KR20070080367A - Relay communication method using relay station - Google Patents

Abstract

The present invention provides a method of receiving data from a base station using an allocated downlink radio resource in a first frame, and using a downlink map of a second frame, to a mobile station in the relay station area. Transmitting resource allocation information and transmitting data to the mobile stations in the area by using radio resources according to the radio resource allocation information in the second frame, respectively. In this regard, by performing relay communication, data can be transmitted to mobile stations in a shadowed area, and high throughput can be supported for mobile stations not in a shadowed area.

Description

Relay communication method using relay station {Method for Relay Communication Using Relay Station}

1 is a diagram illustrating an embodiment of a communication network having a mesh structure.

2 is a diagram illustrating an embodiment of a mesh mode frame structure.

FIG. 3 is a diagram for explaining an embodiment of a subchannel in an OFDMA physical layer. FIG.

4 is a diagram illustrating an embodiment of a resource allocation scheme in OFDMA.

FIG. 5 is a diagram for explaining a subchannel mapping method in an uplink / downlink frame; FIG.

FIG. 6 is a diagram illustrating an embodiment of a frame structure of an OFDMA physical layer in a broadband wireless access system. FIG.

7A to 7C are diagrams illustrating a first embodiment showing a radio resource allocation method in a communication system having RS.

8A to 8C are explanatory diagrams of a second embodiment showing a radio resource allocation method in a communication system having RS.

9 is a diagram illustrating an embodiment of a feedback header.

The present invention relates to a relay communication method using a relay station, and more particularly, to a radio resource allocation method when transmitting downlink data from a base station to a mobile station.

1 is a diagram illustrating an embodiment of a communication network having a mesh structure. In general, in a broadband wireless connection, communication may be performed using a mesh structure as shown in FIG. 1 as well as a point-to-multipoint (PMP) structure. The mesh mode may be connected to a base station through a relay of another subscriber group, thereby actively responding to a non-linear wave communication environment in a city in which radio wave regions exist due to a large building. .

In the broadband wireless access system, since the IEEE 802.16a standard considers non-linear wave communication in the 2-11 GHz band, signal attenuation due to multipath fading is problematic. Accordingly, in order to secure the reliability of signal transmission, an Automatic Retransmission Request (ARQ) scheme is applied in a medium access control (MAC) layer. In addition, an advanced antenna system (AAS) for improving cell coverage and system capacity through beam forming using multiple antennas is considered. In addition, in order to solve a coexistence problem with another system in an unlicensed band, a dynamic frequency selection (DFS) function is supported.

2 is an exemplary diagram illustrating a mesh mode frame structure. As shown in FIG. 2, a control subframe and a data subframe may be used in the mesh mode. The control subframe has two basic functions. In a network control subframe, a function of making and maintaining a combination between different systems is performed, and in a schedule control frame, an equal scheduling function is performed between systems. All other frames other than the periodically occurring network control subframe are schedule control frames. After the network entry is allocated during the network control subframe, a mesh mode network is configured, and a network engineer who performs distributed scheduling during the schedule control subframe generates a schedule control frame. The network descriptor refers to a central mobile station capable of performing a function similar to a base station (BS) in a mesh mode.

3 is a diagram for explaining an embodiment of a subchannel in an OFDMA physical layer. Referring to FIG. 3, the characteristics of the OFDMA physical layer in a broadband wireless access system are as follows. In the OFDMA physical layer, active carriers are divided into groups and transmitted to different receivers for each group. In this way, the group of carriers transmitted to the receiver is called a sub-channel. In this case, carriers constituting each subchannel may be adjacent to each other or spaced at equal intervals. As such, when multiple accesses are possible in subchannel units, frequency diversity gain and gain due to concentration of power can be obtained, and forward power control can be efficiently performed.

