KR101128800B1 - Method of Controlling Relay Communication - Google Patents

Abstract

The present invention provides a relay communication control method applied to a broadband wireless access system having a relay station, the method comprising: acquiring information on a channel state between a base station and a mobile station; If satisfied, obtaining information regarding the channel state between the relay station and the mobile station, comparing the channel state between the base station and the mobile station, the channel state between the relay station and the mobile station, and comparing the result of the comparison. Accordingly, the present invention relates to a relay communication control method comprising the step of performing direct communication or relay communication, and the base station determines the direct communication or relay communication with the mobile station and has an effect of increasing throughput.

Broadband Wireless Access System, Relay Station, CQICH, MAC Message, Signal Quality

Description

Relay communication control method {Method of Controlling Relay Communication}

1 illustrates an embodiment of a communication system with an RS.

2 is a diagram illustrating a frame structure of a mobile communication system equipped with a relay station.

3 is a diagram illustrating an embodiment of a frame structure in an orthogonal frequency division multiple access (OFDMA) based mobile communication system.

4 is a flowchart of a first embodiment showing a method of determining whether direct communication or relay communication;

5 is a flowchart of a second embodiment showing a method of determining whether direct communication or relay communication;

6 is a flowchart of a third embodiment showing a method of determining whether direct communication or relay communication;

7 is a flowchart of a fourth embodiment showing a method of determining whether direct communication or relay communication;

8 is a flowchart of a fifth embodiment showing a method of determining whether direct communication or relay communication;

9 is a flowchart of a sixth embodiment showing a method of determining whether direct communication or relay communication;

The present invention relates to a relay communication method applied to a broadband wireless access system, and more particularly, to a method for controlling a process of switching from relay communication to direct communication or vice versa.

1 is a diagram illustrating an embodiment of a communication system having an RS. As shown in FIG. 1, the mobile station may receive a signal directly from the base station or may receive a relayed signal from a relay station.

Such a relay station (RS) is used to increase cell coverage and throughput of a mobile communication system. RS may perform the function of a base station (BS), and network entry, mobility, RRM (Radio Resource Management), and security functions of a point to multipoint (PMP) -based RS May have For example, the signal received from the transmitter can be decoded, encoded again, and passed to the receiver to remove noise, and the throughput can be increased by using a coding having a higher data rate.

For example, the RS may be operated as a fixed RS, may be operated as a nomadic RS, or may be operated as a mobile RS. The fixed RS may be used to eliminate shadow areas or increase cell coverage, and may also function as a repeater. On the other hand, the semi-fixed type is installed so that when the user suddenly increases or temporarily move within the building. In addition, the mobile RS may be provided in public transportation such as a bus or subway.

In addition, RS may be operated as follows according to a method using a frequency band. That is, the service can be performed using a new frequency band irrespective of the frequency band used by the base station, and the frequency band used by the base station can be used, but the RS can be assigned to perform a service. A frequency band may be used, but a control signal or a data signal received from a base station may be amplified and transmitted to a mobile station.

The RS mentioned in the prior art can be mounted on a fixed or moving public transport between a base station and a mobile station to expand the service area coverage of the base station or to eliminate shadow areas. However, the prior art does not indicate when the base station and the mobile station communicate directly and when the relay communication is performed through the RS.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for a base station to determine and control direct communication or relay communication with a mobile station in a broadband wireless access system.

According to an aspect of the present invention, there is provided a relay communication control method applied to a broadband wireless access system including a relay station, the method comprising: acquiring information about a channel state between a base station and a mobile station; If the determined result is satisfied, acquiring information about a channel state between the relay station and the mobile station, comparing a channel state between the base station and the mobile station with a channel state between the relay station and the mobile station; And performing the direct communication or the relay communication according to the comparison result.

In addition, the present invention is a relay communication control method applied to a broadband wireless access system having a relay station, periodically, information about the channel state between the base station and the mobile station and information about the channel state between the relay station and the mobile station And obtaining a channel state, comparing a channel state between the base station and the mobile station, a channel state between the relay station and the mobile station, and performing direct communication or relay communication according to the comparison result.

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

2 is a structural diagram of an embodiment of a frame structure of a mobile communication system equipped with a relay station. As shown in FIG. 2, a DL relay zone and an UL relay zone for RS are allocated in a frame. Data transmitted by the BS to the RS is allocated to the downlink region of the frame in burst form, and data transmitted by the RS to the mobile station is transmitted using the downlink region of the subframe for the RS. When there is data to be transmitted to the base station by the mobile station, it is transmitted using the burst allocated to the uplink region of the subframe for the RS.

3 is a diagram illustrating an embodiment of a frame structure in a mobile communication system based on Orthogonal Frequency Division Multiple Access (OFDMA).

The downlink subframe starts with a preamble used for synchronization and equalization in the physical layer, and a downlink map defining positions and uses of bursts allocated to downlink and uplink. The structure of the entire frame is defined through a DL-MAP message and an UL-MAP message.

Table 1 shows an example of DL-MAP messages.

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 2 shows an example of the UL-MAP message.

