KR101648582B1 - Method of transmitting data block in wireless communication system - Google Patents

Abstract

A method of transmitting a data block in a wireless communication system. The method includes generating a lower data block including a higher block and a subheader for the upper block, the upper data block and the upper data block, and transmitting the lower data block.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of transmitting a data block in a wireless communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication, and more particularly, to a data block transmission method in a wireless communication system.

Background of the Invention [0002] Wireless communication systems are widely deployed to provide various types of communication services such as voice and data. The purpose of a wireless communication system is to allow multiple users to communicate reliably regardless of location and mobility. However, a wireless channel is a wireless channel that can be used for a wide variety of applications such as path loss, noise, fading due to multipath, intersymbol interference (ISI) There is a non-ideal characteristic such as a Doppler effect. A variety of techniques have been developed to overcome the non-ideal characteristics of wireless channels and to increase the reliability of wireless communications.

ARQ (automatic repeat request) is one of techniques for increasing the reliability of wireless communication. ARQ is the retransmission of data at the transmitter if the receiver fails to receive data. The receiver can inform the transmitter of the success or failure of data reception through a feedback message.

In order to increase the reliability of the wireless communication, it is preferable that the wireless communication process is implemented as a plurality of independent layers rather than one single layer, while supporting high-speed data service. A plurality of vertical hierarchical structures is called a protocol stack. The protocol stack can refer to an open system interconnection (OSI) model, which is a model for a protocol structure well known in communication systems.

A protocol data unit (PDU) is a data block to which a corresponding layer sends / receives data to and from a peer layer through a lower layer. That is, the layer transfers the protocol data unit to the lower layer or receives the protocol data unit from the lower layer. A service data unit (SDU) is a data block that the layer receives from an upper layer or transmits to an upper layer. A PDU may include at least one SDU (or a fragment of SDUs). At this time, there is a problem in efficient data block transmission method related to the PDU generation method and the ARQ performing method.

SUMMARY OF THE INVENTION The present invention provides a method of transmitting a data block in a wireless communication system.

In one aspect, a method of transmitting a data block in a wireless communication system is provided. The method includes generating a lower data block including a higher block and a subheader for the upper block, the upper data block and the upper data block, and transmitting the lower data block.

In another aspect, a method for transmitting an ARQ feedback message in a wireless communication system is provided. Receiving the lower data block including the upper block and the subheader for the upper block, the upper data block and the upper data block, and transmitting the ARQ feedback message to the upper block; .

According to another aspect of the present invention, there is provided a radio frequency (RF) unit for generating and transmitting a radio signal and a radio frequency (RF) unit connected to the RF unit, And a processor for generating the lower data block containing the lower data block and transmitting the lower data block.

An efficient data block transmission method in a wireless communication system is provided. Thus, the overall system performance can be improved.

The following description is to be understood as illustrative and not restrictive, with reference to the accompanying drawings, in which: FIG. 1 is a block diagram of a mobile communication system according to an embodiment of the present invention; And the like. CDMA may be implemented in radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. The TDMA may be implemented in a wireless technology such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in wireless technologies such as IEEE (Institute of Electrical and Electronics Engineers) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) is a part of E-UMTS (Evolved UMTS) using E-UTRA, adopting OFDMA in downlink and SC-FDMA in uplink. IEEE 802.16m is the evolution of IEEE 802.16e.

For clarity of description, IEEE 802.16e / IEEE 802.16m is mainly described, but the technical idea of the present invention is not limited thereto.

1 shows a wireless communication system.

Referring to FIG. 1, a wireless communication system 10 includes at least one base station 11 (BS). Each base station 11 provides a communication service to a specific geographical area (generally called a cell) 15a, 15b, 15c. The cell may again be divided into multiple regions (referred to as sectors). A mobile station (MS) 12 may be fixed or mobile and may be a user equipment (UE), a user terminal (UT), a subscriber station (SS), a wireless device, a personal digital assistant A wireless modem, a handheld device, and the like. The base station 11 generally refers to a fixed station that communicates with the terminal 12 and may be referred to by other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point have.

