KR20070031810A - Method and apparatus for transmitting/receiving status report comprising receive status of packet data in a mobile telecommunications system and therefor apparatus - Google Patents

Abstract

The present invention relates to a method and apparatus for transmitting and receiving a status report indicating a reception state of packet data in a mobile communication system. The method may further include determining whether an implicit NACK is required to request retransmission of at least one unreceived data packet whose serial number is unknown while receiving data packets from a transmitter, and transmitting the implicit NACK. Generating an implicit NACK including a serial number of a last packet among successfully received data packets, and transmitting a status report including the implicit NACK to the transmitter; If transmission of an NACK is not necessary, a status report is sent to the transmitter, the status report comprising at least one of an ACK indicating a serial number of a successfully received data packet and an explicit NACK indicating a serial number of an unreceived data packet having a known serial number. The process of transmitting.

Hybrid Automatic Retransmission request, Sequence number, Implicit NACK, Explicit NACK

Description

METHOD AND APPARATUS FOR TRANSMITTING / RECEIVING STATUS REPORT COMPRISING RECEIVE STATUS OF PACKET DATA IN A MOBILE TELECOMMUNICATIONS SYSTEM AND THEREFOR APPARATUS}

1 is a diagram illustrating an example of a structure of a next generation mobile communication system.

2A and 2B illustrate a hierarchical structure and frame format for framing higher layer data in a typical UMTS communication system.

3 illustrates a hierarchical structure of a wireless protocol according to a preferred embodiment of the present invention.

4 illustrates a frame format according to a preferred embodiment of the present invention.

FIG. 5 is a diagram for describing split retransmission according to a frame size determined according to the amount of scheduled transmission resources. FIG.

6a and 6b show in more detail the frame format according to the first embodiment of the invention.

7 illustrates an example of split retransmission according to the first embodiment of the present invention.

8 illustrates a structure of a transmitter according to a first embodiment of the present invention.

9 illustrates a receiver structure according to the first embodiment of the present invention.

10 is a signaling flowchart illustrating split retransmission according to a retransmission request.

11A and 11B illustrate the format of NACKs in accordance with a preferred embodiment of the present invention.

12 is a flowchart showing the operation of a transmitter according to the first embodiment of the present invention.

13 is a flowchart showing operation of a receiver according to the first embodiment of the present invention.

14 is a diagram showing an example of an operation of determining continuity of serial numbers;

15 illustrates a frame format according to a second embodiment of the present invention.

16 illustrates an example of split retransmission according to the second embodiment of the present invention.

17 is a flowchart showing the operation of a transmitter according to a second embodiment of the present invention.

18 is a flowchart showing operation of a receiver according to the second embodiment of the present invention.

19 illustrates a frame format according to a third embodiment of the present invention.

20 is a diagram showing examples of split transmission and split retransmission according to the third embodiment of the present invention.

21 is a diagram showing the structure of a transmitter according to a third embodiment of the present invention.

Fig. 22 is a diagram showing the structure of a receiver according to the third embodiment of the present invention.

23 is a flowchart showing a transmitter operation according to the third embodiment of the present invention.

24 is a flowchart showing operation of a receiver according to the third embodiment of the present invention.

25 is a diagram for explaining an example of using an implicit NACK according to a preferred embodiment of the present invention.

FIG. 26 is a flowchart illustrating an operation of transmitting an implicit NACK in accordance with a preferred embodiment of the present invention. FIG.

27 is a flowchart illustrating an operation of receiving an implicit NACK according to a preferred embodiment of the present invention.

28 is a flowchart illustrating operation of an RLC acknowledgment mode (AM).

29 is a signaling flowchart illustrating a HSDPA cell change procedure.

30 is a diagram illustrating a problem of a HSDPA cell change process;

FIG. 31 illustrates an example of an implicit NACK in RLC AM layer operation according to a preferred embodiment of the present invention. FIG.

32 is a signaling flow diagram illustrating the overall operation of using an implicit NACK in accordance with a preferred embodiment of the present invention.

33 is a flowchart illustrating an implicit NACK transmission operation when a cell is changed according to a preferred embodiment of the present invention.

34 is a flowchart illustrating a transmission operation of an implicit NACK when a cell is changed according to another embodiment of the present invention.

35 is a flowchart illustrating a reception operation of an implicit NACK when a cell is changed according to another embodiment of the present invention.

36 is a signaling flowchart illustrating a transmission operation of a status report when a cell is changed according to an exemplary embodiment of the present invention.

37 is a flowchart illustrating a transmission operation of a status report when a cell is changed according to another embodiment of the present invention.

38 is a flowchart illustrating a transmission operation of a status report according to another embodiment of the present invention.

FIG. 39 illustrates a structure of an apparatus for transmitting a status report when a cell is changed according to an embodiment of the present invention. FIG.

40 is a diagram illustrating a structure of an apparatus for receiving a status report when a cell is changed according to a preferred embodiment of the present invention.

The present invention relates to a mobile communication system, and more particularly, to a method and apparatus for transmitting and receiving a status report indicating a reception state of packet data.

UMTS (Universal Mobile Telecommunication Service) system is based on the European mobile communication system Global System for Mobile Communications (GSM) and General Packet Radio Services (GPRS), and Wideband Code Division Multiple Access: Third generation asynchronous mobile communication system using WCDMA).

A general UMTS system is composed of a core network and a plurality of radio network subsystems (hereinafter referred to as RNS). The plurality of RNSs constitute a UMTS Terrestrial Radio Access Network (UTRAN). The CN consists of a Serving GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN) to connect the UTRAN to a packet data network such as the Internet.

The RNS is composed of Radio Network Controllers (hereinafter referred to as RNCs) and a plurality of base stations (Node Bs). Each RNC and base stations are connected through an interface called Iub, and the RNCs are connected through an interface called Iur. In addition, a user equipment (UE) and the UTRAN are connected by an interface called Uu. The RNC allocates radio resources to a plurality of base stations managed by the RNC, and the base stations actually provide radio resources allocated from the RNC to the terminal. The radio resource is configured for each cell, and the radio resource provided by each base station means a radio resource for a specific cell managed by the base station. The terminal sets a radio channel using radio resources for a specific cell managed by the base station, and transmits / receives data through the set radio channel.

Meanwhile, the 3rd Generation Partnership Project (3GPP), which is in charge of UMTS standardization, is discussing the Long Term Evolution (LTE) of the UMTS system. LTE is a technology that implements high-speed packet-based communication of about 100 Mbps, aiming for commercialization in 2010. To this end, various methods are discussed. For example, the network structure can be simplified to reduce the number of nodes located on the communication path, or the wireless protocols can be as close to the wireless channel as possible. As a result, the structure of LTE is expected to change from the 4-node structure of the existing UMTS system to a 2-node or 3-node structure.

1 illustrates an example of a structure of a next generation (Evolved) UMTS mobile communication system. As shown, the Evolved Radio Access Network (hereinafter referred to as E-RAN) 110, 112 is an Evolved Node B (ENB) 120, 122, 124, 126, 128 and an Evolved Gateway (EGGSN). GPRS Serving Nodes 130, 132 are simplified to a two node structure. The user equipment (UE) 101 connects to the Internet Protocol (IP) network 114 by the E-RANs 110 and 112.

The ENBs 120 to 128 correspond to legacy Node Bs of the UMTS system and are connected to a user equipment (UE) 101 through a wireless channel. Unlike the existing Node B, ENBs 120 to 128 play a more complex role. In LTE, all user traffic including a real-time service such as Voice over IP (VoIP) is serviced through a shared channel, so an apparatus for collecting and scheduling situation information of UEs is required. As an example, the ENBs 120 to 128 are responsible for the scheduling.

Similar to High Speed Downlink Packet Access (HSDPA) or Enhanced Uplink Dedicated Channel (E-DCH) supported by the UMTS system, hybrid ARQ (HARQ) is performed between the ENBs 120 to 128 and the UE 101 in LTE. HARQ is a technique of increasing reception success rate by soft combining with retransmitted data without discarding previously received data. However, since HARQ alone cannot satisfy various Quality of Service (QoS) requirements, a separate outer automatic re-transmission request (ARQ) may be performed at a higher layer, and the separate ARQ may also be performed by the UE 101. ) And ENB 120 to 128.

LTE can use orthogonal frequency division multiplexing (OFDM) as a radio access technology in the 20 MHz bandwidth to achieve a transmission rate of up to 100 Mbps. In addition, an adaptive modulation & coding (AMC) scheme that determines a modulation scheme and a channel coding rate according to the channel state of the terminal may be applied.

Meanwhile, the wireless communication includes a process of dividing or concatenating packets of various sizes generated in an application layer into appropriate sizes, attaching a header containing necessary additional information, and transmitting them through a wireless channel. As described above, the operation of adjusting the size of a packet to a size suitable for transmitting and receiving a wireless channel is called framing.

In a typical UMTS communication system, transmission data is framed once in a radio link control (RLC) layer, and then framed again in a medium access control (MAC) layer. This is because the UMTS communication system is designed around dedicated channels that operate only with RLC framing, but the framing of the MAC layer is required due to the introduction of a common channel such as HSDPA / E-DCH. In more detail, the RLC layer performs an operation of matching a packet of a higher layer to a predetermined size, and in the MAC layer, a concatenation is performed according to the amount of packets transmitted from the RLC layer in a next transmission time interval (TTI). To perform the operation. Here, the upper layer may be an IP layer in case of IP communication.

2A and 2B illustrate the hierarchical structure and frame format for framing higher layer data in a typical UMTS communication system.

Referring to FIG. 2A, the radio protocol of UMTS includes a physical layer 275, a MAC layer 270, and an RLC layer 260 and 265. When data (e.g., Internet Protocol (IP) packets) originating from the upper layers 250 and 255 are delivered to either RLC entity 260 or 265, the RLC entity 260 or 265 may send the IP packet to a predetermined size. The RLC Protocol Data Units (PDUs) are cut to fit and headers for each segment.

As shown in FIG. 2B, the header includes a sequence number (SN) 210, an E bit 215, and a length indicator (LI) 220. The length indicator 220 is information indicating the end position of the IP packet and is optional header information inserted when the last part of the IP packet is included in the RLC PDU. For example, since the RLC PDU 205 includes the last part of the IP packet 204, LI is inserted into the RLC PDU 205.

The MAC layer 270 receives the RLC PDUs from the RLC layers 260 and 265 and then concatenates the RLC PDUs according to the size of the MAC PDU 206. In a system in which Node B scheduling is applied, such as HSDPA or E-DCH, the size of the MAC PDU 206 is variable depending on the amount of scheduled transmission resources. Therefore, as the header information, the MAC PDU 206 is inserted with a SID (Size Index) 208 indicating the size of each RLC PDU and an N bit 209 indicating the number of RLC PDUs stored therein. One MAC PDU 206 may be concatenated with RLC PDUs delivered from two or more RLC entities. In order to distinguish the RLC PDUs, a multiplexing identifier (MID) 211 is inserted in front of the MAC PDU 206. The multiplexing information 211 indicates to which RLC entities the received RLC PDUs should be delivered.

In the HARQ operation, a reversed sequence of received packets may occur. In order to eliminate the reversed sequence at the receiving side of the MAC PDU 206, a separate serial number may be required. Therefore, a transmission sequence number (TSN) 207 is assigned to RLC PDUs generated in one RLC entity among RLC PDUs concatenated and stored in the MAC PDU 206. That is, the RLC PDUs 202 and 203 generated in different RLC entities have different TSN values.

As illustrated in FIGS. 2A and 2B, the redundant framing scheme used in a typical UMTS network has a disadvantage in that duplicate information is used in a header. As an example, an SN 210 is inserted into each RLC PDU and a TSN 207 is inserted into a MAC PDU 206. In addition, the SN 210 is inserted into each RLC PDU having a relatively small size, thereby increasing overhead.

Accordingly, the present invention devised to solve the problems of the prior art operating as described above, provides a method and apparatus for accurately transmitting and receiving a series of data packets in a hierarchical mobile communication system.

The present invention provides a method and apparatus for transmitting and receiving a status report indicating a reception status of data packets in a mobile communication system.

In a preferred embodiment of the present invention, in a method for transmitting a status report indicating a reception state of packet data in a mobile communication system,

Determining whether an implicit NACK is required to request retransmission of at least one unreceived data packet whose serial number is not known while receiving data packets from a transmitter;

If the implicit NACK needs to be transmitted, generating the implicit NACK including the serial number of the last packet among the successfully received data packets, and transmitting a status report including the implicit NACK to the transmitter; and,

If transmission of the implicit NACK is not necessary, reporting a status report comprising at least one of an ACK indicating a serial number of a successfully received data packet and an explicit NACK indicating a serial number of an unreceived data packet having a known serial number; And transmitting to the transmitter.

According to a preferred embodiment of the present invention, in a method for receiving a status report indicating a reception state of packet data in a mobile communication system,

Transmitting data packets to a receiver,

Receiving, from the receiver, a status report indicating a reception status of the transmitted data packets;

Determining whether the status report includes an implicit NACK including the serial number of the last packet among successfully received data packets to request retransmission of an unreceived data packet whose serial number is not known;

If the implicit NACK is included, transmitting data packets after the last packet indicated by the implicit NACK to the receiver;

If the status report does not include the implicit NACK, at least at least one of an ACK indicating a serial number of a successfully received data packet and an explicit NACK indicating a serial number of an unreceived data packet having a known serial number from the status report. Detecting one and retransmitting an unreceived data packet having the serial number indicated by the explicit NACK.

In a preferred embodiment of the present invention, an apparatus for transmitting a status report indicating a reception status of packet data in a mobile communication system,

A data receiver for receiving and storing data packets from a transmitter;

While receiving the data packets, it is determined whether an implicit NACK transmission is required to request retransmission of an unreceived data packet whose serial number is not known.

If the transmission of the implicit NACK is necessary, generate a status report including an implicit NACK indicating the serial number of the last packet among successfully received data packets,

If transmission of the implicit NACK is not necessary, generate a status report comprising at least one of an ACK indicating a serial number of a successfully received data packet and an explicit NACK indicating a serial number of an unreceived data packet having a known serial number. and,

And a control unit for transmitting the status reports to the transmitter.