Syntax Size Notes UL-MAP_Message_Format () { Management Message Type = 3 8 bits reserved 8 bits Shall be set to zero. UCD Count 8 bits Allocation Start Time 32 bits Begin PHY Specific Section { See applicable PHY section. if (WirelessMAN-OFDMA) { No. OFDMA symbols 8 bits Number of OFDMA symbols in the UL subframe } for ( i = 1; i <= n ; i ++) { For each UL-MAP element 1 to n . UL-MAP_IE () variable See corresponding PHY specification. } } if! (byte boundary) { Padding nibble 4 bits Padding to reach byte boundary. } }

The DL-MAP message defines the usage for each burst allocated for the downlink period in the burst mode physical layer, and the UL-MAP message defines the usage of the burst allocated for the uplink period. Information element (IE) constituting DL-MAP includes Downlink Interval Usage Code (DIUC), Connection ID (CID), and location information of a burst (subchannnel offset, symbol offset, minor). Downlink traffic intervals are classified by the number of channels and the number of symbols). On the other hand, the information element constituting the UL-MAP message is determined by the Uplink Interval Usage Code (UIUC) for each CID (Connection ID), the location of the interval is defined by the 'duration' field. That is, the information element is determined for each section according to the UIUC value used in the UL-MAP, each section starts at a point away from the previous IE start point by the 'duration' specified in the UL-MAP IE.

The UL-MAP allocates usage rights for the uplink channel. The usage of uplink bursts is defined using successive information elements defining usage of each uplink interval, and the usage of uplink resources allocated as a unit of an OFDMA symbol and a subchannel block is defined.

Meanwhile, the UL-MAP Information Element (IE) specifies band allocation information for uplink. Table 3 shows an example of OFDMA UL-MAP IE.

Syntax Size  (bits) Notes UL-MAP_IE () { CID 16 UIUC 4 if (UIUC == 11) { Extended UIUC 2 dependent IE variable See subclause 8.4.5.4.4.2 } elseif (UIUC == 12) { OFDMA symbol offset 8 Subchannel offset 7 No. OFDMA symbols 7 No. subchannels 7 Ranging method 2 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 Dedicated ranging indicator One 0: the OFDMA region and Ranging Method defined are used for the purpose of normal ranging
1: the OFDMA region and Ranging Method defined are used for the purpose of ranging using dedicated CDMA code and transmission opportunities assigned in the MOB_PAG-ADV message or in the MOB_SCN-RSP message. } else if (UIUC == 13) { PAPR_Reduction_and_Safety_Zo ne_Allocation_IE 32 } else if (UIUC == 14) { CDMA_Allocation_IE () 32 } else if (UIUC == 15) { Extended UIUC dependent IE variable See subclauses following 8.4.5.4.3 } else if (UIUC == 0) { FAST-FEEDBACK_Allocation_IE () 32 } else { Duration 10 In OFDMA slots (see 8.4.3.1) Repetition coding indication 2 0b00 No repetition coding
0b01 Repetition coding of 2 used
0b10 Repetition coding of 4 used
0b11 Repetition coding of 6 used if (AAS or AMC UL Zone) { AAS / AMC Allocations include absolute slot off-set. Slot offset 12 Offset from start of the AAS or AMC zone for this allocation, specified in slots. } } }

Each UL-MAP message includes at least one IE to indicate the end of the last burst. The order of the IEs sent by the UL-MAP is determined by the physical layer used. The CID assigns IE to unicast, multicast, and broadcast addresses. If a bandwidth grant is explicitly specified to be assigned, the mobile station's basic CID is used as the CID value. UIUC is used to specify an uplink usage type and an associated uplink burst profile. For each UIUC to be used in UL-MAP, Uplink_Burst_Profile is included in UCD. IEs are all supported by mobile stations. The base station may use any of the above information elements when generating the UL-MAP message.

In the mobile communication system, an operation of a base station using a CQICH channel and a REP-REQ / RSP MAC message for requesting downlink signal quality information to a mobile station will be described.

As a method for acquiring downlink signal quality information of a mobile station by a base station, after allocating some zones to a CQICH-dedicated channel in the uplink two-dimensional map, a subchannel to be used for each mobile station may be designated. That is, as shown in the example of FIG. 3, the CQICH channel zone is pre-allocated using the fast feedback channel in the UL-MAP IE in the UL-MAP, and then the slot to be used by each mobile station is designated using CQICH_Alloc_IE or CQICH_Enhance_Allocation_IE. For example, CQICH # 1 can be designated for MS # 1, CQICH # 2 and CQICH # 3 can be designated for MS # 2, and CQICH # 4 can be designated for MS # 3.

Dynamically allocate the CQICH to the uplink of the mobile station through the CQICH_Alloc_IE or cancel the allocated area. Once assigned, the mobile station transmits signal quality information to the allocated CQICH region at a period set in CQICH_Alloc_IE. When the mobile station cancels the assigned CQICH, i.e., if duration = 0 in CQICH_Alloc_IE, the mobile station does not transmit signal quality information to the base station.