Hereinafter, downlink (DL) means communication from a base station to a terminal, and uplink (UL) means communication from a terminal to a base station. In the downlink, the transmitter may be part of the base station, and the receiver may be part of the terminal. In the uplink, the transmitter may be part of the terminal, and the receiver may be part of the base station.

2 shows an example of an automatic repeat request (ARQ) performance method. This is a case where the base station transmits downlink data to the terminal, but the present invention can also be applied to a case where the terminal transmits uplink data to the base station.

Referring to FIG. 2, the BS transmits an ARQ block to the MS (S11). An ARQ block is a unit of data in which ARQ is performed. The terminal transmits an ARQ feedback message to the base station (S12). The ARQ feedback message includes ACK (acknowledgment) / NACK (not-acknowledgment) information for the ARQ block. If the ARQ block is received successfully at the terminal, the ARQ feedback message includes ACK information, and if the ARQ block is not successfully received at the terminal, the ARQ feedback message includes NACK information. If the ARQ feedback message includes NACK information, the base station retransmits the ARQ block to the terminal (S13).

3 is a block diagram illustrating a protocol stack.

Referring to FIG. 3, the protocol stack is composed of a plurality of layers (Layer N-1, N, N + 1). Layer N-1 is a higher layer of the Nth layer N-1, and the (N-1) th layer N-1 is a lower layer of the Nth layer, (lower layer).

A protocol data unit (PDU) is a data block to which a layer is exchanged with a peer layer through a lower layer. That is, the layer transfers the PDU to the lower layer or receives the lower layer. Hereinafter, the PDU is also referred to as a lower data block. A service data unit (SDU) is a data block that the layer receives from or transfers to an upper layer. Hereinafter, the SDU is also referred to as an upper data block.

Data blocks move between layers via service access points (SAPs). (N-1) SAP) is an SAP between an (N + 1) th layer and an (N-1) Of SAP.

The protocol stack can refer to an open system interconnection (OSI) model, which is a model for a protocol structure well known in communication systems. For example, the (N-1) th layer may be a physical layer, the Nth layer may be a medium access control (MAC) layer, and the (N + 1) th layer may be a network layer. The MAC layer performs physical layer control, MAC PDU generation, and ARQ. The physical layer receives the MAC PDU from the MAC layer, and generates and transmits a radio signal from the MAC PDU.

Hereinafter, the structure of the PDU and the PDU generation method will be described in detail. For example, the PDU may be a MAC PDU and the SDU may be a MAC SDU.

4 shows an example of a PDU structure.

Referring to FIG. 4, the PDU 10 includes a header 11 and a payload 12. The header 11 contains the overall information of the PDU. The header 11 may include the length of the PDU 10, the encryption of the payload 12, the CID (connection identifier), the packing / fragmentation information of the SDU, have. The CID is an identifier for distinguishing the connection within the terminal. In IEEE 802.16m, a terminal ID for identifying a terminal and a flow ID for defining a connection flow are defined in the terminal. The terminal ID is used for physical layer control signaling, and the header 11 of the PDU 10 may include a flow ID, not a CID.

The payload 12 includes at least one ARQ block. The ARQ block is an SDU or SDU fragment.

5 shows an example of a PDU generation method.

Referring to FIG. 5, the first SDU and the second SDU are virtually divided into ARQ blocks according to an ARQ block size value. Each of the ARQ blocks is assigned a block sequence number (BSN) in order. Here, the first SDU is fragmented into three ARQ blocks with BSNs of 0, 1, and 2. The second SDU is fragmented into three ARQ blocks with BSNs of 3, 4, and 5.

The ARQ block size value is set by negotiation. The ARQ block size value can be set by exchanging a dynamic service addition request (DSA-REQ) / dynamic service addition response (DSA-RSP) between the BS and the MS. The DSA-REQ may be transmitted by the base station or the terminal to create a new service flow. The DSA-RSP is sent in response to the DSA-REQ.