4 is a diagram illustrating an embodiment of a resource allocation method in OFDMA. Referring to FIG. 4, a slot allocated to each mobile station is defined by a data region of two-dimensional space, which is a set of consecutive subchannels allocated by a burst. As shown in FIG. 4, one data region in OFDMA is shown as a rectangle determined by a two-dimensional combination of a time domain and a subchannel domain. The data area may be allocated to uplink of a specific mobile station, and in downlink, information may be transmitted to a specific mobile station through the data area. To define such a data region in two-dimensional space, the number of OFDM symbols in the time domain and the number of consecutive subchannels starting at a position separated by an offset from the reference point in the frequency domain should be given.

5 is an exemplary diagram illustrating a subchannel mapping method in an uplink / downlink frame. Referring to FIG. 5, an area of an allocated subchannel is displayed in two dimensions, and data is mapped from a subchannel of a first symbol with respect to the allocated two-dimensional subchannel region. In the case of uplink, the allocated subchannel first determines an allocation area in one dimension. That is, the duration is determined, and the subchannel is allocated along the symbol axis after the subchannel previously allocated to another Protocol Data Unit (PDU) burst. At this time, when the end symbol of the specific subchannel region is reached, allocation continues from the next subchannel.

FIG. 6 is a diagram illustrating an embodiment of a frame structure of an OFDMA physical layer in a broadband wireless access system. FIG. As shown in FIG. 6, the downlink subframe starts with a preamble used for synchronization and equalization in the physical layer. The structure of the entire frame is defined through a downlink map (DL-MAP) message and an uplink map (UL-MAP) message in a broadcast form that defines the location and use of bursts allocated to downlink and uplink. . That is, the DL-MAP message defines the use allocated for each burst for the downlink period in the burst mode physical layer, and the UL-MAP message defines the use of the burst allocated for the uplink period.

Table 1 shows an example of a DL-MAP message.

Syntax Size Notes DL-MAP_Message_Format () { Management Message Type  = 2 8 bits PHY Synchronization Field variable See appropriate PHY specification. DCD Count 8 bits Base Station ID 48 bits Begin PHY Specific Section { See applicable PHY section. for ( i = 1; i <= n ; i ++) { For each DL-MAP element 1 to n . DL-MAP_IE () variable See corresponding PHY specification. } } if! (byte boundary) { Padding Nibble 4 bits Padding to reach byte boundary. } }

Table 2 shows an example of an UL-MAP message.

Syntax Size Notes UL-MAP_IE () { CID 16 bits UIUC 4 bits if (UIUC == 12) { OFDMA Symbol offset 8 bits Subchannel offset 7 bits No . OFDMA Symbols 7 bits No . Subchannels 7 bits Ranging Method 2 bits 0b00-Initial Ranging / Handover Ranging over two symbols 0b01-Initial Ranging / Handover Ranging over four symbols 0b10-BW Request / Periodic Ranging over one symbol 0b11-BW Request / Periodic Ranging over three symbols reserved 1 bit Shall be set to zero } else if (UIUC == 14) { CDMA _ Allocation _ IE () 32 bits else if (UIUC == 15) { Extended UIUC  dependent IE variable See clauses following 8.4.5.4.3 } else { Duration 10 bits In OFDMA slots (see 8.4.3.1) Repetition coding  indication 2 bits 0b00-No repetition coding of 0b01-Repetition coding of 2 used 0b10-Repetition coding of 4 used 0b11-Repetition coding of 6 used } Padding nibble, if needed 4 bits Completing to nearest byte, shall be set to 0. }

The information element constituting the DL-MAP includes a downlink interval usage code (DIUC), a connection ID (CID), and position information (subchannel offset, symbol offset, subchannel number, symbol number) of the burst. The downlink traffic interval corresponding to each mobile station is distinguished by the information element. On the other hand, the information element constituting the UL-MAP message defines the use by UIUC (Uplink Interval Usage Code) for each CID (Connection ID), and defines the location of the interval using the 'duration' field. The use of each section is determined according to the UIUC value used in the UL-MAP, and each section starts at a point separated from the previous IE starting point by the 'duration' defined in the UL-MAP IE.

Table 3 shows an example of DL-MAP IE.