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

Syntax Size Notes CQICH_Alloc_IE () () { Extended UIUC 4 bits CQICH = 0x03 Length 4 bits Length of the message in bytes (variable). CQICH _ ID variable Index to uniquely identify the CQICH resource assigned to the SS. The size of this field is dependent on system parameter defined in UCD. Allocation offset 6 bits Index to the fast feedback channel region marked by UIUC = 0. Period  (p) 2 bits A CQI feedback is transmitted on the CQICH every 2 ^p frames. Frame offset 3 bits The SS starts reporting at the frame of which the number has the same 3 LSB as the specified frame offset. If the current frame is specified, the SS should start reporting in eight frames Duration  (d) 3 bits A CQI feedback is transmitted on the CQI channels indexed by the CQICH_ID for 10 x 2dframes.
If d == 0, the CQICH is deallocated.
If d == 0b111, the SS should report until the BS command for the SS to stop. Report configuration included 1 bits Update to CINR report configuration is included. If (report configuration included == 1) { Feedback Type 2 bits 0b00 = physical CINR feedback
0b01 = effective CINR feedback
0b10-0b11 = Reserved Report type 1 bit 0: Report for preamble
1: Report for specific permutation zone If (Report type == 0) { CINR preamble report type 1 bit The type of preamble-based CINR report
0-Frequency reuse factor = 1 configuration.
1-Frequency reuse factor = 3 configuration. } Else { report for permutation zone. Zone permutation 3 bits The type of zone for which to report 0b000-PUSC with 'use all SC = 0'
0b001-PUSC with 'use all SC = 1'
0b010-FUSC
0b011-Optional FUSC 0b100-Safety Channel region 0b101-AMC zone (only applicable to AAS mode) 0b110-111-Reserved Zone type 2 bits 0b00-non-STC zone 0b01-STC zone
0b10-AAS zone
0b11-reserved Zone PRBS _ ID 2 bits The PRBS_ID of the zone on which to report If (Zone type == 0b000 or 0b001) { Major group indication 1 bit If '0' then the report may refer to any subchannel in the PUSC zone. If (Major group indication == 1) { PUSC Major group bitmap 6 bits Reported CINR shall only apply to the subchannels of PUSC major groups for which the corresponding bit is set. Bit # k refers to major group k . } } CINR zone measurement type 1 bit 0: measurement from pilot subcarriers and, if AAS zone, from AAS preamble.
1: measurement from data subcarriers } If (feedback type == 0b00) { Physical CINR feedback Averaging parameter included 1 bit If (Averaging parameter included == 1) { Averaging parameter 4 bits Averaging parameter used for deriving physical CINR estimates reported through CQICH. This value is given in multiples of 1/16 in the range of [1 / 16..16 / 16] in increasing order. avg } } } MIMO _ permutation _ feedback _ cycle 2 bits 0b00 = No MIMO and permutation mode feedback
0b01 = The MIMO and permutation mode indication shall be transmitted on the CQICH indexed by the CQICH_ID every four allocated CQICH transmission opportunity. The first indication is sent on the fourth allocated CQICH frame transmission opportunity.
0b10 = The MIMO mode and permutation mode indication shall be transmitted on the CQICH indexed by the CQICH_ID every eight allocated CQICH transmission opportunity. The first indication is sent on the eighth allocated CQICH trans-mission opportunity.
0b11 = The MIMO mode and permutation mode indication shall be transmitted on the CQICH indexed by the CQICH_ID every 16 allocated CQICH transmission opportunity. The first indication is sent on the 16th allocated CQICH transmission opportunity. Padding variable Number of bits required to align to byte length, shall be set to zero. }

Table 5 shows an example of a channel measurement report request message (REP-REQ).

Syntax Size Notes Report_Request_Message_Format () { Management Message Type  = 36 8 bits Report Request TLVs variable }

The channel measurement report request message (REP-REQ) is used when a base station operating in a band of 11 GHz or less requests a downlink channel measurement result such as RSSI and CINR of a mobile station. That is, it is used by the mobile station to respond to the listed channel measurements in the received report request. The mobile station includes the measurement results for the channels listed in the received channel measurement result request message in the channel measurement result response message and transmits them. The type of channel quality reported depends on the type of channel currently being used for communication with the base station.

Table 6 shows an example of a channel measurement report request message (REP-REQ) type length value (TLV) encoded parameter.

Name Type Length Value Report request One variable Compound

The signal quality information report response message is configured to correspond to the measurement request of the channel measurement report request message received by the mobile station.

Table 7 shows an example of the report request list of Table 6.