The ARQ blocks fragmented according to the ARQ block size value from the SDU are mapped to the payload of the PDU. PDU is smaller than the ARQ block size, padding is performed in a space where the ARQ block can not be mapped. Here, the payload of the first PDU includes ARQ blocks of BSN 0, 1, 2, and 3, and padding is performed on the remaining space. The payload of the second PDU includes ARQ blocks with BSNs 4 and 5.

If the ARQ block size value is large, the probability of padding occurring at the time of PDU generation increases. This wastes a limited amount of radio resources, which may reduce system efficiency. On the contrary, when the ARQ block size value is small, the number of ARQ blocks included in the PDU increases. This causes the ARQ window to advance quickly. The receiver may have a problem of frequently sending an ARQ feedback message. The ARQ block size value is known to both the receiver and the transmitter. Therefore, overhead can occur when the transmitter signals the receiver every time the length of the ARQ block is signaled. A subheader management method is required for efficient ARQ performance.

It is not easy to set an appropriate ARQ block size value. In addition, the size of the ARQ block is constant, which makes the use of radio resources inconvenient. Therefore, it is possible to flexibly determine the ARQ block size according to radio resources when PDU is generated.

6 shows another example of the PDU structure.

Referring to FIG. 6, the PDU 100 includes a header 110, a plurality of upper blocks 130-1, 130-2, ..., 130-N, N being natural numbers, and a subheader 120 -1,120-2, ..., 120-N. The upper block and the subheader correspond one to one. The first upper block 130-1 or the Nth upper block 130-N may be an SDU fragment. The top block is an SDU or SDU fragment. The SDU fragment is the SDU divided in the PDU generation process. When the payload 12 includes a plurality of upper blocks, information for distinguishing each upper block and performing ARQ is required. To this end, the PDU 10 may further include a subheader for storing information for distinguishing each upper block for each upper block.

The structure of the PDU is merely an example, and the position of the subheader or the number of the subheader included in the PDU can be variously changed. Here, each subheader is located in front of the corresponding upper block, but this is only an example. Each subheader may be located consecutively following the header apart from the corresponding upper block.

7 shows an example of a sub-header structure included in the PDU.

7, the subheader 120 includes a sequence number field 121, a fragmentation information field 122, a re-fragmentation information field 123, a length field 124, and an optimized length indicator optimized length indicator 125). The subheader 12 may further include a flow ID. The structure of the subheader is merely an example, and the fields may be omitted in the subheader. The structure of the subheader may vary depending on the corresponding upper block. For example, a 1-bit flag can indicate whether or not a sub-header of a specific field is included. For example, if the flag is 0, the specific field is not included in the subheader, and if the flag is 1, the specific field can be included in the subheader.

The sequence number field 121 indicates the sequence number of the corresponding upper block. The sequence number may correspond to the transmission order of the upper block. The fragmentation information field 122 indicates information on the SDU fragment. The segmentation information field 122 may explicitly or implicitly indicate whether the upper block is an SDU fragment and the upper block is a fraction of the SDU. The fragmentation information field 122 may be a single field or a composite field composed of a plurality of subfields. In one example, the fragmentation information field 122 may explicitly indicate either a no fragment, a first fragment, an intermediate fragment, and a last fragment of the SDU . For example, if the segmentation information field 122 indicates an intermediate fragment, it means that the upper block is an intermediate fragment of the SDU. In this case, the fragmentation information field 122 may be a single field of 2 bits. As another example, the fragmentation information field 122 may be a complex field composed of an offset subfield and a last fragment indicator. The offset subfield indicates which fraction of the SDU the upper block is. The last fragment indicator indicates whether the parent block is the last fragment in the SDU. The receiver can reconstruct the SDU by placing the SDU fragment using the offset subfield until the last fragment indicator is triggered.

If the initially transmitted SDU fragment included in the PDU is not successfully received at the receiver, the SDU fragment may be included in another PDU and retransmitted. However, if the length of the initially transmitted SDU fragment is different from the length of the retransmitted SDU fragment, additional signaling is required to inform it. The re-fragmentation information field 123 is used for the case where the length of the initially transmitted SDU fragment is different from the length of the retransmitted SDU fragment. The re-segmentation information field 123 can be used in combination with the segmentation information field 122. [

The length field 124 indicates the length of the corresponding upper block. The length can be expressed in units of bits or bytes. The optimized length indicator 125 indicates whether the size of the length field 124 is an optimized length. If it is not necessary to use an unnecessarily long length field because the length of the upper block is not long, the size of the length field 124 becomes an optimized length.

