected to be received at a time point when the status report is transmitted; and a sequence number of a PDU which has been identified as being a non- received unit at the time point when the status report is transmitted.
28. The apparatus as claimed in claim 27, wherein the status report comprises: a sequence number of a PDU which is expected to be received at a time point when the status report is transmitted; and a sequence number of a PDU which has been identified as being a non- received unit at the time point when the status report is transmitted.
PCT/KR2006/000442 2005-02-07 2006-02-07 Method and apparatus for requesting/transmitting status report of a mobile communication system WO2006083149A1 (en)
WO2006083149A1 true WO2006083149A1 (en) 2006-08-10
PCT/KR2006/000442 WO2006083149A1 (en) 2005-02-07 2006-02-07 Method and apparatus for requesting/transmitting status report of a mobile communication system
WO2010063231A1 (en) * 2008-12-05 2010-06-10 华为技术有限公司 Global system for mobile communications (gsm) packet switched domain coding method, device and system
CN103078722A (en) * 2007-08-14 2013-05-01 华为技术有限公司 Method and device for requesting data retransmission
RU2007130081A (en) 2009-02-20
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