Name Type Length Value Report type 1.1 One Bit # 0 = 1 Include DFS Basic report
Bit # 1 = 1 Include CINR report
Bit # 2 = 1 Include RSSI report
Bit # 3 6 a _vg \ in multiples of 1/32 (range [1/32, 16/32])
Bit # 7 = 1 Include current transmit power report Channel number 1.2 One Physical channel number (see 8.5.1) to be reported on. (license-exempt bands only) Channel Type request 1.3 One 0b00 = Normal subchannel,
0b01 = Band AMC Channel,
0b10 = Safety Channel,
0b11 = Sounding Zone-specific
physical CINR
request 1.4 3 Bits # 0-2: Type of zone on which CINR is to be reported
0b000: PUSC zone with 'use all SC = 0'
0b001: PUSC zone with 'use all SC = 1' / PUSC AAS zone
0b010: FUSC zone
0b011: Optional FUSC zone
0b100: Safety Channel region
0b101: AMC zone (only applicable to AAS mode)
0b110-0b111: Reserved
Bit # 3: 1 if zone for which CINR should be estimated is STC zone, 0 otherwise.
Bit # 4: 1 if zone for which CINR should be estimated is AAS zone, 0 otherwise.
Bits # 5-6: PRBS_ID of the zone for which CINR should be estimated. Ignored for Safety Channel.
Bit # 7: Data / pilot-based CINR measurement:
0-Report the CINR estimate from pilot subcarriers,
1-Report the CINR estimate from data subcarriers
Bits # 8-13: Reported CINR shall only be estimated for the subchannels of PUSC major groups for which the corresponding bit is set. Bit # ( k +7) refers to major group k. Only applicable for CINR measurement on a PUSC zone
Bits # 14-17: avg in multiples of 1/16 (range is [1 / 16,16 / 16])
Bit # 18: 0-report only mean of CINR
1-report both mean and standard deviation of CINR
Bits # 19-23: Reserved , shall be set to zero Preamble physical CINR request 1.5 One Bits # 0-1: Type of preamble physical CINR measurement
0b00-Report the estimation of CINR measured from preamble for frequency reuse configuration = 1
0b01-Report the estimation of CINR measured from preamble for frequency reuse configuration = 3
0b10-Report the estimation of CINR measured from preamble for band AMC
0b11- Reserved
Bits # 2-5: in multiples of 1/16 (range is [1 / 16,16 / 16]) Bit # 6: 0-report only mean of CINR 1-report both mean and standard deviation of CINR
Bit # 7: Reserved , shall be set to zero avg Zone-specific effective CINR request 1.6 2 Bits # 0-2: Type of zone on which effective CINR is to be reported
0b000: PUSC zone with 'use all SC = 0'
0b001: PUSC zone with 'use all SC = 1' / PUSC AAS zone
0b010: FUSC zone
0b011: Optional FUSC zone
0b100: Reserved
0b101: AMC zone (only applicable to AAS mode)
0b110-0b111: Reserved
Bit # 3: 1 if zone for which effective CINR should be reported is STC zone, 0 otherwise.
Bit # 4: 1 if zone for which effective CINR should be estimated is AAS zone, 0 otherwise.
Bits # 5-6: PRBS_ID of the zone for which effective CINR should be reported. Ignored for Safety Channel. Bit # 7: Data / pilot-based effective CINR measurement: 0-Report the CINR estimate from pilot subcarriers,
1-Report the CINR estimate from data subcarriers
Bits # 8-13: Reported effective CINR shall only be estimated for the subchannels of PUSC major groups for which the corresponding bit is set. Bit # ( k +7) refers to major group k . Only applicable for CINR measurement on a PUSC zone
Bit # 14-15: Reserved , shall be set to zero Preamble effective CINR request 1.7 One Bits # 0-1: Type of preamble-based effective CINR measurement
0b00-Report the estimation of effective CINR measured from preamble for frequency reuse configuration = 1
0b01-Report the estimation of effective CINR measured from preamble for frequency reuse configuration = 3
0b10-11- Reserved
Bit # 2-7: Reserved , shall be set to zero Channel selectivity report 1.8 One Bit # 0: 1-include frequency selectivity report
Bit # 1-7: Reserved , shall be set to zero

Table 8 shows an example of a channel measurement report request message (REP-REQ).

Syntax Size Notes Report_Response_Message_Format { Management Message Type  = 37 8 bits Report Response TLVs variable }

Table 9 is an example of the request response list of Table 8.

Name Type Length Value Report One variable Compound Channel Type Report in WirelessMAN OFDMA PHY 2 variable Compound Current transmitted power 147 One See 8.3.7.4 and 11.1.1

Table 10 is an example of a report list of Table 9.

REP - REQ  Report type Name Type Length Value bit # 0 = 1 Channel number 1.1 One Physical channel number (see 8.5.1) to be reported on bit # 0 = 1 Start frame 1.2 2 16 LSBs of Frame number in which measurement for this channel started bit # 0 = 1 Duration 1.3 3 Cumulative measurement duration on the channel in multiples of Ts. For any value exceeding 0xFFFFFF, report 0xFFFFFF bit # 0 = 1 Basic report 1.4 One Bit # 0: WirelessHUMAN detected on the channel
Bit # 1: Unknown transmissions detected on the channel
Bit # 2: Specific Spectrum User detected on the channel
Bit # 3: Unmeasured. Channel not measured bit # 1 = 1 CINR report 1.5 2 1 byte: mean (see also 8.2.2, 8.3.9, 8.4.11) for details) 1 byte: standard deviation bit # 2 = 1 RSSI report 1.6 2 1 byte: mean (see also 8.2.2, 8.3.9, 8.4.11) for details) 1 byte: standard deviation

Table 11 shows an example of the channel type report list of Table 9.

REP - REQ Channel  Type request  ( binary ) Name Type Length Value 01 Band AMC Report
(CQI value)
2.2 5 First 12 bits for the band indicating bitmap and next 20 bits for CINR measurement (5 bits per each band) 11 Sounding report 2.5 One Average SINR.
8 bits in the same format used in
8.4.11.3

The base station compares the uplink signal quality of a specific mobile station with the uplink signal quality received by the base station, and determines whether the base station and the mobile station communicate directly or relay the signal through the RS. . In addition, when it is determined that the base station needs to increase throughput, the base station relays a signal to the mobile station through RS.

In order for the base station to obtain uplink signal quality information of the mobile station, the mobile station periodically transmits the signal quality information, or transmits the signal quality information when certain conditions are satisfied.

On the other hand, when the mobile station transmits the signal quality information according to the periodic or constant conditions as described above, it may use a specific channel or use a MAC message. For example, the specific channel is CQICH, and the MAC message is a REP-REQ / RSP MAC management message.