Hereinafter, the sequence number field included in the subheader will be described in detail.

The sequence number field indicates the sequence number of the corresponding upper block. However, a method of assigning sequence numbers to SDU and SDU fragments is problematic.

First, the sequence number can be allocated for each SDU. In this case, the SDU fragments segmented from the same SDU all have the same sequence number.

FIG. 8 shows an example of a PDU generation process.

Referring to FIG. 8, the sequence number of the first SDU is p and the sequence number of the second SDU is p + 1. The first PDU includes the first SDU and the first piece of the second SDU as the upper block. The second PDU includes the last piece of the second SDU as the upper block. The first piece of the second SDU and the last piece of the second SDU are all of sequence number p + 1.

It is assumed that the receiver succeeds in receiving the first piece of the first SDU and the second SDU but fails to receive the last piece of the second PDU. The receiver can inform the transmitter of the success of the reception of the SDU with the sequence number p and the reception failure of the SDU of the sequence number p + 1 through the ARQ feedback message. The transmitter will retransmit the second SDU with sequence number p + 1. In this case, the receiver fails to receive the last piece of the second SDU, but the entire second SDU can be retransmitted. This results in a waste of limited radio resources. In order to prevent this, it is necessary to distinguish SDU fragments divided from the same SDU.

Second, sequence numbers can be assigned per SDU fragment. In this case, the SDU fragments segmented from the same SDU all have different sequence numbers. If the SDU is not segmented, one sequence number is assigned to the SDU. If the SDU is divided into three SDU fragments, three sequential consecutive sequence numbers are assigned to the three SDU fragments in order.

9 shows another example of the PDU generation process.

9, the sequence number of the first SDU is p, the sequence number of the first fragment of the second SDU is p + 1, and the sequence number of the last fragment of the second SDU is p + 2. The first PDU includes the first SDU and the first piece of the second SDU as the upper block. The second PDU includes the last piece of the second SDU as the upper block.

It is assumed that the receiver succeeds in receiving the first piece of the first SDU and the second SDU but fails to receive the last piece of the second PDU. The receiver can notify the sender of the success of receiving the first fragment of the first SDU and of the first SDU of sequence number p, p + 1 and of the last fragment of the second SDU of sequence number p + 2 via the ARQ feedback message . The transmitter will retransmit the last fragment of the second SDU with sequence number p + 2. In this case, the transmitter can retransmit only the failed SDU fragments to the receiver. Thus, limited radio resources can be efficiently utilized. In addition, ARQ can be efficiently performed. The reliability of the wireless communication can be increased, and the overall system performance can be improved.

In this way, the sequence number can be allocated for each SDU or SDU fragment. Whether a sequence number is allocated to each SDU or an SDU piece is determined by exchanging DSA-REQ / DSA-RSP or SBC-REQ (SS-basic capability request) / SBC-RSP (SS-basic capability response) Can be set.

10 is a flowchart illustrating a data block transmission method according to an embodiment of the present invention. This is an example of a case where a base station transmits a data block, but it can be applied as it is when a terminal transmits a data block.

Referring to FIG. 10, a base station generates a first lower data block including a first subheader for an upper block and an upper block (S110). The upper block is one of the upper data block and the upper data block. The base station transmits the first lower data block to the mobile station (S120).

The UE transmits a first ARQ feedback message to the base station for the upper block (S130). The ARQ feedback message may indicate that it is for the upper block using the sequence number. If the ARQ message indicates reception failure for the upper block, the base station can retransmit the upper block. To this end, the base station generates a second lower data block including an upper block and a second sub-header for the upper block (S140). At this time, the first sub-header and the second sub-header may include a sequence number field indicating the same sequence number. The UE transmits a second ARQ feedback message to the base station for the retransmitted upper block (S140).