According to a preferred embodiment of the present invention, in a mobile communication system, a device for receiving a status report indicating a status of receiving packet data,

A data transmitter for transmitting data packets to a receiver;

Receive a status report indicating a reception status of the transmitted data packets from the receiver,

If the status report includes an implicit NACK including the serial number of the last packet among the successfully received data packets to request retransmission of an unreceived data packet whose serial number is not known, the implicit NACK is indicated. Controlling the data transmitter to transmit data packets after the last packet to the receiver,

If the status report does not include the implicit NACK, at least at least one of an ACK indicating a serial number of a successfully received data packet and an explicit NACK indicating a serial number of an unreceived data packet having a known serial number from the status report. And a control unit which detects one and controls the data transmitter to retransmit an unreceived data packet having the serial number indicated by the explicit NACK.

According to a preferred embodiment of the present invention, in a method for transmitting a status report indicating a reception state of packet data in a terminal of a mobile communication system,

A process of the UE receiving data packets moving from the source cell to the target cell by handover;

Waiting for a data packet to be first received from the target cell after moving to the target cell;

And when the data packet is received, transmitting a status report indicating a reception state of the terminal to a radio network controller (RNC) that controls a radio resource of the terminal.

In a preferred embodiment of the present invention, a terminal apparatus for transmitting a status report indicating a reception status of packet data in a mobile communication system,

A data receiver for receiving and storing a series of data packets from a network;

When the terminal moves from the source cell to the target cell by handover, the terminal waits until a data packet is first received from the target cell, and when the data packet is received, a status report indicating a reception state of the terminal is received. It characterized in that it comprises a control unit for transmitting to a radio network controller (RNC) for controlling the.

Hereinafter, with reference to the accompanying drawings will be described in detail the operating principle of the preferred embodiment of the present invention. In the following description of the present invention, detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be based on the contents throughout the specification.

One of the main points of the present invention to be described below is a MAC (Radio Link Control) layer for splitting a packet of a higher layer according to a predetermined size and a MAC for concatenating packets of an RLC layer according to a transmission resource allocated according to scheduling ( In the mobile communication system including the Medium Access Control (Layer) layer, the RLC layer and the MAC layer perform only framing instead of the MAC layer. The MAC layer performs framing according to the size of the MAC PDU to be transmitted in the next transmission period. When the size of the frame is variably used as described above, when retransmission is requested by ARQ, the size of the packet to be retransmitted and the amount of the scheduled transmission resource do not match, which may cause a problem in that retransmission cannot be performed. To solve this problem, the concept of split retransmission is introduced.

3 and 4 illustrate a hierarchical structure and a frame format of a wireless protocol according to a preferred embodiment of the present invention.

As shown in FIG. 3, the wireless protocol includes a MAC layer 320 and a physical layer 325, and the MAC layer 320 includes a MAC-framing (MAC-f) layer 310 and a MAC-m (MAC-). consists of two sub-layers called multiplexing layers 315. The MAC-f layer 310 plays a role similar to that of the RLC layer. Like the RLC layer, one entity may be configured per service. The MAC-f layer 310 receives MAC Service Data Units (SDUs) from the upper layer 305 and uses the MAC SDUs to match the size 330 requested by the MAC-m layer 315. f Frame the PDUs. In addition, ARQ is performed on the MAC-f PDUs 335.

The MAC-m layer 315 is connected with a plurality of MAC-f entities 310, and the MAC-f PDUs 335 from the MAC-f entities 310 are connected to one MAC-m PDU 340. Multiplex with. In addition, the HARQ operation is performed on the MAC-m PDU 340. The MAC-m layer 315 determines the size of the MAC-m PDU 340 according to the channel condition of the terminal, and considers the buffer status and priority of the MAC-f entities 310 to determine the size of the MAC-f PDU. Determine size 330.

Referring to FIG. 4, each MAC-f PDU 335 includes a serial number 430, a size field 433, a framing header (FH) 435, and a payload 410. The MAC-f layer 310 is informed of the MAC-f PDU size 330 from the MAC-m layer 315, and splits the IP packet (s) from the upper layer 305 according to the size 330 or The payload 410 is formed in contiguous manner. In addition, a MAC-f PDU 335 is configured by inserting a serial number 430 monotonically increasing by 1, a size field 433 indicating a payload size, and a framing header 435 to the MAC-m layer 315. To pass. The framing header 435 includes information related to concatenation / division.

The MAC-m PDU 340 is composed of at least one multiplexing header 440 and a payload 420. Each multiplexing header 440 includes multiplexing information for each MAC-f PDU 335 stored in the payload 420. For example, the multiplexing information may be an identifier of a corresponding MAC-f entity.

As described above, when the size of the MAC-m PDU and the size of the MAC-f PDU are variably set according to channel conditions, an example of an ARQ operation will be described with reference to FIG. 5. For convenience of explanation, it is assumed here that MAC-m multiplexing has not been performed. In addition, only the sub-serial number field is shown in the entire header of each MAC-f PDU.

Referring to FIG. 5, four IP packets 505, 510, 515, and 520 are buffered in the MAC-f layer. First, the MAC-f layer configures and transmits a MAC-f PDU 525 having a serial number of 0 according to the indication of the MAC-m layer. At this time, the size of the MAC-f PDU 525 determined according to the channel condition is 1000 bytes. Next, the MAC-f layer transmits the MAC-f PDU 530 having the serial number 1 and the MAC-f PDU 535 having the 2 according to the indication of the MAC-m layer. The MAC-f PDU 540 having a serial number 3 is transmitted. In this case, the channel condition is good, and the payload size of the MAC-f PDU 540 is set to 1500 bytes.

The receiving MAC-f layer received the MAC-f PDUs 525 to 535 having serial numbers 0 to 2, but did not receive the MAC-f PDU 540 having the serial number 3, and thus the transmitting MAC. Requests to retransmit the MAC-f PDU 540 with the serial number 3 to the -f layer. However, when the transmitting MAC-f layer receives the retransmission request and prepares for retransmission, the channel situation worsens, so that the size of the transmittable MAC-f PDU payload is reduced to 1000 bytes. The PDU 540 cannot be transmitted as it is.

In this case, when the channel condition changes when a retransmission is needed and a packet of the original size cannot be retransmitted, the packet should be divided and transmitted again. At this time, the sender informs the receiver that the packet is a retransmission for a particular packet and is divided. To this end, the serial number of each of the divided retransmission packets uses the serial number of the original packet as it is, and further includes a sub serial number (sub SN).

As in the example of FIG. 5, when the MAC-f PDU 540 is divided into two MAC-f PDUs 545 and 550 and retransmitted, the MAC-f PDUs 545 and 550 have an original sequence of three. In addition to the numbers, additional serial numbers 0 and 1 are inserted respectively. That is, the total serial number of the MAC-f PDU 545 is [3.0], and the total serial number of the MAC-f PDU 550 is [3.1].

Such division retransmission may be repeated as many times as necessary. For example, if the MAC-f PDU 545 is also required to be retransmitted, the MAC-f PDUs 555 and 560 that are divided and retransmitted are [3.0]. Including a common serial number and a subserial number, another subserial number of 0 and 1 is used to have the entire serial number of [3.0.0] and [3.0.1].

For convenience of description below, terms are defined as follows.

Segment: MAC-f PDU split for retransmission

Segment level: The number of times the original MAC-f PDU has been split for split retransmission. For example, the segment level of the MAC-f PDUs 545 and 550 is 1, and the segment level of the MAC-f PDUs 555 and 560 is 2.

<< first embodiment >>

6A and 6B illustrate the frame format according to the first embodiment of the present invention in more detail.

Referring to FIG. 6A, the MAC-m PDU 605 is composed of a plurality of multiplexed headers 610 and MAC-f PDUs 615. The multiplexed headers 610 exist as many as the MAC-f PDUs 615 stored in the MAC-m PDU 605. The order of the multiplex headers 610 and the order of the MAC-f PDUs 615 are the same. That is, the first multiplexing header includes multiplexing information for the first MAC-f PDU, and the second multiplexing header includes multiplexing information for the second MAC-f PDU. Each of the multiplexing headers 610 is composed of an identifier of a MAC-f entity to which the corresponding MAC-f PDU is processed and flag bits indicating whether the following information is other multiplexing information or the first MAC-f PDU.

Each MAC-f PDU 615 is composed of an SN header 620, a total length (TL) 622, an E bit 624, a framing header 626, and a payload 630. The payload 630 receives the packet (s) of the upper layer, i.e., the IP packet (s), by being divided or concatenated.

The SN header 620 is composed of a serial number 632, an F1 bit 634, and a minor serial number header 636. The subserial number header 636 is included only in the MAC-f PDU which is partly retransmitted, and is composed of a subserial number 638, a last segment indicator (LSI) 640, and an F2 bit 642. In one MAC-f PDU, there are as many serial number header (s) as the segment level. For example, one sub serial number header exists in the SN header of the MAC-f PDU having the segment level 1, and two sub serial number headers exist in the SN header of the MAC-f PDU having the segment level 2.

Serial number 632 is an integer that increases monotonically by one each time the MAC-f PDU is first transmitted. The F1 bit 634 is one bit of information indicating whether the following bit is the subserial number header 638 or the full length field 622. If it is '0', it means that the full length field 622 is followed, and if it is '1', the sub serial number header 636 is followed.

The LSI 640 is part of the sub serial number header 636 and is information indicating whether or not the corresponding MAC-f PDU to be retransmitted is the last segment. The subserial number 638 is an integer that monotonically increases by '1' starting from 0 each time a segmented MAC-f PDU of the same segment level is retransmitted. The F2 bit 642 is one bit of information indicating whether the following information is the next subserial number header or the full length field 622. '0' means that the full length field 622 is followed, and '1' means that the next minor serial number field is followed.

The total length 622 represents the size of the payload 630 in bytes.

The E bit 624 is a bit indicating whether the following information is the framing header 626 or payload 630 including the length indicator 644. For example, if the E bit 624 is '0', the payload 630 is followed, and if it is '1', the length indicator 644 is followed.

The framing header 626 contains information about segmentation / concatenation of IP packets stored in the payload 630. The framing header 626 consists of a length indicator 644 and an E bit 646. The length indicator 644 is information indicating the position of the last part when the payload 630 includes the last part of the IP packet. Therefore, when several IP packets are concatenated in the payload 630, several length indicators are included in the framing header 626. An E bit 646 is inserted after each length indicator 644 and indicates whether there is a next length indicator or whether the payload 630 is followed.

The receiving MAC-f layer may extract the IP packets from the payload 630 by examining the framing header 626 of the MAC-f PDUs listed as serial number 632. Since the portion indicated by the length indicator 644 is the end point of one IP packet and the start point of the next IP packet, the payloads are listed in the corresponding serial number 632, and then the position indicated by the length indicator 644 is referred to. Once cut, IP packets are extracted.

FIG. 6B shows the structure of the MAC-f PDU 555 shown in FIG. The full length field and the E bit are omitted here. The entire serial number of the MAC-f PDU 555 is [3.0.0] and the segment level is 2 has already been described. Therefore, two minor serial number fields 654 and 660 are provided so that the first minor serial number field 654 is '0' and the second minor serial number field 660 is '0'. The F1 bit 652 following the serial number 650 is a '1' indicating that a subsequent serial number field 654 is present.

The LSI 656 following the first sub-serial number field 654 is set to '0 (false)' indicating that the MAC-f PDU 555 is not the last segment to be split transmitted, and F2 following the LSI 656. Bit 658 is set to '1' (true), indicating that a subsequent subnumber field 660 is present. The LSI 662 following the second subserial number field 660 is '0' indicating that the MAC-f PDU 555 is not the last segment to be split transmitted, and the F2 bit 664 following the LSI 662 is '0' indicating that the full length field (not shown) follows.

LI 670 of the framing header is '800' indicating that payload 674 is 800 bytes in length, and E field 672 is set to '0' indicating that payload 674 is followed.

The frame structure shown in FIGS. 6A and 6B is merely an example, and various modifications may exist in addition to the above-described structure. In other words, the present invention is not directed to the frame structure itself, but to be understood as framing IP packets in various sizes according to communication conditions. In addition, a method and apparatus are provided to suitably size a retransmission packet when the original packet cannot be retransmitted as it is due to a deterioration of a radio channel during retransmission. To this end, the concept of serial number and subserial number was introduced, and the serial number is fixed to the value used at the initial transmission, and the packet is divided by the receiver by inserting the subserial number at the time of split retransmission. To be assembled.

7 shows an example of split retransmission according to the first embodiment of the present invention.

Referring to FIG. 7, there are three IP packets 701, 702, and 703 having predetermined sizes, the last part of the IP packet 701 and one complete IP packet 702 and the IP packet 703. The first portion of) is housed in payload 708 of one MAC-f PDU 705. At this time, the size of the portion related to the IP packet 701 stored in the payload 708 is 700 bytes, the size of the entire IP packet 702 is 600 bytes, the size of the portion related to the IP packet 703 is 700 bytes. .

The size of the MAC-f PDU 705 slightly exceeds 2000 bytes, and the MAC-f PDU 705 is first transmitted at a first time point. At this time, the transmitter sets the serial number SN of the MAC-f PDU 705 to x and the total length TL to 2000. FIG. Thereafter, a retransmission request has occurred, and the size of the MAC-f PDU that can be transmitted at a second time point for retransmission is assumed to be 1200 bytes. Since the transmitting side cannot transmit the MAC-f PDU 705 as it is, the MAC-f PDU 705 is divided and retransmitted.

Partial retransmission is the re-transmission after splitting the original packet. A part of the split packet is newly created and a part of the original packet is split. In this case, when the segmented portion of the original packet is called a 'retransmission unit', there are two approaches to what part of the original packet is to be regarded as a retransmission unit.

The first approach is to consider only the payload 708 of the MAC-f PDU 705 as the retransmission unit 710. The second method is to consider the portion of the sum of the framing header 707 and the payload 708 as the retransmission unit 715. With this second scheme, the sender does not need to reconfigure the framing header each time a split retransmission is performed, but before the receiver receives all the retransmitted packets and reconstructs the original packet, the original IP packet is reconfigured. It cannot be extracted. On the other hand, when the first method is used, the sender must newly configure a framing header each time the split retransmission is performed, but the receiver can extract the original IP packet using the framing header of the split retransmitted packet.

Hereinafter, an operation in the case of using the retransmission unit 715 including the payload 708 and the framing header 707 will be described.