First, a base station and a mobile station perform direct communication, and then a process of relaying a signal through RS will be described. When the mobile station receives service from the base station and moves to the area of the RS, or the distance between the mobile station and the base station increases, the uplink signal quality of the mobile station received by the base station is degraded, or the base station attempts to increase throughput with the mobile station through the RS. In this case, the base station compares the uplink signal quality information between the mobile station and the base station and the uplink signal quality information when the RS exists between the base station and the mobile station, so that the mobile station communicates with the base station through the RS rather than the uplink signal quality between the base station and the mobile station. When communicating, if the signal quality improves or throughput increases, the base station provides a service to the mobile station through the RS.

As examples of a method for acquiring signal quality information of a mobile station received by an RS, there are a method using a CQICH channel and a method using a REP-REQ / RSP MAC management message. The mobile station is in the coverage of the base station, and the mobile station in the RS area can be served by the base station. The uplink signal quality information between the mobile station and the RS may be transmitted to the base station when certain conditions are satisfied or periodically.

First, a method of transmitting signal quality information through a CQICH when a specific condition is satisfied will be described below. When the base station allocates the CQICH channel of the mobile station to uplink and requests downlink signal quality information, the downlink signal quality information measurement value transmitted by the mobile station to the base station or the uplink signal quality when the base station receives this information If this value is less than or equal to the reference value, the base station requests the mobile station that is less than or equal to the reference value to include downlink signal quality information in the CQICH channel.

In addition, the base station sets the RS to monitor the uplink from the mobile station, and the RS that acquires the uplink signal quality information of the mobile station requests the base station to allocate the CQICH region. That is, when the mobile station transmits downlink signal quality information through the CQICH region allocated to the mobile station, the RS, which has received this information from the mobile station, confirms uplink signal quality information between the mobile station and the RS. The RS transmits uplink signal quality information between the mobile station and the RS through a CQICH region corresponding to each mobile station allocated from the base station. When the base station receives this information and the uplink signal quality information and the uplink signal quality information of the mobile station obtained by the RS is higher than the signal quality information directly received from the mobile station and the reference value or more, the base station provides service to the mobile station through the RS. to provide.

4 is a flowchart of a first embodiment showing a method of determining whether direct communication or relay communication is performed. 4, the base station allocates a CQICH to the first mobile station, the second mobile station, and the third mobile station, and requests downlink signal quality information (S401 to S403). Signal quality information is received from each of the base stations (S404 to 406), and it is checked whether the reception quality is below a reference value.

If less than the reference value, the base station requests to monitor the uplink of the second mobile station and the third mobile station that is less than the reference value to the RS (S408 ~ S409). The second mobile station and the third mobile station transmit signal quality information through the CQICH, respectively (S410 to S413). The RS acquires the signal quality information transmitted from the second mobile station and the third mobile station, and receives a radio resource for transmitting the signal quality information from the base station (S414), for the second mobile station and the third mobile station through the CQICH region. The UL signal quality information is transmitted (S415 to S416). When the base station receives the uplink signal quality information received through the RS and the uplink signal quality information of the mobile terminal obtained by the RS is higher than the uplink signal quality information directly received from the mobile terminal, the base station determines the second mobile station and the first mobile station through the RS. 3 Perform relay communication with the mobile station (S417 to S419).

A method of transmitting signal quality information using a MAC management message when a specific condition is satisfied is described below. If the downlink signal quality information transmitted by the mobile station to the base station or the uplink signal quality when the base station receives the downlink signal quality information of the mobile station is less than or equal to the reference value, the base station allocates an uplink radio resource to the mobile station, and RS Transmits a message for monitoring the uplink signal quality of the mobile station. Each mobile station allocated an uplink radio resource from the base station transmits data when there is data to be transmitted to the base station, and performs periodic ranging when there is no data to be transmitted to the base station.

When the mobile station transmits data, the RS transmits uplink signal quality information of the data received from the mobile station to the base station, but transmits the uplink signal quality information to the base station by using the radio resource allocated by the RS. When the mobile station performs periodic ranging, that is, the mobile station can obtain uplink signal quality information from the mobile station through a message for requesting ranging to the base station. The uplink signal quality information of the mobile station obtained by the RS may be transmitted to the base station by the RS in the form of a MAC message. The base station compares the uplink signal quality information of the mobile station transmitted by the RS with the uplink signal quality information directly received from the mobile station, and determines whether to perform direct communication or relay communication with the mobile station.

5 is a flowchart of a second embodiment showing a method of determining whether direct communication or relay communication is performed. Referring to FIG. 5, when the base station requests downlink signal quality information from the first mobile station and the second mobile station through the REP-REQ message (S501, S503), the mobile stations transmit the downlink signal quality to the base station in the REP-RSP message. Information is transmitted (S502, S504). Checking the downlink signal quality of the mobile station received by the base station and / or the uplink signal quality when the base station receives the REP-RSP message, if the base value is less than or equal to the reference value, the base station determines that the downlink signal quality information of the mobile station is equal to or less than the reference value. An uplink radio resource is allocated (S505). The base station requests the RS to monitor uplink between the RS and the mobile stations (S506, S507).