Thus, an efficient data block transmission method in a wireless communication system can be provided. It is possible to utilize limited radio resources efficiently. In addition, ARQ can be efficiently performed. The reliability of the wireless communication can be increased, and the overall system performance can be improved.

11 is a block diagram showing an example of a device for wireless communication. The device 50 for wireless communication may be part of a terminal. The apparatus 50 for wireless communication includes a processor 51, a memory 52, an RF unit 53, a display unit 54, a user interface unit 55). The RF unit 53 is connected to the processor 51 to transmit and / or receive a radio signal. The memory 52 is coupled to the processor 51 to store the drive system, applications and general files. The display unit 54 displays various information of the terminal and can use well known elements such as a liquid crystal display (LCD) and an organic light emitting diode (OLED). The user interface unit 55 may be a combination of a well-known user interface such as a keypad or a touch screen. The processor 51 performs all the methods related to data block generation, transmission and ARQ performance described above.

12 is a block diagram showing an example of a base station. The base station 60 includes a processor 61, a memory 62, a scheduler 63 and an RF unit 64. The RF unit 64 is connected to the processor 61 to transmit and / or receive a radio signal. The processor 61 may perform all the methods related to data block generation, transmission and ARQ performance described above. The memory 62 is connected to the processor 61 and stores the processed information in the processor 61. [ The scheduler 63 is connected to the processor 61 and can perform all the methods related to the scheduling for data block transmission such as the sequence number allocation and the sub-header management described above.

All of the functions described above may be performed by a processor such as a microprocessor, a controller, a microcontroller, an application specific integrated circuit (ASIC), etc. according to software or program code or the like coded to perform the function. The design, development and implementation of the above code will be apparent to those skilled in the art based on the description of the present invention.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention. You will understand. Therefore, it is intended that the present invention covers all embodiments falling within the scope of the following claims, rather than being limited to the above-described embodiments.

1 shows a wireless communication system.

2 shows an example of an ARQ performance method.

3 is a block diagram illustrating a protocol stack.

4 shows an example of a PDU structure.

5 shows an example of a PDU generation method.

6 shows another example of the PDU structure.

7 shows an example of a sub-header structure included in the PDU.

FIG. 8 shows an example of a PDU generation process.

9 shows another example of the PDU generation process.

10 is a flowchart illustrating a data block transmission method according to an embodiment of the present invention.

11 is a block diagram showing an example of a device for wireless communication.

12 is a block diagram showing an example of a base station.

Claims (10)

A method of transmitting a data block in a wireless communication system, Generating a lower data block including a higher block and a sub-header for the higher block; Transmitting the lower data block; And And receiving an ARQ (Automatic Repeat reQuest) feedback message for the upper block, Wherein the upper block includes a whole or a piece of upper data blocks, Wherein the subheader includes fragmentation information indicating whether the superordinate block includes the entire upper data block or a fragment of the upper data block, Wherein the subheader includes a sequence number field indicating a sequence number corresponding to a transmission order of the upper block, Wherein the sequence number is allocated differently for each fragment divided from the upper data block, Wherein the ARQ feedback message indicates a reception failure for each piece based on a sequence number assigned differently for each piece. The method according to claim 1, Wherein the upper data block is a MAC (medium access control) SDU (service data unit), and the lower data block is a MAC PDU (protocol data unit). delete A transmission apparatus for transmitting a data block in a wireless communication system A radio frequency (RF) unit for generating and transmitting a radio signal; And And a processor coupled to the RF unit, Generating a lower data block including a higher block and a sub-header for the higher block; Transmitting the lower data block through the RF unit; And Receiving an ARQ feedback message for the upper block, Wherein the upper block includes a whole or a piece of upper data blocks, Wherein the subheader includes fragmentation information indicating whether the superordinate block includes the entire upper data block or a fragment of the upper data block, Wherein the subheader includes a sequence number field indicating a sequence number corresponding to a transmission order of the upper block, Wherein the sequence number is allocated differently for each fragment divided from the upper data block, Wherein the ARQ feedback message indicates a reception failure for each piece based on a sequence number assigned differently for each piece. delete delete delete delete delete delete

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