In the first retransmission, the MAC-f PDU 705 is divided and retransmitted into the MAC-f PDU 720 and the MAC-f PDU 733, and in the second retransmission, the MAC-f PDU 720 is a MAC-f PDU ( 748 and the MAC-f PDU 770 are retransmitted. Therefore, the segment level of the MAC-f PDU 720 and the MAC-f PDU 733 is 1, and the segment level of the MAC-f PDU 748 and the MAC-f PDU 770 is 2. The following describes how the values of the header fields of the MAC-f PDUs 720, 735, 748, and 770 that are split retransmitted are then determined.

As mentioned above, each MAC-f PDU that is retransmitted consists of a serial number, one or more sub-serial number headers, a full length field, a framing header, and a payload.

In the serial number fields 723, 735, 750, and 775, a value identical to the serial number of the first transmitted MAC-f PDU is inserted. Therefore, x is inserted into the serial number fields 723, 735, 750, and 775 of the MAC-f PDU 720, the MAC-f PDU 733, the MAC-f PDU 748, and the MAC-f PDU 770. .

The number of subserial number headers 725, 740, 755, 760, 780, 785 is determined according to the segment level. For example, there are one minor serial number header 725 and 740 in the MAC-f PDU 720 and the MAC-f PDU 733 having the segment level of 1, respectively.

In the sub serial number field (not shown) included in each sub serial number header, order information of the MAC-f PDU to be retransmitted is inserted, and the order information is an integer monotonically increasing by 1 starting from 0. For example, since the MAC-f PDU 720 is the first MAC-f PDU at the segment level, it has a minor number of '0', and the MAC-f PDU 733 has the second MAC-f PDU at the segment level. Has a subserial number of '1'.

-LSI (not shown) included in each sub serial number header is a field indicating whether the MAC-f PDU is the last MAC-f PDU at the corresponding segment level. If '0 (false)' is not the last MAC-f PDU and '1 (true)' is the last MAC-f PDU, then the MAC-f PDU 720 indicates that the last MAC-f PDU at that segment level If not, it has an LSI value of '0' and the MAC-f PDU 733 has an LSI value of '1' since it is the last MAC-f PDU at the corresponding segment level.

For MAC-f PDUs 748 and 770 with segment level 2, each has two minor serial number headers 755-760 and 780-785. At this time, only the subserial number and LSI of the last subserial number header 760 and 785 are significant at the corresponding segment level, and the value used at the previous segment level is used for the subserial number and LSI of the remaining subserial number header 755 and 780. The same values as are inserted. Taking the MAC-f PDU 748 as an example, the subserial number and the LSI of the first subserial number header 755 of the MAC-f PDU 748 are the subserial of the parent MAC-f PDU 720. The subserial number of the number header 725 and the LSI are the same. The subserial number and the LSI of the second subserial number header 760 of the MAC-f PDU 748 are determined according to the aforementioned method.

In the present specification, a parent MAC-f PDU and a child MAC-f PDU are terms indicating a relationship between MAC-f PDUs which are retransmitted separately. When divided and retransmitted into MAC-f PDUs, the original MAC-f PDU is referred to as a parent MAC-f PDU, and the divided MAC-f PDUs are referred to as a child MAC-f PDU.

As described above, since the full length fields 706, 730, 745, 765, and 790 are information indicating the size of the corresponding payload in units of bytes, a new value is inserted for each MAC-f PDU that is retransmitted. For example, a value '2000' is inserted into the full length field 706 of the MAC-f PDU 705, and the MAC-f PDU 720 of the MAC-f PDU 705 is a child MAC-f PDU. In the full length field 730, for example, a new value '1200' is inserted.

The length indicator is inserted into the framing header 707 as described above. The length indicator is inserted into the MAC-f PDU 705 to indicate whether the last byte of the IP packet is included and, if so, the location. Since the retransmission unit 715 including the framing header 707 and the payload 708 is used here as described above, the framing header 707 is a non-partitioned MAC-f PDU 705. Is used only, and each divided MAC-f PDUs 720, 733, 748, and 770 do not include a framing header. On the other hand, when the retransmission unit 710 including only the payload 708 is used, for example, the framing header 707 of the MAC-f PDU 705 may have two values for the IP packet 701 and the IP packet 702. Length indicators are included, but the framing header (not shown) of the MAC-f PDU 720 that is the child of the MAC-f PDU 707 includes only the length indicator indicating the end of the IP packet 701. Is inserted.

As described above, there is a header field in which the value of the parent MAC-f PDU is used as it is during retransmission, and a header field newly inserted in the child MAC-f PDU. For convenience of description, the header field used as the value used in the parent MAC-f PDU is referred to as a 'copy header', and the header field into which the field value is newly inserted is referred to as a 'new header'. Then, the header to be copied includes the serial number field, the subserial number field of the subserial number header except the meaningful subserial number header, and the LSI. The newly inserted headers include the meaningful subserial number header and the full length field. There is a framing header field. Here, the meaningful subserial number header is a subserial number header containing meaningful information at the corresponding segment level. At the segment level n, the nth subserial number header is a meaningful subserial number header.

8 is a block diagram showing the structure of a transmitter according to a first embodiment of the present invention.

Referring to FIG. 8, the transmitter includes a transmit buffer 805, a header insertion block 815, a MAC-f control block 820, a retransmission buffer 825, a split retransmission block 827, a multiplexing block 830, and HARQ. It is composed of a block and a physical layer 835. The dual transmit buffer 805, the header insertion block 815, the MAC-f control block 820, the retransmission buffer 825, and the fragment retransmission block 827 constitute a MAC-f entity. Although only one MAC-f entity is shown here, a plurality of MAC-f entities for a plurality of services may be provided.

The transmit buffer 805 stores the IP packets delivered from the upper layer until transmitted through the physical layer. The transmit buffer 805 outputs the stored IP packets to the header insertion block 815 by the required amount of data of the MAC-f control block 820.

The multiplexing block 830 determines the amount of data to be transmitted in the next transmission period for each MAC-f entity according to the radio transmission resource allocated by the Node B scheduler, and notifies the MAC-f control block 820. The MAC-f control block 820 determines data to be transmitted in the next transmission period according to the priority of initial transmission and retransmission. If a decision is made to transmit a new IP packet in the next transmission period, the transmission buffer 805 is notified of the amount of data to be transmitted. On the other hand, if it is decided to execute retransmission in the next transmission period, the retransmission buffer 825 is instructed to retransmit, and the fragment retransmission block 827 is notified of the amount of data to be retransmitted.

The transmit buffer 805 delivers the informed amount of IP packet (s) to the header insertion block 815. At this time, if the amount of data to be transmitted does not match the size of one IP packet, the transmission buffer 805 may divide one IP packet and deliver only a part of it, or may deliver a plurality of IP packets.

The header insertion block 815 configures a MAC-f PDU by inserting an SN header, a full length (TL), an E bit, and a framing header into the IP packet (s) delivered by the transmission buffer 805.

The MAC-f PDU is delivered to the retransmission buffer 825 and the multiplexing block 830. The retransmission buffer 825 stores the MAC-f PDU, and either discards the stored MAC-f PDU or schedules a retransmission according to a feedback signal received from a counterpart entity. In detail, when a positive feedback signal (hereinafter referred to as an ACK) is received from the counterpart ARQ entity, the retransmission buffer 825 discards the MAC-f PDU corresponding to the ACK in the retransmission buffer 825. On the other hand, when a negative feedback signal (hereinafter referred to as NACK) is received from the opposite ARQ entity, the retransmission buffer 825 prepares for retransmission for the MAC-f PDU corresponding to the NACK. That is, when the retransmission buffer 825 receives the retransmission command from the MAC-f control block 820, the retransmission buffer 825 transfers the MAC-f PDU corresponding to the NACK to the fragment retransmission block 827. The ACK and / or NACK may be stored together in a status report transmitted according to a predetermined occurrence time or a different triggering condition according to a predetermined cycle.

Split retransmission block 827 performs split retransmission on the MAC-f PDU from retransmission buffer 825. If split retransmission is not needed, the MAC-f PDU delivered by retransmission buffer 825 is passed to multiplexing block 830 without modification. If split retransmission is needed, split retransmit block 827 divides the retransmission unit of the parent MAC-f PDU from retransmission buffer 825 into the required size, and then assigns an SN header and a full length field to each split segment. Attach and, if necessary, attach a framing header to generate child MAC-f PDUs.

In detail, the fragment retransmission block 827 adds a subserial number header to the SN header of the parent MAC-f PDU, resets the total length to match the payload size of the child MAC-f PDU, and corresponds to the child MAC-f. Each MAC-f PDU is generated by setting a framing header according to whether the last byte of the IP packet exists in the f PDU. The split retransmission block 827 also serves as a retransmission buffer for the child MAC-f PDUs. That is, the fragment retransmission block 827 stores the child MAC-f PDUs until the ACKs for the child MAC-f PDUs are delivered, and discards the child MAC-f PDU when the ACKs are received.

The multiplexing block 830 multiplexes MAC-f PDUs delivered from multiple MAC-f entities into one MAC-m PDU and inserts multiplexed headers into the MAC-m PDU. The MAC-m PDU is transmitted through a HARQ operation by the HARQ block and the physical layer 835 over a radio channel.

9 is a block diagram illustrating a receiver structure according to the first embodiment of the present invention.

Referring to FIG. 9, the transmitter includes an assembly block 905, a reception buffer 910, a retransmission management block 915, a demultiplexing block 920, an HARQ block, and a physical layer 925. The dual assembly block 905, the receive buffer 910, and the retransmission management block 915 constitute a MAC-f entity. Although only one MAC-f entity is shown here, a plurality of MAC-f entities for a plurality of services may be provided.

The HARQ block and the physical layer 925 perform a HARQ process on the MAC-m PDU through the physical channel, and transfer the successfully received MAC-m PDU to the demultiplexing block 920 through the HARQ process. The demultiplexing block 920 interprets the multiplexing headers of the MAC-m PDUs transmitted from the HARQ block and the physical layer 925, demultiplexes the MAC-m PDU into a plurality of MAC-f PDUs, and then demultiplexes the demultiplexing block. The MAC-f PDUs are transmitted to MAC-f entities indicated by corresponding multiplexing headers.

The reception buffer 910 stores the MAC-f PDUs received from the demultiplexing block 920 at a location according to the serial number, and the MAC-f PDUs that can be assembled among the stored MAC-f PDUs are assembled in the assembly block 905. To pass. Here, assembling MAC-f PDUs means MAC-f PDUs arranged in sequence of serial numbers without a gap.

The retransmission management block 915 checks the serial number and the serial number of the MAC-f PDUs stored in the reception buffer 910 and transmits an ACK / NACK to the counterpart ARQ entity by the physical layer. In this case, the NACK is transmitted to request retransmission of a specific MAC-f PDU that has not been received, or when the MAC-f PDU does not know which retransmission to request. In each case, a detailed description of the NACK will be described later. The ACK may be sent if there is no gap. The assembling block 905 reconstructs the divided MAC-f PDUs among the MAC-f PDUs into original IP packets by referring to a framing header of the MAC-f PDUs delivered from the reception buffer 910. Performs an operation of delivering an IP packet to a higher layer.

10 is a signaling flowchart illustrating a split retransmission operation according to the first embodiment of the present invention.

Referring to FIG. 10, in step 1015, the transmitting side 1005 transmits a MAC-f PDU having a serial number 14 (hereinafter, referred to as PDU [14]) to the receiving side 1010. In step 1020, the receiver transmits a NACK (hereinafter, referred to as NACK [14]) indicating that the PDU [14] was not successfully received to the transmitter 1005.

In response to the NACK [14], the transmitting side 1005 tries to retransmit the PDU [14], but if the amount of allowed radio transmission resources is insufficient to transmit the original size of the PDU [14], the transmitting side in step 1025. 1005 divides the PDU [14]. Here, PDU [14] is divided into PDU [14.0] and PDU [14.1]. At this time, the LSI of the first subserial number header of the PDU [14.1] is set to '1', indicating that the PDU [14.1] is the last segment related to the PDU [14]. In step 1030, the transmitting side 1005 transmits a PDU [14.0], and in step 1035 transmits a PDU [14.1].

Thereafter, in step 1040, the receiving side 1010 transmits a NACK (ie, NACK [14.1]) for the PDU [14.1] to the transmitting side 1005. In response to the NACK [14.1], the transmitting side 1005 attempts to retransmit the PDU [14.1], but if the amount of allowed radio transmission resources is insufficient to transmit the PDU [14.1], the transmitting side 1005 in step 1045. Repartitions the PDU [14.1]. Here, PDU [14.1] is divided into PDU [14.1.0], PDU [14.1.1], PDU [14.1.2], and PDU [14.1.3]. The first sub serial number header of the PDU [14.1.0], PDU [14.1.1], PDU [14.1.2], and PDU [14.1.3] is the same as the first sub serial number header of PDU [14.1]. In the second subserial number header, new subserial numbers and LSIs are set. At this time, the LSI of the second sub serial number header of the PDU [14.1.3] is set to '1', indicating that the PDU [14.1.3] is the last segment related to the PDU [14.1]. In steps 1050, 1055, 1060, and 1065, the transmitting side 1005 receives the PDU [14.1.0], PDU [14.1.1], PDU [14.1.2], and PDU [14.1.3]. Are transmitted sequentially.

As described above, in the preferred embodiment of the present invention, retransmission may be selectively requested and performed for MAC-f PDUs which are partially retransmitted. For example, when PDU [14] is divided into PDU [14.0] and PDU [14.1] and transmitted, if receiving 1010 receives PDU [14.0] and not PDU [14.1], PDU [14] is received. 14.1] only send NACK. Likewise, if the receiving side 1010 has not received the PDU [14.1.2], it transmits only the NACK for the PDU [14.1.2].

The problem that may occur when the retransmission request for the split retransmission as described above is that if the receiving side does not receive the last segment, the receiving side does not recognize the fact and as a result cannot transmit the NACK for the last segment. This is because the ARQ system based on the serial number cannot determine whether a previous PDU has not been received without receiving a subsequent PDU of the same segment level. For example, the receiving side 1010 cannot recognize that the PDU [14] has not been completely received until the time at which the PDU [15] is received is reached.