The mobile station allocated the uplink from the base station checks whether there is data to be transmitted to the base station, and transmits the data through the allocated uplink radio resource (S508). When the mobile station transmits data to the base station, the RS includes uplink signal quality information of the data received from the mobile station in the MAC message and transmits the data to the base station. If there is no data to transmit to the base station, the mobile station performs periodic ranging. That is, the mobile station transmits a ranging request message (RNG-REQ) to the base station and the RS (S511 and S512), and the RS can check uplink signal quality information from the ranging request message received from the mobile station. The RS transmits signal quality information between the RS and the mobile station to the base station using the MAC message signal quality report response message (REP-RSDetect-RSP).

The base station receiving the signal quality report response message (REP-RSDetect-RSP) from the RS receives the uplink signal quality information when receiving this information and the uplink signal quality information of the mobile station obtained by the RS transmitted from the RS from the mobile station. If the uplink signal quality information of the mobile station received through the RS is high and is higher than or equal to the reference value, the base station provides a service to the mobile station through the first RS.

The base station may periodically report the uplink signal quality information between the mobile station and the RS, and determine whether to perform direct communication or relay communication using the RS. First, a method of receiving signal quality information through CQICH will be described.

The base station allocates the CQICH channel of the mobile station to the uplink, and periodically checks the downlink signal quality information transmitted by the mobile station to the base station or the uplink signal quality information of the information. That is, the base station requests to include the downlink signal quality information of the mobile station in the CQICH channel and sets the RS to monitor the uplink from the mobile station for the period. The RS, which has acquired uplink signal quality information of the mobile station, requests the base station to allocate the CQICH region of the mobile station. When the mobile station transmits downlink signal quality information through the CQICH region allocated to each terminal, the RS, which has received this information from the mobile station, checks the uplink signal quality information and through the CQICH region of each mobile station of the RS allocated from the base station. Transmit signal quality information between the mobile station and the RS.

The base station compares two values of the signal quality information between the mobile station and the RS and the signal quality information directly received from the mobile station. If the uplink signal quality information of the former is higher and higher than the reference value, the base station provides a service to the mobile station through the RS. . This process is repeated for the cycle. If the cycle ends or the base station releases the CQICH channel (de-allocation), the process is canceled.

6 is a flowchart of a third embodiment showing a method of determining whether direct communication or relay communication is performed. Referring to FIG. 6, the base station allocates regions for the first RS, the first mobile station, the second mobile station, and the third mobile station to the FAST-Feedback Channel. The base station requests downlink signal quality information of the first RS, the first mobile station, the second mobile station, and the third mobile station (S601 to 604). The base station requests the first RS to monitor uplink signal quality information received from the first mobile station, the second mobile station, and the third mobile station (S605). The first mobile station, the second mobile station, and the third mobile station transmit signal quality information through the corresponding CQICH (S606 to S612).

The base station allocates the CQICH of the first RS to obtain uplink signal quality information of each mobile station acquired by the first RS (S613). The uplink quality information of the first mobile station, the second mobile station, and the third mobile station acquired by the RS is transmitted to the CQICH region of the allocated first RS (S614 to S616).

The base station performs relay communication through the RS when the uplink signal quality information received through the first RS and the uplink signal quality information of the mobile station obtained by the first RS are better than the uplink signal quality directly received from the mobile station and are higher than a reference value. (S617 ~ S619).

Hereinafter, a method of periodically receiving signal quality information using a MAC message will be described. The base station periodically allocates the uplink of the mobile station to obtain the uplink signal quality of the mobile station, and transmits a MAC message to the RS to monitor the uplink of the mobile station. Each mobile station assigned uplink from the base station transmits data when there is data to be transmitted to the base station, and performs periodic ranging when there is no data to be transmitted to the base station.

When the mobile station transmits data to the base station, the RS includes uplink signal quality information of the data obtained from the mobile station in the area allocated by the RS and transmits the data to the base station. When the mobile station performs periodic ranging, that is, the mobile station can receive uplink signal quality information from the mobile station through a message for requesting the mobile station to raise the ranging. The uplink signal quality information of the mobile station received by the RS is transmitted by the RS to the base station in the form of a MAC message. The base station receiving data from the RS compares the uplink signal quality information when receiving this information with the uplink signal quality information received directly from the mobile station by comparing the uplink signal quality information between the RS transmitted by the RS and the mobile station through the RS. If the uplink signal quality information of the received mobile station is high and equal to or greater than the reference value, the base station provides a service to the mobile station through the RS.

7 is a flowchart of a fourth embodiment showing a method of determining whether direct communication or relay communication is performed. The base station allocates an uplink radio resource to each mobile station (S701, S702). The base station transmits a signal quality measurement report request message (REP-RSDetect-REQ) RS so that the RS monitors uplinks from the first mobile station and the second mobile station (S703, S704).

If there is data to be transmitted to the base station by the first mobile station allocated the uplink radio resource from the base station, the data is transmitted using the allocated uplink radio resource (S705 and S706). When the first mobile station transmits data to the base station, the RS confirms the uplink signal quality of the data obtained from the mobile station and transmits the signal quality information to the base station through the signal quality measurement report response message (REP-RSDetect-RSP). (S707).