Syntax Size Notes DL-MAP_IE () { DIUC 4 bits if (DIUC == 15) { Extended DIUC dependent IE variable See clauses following 8.4.5.3.1 } else { if (INC_CID == 1) { The DL-MAP starts with INC_CID = 0. INC_CID is toggled between 0 and 1 by the CID-SWITCH_IE () (8.4.5.3.7) N_ CID 8 bits Number of CIDs assigned for this IE for (n = 0; n <N_CID; n ++) { CID 16 bits } } OFDMA Symbol offset 8 bits Subchannel offset 6 bits Boosting 3 bits 000: normal (not boosted); 001: +6 dB; 010: -6 dB; 011: +9 dB; 100: +3 dB; 101: -3 dB; 110: -9 dB; 111:-12 dB; No . OFDMA Symbols 7 bits No . Subchannels 6 bits Repetition Coding Indication 2 bits 0b00-No repetition coding of 0b01-Repetition coding of 2 used 0b10-Repetition coding of 4 used 0b11-Repetition coding of 6 used } }

Table 4 shows an example of the UL-MAP IE.

Syntax Size Notes UL-MAP_IE () { CID 16 bits UIUC 4 bits if (UIUC == 12) { OFDMA Symbol offset 8 bits Subchannel offset 7 bits No . OFDMA Symbols 7 bits No . Subchannels 7 bits Ranging Method 2 bits 0b00-Initial Ranging / Handover Ranging over two symbols 0b01-Initial Ranging / Handover Ranging over four symbols 0b10-BW Request / Periodic Ranging over one symbol 0b11-BW Request / Periodic Ranging over three symbols reserved 1 bit Shall be set to zero } else if (UIUC == 14) { CDMA _ Allocation _ IE () 32 bits else if (UIUC == 15) { Extended UIUC dependent IE variable See clauses following 8.4.5.4.3 } else { Duration 10 bits In OFDMA slots (see 8.4.3.1) Repetition coding indication 2 bits 0b00-No repetition coding of 0b01-Repetition coding of 2 used 0b10-Repetition coding of 4 used 0b11-Repetition coding of 6 used } Padding nibble, if needed 4 bits Completing to nearest byte, shall be set to 0. }

The uplink interval defined by UIUC 12 is allocated for initial ranging, handover ranging, periodic ranging, or band request, and has a contention-based feature.

In the OFDMA-based wireless communication system, when performing relay communication through a relay station, it is a question of how to allocate radio resources and transmit radio resource allocation information.

An object of the present invention is to allocate radio resources more efficiently in relay communication using a relay station and to perform relay communication using the same.

According to an aspect of the present invention, there is provided a communication method in which a relay station relays data transmission from a base station to a mobile station, the method comprising: receiving data from a base station using an allocated downlink radio resource in a first frame; Transmitting downlink radio resource allocation information to mobile stations in the relay station area by using a downlink map of a second frame; and using the radio resource according to the radio resource allocation information in the second frame. And transmitting data to mobile stations in the area, respectively.

In addition, the present invention relates to a communication method in which a relay station relays data transmission from a base station to a mobile station, the method comprising: receiving data from a base station in a first frame; transmitting radio resource allocation information for sub-frame configuration to the base station; transmitting information on radio resource allocation of the subframe to mobile stations in the region; and radio resource according to the radio resource allocation information. And transmitting the data to the mobile stations in the area, respectively.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Relay stations (hereinafter, referred to as 'RS') may be classified as follows according to a method of using a frequency band. That is, a frequency band independent of a frequency band used by the base station can be used, and a portion of the frequency band used by the base station can be allocated and used by the RS. In addition, by using the same frequency band as the base station, it is also possible to amplify and retransmit the control signal or data received from the base station. On the other hand, the RS may be operated in a fixed (fixed RS), may be operated in a semi-fixed (nomadic RS), may be operated in a mobile (mobile RS). In the present invention, a case in which an RS allocates and uses a portion of a frequency band used by a base station is considered.

7A to 7C are diagrams illustrating a first embodiment of a radio resource allocation method in a communication system having an RS. In the first embodiment, a method of allocating radio resources corresponding to each mobile station at a base station will be described.