However, even in the case of receiving subsequent PDUs in split retransmission, a case in which PDUs that have not been received may not be correctly recognized may occur. For example, if the receiving side 1010 receives the PDU [14.1.0] and the PDU [15], the receiving side 1010 indicates that there is a segment that has not been received because the LSI of the PDU [14.1.0] is '0'. I know that, but I don't know how many more segments to receive. Therefore, it is also unknown that the receiving side 1010 should request retransmission for the PDU [14.1.1], PDU [14.1.2], PDU [14.1.3].

In order to solve this problem, the preferred embodiment of the present invention defines the format of the NACK. FIG. 11A illustrates the format of an explicit NACK according to an embodiment of the present invention, and FIG. 11B illustrates the format of an implicit NACK according to another embodiment of the present invention. As shown, explicit NACK and implicit NACK are distinguished by their type values.

The explicit NACK 1105 shown in FIG. 11A is used when the PDU which is not received is correctly known, and is composed of a Type field, a Serial Number field, and a Sub-SN field. do. In the type field, a unique type value representing an explicit NACK 1105 is inserted. In the serial number field and the serial number fields, the serial number and the serial number of the PDU which is the target of the explicit NACK 1105 are inserted. In this case, when the request for retransmission of the MAC-f PDU not divided into the explicit NACK 1105 is performed, the sub-serial number fields are not included. In the E field subsequent to the serial number field and the sub serial number fields, '1' is inserted if the next bit is another sub serial number field, otherwise '0' is inserted.

For example, '14' is inserted in the serial number field of the explicit NACK to request retransmission of the PDU [14], '0' is inserted in the E field, and the subserial number field is not used. To request retransmission of the PDU [14.1] insert '14' in the serial number field, '1' in the first E field, '1' in the subserial field and '0' in the second E field do. When the transmitting side receives the explicit NACK 1105, the transmitting side retransmits the PDU having the serial number included in the explicit NACK.

The implicit NACK 1110 shown in FIG. 11B is used when the receiving side does not know which PDU to request for retransmission and is composed of a type field, a serial number field, and a serial number field. The serial number field and the subserial number fields are each followed by an E field. The receiving side transmits the implicit NACK 1110 when receiving the segment in which the LSI is set to '1' during the reception of the segment retransmitted. In the type field, a unique type value representing an implicit NACK 1110 is inserted. This value is different from the type value representing the explicit NACK 1105 above.

The receiver inserts and transmits the highest overall serial number among the serial numbers of PDUs already received at the segment level in the serial number field and the sub serial number fields of the implicit NACK 1110. For example, if a PDU [14.1.0] is received and no segment with an LSI set to '1' at that segment level is received, then the receiving party receives the serial number '14', the first subserial number '1', and the second subpart. The implicit NACK 1110 set with the serial number '0' is transmitted. When the transmitting side receives the implicit NACK 1110, PDUs having serial numbers greater than the serial number [14.1.0] at the corresponding segment level, that is, PDUs [14.1.1], PDUs [14.1.2], and PDUs Resend [14.1.3].

12 is a flowchart illustrating a split retransmission operation according to the first embodiment of the present invention. Here, the initial transmission is omitted, and only the operation when the retransmission is performed is shown.

Referring to FIG. 12, in step 1205, retransmission of the next transmission period is scheduled, and the amount of data to be retransmitted is determined. Hereinafter, the amount of data to be retransmitted is called a retransmission capacity.

In step 1210, the MAC-f entity compares the retransmission capacity with the size of the MAC-f PDU having the highest retransmission priority among the stored MAC-f PDUs. The retransmission priority may be set according to various criteria. For example, the retransmission priority may be inversely proportional to the serial number. That is, the lower the serial number MAC-f PDU has a higher retransmission priority. This gives high priority to the MAC-f PDU that occurred first, which is the most common criterion. If there are several MAC-f PDUs to be retransmitted, the order of retransmission is determined based on the above priority. As another example, a MAC-f PDU associated with a service requiring very little transmission delay, even with the lowest serial number, may have a relatively high retransmission priority.

In step 1210, if the retransmission capacity is greater than the size of the MAC-f PDU with the highest retransmission priority, step 1215; otherwise, step 1220. In step 1215, the MAC-f entity delivers the MAC-f PDU having the highest retransmission priority to the MAC-m layer, and proceeds to step 1217. In step 1217, the MAC-f entity updates the retransmission capacity as follows, and returns to step 1210.

Retransmission capacity = (existing retransmission capacity)-(size of MAC-f PDU delivered to MAC-m)

In step 1220, the MAC-f entity divides the MAC-f PDU having the highest retransmission priority according to the retransmission capacity and proceeds to step 1225. Although not shown, if the MAC-f PDU having the highest retransmission priority cannot be divided according to the retransmission capacity, that is, when the retransmission capacity is smaller than the minimum size of the MAC-f PDU, the operation ends. Here, the minimum size of the MAC-f PDU means the size of the MAC-f header, and its value varies depending on the segment level of the MAC-f PDU. The minimum size of the MAC-f PDU is determined as follows, for example.

Minimum size of MAC-f PDU = (serial field size + 1) + segment level * (serial field size + 2) + full length field size + 1 + framing header size

In step 1225, the MAC-f entity inserts a subserial number header into the serial number header of the divided MAC-f PDU, and in step 1230, delivers the MAC-f PDU to the MAC-m layer. The MAC-f PDU is transmitted after being multiplexed with MAC-f PDUs from another MAC-f entity in the MAC-m layer.

An example of a split retransmission operation will be described with reference to FIG. 12.

The following MAC-f PDUs are stored in the retransmission buffer.

-MAC-f PDU [10] = [SN = 10, F1 = 0, Total Length = 1000, E = 0]

-MAC-f PDU [12.1] = [SN = 12, F1 = 1, sub-SN = 1, LSI = 1, F2 = 0, Total Length = 800]

Here the MAC-f PDU [10] with the lower serial number has a higher retransmission priority.

If a retransmission capacity of 1500 bytes is then scheduled, the MAC-f entity compares the retransmission capacity 1500 with the size 1000 of the MAC-f PDU [10] having the highest retransmission priority in step 1210. Since the retransmission capacity is large, the process proceeds to step 1215 and delivers the MAC-f PDU [10] to the MAC-m layer without partitioning. In step 1217, the MAC-f entity updates the retransmission capacity to 500 and proceeds to step 1210.

Next, in step 1210, the updated retransmission capacity 500 is compared with the size 800 of the MAC-f PDU [12.1] having the second highest retransmission priority. Since the size of the MAC-f PDU [12.1] is large, the process proceeds to step 1220 and the MAC-f PDU [12.1] is divided into 500 bytes and 300 bytes of MAC-f PDUs.

In step 1225, the MAC-f entity inserts subserial numbers [12.1.0], [12.1.1], and LSI into the divided MAC-f PDUs. As a result, the following MAC-f PDUs [12.1.0] and MAC-f PDUs [12.1.1] are configured.

-MAC-f PDU [12.1.0] = [SN = 12, F1 = 1, sub-SN = 1, LSI = 1, F2 = 1, sub-SN = 0, LSI = 0, F2 = 0, Total Length = 500]

-MAC-f PDU [12.1.1] = [SN = 12, F1 = 1, sub-SN = 1, LSI = 1, F2 = 1, sub-SN = 1, LSI = 1, F2 = 0, Total Length = 300]

Finally, in step 1230, the MAC-f PDU [12.1.0] is delivered to the MAC-m layer, the MAC-f PDU [12.1.1] is buffered until the retransmission capacity is allocated again.

13 is a flowchart illustrating a receiving operation according to the first embodiment of the present invention.

Referring to FIG. 13, in step 1305, the MAC-m layer receives a MAC-m PDU, in step 1310, interprets the multiplex headers of the MAC-m PDU, and in step 1315, the MAC multiplexed into the MAC-m PDU. -f Deliver each PDU to the receive buffer of the corresponding MAC-f entity. The following steps 1320 to 1340 illustrate only operations by any one MAC-f entity.

In step 1320, the MAC-f entity examines the serial number header of the MAC-f PDU delivered from the MAC-m layer, and stores the MAC-f PDU in an appropriate location. The storage location of the MAC-f PDU is determined based on the entire serial number. The full serial number includes the serial number and the minor serial number. The importance of the serial number is determined according to the segment level. That is, the minor serial number of segment level 1 has a higher importance level than the minor serial number of segment level 2. When the receiver determines previously stored MAC-f PDUs and the order of the MAC-f PDUs transmitted from the MAC-m layer, the receiver first compares serial numbers of the MAC-f PDUs. If the serial numbers are identical to each other, then the minor serial numbers of segment level 1 are compared. If the minor serial numbers are also the same, the operation of comparing the minor serial numbers of segment level 2 is repeated.

In step 1325, the MAC-f entity checks whether there are MAC-f PDUs that can be assembled into a higher level MAC-f PDU among the stored MAC-f PDUs, and assembles them if possible.

1. Whether the MAC-f PDUs can be assembled is determined as follows.

1.1. At a given segment level, the MAC-f PDUs with the same 'serial number and subserial numbers' except for the last subserial number are grouped into one split MAC-f PDU set. For example, MAC-f PDUs [12.0.0] and MAC-f PDUs [12.0.1] are grouped into the same split MAC-f PDU set. On the other hand, the MAC-f PDU [12.0.0] and the MAC-f PDU [12.1.1] are not the same divided MAC-f PDU sets. Here, the divided MAC-f PDU set includes divided MAC-f PDUs that can be assembled into higher-level MAC-f PDUs, and when one divided MAC-f PDU set is completely collected, the divided MAC-f PDU set f PDUs are assembled into higher MAC-f PDUs.

1.2. If the MAC-f PDUs belonging to a given split MAC-f PDU set, from the MAC-f PDU of the last sub serial number 0 to the MAC-f PDU with the LSI set to 1, have consecutive last sub serial numbers, the split MAC -f PDU set can be assembled.

2. Assemble splitting MAC-f PDU sets are assembled into higher-level MAC-f PDUs as shown below.

2.1. The payloads of all MAC-f PDUs included in the divided MAC-f PDU set are concatenated in order to be payloads of the higher level MAC-f PDU.

2.2. The header of the high level MAC-f PDU is configured as follows.

2.2.1. Selecting one of the MAC-f PDUs included in the divided MAC-f PDU set, and removing the last serial number header from the serial number header of the selected MAC-f PDU, the portion of the higher-level MAC-f PDU It is a serial number header.

2.2.2. The full length field is newly calculated according to the payload size of the higher level MAC-f PDU.

2.2.3. The framing header is set again according to the framing state of the IP packet in the payload of the higher level MAC-f PDU.

2.3. When the header and payload of the higher level MAC-f PDU are combined, the assembly of the higher level MAC-f PDU is completed.

In step 1330, the MAC-f entity checks whether the MAC SDU can be assembled using the assembled MAC-f PDUs. If the following conditions are met, the MAC SDU can be assembled.

The i-th length indicator among length indicators included in each MAC-f PDU stored in the reception buffer is called LI (i).

If there is no unreceived MAC-f PDU between the MAC-f PDU with LI (i) and the MAC-f PDU with LI (i + 1), LI (i) is the starting point and LI (i + 1) It is possible to assemble a MAC SDU as an endpoint.

The presence of an unreceived MAC-f PDU may be determined by the continuity of serial numbers. That is, if the serial numbers are consecutive, the unreceived MAC-f PDUs do not exist, and the unreceived MAC-f PDUs exist at the portion where the serial numbers are broken.

Continuity of serial numbers between non-partitioned MAC-f PDUs and split MAC-f PDU sets, between split MAC-f PDU sets and non-partitioned MAC-f PDU sets, between split MAC-f PDU sets, and within split MAC-f PDU sets Is determined as follows.

Continuity between the undivided MAC-f PDU and the divided MAC-f PDU set: The serial numbers of the undivided MAC-f PDU and the divided MAC-f PDU set are consecutive, and the first MAC-f of the divided MAC-f PDU set is continuous. If all subserial numbers in a PDU are zero, they are consecutive or discontinuous. Referring to FIG. 14A, the serial number of the undivided MAC-f PDU [11] is 11, the total serial numbers of the divided MAC-f PDU sets are consecutive to 12.0 and 12.1, and the first of the divided MAC-f PDU sets is shown. Since the subserial number of the MAC-f PDU is 0, the split MAC-f PDU set is a continuation of the non-divided MAC-f PDU.

Continuity between the split MAC-f PDU set and the non-partitioned MAC-f PDU: The serial numbers of the split MAC-f PDU set and the unpartitioned MAC-f PDU are consecutive, and the last MAC-f PDU of the split MAC-f PDU set is continuous. If the last LSI of is 1, it is continuous or discontinuous. Referring to FIG. 14B, the serial number of the divided MAC-f PDU set is 12, the serial number of the non-divided MAC-f PDU [13] is 13 consecutive, and the last MAC-f PDU [of the split MAC-f PDU set is continuous. 12.4], so that the undivided MAC-f PDU [13] is a continuation of the split MAC-f PDU set.

Continuity between split MAC-f PDU sets: The serial numbers of split MAC-f PDU sets are contiguous, the last LSI of the last MAC-f PDU of the first split MAC-f PDU set is 1, and the second split MAC- f If all sub-serial numbers of the first MAC-f PDU in the PDU set are zero, they are continuous or discontinuous. Referring to FIG. 14C, the serial number of the first divided MAC-f PDU set is 12, the serial number of the second divided MAC-f PDU set is consecutive to 13, and the last MAC- of the first divided MAC-f PDU set is consecutive. Since the LSI of f PDU [12.4] is 1 and the subserial number of the first MAC-f PDU [13.0] of the second divided MAC-f PDU set is 0, the second divided MAC-f PDU set is the first divided MAC. -f is a sequence of PDU sets.

Continuity in the split MAC-f PDU set: At the point where the segment level changes, the last LSI of the MAC-f PDU just before the segment level changes is 1, and the last sub-number of the first MAC-f PDU whose segment level has changed is 0. Is continuous or discontinuous. Also, at a segment level where the serial numbers are the same as the serial numbers except for the last serial number, where the last serial number is consecutive is continuous, where the discontinuous is discontinuous. Referring to FIG. 14D, the MAC-f PDUs [12.3] and MAC-f PDUs [12.4] are contiguous with each other since the last sub-numbers are consecutive at the segment level having the same serial number 12. The segment level changes between the MAC-f PDU [12.4] and the MAC-f PDU [12.5.0]. The LSI of the MAC-f PDU [12.4] immediately before the segment level changes is 1, and the first segment level changes. Since the last subserial number of the first MAC-f PDU [12.5.0] is 0, the MAC-f PDU [12.5.0] is a continuation of the MAC-f PDU [12.4].