If there is no data to transmit to the base station, the second mobile station performs periodic ranging. That is, the second mobile station transmits a ranging request message (RNG-REQ) (S708, S709), and the second RS receives uplink signal quality information from the ranging request message (RNG-REQ) obtained from the second mobile station. You can check it. The second RS transmits the received uplink signal quality information of the mobile station to the base station in the form of a signal quality measurement report response message (REP-RSDetect-RSP) (S710). When the base station and the mobile station perform direct communication using the received information, the base station performs direct communication when it is determined that the signal quality is better than when performing relay communication using RS. On the other hand, when the base station and the mobile station performs direct communication, when it is determined that the signal quality is lowered than when performing the relay communication using the RS, the relay communication using the RS is performed.

The base station provides a service to the mobile station through the RS (S711, S712). When uplink signal quality information directly received from the mobile station is better than the uplink signal quality information of the mobile station received through the RS, the base station does not pass through the RS (S713).

If the period for checking uplink signal quality information is not '0' and the base station provides a service to the mobile station through the RS, the base station allocates the uplink of the mobile station through the RS and the terminal has data to transmit to the base station. If present, it is included in the corresponding area (S714 to S717). When the first mobile station transmits data to the base station, the first RS confirms uplink signal quality information of the data received from the mobile station and includes the information in the REP-RSDetect-RSP message, which is a response to the REP-RSDetect-REQ message, to the base station. It transmits (S718).

If there is no data to be transmitted to the base station, the first base station performs periodic ranging. When the mobile station performs periodic ranging, the first mobile station transmits an RNG-REQ message to the base station through the first RS (S719 and S720). The first RS may confirm uplink signal quality information from the RNG-REQ message received from the first mobile station. The uplink signal quality information of the mobile station acquired by the first RS is transmitted to the base station by the first RS in the form of a REP-RSDetect-RSP message. If the base station directly requests the mobile station's downlink signal quality information to the mobile station without RS, the process returns to step S701.

Hereinafter, a method in which a base station and a mobile station perform relay communication using RS and then performs direct communication between the base station and the mobile station will be described. When the mobile station in the RS region transmits uplink signal quality information between the base station and the mobile station directly to the base station without using the RS, the uplink signal quality information received directly from the mobile station by the base station is higher than the uplink signal quality of the mobile station received by the RS. If better or similar, the base station provides the service directly to the mobile station rather than via the RS.

The mobile station receives the service from the base station through the RS and moves out of the area of the RS, or the distance from the base station becomes closer, so that the uplink signal quality information of the mobile station received by the base station is improved or the base station directly transmits data to the mobile station without passing through the RS. In case of transmitting a signal, the base station compares the uplink signal quality information of the mobile station received by the base station with the uplink signal quality information when the RS exists in the middle, and the uplink signal quality information between the base station and the mobile station is determined by the base station RS. The base station provides a service directly to the mobile station without passing through the RS if it is similar or better than the uplink signal quality between the mobile stations received through.

A process of allowing a base station and a mobile station to perform direct communication and relaying a signal through RS is as follows.

The downlink signal quality information of the mobile station received by the base station through RS or the uplink signal quality information when the base station receives this information is equal to or less than the reference value, or the downlink / uplink signal quality information received from the mobile station by the base station is referenced. When the value is greater than or equal to and better than or similar to the downlink / uplink signal quality information of the mobile station received through the RS, the base station requests uplink signal quality information of the mobile station.

The base station allocates a CQICH region of the mobile station to obtain downlink signal quality information of the mobile station. The uplink CQICH region may be allocated by the base station to the mobile station directly or through the RS. If the downlink signal quality information of the terminal included in the CQICH region of each terminal or the uplink signal quality information when receiving this information is higher than the reference value, and is better than the uplink quality information of the terminal received through the RS, the base station Provides the service directly to the mobile terminal, not through the corresponding RS.

8 is a flowchart of a fifth embodiment showing a method of determining whether direct communication or relay communication is performed.

When the base station allocates a CQICH region for receiving downlink signal quality information of the mobile station, the base station requests downlink signal quality information of the first mobile station (S801). If the base station checks the received downlink signal quality of the mobile station or the uplink signal quality information of the mobile station when receiving this information (S802) and is equal to or greater than the reference value, the base station determines that the corresponding mobile station, i.e. The base station requests to monitor the uplink (S803), and the base station requests to transmit downlink signal quality information of the corresponding mobile station having a reference value or more through the CQICH assigned to each mobile station (S804).

The first mobile station includes downlink signal quality information between the base station and the mobile station in the allocated CQICH region and transmits the information to the base station (S805). The first RS receives uplink signal quality information between the first RS and the first mobile station (S806). The base station allocates the CQICH region of the first RS to transmit the uplink signal quality information of the first mobile station received by the first RS (S807). The uplink signal quality information of the first mobile station received by the first RS is transmitted to the CQICH region of the allocated first RS (S808). The base station does not go through the first RS, and when the uplink signal quality information received directly from the first mobile station is better than the uplink signal quality information of the first mobile station received through the first RS, the base station does not go through the first RS. The service is directly provided to the first mobile station (S809).

The base station allocates an uplink region of the mobile station through RS to obtain uplink signal quality information received from the mobile station, or the base station directly assigns an uplink to the mobile station without RS.