7A is a diagram illustrating an embodiment of a frame showing a radio resource allocation information transmission and radio resource allocation scheme. FIG. 7A is a diagram for describing an operation of a base station side in transmitting radio resource allocation and radio resource allocation information. FIG.

Referring to FIG. 7A, a base station transmits data through a downlink map (DL-MAP) 71 in a T frame to a downlink radio resource (region on an OFDMA map, hereinafter referred to as 'region'). Transmits allocation information. In addition, downlink data is transmitted to the RS through the region 72 allocated by the downlink map (DL-MAP) 61. Meanwhile, the RS receives downlink data transmitted from the base station and transmits the received data to the mobile station in a T + 1 frame.

In order to prevent data transmission and collision (interference) from the RS to the mobile station, an area 74 in which the RS transmits data to the mobile station among the downlink areas of the T + 1 frame of the base station is not allocated for other purposes. This area allocation information is transmitted to the RS and the mobile station in the area via the downlink map 73 of the T + 1 frame. The control signal transmitted from the base station to the RS in the T frame may be transmitted in the same frame. The control signal includes a preamble, a downlink map (DL-MAP), a DCD, and a UCD.

7B is a diagram illustrating an embodiment of a frame showing a radio resource allocation information transmission and radio resource allocation scheme. 7B is a diagram for explaining an operation of a base station side in transmitting radio resource allocation and radio resource allocation information.

Referring to FIG. 7B, in the T frame, the RS receives area allocation information for receiving downlink data transmitted from a base station through a downlink map (DL-MAP) 75. In addition, downlink data is received from the base station through the region 76 (corresponding to 72 in FIG. 7A) allocated by the downlink map (DL-MAP) 75. On the other hand, the RS receives downlink data transmitted from the base station and transmits data corresponding to each mobile station to each mobile station in a T + 1 frame. As mentioned above, the base station does not allocate areas 78a, 78b, 78c for transmitting data corresponding to each mobile station as areas for other purposes. Accordingly, the RS can transmit downlink data corresponding to each mobile station through the allocated areas 78a, 78b, 78c (corresponding to 74 in FIG. 7A).

The area information allocated for the mobile station is transmitted to the RS and each mobile station through a downlink map (DL-MAP) 77 (corresponding to 73 in FIG. 7A). At this time, the area 78a, 78b, 78c allocation to the mobile station is performed by the base station. Therefore, every frame, the base station can allocate an area for transmitting data from the base station to the RS and an area for transmitting data from the RS to the mobile station.

Table 5 shows an example of a downlink map information element including the mobile station to which data transmission is relayed through the RS and area allocation information for each mobile station.

Syntax Size Notes DL-MAP-IE () {  DIUC 4 bits  if (DIUC == 15) {   Extended DIUC dependent IE Variable   } else {  INC_RS_ID 1 bit 0 = RS not included in this IE 1 = RS included in this IE   If (INC_RS_ID == 1) {    N_MS_CID 8 bits Number of MS CIDs assigned in RS    For (i = 0; i <N_MS_CID; i ++) {    CID    }    Else {     N_CID 8 bits Number of CIDs assigned for this IE

The area allocation information for the mobile stations belonging to each RS may be transmitted to the RS through the DL-MAP information element 77 (corresponding to 73 in FIG. 7A) as shown in the example of Table 5.

7C is a diagram illustrating an embodiment of a frame showing a radio resource allocation information transmission and radio resource allocation scheme. 7C is a diagram for explaining the operation of the mobile station side in radio resource allocation and radio resource allocation information transmission. 7C shows an example of receiving data at the side of the first mobile station 1.

Data transmitted by the base station in the T frame is transmitted to the mobile station in the T + 1 frame via the RS. Accordingly, each mobile station can know the area allocated to itself by receiving the downlink map 80 (corresponding to 73 in FIG. 7A and 77 in FIG. 7B) transmitted in the T + 1 frame. Accordingly, as shown in FIG. 7C, the first mobile station assigned the downlink region may receive downlink data through the allocated region 81.