If it is determined that there are MAC-f PDUs that can be assembled in step 1330, the process proceeds to step 1335, and the MAC-f entity assembles MAC SDUs from the MAC-f PDUs and delivers them to a higher layer. Wait for the next MAC-f PDU to arrive. On the other hand, if it is determined in step 1330 that there are no MAC-f PDUs that can be assembled, the process proceeds to step 1340 and waits for the arrival of the next MAC-f PDU.

<< 2nd Example >>

As a second embodiment of the present invention, a method of differently setting a serial number at the time of initial transmission and retransmission is proposed. There are two ways to assign a serial number. First, serial numbers may be assigned for each packet, and serial numbers may be assigned for each predetermined size. As a representative example, it is possible to assign a serial number for each byte. The method of assigning a serial number for each packet has an advantage that the length of the serial number is small, while the number of subserial number headers is not constant when split retransmission is performed. When the serial number is assigned in byte unit, the header format is simple when splitting and retransmitting, while the length of the serial number is large.

In the second embodiment of the present invention, in order to take advantage of the above two schemes, serial numbers are assigned for each packet at the time of initial transmission, and serial numbers are assigned for each byte at the time of split retransmission.

15 shows a frame format according to a second embodiment of the present invention.

Referring to FIG. 15, the MAC-m PDU 1505 is composed of at least one multiplexing header 1530 and at least one MAC-f PDU 1510. Each multiplexing header 1530 includes multiplexing information for each MAC-f PDU 1510 stored therein. For example, the multiplexing information may include sizes of the multiplexing identifier 1515 and the MAC-f PDU 1510 indicating an identifier of a MAC-f entity (ie, logical channel or data flow) to which the MAC-f PDU 1510 belongs. It consists of a length field 1520 and an F1 bit 1525. The F1 bit 1525 is a 1-bit flag indicating whether the following byte is another multiplexing information 1527 or a MAC-f PDU 1510.

Each MAC-f PDU 1510 consists of a MAC-f header 1538 and a MAC-f payload 1555, with the MAC-f payload 1555 having 'part of the IP packet' or 'one intact'. IP packet 'or' a portion of an IP packet and one or more IP packets' or 'multiple IP packets' are stored.

In the MAC-f header 1538, a serial number 1535, an F2 bit 1536, and an F3 bit 1537 of the MAC-f PDU 1510 are inserted. The F2 bit 1536 is a 1-bit flag indicating whether the retransmission subheader 1545 is present. The F3 bit 1537 is a 1-bit flag indicating whether the length indicator 1547 is included in the MAC-f header 1538. The length indicator 1547 is information indicating an end position of each IP packet included in the payload 1555 and is inserted when the last part of the IP packet is included in the payload 1555 of the MAC-f PDU 1510. Optional header information is optional header information. Behind each length indicator 1547 is an F3 bit 1550 indicating whether another length indicator is followed or the payload 1555 is followed.

The retransmission subheader 1545 included in the MAC-f header 1538 includes a start pointer (SP) 1540 and an LSI 1542. The start pointer 1540 is information indicating which part of the original MAC-f PDU corresponds to the segment. The start pointer 1540 is a serial number which is set to 0 by the first byte of the payload of the original MAC-f PDU and is incremented by 1 every byte. If given, this is the serial number of the first byte of the segment. A detailed application of the start pointer 1540 is described with reference to FIG. 16. Here, the original MAC-f PDU means MAC-f PDU that is not divided. The LSI 1542 is a value indicating whether the corresponding segment is the last segment.

Next, an example of split retransmission according to the second embodiment will be described with reference to FIG. 16.

As shown, three IP packets 1605, 1610, 1615 are framed into four MAC-f PDUs 1620, 1625, 1630, 1635. The MAC-f PDUs 1620 to 1635 are assigned serial numbers of 0 to 3, and the MAC-f PDU (ie, MAC-f PDU [2]) 1630, which is serial number 2, fails to transmit. Split retransmission 1660 is executed. The 900-byte MAC-f PDU [2] 1630 is divided into a 500-byte segment 1640 and a 400-byte segment 1645. The serial number of the first segment 1640 is set to 2, the same as the parent MAC-f PDU 1630, the SP is set to 0, and the length field is set to 500. The serial number of the second segment 1645 is set to 2, the same as the parent MAC-f PDU 1630, and the SP is set to 500. This is because the serial number of the first byte of the payload of the second segment 1645 is 500.

When retransmitting the second segment 1645, split retransmission 1660 is possible. In this case, the serial number of each segment 1650 and 1655 takes the serial number of the parent MAC-f PDU 1645, and as SP. The serial number of the first byte of the payload of the segment is used. In detail, the length field of the first segment 1650 is 300, the SP is 500, the length field of the second segment 1655 is 100, and the SP is 800. At each segment level, the LSI of the last segment is set to a value "Y (Yes)" to indicate that it is the last.

17 shows a transmission operation according to the second embodiment of the present invention.

Referring to FIG. 17, in step 1705, transmission of a next transmission period is scheduled, and an amount of data to be transmitted is determined. Hereinafter, the amount of data to be transmitted is called a transmission capacity. In step 1710, the transmitting MAC-f entity has a MAC-f PDU requested for retransmission, for example, depending on whether an ACK / NACK is received for the MAC-f PDU transmitted in a previous transmission period. Check if it is. If retransmission is not needed, go to step 1715 and, if necessary, go to step 1725.

In step 1715, the MAC-f entity configures a MAC-f PDU to be transmitted in a next transmission period and determines a serial number to be used for the MAC-f PDU. The MAC-f entity manages a variable called VT (S) whose initial value is 0. The VT (S) is incremented by one each time the MAC-f PDU is first transmitted. When the MAC-f PDU to be configured in the next transmission period is configured, the MAC-f entity sets the serial number of the MAC-f PDU to the value of the VT (S), and proceeds to step 1720 to increase the VT (S) by one. In step 1740, the MAC-f PDU is delivered to the counterpart through a lower layer.

On the other hand, if retransmission is needed, the process proceeds to step 1725 to select the MAC-f PDU with the highest retransmission priority among the buffered MAC-f PDUs. In step 1730, the MAC-f entity compares the size of the selected MAC-f PDU with the transmission capacity allocated by the schedule and determines whether segmented retransmission is necessary. If the transmission capacity is greater than or equal to the size of the selected MAC-f PDU, split retransmission is not necessary. In step 1740, the MAC-f entity delivers the selected MAC-f PDU to the counterpart through a lower layer. On the other hand, if the transmission capacity is smaller than the size of the selected MAC-f PDU, split retransmission is required and the flow proceeds to step 1735.

In step 1735, the MAC-f entity divides the selected MAC-f PDU according to the transmission capacity and sets a header of the divided MAC-f PDU. If the split MAC-f PDU is split from the original MAC-f PDU (the first undivided MAC-f PDU), a retransmission subheader consisting of a start pointer and an LSI in the MAC-f header of the original MAC-f PDU. Add to set the header of the divided MAC-f PDU. If the split MAC-f PDU is split from a parent MAC-f PDU that has been previously split, the MAC-f header of the parent MAC-f PDU already has a retransmission subheader, so the MAC-f entity is The start pointer and the LSI of the retransmission subheader are updated. In step 1740, the divided MAC-f PDU is delivered to the counterpart through a lower layer.

18 illustrates a receiving operation according to a second embodiment of the present invention.

Referring to FIG. 18, after the MAC-f PDU is received in step 1805, the receiving MAC-f entity determines whether the MAC-f PDU includes a retransmission subheader in step 1810. Determine if it is. If the MAC-f PDU has been retransmitted, go to step 1825; otherwise, go to step 1815.

In step 1815, the MAC-f entity stores the MAC-f PDU in the receiving buffer according to the serial number until the 'transfer condition to the upper layer' is satisfied, and proceeds to step 1845. The 'delivery condition to the upper layer' is differently defined in some cases. For example, if the receiving buffer is set to 'in-sequence delivery', the 'delivery condition to higher layer' is not received among MAC-f PDUs having a serial number lower than that of the MAC-f PDU. Satisfied when there is no PDU (ie gap). When the 'delivery condition to the upper layer' is established, the reception buffer reconfigures the MAC-f PDUs into an upper layer packet and then delivers the MAC-f PDUs to the upper layer. On the other hand, if the receive buffer is set to 'out of sequence delivery', the receive buffer reconfigures MAC-f PDUs that can be reconfigured into higher layer packets among the received MAC-f PDUs into higher layer packets. Then pass it to the upper layer. In this case, the MAC-f PDUs are reordered in an upper layer. In other words, in 'order order delivery', the MAC-f PDUs are delivered to the upper layer according to the received order, and in 'order ignore delivery', the MAC-f PDUs are delivered to the upper layer regardless of the received order.

In step 1825, the MAC-f entity stores the MAC-f PDU in the reception buffer according to the serial number and the start pointer. In step 1830, the MAC-f entity checks whether the MAC-f PDUs stored in the reception buffer can be assembled. Assembly is possible if the following conditions are met.

1. Arrange the MAC-f PDUs with the same serial number in order from smallest to largest.

2. If the LSI of the last MAC-f PDU among the arranged MAC-f PDUs is 'Y' and the MAC-f PDUs are contiguous, a MAC-f entity converts the MAC-f PDUs into a parent MAC-f PDU. Assemble

Continuous here means that the following conditions are met:

When MAC-f PDUs having the same serial number are arranged according to the start pointers, if the start pointers and the lengths of the adjacent MAC-f PDUs are as follows, the adjacent MAC-f PDUs are contiguous.

SP (x + 1) = SP (x) + Length (x)

Here, SP (x + 1) means the start pointer of the x + 1th MAC-f PDU among the MAC-f PDUs having the same serial number, and SP (x) indicates the start pointer of the xth MAC-f PDU. Length (x) means the size of the x-th MAC-f PDU.

If there are no MAC-f PDUs that can be assembled in step 1830, the process proceeds to step 1845 and waits for the arrival of the next MAC-f PDU. On the other hand, if there are MAC-f PDUs that can be assembled in step 1830, the process proceeds to step 1835, and the MAC-f entity assembles MAC-f PDUs having the same serial number into a parent MAC-f PDU, and in step 1840 The parent MAC-f PDU is stored in the reception buffer according to the serial number until the condition 'delivery to the upper layer' is satisfied, and the process proceeds to step 1845.

<< third embodiment >>

In the first and second embodiments of the present invention described above, there is no relationship between the serial number and the higher layer packet. However, when one higher layer packet corresponds to one MAC-f PDU, a separate length indicator is not required, so the header format is simplified. Therefore, in the third embodiment of the present invention, one undivided MAC-f PDU corresponds to one upper layer packet, and a serial number is assigned to each higher layer packet.

19 shows a frame format according to a third embodiment of the present invention.

Referring to FIG. 19, the MAC-m PDU 1905 includes at least one multiplexed header 1930 and at least one MAC-f PDU 1910. Each multiplex header 1930 includes multiplexing information for each MAC-f PDU 1910 to be stored. For example, the multiplexing information includes a length field 1920 and F1 indicating the size of the multiplexing identifier 1915 and the MAC-f PDU 1910 indicating the identifier of the MAC-f entity to which the MAC-f PDU 1910 belongs. Bit 1925. The F1 bit 1925 is a 1-bit flag indicating whether the next byte is another multiplexing information 1927 or a MAC-f PDU 1910.

Each MAC-f PDU 1910 consists of a MAC-f header 1938 and a MAC-f payload 1955, with the MAC-f payload 1955 'part of the IP packet' or 'one intact IP'. Packet 'is stored. In the MAC-f header 1938, a serial number 1935, a partition index 1940, an F2 bit 1937, and an LSI 1942 of the MAC-f PDU 1910 are inserted. Herein, the F2 bit 1937 is a 1-bit flag indicating whether the split subheader 1946 is present. The partition subheader 1946 is composed of a partition index 1940 and an LSI 1942. The partition index 1940 is an integer that monotonically increases by 1 starting from 0, and indicates the number of segments of the corresponding MAC-f PDU. As in the first embodiment of the present invention, the division may be made over several levels.

The LSI 1942 is a value indicating whether the corresponding segment is the last segment at the corresponding segment level. Each split subheader 1946 further includes an F3 bit 1944 indicating whether another split subheader 1944 is followed or a payload 1955 is followed.

An example of split transmission and split retransmission according to the third embodiment will now be described with reference to FIG. 20. For convenience of description, MAC-f (s0, s1, .., sn) denotes a MAC-f PDU whose serial number is s0, the segment index of the first segment level is s1, and the segment index of the nth segment level is sn. Shall be.

As shown, there are three IP packets 2005, 2010 and 2015 to be transmitted. In the third embodiment of the present invention, one serial number is assigned to one upper layer packet, so that serial number 0 is assigned to the first IP packet 2005, serial number 1 is assigned to the second IP packet 2010, and third IP packet ( 2015) is assigned a serial number 2. Then the first IP packet 2005 becomes MAC-f PDU [0], the second IP packet 2010 becomes MAC-f PDU [1], and the third IP packet 2015 becomes MAC-f PDU [2]. do.

When attempting to transmit the first MAC-f PDU [0] (2005), if the channel condition is not sufficient to send the MAC-f PDU [0] (2005), the sender sends the MAC-f PDU [0]. Splitting, and inserting the divided sub-headers in the divided parts, and configures and transmits the MAC-f PDU [0, 0] 2020 and MAC-f PDU [0, 1] 2025. The LSI of the MAC-f PDU [0,1] is set to 'Y'.

When the MAC-f PDU [1] (2010) is not allocated because the allocated transmission resources are sufficient, the MAC-f PDU [1] (2010) is transmitted as shown by reference numeral 2030 without a split subheader. .

Due to the poor channel situation again upon transmission of the MAC-f PDU [2] (2015), the MAC-f PDU [2] (2015) is divided into five segments. At this time, if the size of the partition index is limited to 2 bits, the transmitter overcomes the limitation of the partition index by partitioning the MAC-f PDU [2] (2015) in several steps.

That is, MAC-f PDU [2] (2015) is MAC-f PDU [2,0] (2035), MAC-f PDU [2,1] (2040), MAC-f PDU [2,2] (2045) ), And the remaining data is divided into MAC-f PDUs [2, 3, 0] (2050) and MAC-f PDUs [2, 3, 1] (2055). This is because the size of the MAC-f PDU [2.3] containing all of the remaining data is too large and the partition index does not allow 3 or more.

The split transmission is equally applicable to retransmission. For example, if retransmission is necessary for the MAC-f PDU [0,0] 2020, but the MAC-f PDU [0,0] 2020 cannot be retransmitted at the same time, the transmitting side sends the MAC-f PDU [ 0,0] 2020 is divided into MAC-f PDU [0,0,0] 2060 and MAC-f PDU [0,0,1] 2065 for transmission. Similarly, the LSI of the MAC-f PDU [0.0.1] 2065 is set to 'Y'.

21 shows a structure of a transmitter according to a third embodiment of the present invention.

Referring to FIG. 21, the transmitter includes a serial number insertion block 2102, a transmission buffer 2105, a partition block 2115, a MAC-f control block 2120, a retransmission buffer 2125, a multiplexing block 2130, and HARQ. It consists of a block and a physical layer 2135. The dual serial number insertion block 2102, the transmission buffer 2105, the partition block 2115, the MAC-f control block 2120, and the retransmission buffer 2125 constitute a MAC-f entity. Although only one MAC-f entity is shown here, a plurality of MAC-f entities for a plurality of services may be provided.

The serial number insertion block 2115 serves to assign a serial number to packets (eg, IP packets) delivered from a higher layer. The serial number is monotonically increased by one for each IP packet. The transmission buffer 2105 stores the serial number-inserted IP packets until they are transmitted over the wireless channel. The packet having the serial number inserted therein is called a MAC-f PDU.

The multiplexing block 2130 determines the amount of data to be transmitted in the next transmission period for each MAC-f entity according to the radio transmission resource allocated by the Node B scheduler, and notifies the MAC-f control block 2120. The MAC-f control block 2120 determines data to be transmitted in the next transmission period according to the priority of initial transmission and retransmission. If it decides to send a new IP packet in the next transmission period, the MAC-f control block 2120 notifies the transmission buffer 2105 of the amount of data to send. If it is decided to execute retransmission in the next transmission period, the MAC-f control block 2120 notifies the retransmission buffer 2125 of the amount of data to retransmit.

The transmit buffer 2105 transfers the stored MAC-f PDUs to the retransmission buffer 2125 and the multiplexing block 2130 if the split transmission is not necessary, and transfers the stored MAC-f PDUs to the partition block 2115 if the split transmission is necessary. To pass.

The division block 2115 divides the MAC-f PDU received from the transmission buffer 2105 into an appropriate size, inserts a partition index and an LSI, and then transmits the divided MAC-f PDUs in the next transmission period among the divided MAC-f PDUs. The MAC-f PDU is delivered to a multiplexing block 2130. Then, all the divided MAC-f PDUs including the MAC-f PDU delivered to the multiplexing block 2130 are delivered to the retransmission buffer 2125.

The retransmission buffer 2125 stores the MAC-f PDUs, and discards or schedules retransmission of the stored MAC-f PDUs under the control of the MAC-f control block 2120.

The multiplexing block 2130 multiplexes MAC-f PDUs delivered from multiple MAC-f entities into one MAC-m PDU and inserts multiplex headers into the MAC-m PDU. The MAC-m PDU is transmitted by the HARQ block and the physical layer 2135 through a HARQ operation to a wireless channel.

22 is a block diagram showing a receiver structure according to a third embodiment of the present invention.

Referring to FIG. 22, a transmitter is composed of an assembly block 2205, a reception buffer 2210, a retransmission management block 2215, a demultiplexing block 2220, an HARQ block, and a physical layer 2225. The dual assembly block 2205, the receive buffer 2210, and the retransmission management block 2215 constitute a MAC-f entity. Although only one MAC-f entity is shown here, a plurality of MAC-f entities for a plurality of services may be provided.

The HARQ block and the physical layer 2225 perform a HARQ process on the MAC-m PDU through a physical channel, and transfer the successfully received MAC-m PDU to the demultiplexing block 2220 through the HARQ process. The demultiplexing block 2220 interprets the multiplex headers of the MAC-m PDU delivered from the HARQ block and the physical layer 2225, demultiplexes the MAC-m PDU into a plurality of MAC-f PDUs, and then demultiplexes the demultiplexing block. The MAC-f PDUs are transmitted to MAC-f entities indicated by corresponding multiplexing headers.

The reception buffer 2210 stores the MAC-f PDUs received from the demultiplexing block 2220 in a position according to the serial number, and sets MAC-f PDUs that can be assembled among the stored MAC-f PDUs to the assembly block 2205. To pass. Here, assembling MAC-f PDUs means MAC-f PDUs arranged in sequence of serial numbers without a gap. The retransmission management block 2215 checks the serial and minor serial numbers of the MAC-f PDUs stored in the reception buffer 2210 and transmits ACK / NACK to the counterpart ARQ entity. In this case, the NACK is transmitted to request retransmission of a specific MAC-f PDU that has not been received, or is transmitted when it is not sure which MAC-f PDU should be retransmitted. The assembly block 2205 reconstructs the divided MAC-f PDUs among the MAC-f PDUs into original IP packets by referring to the partition index and the LSI of the MAC-f PDUs delivered from the reception buffer 2210. The IP packet is delivered to an upper layer.

23 is a flowchart showing a transmission operation according to the third embodiment of the present invention.

Referring to FIG. 23, in step 2305, transmission of the next transmission period is scheduled, and an amount of data to be transmitted is determined. Hereinafter, the amount of data to be transmitted is called a transmission capacity. In step 2310, the transmitting MAC-f entity selects a MAC-f PDU to be transmitted among MAC-PDUs stored in the transmission buffer and the retransmission buffer. That is, the MAC-f PDU stored in the retransmission buffer is selected when retransmission is required for the MAC-f PDU transmitted in the previous transmission period, and the MAC-f PDU stored in the transmission buffer is selected when retransmission is not required.

In step 2315, the MAC-f entity compares the size of the selected MAC-f PDU with the transmission capacity to determine whether partitioning is necessary for the selected MAC-f PDU. Partitioning is not necessary if the transmission capacity is greater than or equal to the size of the selected MAC-f PDU, and partitioning is necessary if the transmission capacity is smaller than the size of the selected MAC-f PDU. If partitioning is required, the process proceeds to step 2320, and if partitioning is not required, the process proceeds to step 2330, and the MAC-f PDU is delivered to a lower layer and transmitted through a wireless channel.

In step 2320, the MAC-f entity divides the selected MAC-f PDU into an appropriate size according to the transmission capacity, and in step 2325, a partition composed of a partition index and an LSI in a MAC-f header of the partitioned MAC-f PDU After inserting the sub-header, in step 2330, the MAC-f PDU is delivered to a lower layer and transmitted through a wireless channel.

24 is a flowchart showing the receiving side operation of the third embodiment of the present invention.

Referring to FIG. 24, after the MAC-f PDU is received in step 2405, the receiving MAC-f entity determines whether the MAC-f PDU includes a split subheader in step 2410. To judge. If the divided MAC-f PDU, go to step 2425; otherwise, go to step 2415.

In step 2415, the MAC-f entity stores the MAC-f PDU in the reception buffer according to the serial number until the 'transfer condition to the upper layer' is satisfied, and proceeds to step 2445. The 'delivery condition to the upper layer' is defined depending on the situation. For example, if the receiving buffer is set to 'in-sequence delivery', the 'delivery condition to higher layer' is not received among MAC-f PDUs having a serial number lower than that of the MAC-f PDU. Satisfied when there is no PDU. When the 'delivery condition to the upper layer' is established, the reception buffer reconfigures the MAC-f PDUs into an upper layer packet and then delivers the MAC-f PDUs to the upper layer. On the other hand, if the receive buffer is configured to operate in 'out of sequence delivery', the receive buffer is a higher layer packet of MAC-f PDUs that can be reconstructed into higher layer packets among the received MAC-f PDUs. After reconstructing it, we pass it to the upper layer. In other words, in 'order order delivery', the MAC-f PDUs are delivered to the upper layer according to the received order, and in 'order ignore delivery', the MAC-f PDUs are delivered to the upper layer regardless of the received order.

In step 2425, the MAC-f entity stores the MAC-f PDU in the reception buffer according to the serial number and the partition index.

In step 2430, the MAC-f entity checks whether the MAC-f PDUs stored in the reception buffer are assembled, that is, whether there are MAC-f PDUs that can be assembled. Assembly is possible if the following conditions are met.

1. At a given segment level, MAC-f PDUs with the same 'serial number and partition indexes' except for the last partitioning index are grouped into one partitioned MAC-f PDU set. For example, MAC-f PDUs [12,0,0] and MAC-f PDUs [12,0,1] are grouped into the same split MAC-f PDU set. On the other hand, MAC-f PDUs [12,0,0] and MAC-f PDUs [12,1,1] are not the same divided MAC-f PDU sets. Herein, the divided MAC-f PDU set refers to divided MAC-f PDUs that can be assembled into a higher level MAC-f PDU (ie, a parent MAC-f PDU). The divided MAC-f PDUs of the -f PDU set are assembled into higher MAC-f PDUs.

2. If MAC-f PDUs of the MAC-f PDUs belonging to a given partitioned MAC-f PDU set, the last partitioning indexes from the MAC-f PDU whose last partitioning index is 0 to the MAC-f PDU with LSI set to 1 are contiguous, -f PDU set can be assembled.

In step 2435, the MAC-f entity assembles the assembled MAC-f PDUs. The split MAC-f PDU set is assembled into a higher level MAC-f PDU as shown below.

1. The payloads of all MAC-f PDUs included in the divided MAC-f PDU set are concatenated in order to be the payload of the upper level MAC-f PDU.

2. The header of the high level MAC-f PDU is configured as follows.

2.1. Select one of the MAC-f PDUs included in the divided MAC-f PDU set, and remove the last sub-header from the MAC-f header of the selected MAC-f PDU. -f header.

3. When the header and payload of the higher level MAC-f PDU are combined, the assembly of the higher level MAC-f PDU is completed.

In step 2440, the MAC-f entity stores the assembled high-level MAC-f PDU in the reception buffer until the 'delivery condition to the upper layer' is satisfied and proceeds to step 2445. On the other hand, if there are no MAC-f PDUs that can be assembled in step 2430, the process proceeds to step 2445 and waits for the arrival of the next MAC-f PDU.

In the following, the use of the implicit NACK described above is described in more detail.

In a system supporting retransmission, the receiving side generates a status report when the predetermined condition is met and transmits it to the transmitting side. In the status report, the last serial number of a successfully received PDU and the serial number of the PDU (s) requiring retransmission are stored until the status report is generated, and the serial number of the PDU requiring retransmission is NACK. The receiving side checks whether the serial numbers of the received PDUs are consecutive to confirm a gap on the serial numbers. If there is a gap, a PDU having a serial number corresponding to the gap is regarded as an unreceived PDU, and the status report stores a NACK indicating a serial number for the unreceived PDU, and transmits a retransmission of the unreceived PDU. Ask.

However, when the PDU is divided, the receiving side may not be able to identify a gap on the serial numbers. For example, among three segments, an 'indicator indicating the last segment', that is, a segment including an LSI may not be received. In this case, the receiver recognizes that there is an unreceived PDU, but cannot know the serial number of the unreceived PDU. In this case an implicit NACK is used.

25 illustrates an example of using an implicit NACK according to a preferred embodiment of the present invention.

Referring to FIG. 25, the transmitting side 2505 transmits a PDU [14] 2515, a PDU [15.0] 2520, a PDU [15.1] 2525, a PDU [15.2] 2530, to a receiving side 2510. PDU [15.3] (2535), PDU [16] (2540), PDU [17] (2545) is transmitted. That is, for some reason, PDU [15] has been divided into four segments, PDU [15.0] 2520, PDU [15.1] 2525, PDU [15.2] 2530, PDU [15.3] (2535) Each segment associated with the PDU [15] is included to form the same segment set 2585. The PDU [15.3] 2535 including the last segment of the segment set 2585 has an LSI set to '1'.

As shown at 2570, the PDU [15.3] 2535 containing the last segment of the set of segments 2585 having serial number 15 is lost without being successfully received at the receiving side 2510. Since the receiving side 2510 received the PDUs [15.0] to PDUs [15.2] but did not receive the information indicating the last segment (that is, the LSI), at least one unreceived PDU having a serial number greater than that of the PDU [15.2] was received. Recognize that it exists. However, the receiving side 2510 may not know whether there is only one unreceived PDU or two or more unreceived PDUs having a larger serial number.

In this case, the receiver 2510 transmits an implicit NACK through a status report.

26 is a flowchart illustrating an operation of transmitting an implicit NACK according to a preferred embodiment of the present invention.

Referring to FIG. 26, in step 2605, a condition for generating a status report is satisfied. The generation condition may be, for example, a case where a status report generation time point according to a predetermined cycle is reached, or a command to transmit a status report is received from a transmitting side. In step 2610, the receiving side checks the serial numbers of successfully received PDUs until the condition of generating the status report is satisfied, confirms the serial numbers of the unreceived PDUs, and then constructs an explicit NACK for the unreceived PDUs. Stored in the status report. In step 2615, the receiver checks whether there is an unreceived PDU whose serial number cannot be confirmed. If there is an unreceived PDU whose serial number cannot be confirmed, the operation proceeds to step 2620, and if not, the operation proceeds to step 2625. In step 2615, if there is an unreceived PDU that can confirm the serial number, in step 2625, the receiving side generates an explicit NACK including the serial number of the unreceived PDU, and puts the explicit NACK in the status report to the sender send.

A more detailed description of step 2615 is as follows. The receiving side checks whether there is a segment set in which the PDU in which the indicator indicating the last segment is set to '1' is not received among the segment sets including the PDUs whose assembly is not completed after receiving. If there is a segment set that satisfies the above condition, since there is an unreceived PDU whose serial number cannot be confirmed, the flow proceeds to step 2620. The segment set is a set of PDUs divided from the same PDU, share the same serial number, and are distinguished from each other by sub-serial numbers. If the segment is advanced over several levels, the divided PDUs belonging to the segment set have the same sub serial numbers except the serial number and the last sub serial number, and are divided into the last sub serial numbers.