8A to 8C are explanatory diagrams of a second embodiment showing a radio resource allocation method in a communication system having RS. In the second embodiment, data corresponding to each mobile station is transmitted through a subframe, and in the subframe, a method of allocating radio resources corresponding to each mobile station in the RS will be described.

8A is a diagram illustrating an embodiment of a frame showing a radio resource allocation information transmission and radio resource allocation scheme. 8A is a diagram for describing an operation of a base station side in transmitting radio resource allocation and radio resource allocation information.

Referring to FIG. 8A, a base station transmits data through a downlink map (DL-MAP) 81 in a T frame to a downlink radio resource (region on an OFDMA map, hereinafter referred to as 'region'). Transmits allocation information. The base station transmits downlink data to the RS through the area 82 allocated by the downlink map (DL-MAP) 81. Meanwhile, the RS receives downlink data transmitted from the base station and transmits the received data to the mobile station in a T + 1 frame.

In this case, the base station allocates an area 85 to which the RS transmits data to the mobile station in a downlink region of the T + 1 frame of the base station to prevent data transmission and collision (interference) from the RS to the mobile station. I never do that. The area allocation information of this T + 1 frame is transmitted to the RS and the mobile station in the area through the downlink map 84 of the T + 1 frame.

8B is a diagram illustrating an embodiment of a frame showing a radio resource allocation information transmission and radio resource allocation scheme. 8B is a diagram for explaining the operation of the RS side in radio resource allocation and radio resource allocation information transmission.

Referring to FIG. 8B, the RS receives area allocation information for transmitting data to the RS through a downlink map (DL-MAP) 86 in a T frame. In addition, the RS receives downlink data from the base station through the region 87 allocated by the downlink map (DL-MAP) 86. On the other hand, the RS receives downlink data transmitted from the base station and transmits data corresponding to each mobile station in a T + 1 frame.

In this case, in order for the RS to transmit the received downlink data to each mobile station, regions 90b, 90c, and 90d corresponding to each mobile station may be allocated. That is, in the T + 1 frame, the RS may determine how to allocate an area allocated from the base station (90a to 90d, corresponding to 85 in FIG. 8a) to each mobile station. In order to inform each mobile station of information on the area to be allocated to each mobile station, a portion 90a of the area allocated from the base station can be used as a DL-MAP from the RS to the mobile station. That is, the RS may configure an area allocated from the base station into one subframe to perform area allocation and area allocation information for each mobile station.

On the other hand, the RS can report the area allocation information for the mobile station to the base station. That is, as illustrated in FIGS. 8A and 8B, the RS belongs to a next frame (T + 1 frame) through an uplink region (83 in FIG. 8A and 88 in FIG. 8B) allocated to the RS in the T frame. Downlink region allocation information to be used for the frames 90a to 90d may be previously reported to the base station. In this case, the RS may report the downlink allocation information to the base station using a feedback header.

FIG. 8 is a diagram illustrating an embodiment of a feedback header. Referring to FIG. Meanwhile, Table 6 shows an example of feedback information for reporting downlink allocation information according to the feedback header format of FIG. 8.

Feedback Type Feedback contents Description 1110 OFDMA symbol offset (8bits) + Subchannel offset (8bits) + No.OFDMA symbol (8bits) + No.subchannels (8bits) Area to be used by RS

Meanwhile, the uplink region (83 in FIG. 8A and 88 in FIG. 8B) allocated to the RS for reporting downlink allocation information for the mobile station in the T frame includes DL-MAP (80 in FIG. 8A and FIG. 8A). 91 in 8b). In this case, the uplink region allocation information may be transmitted through the information element RS_Feedback_allocation_IE included in the downlink map DL-MAP.

Table 7 shows an example of an information element (RS_Feedback_allocation_IE) having uplink region information allocated to the RS for reporting downlink allocation information for the mobile station.

Syntax Size Index RS_Feedback_allocation_IE { RS_ID Variable UIUC 4 bits OFDMA symbol offset 7 bits subchannel offset 7 bits No.OFDMA symbols 7 bits No.Subchannel 7 bits }

As described above, the RS reports downlink allocation information for the mobile station to the base station through an uplink region allocated to the RS (83 in FIG. 8A and 88 in FIG. 8B). In this case, downlink allocation information may be transmitted through the feedback header.