In step 2620, the receiver receives the serial number of the highest PDU belonging to the segment set that satisfies the condition of step 2615 among the received PDUs in the implicit NACK and proceeds to step 2625. In the example of FIG. 25, serial number [15.2] is reported via implicit NACK. In other words, if a partitioned PDU indicating that the last segment is not received among the partitioned PDUs that are not yet assembled, the highest serial number among the partitioned PDUs that are not assembled is stored in the implicit NACK.

In step 2625, the receiving side transmits a status report including the implicit NACK to the transmitting side.

27 is a flowchart illustrating an operation of receiving an implicit NACK according to a preferred embodiment of the present invention.

Referring to FIG. 27, after a status report is received in step 2705, the transmitter checks whether an implicit NACK is stored in the status report in step 2710, and proceeds to step 2720 if the implicit NACK is not received. The format of the NACK can be known from the type value of the NACK included in the status report. If the implicit NACK is stored, the transmitter proceeds to step 2715 and schedules retransmission in response to the implicit NACK, and proceeds to step 2720. In detail, in step 2715, the transmitting side checks the serial number stored in the implicit NACK, and retransmits the PDUs having the serial number higher than the serial number in the segment set corresponding to the serial number. Here, the segment set corresponding to a specific serial number refers to PDUs belonging to the same segment set as the PDU having the specific serial number.

For example, in the case of FIG. 25, if the serial number [15.2] is stored in the implicit NACK, the segment set corresponding to the serial number is PDU [15.0], PDU [15.1], PDU [15.2], and PDU [15.3]. . Since the PDU having a serial number higher than the serial number [15.2] is a PDU [15.3], the transmitting side schedules retransmission of the PDU [15.3].

In step 2720, the transmitter properly processes the remaining state information except for the implicit NACK. That is, for normal explicit NACK, retransmission of PDUs corresponding to the serial numbers is performed, and for ACK, PDUs corresponding to the serial numbers are discarded in the retransmission buffer.

On the other hand, the use of the implicit NACK as described above is applicable to all kinds of systems that receive and transmit the data packet to be transmitted in a plurality of PDUs, and whether the successful reception of the PDUs from the receiving side. As a specific example, the RLC layer responsible for establishing and releasing logical channels in a UMTS system may include an acknowledgment mode (hereinafter referred to as AM mode), an unacknowledged mode (hereinafter referred to as UM mode), and a transmission mode ( Transparent mode (hereinafter, referred to as TM mode).

In this case, an RLC layer (hereinafter, referred to as an RLC AM layer) operating as an AM divides, concatenates, or pads data transmitted from an upper layer, that is, an RLC service data unit (hereinafter, referred to as an RLC SDU). The RLC PDU is transferred to a lower layer by creating a protocol data unit (hereinafter referred to as RLC PDU) by inserting the serial number and information on the division / concatenation / padding. do. The RLC AM layer of the receiver checks the serial numbers of the RLC PDUs transmitted by the transmitter to determine whether there is a PDU that has not been received, and performs a retransmission request when there is a PDU that has not received.

As such, the RLC AM layer performs retransmission by identifying unreceived PDUs. Hereinafter, the operation of the RLC AM layer will be described in more detail with reference to FIG. 28. Here, the side for transmitting user data is called an RLC transmitting entity 2810, and the side for receiving user data and transmitting a status report is called an RLC receiving entity 2805. In the case of HSDPA, the RLC transmitting entity 2810 is included in the terminal, and the RLC receiving entity 2805 is provided in the RNC.

Referring to FIG. 28, an RLC transmitting entity 2810 transmits a serial number to user data called an RLC PDU. For convenience of explanation, the RLC PDU having a serial number x will be referred to as an RLC PDU [x].

The RLC receiving entity 2805 examines the serial numbers of the RLC PDUs 2815, 2820, 2825, 2830 transmitted by the RLC transmitting entity 2810 to determine whether there is an unreceived PDU. For example, if an RLC PDU [x + 2] 2825 is lost during transmission, the RLC receiving entity 2805 receives an RLC PDU [x + 3] 2830 and then receives an RLC PDU [x + 2] 2825. It is recognized that is lost and that it must request retransmission for the RLC PDU [x + 2] 2825. Thereafter, the RLC receiving entity 2805 may transmit feedback information called a STATUS PDU to the RLC transmitting entity 2810 to request retransmission.

The RLC receiving entity 2805 transmits a STATUS REPORT 2835 periodically or when a specific event occurs to notify the RLC transmitting entity 2810 of the reception status. STATUS REPORT 2835 includes ACK, which is the serial numbers of RLC PDUs received from RLC transmitting entity 2810, and NACK, which is the serial numbers of RLC PDUs not received. The RLC transmitting entity 2810 executes retransmission for the RLC PDUs marked NACK in the STATUS REPORT 2835 to increase the reliability of the communication.

In the RLC AM layer operation as described above, as described above, there may be a case in which the receiving side does not know exactly which RLC PDU has not been received, but the RLC PDU loss is likely to occur. As a specific example, in High Speed Downlink Packet Access (HSDPA) that implements high-speed forward data communication, when a terminal receiving data moves to a cell (ie, a target cell) controlled by a new base station through handover, The base station can not know the data remaining in the transmission from the previous base station to the terminal. To solve this problem, when the terminal moves to a new base station, the terminal transmits a STATUS REPORT to the new base station to execute retransmission in the RLC layer. In this way, however, retransmission of the data remaining in the previous base station is not performed.

29 is a signaling flowchart illustrating an HSDPA cell change procedure.

Referring to FIG. 29, in step 2925, the RNC 2920, which controls radio resources of the UE 2905, transmits RLC PDUs to a source cell 2910. In operation 2930, the cell change starts when a measurement report of the terminal 2905 that the channel environment of the target cell 2915 is better than the source cell 2910 is transmitted to the RNC 2920.

Upon receiving the measurement report, the RNC 2920 stops transmitting RLC PDUs to the source cell 2910 at step 2935, and establishes a new communication link for the terminal 2905 at the target cell 2915 at step 2940. Release the communication link of the source cell 2910. When the communication link of the source cell 2910 is released, the communication to the terminal 2905 is stopped in the source cell 2910, and thus, in step 2945, the RLC is not transmitted to the terminal 2905 in the transmission buffer of the source cell 2910. PDUs may remain.

The RNC 2920 instructs the terminal 2905 to handover to the target cell 2915 in step 2950, and when receiving a response message indicating that the handover is completed from the terminal 2905 in step 2955, the RLC PDU in step 2960. Start transmitting to the target cell 2915. The UE 2905 handing over to the target cell 2915 sends a STATUS REPORT to the RNC 420 in step 2965 to request retransmission at the RLC level for RLC PDUs not received at the source cell 2910. . The RNC 2920 then retransmits the PDUs NACKed in the STATUS REPORT in step 2970.

However, the above scheme has a disadvantage in that a STATUS REPORT containing only a reception state from the source cell cannot request retransmission for PDUs not transmitted in the source cell.

This situation will be described in more detail with reference to FIG. 30. The terminal 3035 moves to the target cell 3025 at some point while performing communication in the source cell 3020, and receives an RLC PDU (that is, PDU [x]) having a serial number x to receive a buffer 3030. Saved in At this time, the PDUs [x + 1] to PDU [x + 4] are not transmitted to the terminal 3035 while being stored in the transmission buffer 3015 of the source cell 3020. Therefore, the RLC transmit buffer 3010 of the RNC 3005 stores PDUs [x + 5] and PDUs with higher serial numbers.

If the terminal 3035 transmits the STATUS REPORT 3050 as soon as it moves to the target cell 3025, only the information indicating that the PDU [x] is well received is written in the STATUS REPORT 3050 of the terminal 3035. Therefore, the RNC 3005 does not recognize that the UE 3035 needs to retransmit PDU [x + 1] to PDU [x + 4].

In the following embodiment, implicit NACK is used in this case.

31 illustrates an example of an implicit NACK usable for RLC AM layer operation during handover according to a preferred embodiment of the present invention. Unlike the format of the implicit NACK described above, only one serial number field 3110 is included here.

Referring to FIG. 31, a type field 3105 includes a type value indicating implicit NACK. In the RLC standard of 3GPP, 4 bits are used as the type field 3105, and the use of 1000 to 1111 is not defined. Therefore, one of the unused type values can be used to indicate an implicit NACK. The highest serial number of the RLC PDU received by the RLC receiving entity is inserted into the serial number field 3110 of the implicit NACK. In the example of FIG. 30, a serial number x is inserted into the serial number field 3110.

The RLC transmitting entity receiving the implicit NACK having such a configuration executes retransmission for RLC PDUs having serial numbers higher than the serial number field 3110 of the implicit NACK. In the example of FIG. 30, RLC PDUs [x + 1] to PDU [x + 4] will be retransmitted.

32 is a diagram illustrating a transmission / reception operation of an RLC AM layer during handover according to an embodiment of the present invention. Here, the operation according to the high speed downlink packet access (HSDPA) in the UMTS system is shown.

Referring to FIG. 32, in step 3220, the RNC 3215 determines that the UE 3205 performs a handover to the target cell 3210. Then, the RNC 3215 sets the target cell 3210 to perform packet data communication with the terminal 3205 in step 3225, and instructs the terminal 3205 to handover to the target cell 3210 in step 3230. . A TRANSPORT CHANNEL RECONFIGURATION message may be used as the handover command.

The terminal 3205 establishes a communication link with the target cell 3210 according to the configuration information of the TRANSPORT CHANNEL RECONFIGURATION message, and indicates that the transmission channel setting for the target cell 3210 has been completed in step 3235. Send a message to the RNC 3215.

As described above, when the UE 3205 hands over to the target cell 3210, it is assumed that there is at least one RLC PDU that is not recognized successfully from the network. Accordingly, in step 3240, the terminal 2205 transmits a STATUS REPORT including an implicit NACK to the RNC 3215.

33 illustrates an operation of an RLC receiving entity when changing a cell according to an embodiment of the present invention.

Referring to FIG. 33, when the UE completes the handover to the target cell in step 3305, the RLC receiving entity provided in the UE is instructed to transmit a STATUS REPORT from the entity managing the handover in step 3310. The RLC receiving entity then constructs an implicit NACK in step 3315. In the implicit NACK, the serial number of the PDU having the highest serial number among the PDUs received so far by the RLC receiving entity is written. In step 3320, the RLC receiving entity transmits a STATUS REPORT including the implicit NACK to the RNC controlling the radio resource of the UE. In this case, the status report may be transmitted to the RNC through the target cell.

As described above, although the terminal may transmit an implicit NACK immediately after completing the handover, the terminal may transmit an implicit NACK immediately before or after the handover is executed.

34 illustrates an operation of an RLC receiving entity when changing a cell according to another embodiment of the present invention.

Referring to FIG. 34, if the UE determines to start handover to the target cell in step 3405, the RLC receiving entity provided in the UE is instructed to transmit a STATUS REPORT from the RRC layer in step 3410. Here, the handover of the terminal can be started by receiving a message instructing to execute the handover from the network, and is completed by sending a message to the network that the handover is completed. Therefore, when the RRC layer of the UE receives the handover command, it instructs to transmit the STATUS REPORT to the RLC receiving entity.

The RLC receiving entity of the UE commanded to transmit the STATUS REPORT configures an implicit NACK in step 3415. In the implicit NACK, the serial number of the PDU having the highest serial number among the PDUs received so far by the RLC receiving entity is written. In step 3420, the RLC receiving entity transmits a STATUS REPORT including the implicit NACK to the RNC controlling the radio resource of the terminal. In this case, the STATUS REPORT may be delivered to the RNC through the source cell.

35 illustrates an operation of an RLC transmitting entity in cell change according to a preferred embodiment of the present invention.

Referring to FIG. 35, in step 3505, the RLC transmitting entity provided to the RNC receives a status report including an implicit NACK from the terminal. In step 3510, the RLC transmitting entity retransmits packets having a serial number higher than the serial number written in the implicit NACK.

Hereinafter, another embodiment for solving a problem in which the UE does not know a PDU not received during handover is disclosed.

In general, in order to recognize that the UE has not received a specific PDU, a PDU having a higher serial number than the specific PDU should be received. That is, referring to the example of FIG. 30, the UE must first receive the PDU [x + 5] to recognize that it needs to request retransmission for the PDU [x + 1] to PDU [x + 4].

Therefore, in an embodiment to be described later, the terminal does not transmit the status report to the RNC immediately after moving to the target cell, but receives at least one PDU from the target cell and then transmits the status report. Through this, the UE can efficiently request retransmission for PDUs that were not transmitted in the source cell.

36 is a signaling flowchart illustrating a transmission operation of a status report when a cell is changed according to an exemplary embodiment of the present invention.

Referring to FIG. 36, in step 3620, the RNC 3615 determines that the UE 3605 performs a handover to the target cell 3610. The RNC 3615 sets the target cell 3610 to perform packet data communication with the terminal 3605 in step 3625, and instructs the terminal 3605 to handover to the target cell 3610 in step 3630. . A TRANSPORT CHANNEL RECONFIGURATION message may be used for the handover command.

The terminal 3605 establishes a communication link with the target cell 3610 according to the configuration information of the TRANSPORT CHANNEL RECONFIGURATION message, and indicates that the transmission channel setting for the target cell 3610 is completed in step 3635. Send a message to the RNC 3615.

In addition, the UE 3605 waits until the first RLC PDU arrives from the target cell 3610 after the handover to the target cell 3610. When the first RLC PDU is received from the target cell 3610 in step 3640, the UE 3605 transmits a status report indicating an RLC PDU successfully received to the RNC 3615 and an RLC PDU that failed to be received in step 3645.

On the other hand, if the data that was not transmitted in the source cell is the last data, new data will not be transmitted from the target cell. Thus, a timer was introduced in the operation of the terminal shown in FIG. 37 to prepare for such a case.

37 is a flowchart illustrating an operation of an RLC receiving entity of a terminal when a cell is changed according to an exemplary embodiment of the present invention.

Referring to FIG. 37, when the UE completes the handover to the target cell in step 3705, the RLC receiving entity provided in the UE is instructed to transmit a STATUS REPORT from the entity managing the handover in step 3710. The RLC receiving entity then drives a timer set to a predetermined time preset in step 3715 and proceeds to step 3720.

In step 3720, the RLC receiving entity monitors whether an RLC PDU is received from a target cell. However, since it is difficult to actually determine whether the RLC receiving entity receives data from the target cell due to the hierarchical structure of the UE, the RLC receiving entity is an RLC PDU received from the target cell after step 3710. Can be considered.

If the UE receives the first RLC PDU after the handover, the UE branches to step 3730 and transmits a STATUS REPORT to the RLC and ends the operation. On the other hand, if the RLC PDU has not been received, the process branches to 3725.

In step 3725, the RLC receiving entity checks whether the timer driven in step 3715 has expired. If the timer has expired, the terminal proceeds to step 3730 and transmits a STATUS REPORT and ends the operation. If the timer has not expired, the process returns to step 3720 to check whether an RLC PDU is received.

In the above-described embodiment, when the UE moves to the target cell, the UE successfully restores the RLC PDUs remaining in the previous cell by generating a STATUS REPORT after receiving the first RLC PDU from the target cell. However, if the first RLC PDU transmitted from the target cell is an RLC PDU retransmitted, the serial number of the retransmitted RLC PDU is lower than the RLC PDU remaining in the previous cell, and thus the UE cannot recover the remaining RLC PDUs. Therefore, in an embodiment to be described later, when the UE moves to the target cell, after receiving the first RLC PDU transmitted instead of the RLC PDU retransmitted from the target cell, a STATUS REPORT is generated.

38 is a flowchart illustrating a transmission operation of a status report according to another embodiment of the present invention.

Referring to FIG. 38, when the UE completes the handover to the target cell in step 3805, the RLC receiving entity provided in the UE is instructed to transmit a STATUS REPORT from the entity managing the handover in step 3810.

The RLC receiving entity then waits until an RLC PDU is received from the target cell in step 3815. If the RLC PDU is received, the RLC receiving entity proceeds to step 3820 to check whether the received RLC PDU is retransmitted. Whether the received RLC PDU is retransmitted can be determined by checking whether the received RLC PDU updates VR (H). Here, VR (H) is a variable that stores a value obtained by adding 1 to the highest serial number among the serial numbers of RLC PDUs received by the RLC receiving entity up to this point in time. When the RLC receiving entity receives a new RLC PDU, it compares the serial number of the received RLC PDU with the stored VR (H) and increases the VR (H) by 1 if the two values are the same. That is, VR (H) is updated with a new value.

If it is determined in step 3820 that the retransmitted RLC PDU, that is, the received RLC PDU does not update the VR (H), the RLC receiving entity branches to step 3815 and waits until a new RLC PDU is received.

On the other hand, if the result of the check in step 3820 is not a retransmitted RLC PDU, that is, if the received RLC PDU updates VR (H), the RLC receiving entity proceeds to step 3825 and configures a STATSU REPORT to transmit to the RNC. End the operation.

FIG. 39 is a diagram illustrating a structure of an apparatus for transmitting a status report when a cell is changed according to a preferred embodiment of the present invention. As shown, the apparatus includes an RLC PDU receiver 3905, a STATUS REPORT controller 3910, a MAC layer 3915 and a physical layer 3920.

Referring to FIG. 39, the physical layer 3920 is responsible for transmitting data of a higher layer to a wireless channel or receiving a signal of a wireless channel and delivering the signal to a higher layer. The MAC layer 3915 multiplexes the data of the upper layer and delivers the data to the physical layer 9320, or demultiplexes the data transmitted by the physical layer 3920 and delivers the data to the appropriate upper layer.

The RLC PDU receiver 3905 includes a reception buffer (not shown) that receives and buffers the RLC PDUs delivered by the MAC layer 3920. The RLC PDU receiver 3905 reassembles the RLC PDUs stored in the reception buffer into an RLC SDU and then a higher layer. It is in charge of conveying The STATUS REPORT control unit 3910 manages a reception state by inspecting the serial numbers of the received RLC PDUs, and when necessary, creates a STATUS REPORT and delivers it to the MAC layer 9315.

In the embodiment of FIG. 33, the STATUS REPORT control unit 3915 forms an implicit NACK upon receiving an indication signal that the handover is completed or an indication signal that the handover has started from the entity managing the handover, and generates the implicit NACK. The included STATUS REPORT is transmitted to the RNC through the MAC layer 3915 and the physical layer 3920.

In the embodiment of FIG. 36, the MAC layer 3915 monitors whether handover is completed and notifies the STATUS REPORT control unit 3910 when the handover is completed. After receiving the indication signal indicating that the handover is completed, the STATUS REPORT control unit 3915 configures and transmits a STATUS REPORT indicating a successful RLC PDU and a failed RLC PDU at the time when the first RLC PDU is received. .

40 is a diagram illustrating a structure of an apparatus for receiving a status report when a cell is changed according to a preferred embodiment of the present invention. Since the role of the transmitter is the same as in the embodiment of FIG. 36, the structure of the transmitter according to the embodiment of FIG. 33 is illustrated in FIG. As shown, the apparatus includes an RLC PDU transmitter 4005, a retransmission controller 4010, a MAC layer 4015, and a physical layer 4020.

Referring to FIG. 40, the physical layer 4020 is responsible for transmitting data of a higher layer to a wireless channel or receiving a signal of a wireless channel and transmitting the signal to the upper layer. The MAC layer 4015 multiplexes the data of the upper layer and delivers the data to the physical layer 4020, or demultiplexes the data transmitted by the physical layer 4020 and delivers the data to the appropriate upper layer.

The RLC PDU transmitter 4002 concatenates or splits an RLC SDU transmitted from an upper layer and inserts a serial number to make at least one RLC PDU and delivers it to the MAC layer 4020. The retransmission control unit 4010 receives a STATUS REPORT from the counterpart, and instructs the RLC PDU transmitter 4005 to retransmit if necessary.

In the embodiment of FIG. 33, when the retransmission control unit 4010 receives an implicit NACK included in the STATUS REPORT, the RLC to perform retransmission for RLC PDUs having a serial number higher than the serial number written in the implicit NACK. Instructs the PDU transmitter 4005.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the appended claims, but also by the equivalents of the claims.

In the present invention operating as described in detail above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

The present invention transmits an implicit NACK including a serial number of a last packet among packets successfully received so far to the transmitting side when the receiving side does not exactly know a PDU not received. It is possible to continue to send packets having serial numbers after the serial number included in. As a result, the present invention performs fast and efficient retransmission for packets that have not been successfully received.

Claims (34)

A method for transmitting a status report indicating a reception status of packet data in a mobile communication system, Determining whether an implicit NACK (negative acknowledge) transmission is required to request retransmission of at least one unreceived data packet whose serial number is unknown while receiving data packets from a transmitter; If the implicit NACK needs to be transmitted, generating the implicit NACK including the serial number of the last packet among the successfully received data packets, and transmitting a status report including the implicit NACK to the transmitter; and, If transmission of the implicit NACK is not necessary, reporting a status report comprising at least one of an ACK indicating a serial number of a successfully received data packet and an explicit NACK indicating a serial number of an unreceived data packet having a known serial number; A data receiving method comprising the step of transmitting to the transmitter. The method of claim 1, wherein the implicit NACK, A type field having a unique type value distinct from the explicit NACK for requesting retransmission of an unreceived data packet having a known serial number; And a serial number field including a serial number of the last packet. The method of claim 1, wherein the determining is performed. Determining whether there is a data set that does not include the last data packet among data sets including data packets received from the transmitter and not assembled into packets of a higher layer; And determining that there is an unreceived data packet that does not know the serial number if there is a data set that does not include the last data packet. The method of claim 3, wherein each of the data sets, And data packets divided from one original data packet. The method of claim 3, wherein each of the status reports, And when the status report generation time point according to a predetermined cycle is reached or when the status report is instructed to be transmitted from the transmitter. The method of claim 1, wherein the determining is performed. In case that the terminal receiving the data packets moves from the source cell to the target cell by handover, it is determined that the implicit NACK needs to be transmitted to a radio network controller (RNC) that controls radio resources of the terminal. How to receive data. The method of claim 6, wherein the implicit NACK, And at the start of the handover or upon completion of the handover. A method for receiving a status report indicating a reception status of packet data in a mobile communication system, Transmitting data packets to a receiver, Receiving, from the receiver, a status report indicating a reception status of the transmitted data packets; Determining whether the status report includes an implicit NACK including the serial number of the last packet among successfully received data packets to request retransmission of an unreceived data packet whose serial number is not known; If the implicit NACK is included, transmitting data packets after the last packet indicated by the implicit NACK to the receiver; If the status report does not include the implicit NACK, at least at least one of an ACK indicating a serial number of a successfully received data packet and an explicit NACK indicating a serial number of an unreceived data packet having a known serial number from the status report. Detecting one and retransmitting an unreceived data packet having the serial number indicated by the explicit NACK. The method of claim 8, wherein the implicit NACK, A type field having a unique type value distinct from the explicit NACK for requesting retransmission of an unreceived data packet having a known serial number; And a serial number field including a serial number of the last packet. 10. The method of claim 8, wherein the transmitting step, And transmitting data packets after the last packet to the receiver in a data set to which the last packet indicated by the implicit NACK belongs. The method of claim 10, wherein the data set, And data packets divided from one original data packet. The method of claim 8, wherein the status report, And receiving when a status report generation time point according to a predetermined period is reached or the receiver is instructed to transmit the status report. The method of claim 8, wherein the status report, And a terminal receiving the data packets when received from the source cell to the target cell by handover. An apparatus for transmitting a status report indicating a reception status of packet data in a mobile communication system, A data receiver for receiving and storing data packets from a transmitter; While receiving the data packets, it is determined whether an implicit NACK transmission is required to request retransmission of an unreceived data packet whose serial number is not known. If the transmission of the implicit NACK is necessary, generate a status report including an implicit NACK indicating the serial number of the last packet among successfully received data packets, If transmission of the implicit NACK is not necessary, generate a status report comprising at least one of an ACK indicating a serial number of a successfully received data packet and an explicit NACK indicating a serial number of an unreceived data packet having a known serial number. and, And a controller for transmitting the status reports to the transmitter. The method of claim 14, wherein the implicit NACK, A type field having a unique type value distinct from the explicit NACK for requesting retransmission of an unreceived data packet having a known serial number; And a serial number field including a serial number of the last packet. The method of claim 14, wherein the control unit, Among data sets including data packets received from the transmitter and not assembled into packets of a higher layer, it is determined whether there is a data set not including the last data packet, And determining that there is an unreceived data packet that does not know the serial number if there is a data set that does not include the last data packet. The method of claim 16, wherein each of the data sets, And a data packet divided from one original data packet. The method of claim 14, wherein each of the status reports, The apparatus of claim 1, wherein the apparatus is transmitted when a status report generation time according to a predetermined period is reached or when the transmitter is instructed to transmit the status report. The method of claim 14, wherein the control unit, In case that the terminal receiving the data packets moves from the source cell to the target cell by handover, it is determined that the implicit NACK needs to be transmitted to a radio network controller (RNC) that controls radio resources of the terminal. Data receiving device. The method of claim 19, wherein the implicit NACK, And at the start of the handover or upon completion of the handover. An apparatus for receiving a status report indicating a reception status of packet data in a mobile communication system, A data transmitter for transmitting data packets to a receiver; Receive a status report indicating a reception status of the transmitted data packets from the receiver, If the status report includes an implicit NACK including the serial number of the last packet among the successfully received data packets to request retransmission of an unreceived data packet whose serial number is not known, the implicit NACK is indicated. Controlling the data transmitter to transmit data packets after the last packet to the receiver, If the status report does not include the implicit NACK, at least at least one of an ACK indicating a serial number of a successfully received data packet and an explicit NACK indicating a serial number of an unreceived data packet having a known serial number from the status report. And a control unit for detecting the one and controlling the data transmitter to retransmit an unreceived data packet having the serial number indicated by the explicit NACK. The method of claim 21, wherein the implicit NACK, A type field having a unique type value distinct from the explicit NACK for requesting retransmission of an unreceived data packet having a known serial number; And a serial number field including a serial number of the last packet. The method of claim 21, wherein the control unit, And in the data set to which the last packet indicated by the implicit NACK belongs, controls the data transmitter to transmit data packets after the last packet to the receiver. The method of claim 23, wherein the data set, And a data packet divided from one original data packet. The method of claim 21, wherein the status report, And receiving when a status report generation time point according to a predetermined period is reached or when the receiver reports to transmit the status report. The method of claim 21, wherein the status report, And a terminal receiving the data packets when received from the source cell to the target cell by handover. A method for transmitting a status report indicating a reception status of packet data in a terminal of a mobile communication system, A process of the UE receiving data packets moving from the source cell to the target cell by handover; Waiting for a data packet to be first received from the target cell after moving to the target cell; And when the data packet is received, transmitting a status report indicating a reception state of the terminal to a radio network controller (RNC) that controls radio resources of the terminal. The method of claim 27, wherein the status report, And at least one of an ACK indicating a serial number of a data packet successfully received by the terminal and an explicit NACK indicating a serial number of an unreceived data packet having a known serial number. 28. The method of claim 27, further comprising: starting a timer set to a predetermined time after moving to the target cell; If the data packet is not received from the target cell until the timer expires, transmitting the status report to the radio network controller. 28. The method of claim 27, further comprising: when the data packet is received, determining whether the received data packet is retransmitted; And if the data packet is retransmitted, waiting for the next data packet to be received from the target cell without transmitting the status report. A terminal apparatus for transmitting a status report indicating a reception state of packet data in a mobile communication system, A data receiver for receiving and storing a series of data packets from a network; When the terminal moves from the source cell to the target cell by handover, the terminal waits until a data packet is first received from the target cell, and when the data packet is received, a status report indicating a reception state of the terminal is received. And a control unit for transmitting to a radio network controller (RNC) for controlling the data. The method of claim 31, wherein the status report, And at least one of an ACK indicating a serial number of a data packet successfully received by the terminal and an explicit NACK indicating a serial number of an unreceived data packet having a known serial number. The method of claim 31, wherein the control unit, Starting the timer set to a predetermined time after the terminal moves to the target cell, and transmitting the status report to the radio network controller when the data packet is not received from the target cell until the timer expires. Data receiving device. The method of claim 31, wherein the control unit, Determining whether the received data packet is retransmitted, and if the data packet is retransmitted, wait for the next data packet to be received from the target cell without transmitting the status report.

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