As shown in FIG. 8B, the RS reports downlink allocation information for the mobile station to the base station using a feedback header in a T frame, and transmits data to each mobile station through a subframe of a T + 1 frame. That is, the RS transmits downlink region information allocated to each mobile station through the downlink map (DL-MAP) 90a. At this time, the downlink region is allocated in consideration of the channel state of each mobile station. On the other hand, it is possible to transmit data using DIUC more suitable for each mobile station.

Table 8 shows an example of a downlink map (DL-MAP) of the subframe.

Syntax Size Index SUB_RS_MAP {  N_CID Variable   For (j = 1; j <N_CID; i ++) {    CID    DIUC 4 bit   OFDMA symbol offset 7 bit   Subchannel offset 7 bit   No.OFDMA symbols 7 bit   No.Subchannel 7 bit   }  }

8C is a diagram illustrating an embodiment of a frame showing a radio resource allocation information transmission and radio resource allocation scheme. 8C is a diagram for explaining the operation of the mobile station side in radio resource allocation and radio resource allocation information transmission. 8C shows an example of receiving data at the side of the first mobile station.

Data transmitted by the base station in the T frame is transmitted to the mobile station in the T + 1 frame via the RS. Accordingly, each mobile station can know the downlink region allocated to itself by receiving the downlink map 94 (corresponding to 90a in FIG. 7B) of the subframe transmitted from the RS in the T + 1 frame. Accordingly, as shown in FIG. 8C, the first mobile station assigned the downlink region may receive downlink data through the allocated region 95.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

According to the present invention, by performing relay communication, data can be transmitted to mobile stations in a shaded area, and high throughput can be supported for mobile stations not in a shaded area.

Claims (12)

A communication method in which a relay station relays data transmission from a base station to a mobile station, Receiving, from the base station, data in the first frame, using the allocated downlink radio resource; Delivering downlink radio resource allocation information to mobile stations in the relay station area using the downlink map of the second frame; And In the second frame, transmitting data to mobile stations in the area by using radio resources according to the radio resource allocation information; Relay communication method using a relay station comprising a. The method of claim 1, The data transmitted to the mobile stations in the second frame is generated by performing decoding on the data received from the base station in the first frame and performing encoding again. The method of claim 1, In the second frame, the radio resources used for transmitting data to the mobile stations, respectively, are excluded from use by the base station. The method of claim 1, The downlink radio resource allocation information transmitted to the mobile stations in the relay station area is transmitted through a downlink map information element (DL-MAP Information Element). The method of claim 4, wherein The downlink map information element (DL-MAP Information Element) includes an identifier (RS_ID) of the RS and the identifier (MS_ID) of the mobile stations belonging to the RS region. The method of claim 1, The downlink radio resource allocation information is generated in a base station, the relay communication method using a relay station. A communication method in which a relay station relays data transmission from a base station to a mobile station, In a first frame, receiving data from a base station; In the first frame, transmitting radio resource allocation information for sub-frame configuration of a second frame to the base station; Transmitting, to mobile stations in the region, information regarding radio resource allocation of the subframe; And Transmitting data to mobile stations in the area using radio resources according to the radio resource allocation information, respectively. Relay communication method using a relay station comprising a. The method of claim 7, wherein The information on the radio resource allocation of the subframe is transmitted using a downlink map (DL-MAP) of the subframe. The method of claim 7, wherein The radio resource allocation information of the subframe is generated in the relay station in consideration of the channel state of each mobile station. The method of claim 7, wherein Radio resource allocation information for sub-frame configuration of the second frame is transmitted through a feedback header, relay communication method using a relay station. The method of claim 10, And receiving uplink radio resource allocation information for transmitting the feedback header by using an uplink map (UL-MAP) of the first frame. The method of claim 7, wherein The data transmitted to the mobile stations in the second frame is generated by performing decoding on the data received from the base station in the first frame and performing encoding again.

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