In the former case, when the base station allocates the uplink of the mobile station through the RS, if the mobile station has data to transmit to the base station, the terminal includes the data in the allocated area and transmits the data to the RS, and the RS transmits the data to the base station again. If there is no data to be transmitted to the base station, the mobile station performs periodic ranging and requests ranging to the base station through the RS. At this time, the base station can obtain the uplink signal quality information of the mobile station received through the RS, and if the uplink signal quality information is less than the reference value, the base station directly allocates the uplink to the mobile station to transmit data or periodic lanes Acquiring the uplink signal quality information of the mobile station received from the RS through the gong process. The base station provides the service to the mobile station directly without passing through the RS, if the received uplink signal quality information of the mobile station is greater than or equal to a reference value and better than the uplink signal quality of the mobile station received through the RS.

In the latter case, if the uplink signal quality information of the mobile station acquired directly by the base station through the mobile station is higher than the reference value and is better than the uplink signal quality information of the mobile station received through the RS, the base station does not go directly through the corresponding RS. To provide services.

9 is a flowchart of a sixth embodiment showing a method of determining whether direct communication or relay communication is performed. Referring to FIG. 9, when the base station communicates with the first mobile station through the first RS, the base station allocates an uplink area of the first mobile station to an area of the first RS of uplink (S901) and the first An uplink allocation area of the first mobile station is secured through the RS (S902). The base station transmits a REP-RSDect-REQ message to the first RS so that the first RS monitors an uplink from the first mobile station (S903).

If there is data to be transmitted to the base station by the first mobile station, the first mobile station transmits data to the first RS and the first RS to the base station (S904 and S905). In this case, the first RS may obtain uplink signal quality information from the first mobile station. The first RS includes the received uplink signal quality information of the first mobile station in the REP-RSDetect-RSP message and transmits it to the base station (S906). If there is no data to be transmitted to the base station by the first mobile station, periodic ranging is performed. For this purpose, the first mobile station requests an RNG-REQ to the first RS and transmits the first RS to the base station again (S907 and S908). At this time, the first RS may obtain uplink signal quality information from the first mobile station. The first RS includes the received uplink signal quality information of the first mobile station in the REP-RSDetect-RSP message and transmits it to the base station (S909). If the uplink signal quality information of the mobile station received by the base station through RS # 1 is less than the reference value, the base station allocates the uplink of the first mobile station (S910), and the first mobile station assigned the uplink from the base station transmits to the base station. If there is data, the data is included in the area allocated to the first mobile station and transmitted (S912). At this time, the base station may receive uplink signal quality information from the first mobile station. If there is no data to be transmitted to the base station by the first mobile station, the first mobile station sends an RNG-REQ message to the base station, and the base station can obtain uplink signal quality information from the first mobile station (S915). The base station, when the uplink signal quality information of the first mobile station is greater than or equal to the reference value and is better than the uplink signal quality information of the first mobile station received through the first RS, the base station is not directly through the first RS. One mobile station service is provided (S918).

On the other hand, when the base station communicates directly to the first mobile station without passing through the first RS, the base station allocates an uplink of the first mobile station (S910), and the base station transmits a REP-RSDetect-REQ message to the first RS. In operation S911, the UE requests to monitor uplink signal quality information received from the first mobile station.

If the first mobile station allocated uplink from the base station has data to transmit to the base station, the first mobile station includes data in the area allocated to the first mobile station and transmits the data. In this case, the base station may receive uplink signal quality information of the mobile station (S912). The first RS may obtain uplink signal quality information from the first mobile station (S913). The first RS includes the received uplink signal quality information of the first mobile station in the REP-RSDetect-RSP message and transmits it to the base station (S914).

If there is no data to be transmitted to the base station by the first mobile station, the first mobile station sends an RNG-REQ message to the base station, where the base station may receive uplink signal quality information of the mobile station (S915). The first RS may obtain uplink signal quality information from the first mobile station. The first RS includes the received uplink signal quality information of the first mobile station in the REP-RSDetect-RSP message and transmits it to the base station (S914). The base station, when the uplink signal quality information of the first mobile station is greater than or equal to the reference value and is better than the uplink signal quality information of the first mobile station received through the first RS, the base station is not directly through the first RS. One mobile station service is provided (S918).

The base station may periodically receive the uplink signal quality information from the mobile station and the RS and use it to determine whether to perform direct communication or relay communication using the RS. That is, the base station periodically requests uplink signal quality information between the mobile station and the RS, and the base station acquires uplink signal quality information of the mobile station through the RS to obtain downlink / uplink signal quality information received from the mobile station, or The base station receives the uplink signal quality information directly to the mobile station, not through the RS.

In the present invention, the base station proposes a method for periodically checking the uplink signal quality information between the mobile station and the RS, if there is a relay station (RS) between the existing base station and the mobile station, whether the base station relays through the RS And uplink signal quality information between the UE and the uplink signal quality information between the base station, the RS, and the UE. Therefore, a seamless base station can be provided, and the service area of the base station can be expanded and smoothed even in a shadowed area. In addition, since the base station can manage a group of mobile stations receiving the service of the RS, it is possible to reduce resource distribution of the serving base station and power consumption of the mobile station.

Table 12 shows an example of UIUC values.

UIUC Usage 0 FAST-FEEDBACK Channel 1-10 Different burst profiles (Data Grant Burst Type) 11 Extended UIUC 2 IE 12 CDMA Bandwidth Request, CDMA Ranging 13 PAPR reduction allocation, safety zone 14 CDMA Allocation IE 15 Extended UIUC

Table 12 shows an example when the type of UIUC is 15, that is, when Extended UIUC is selected, Extended UIUC = 0B indicates RS-Detect-MS_IE and Extended UIUC = 0C indicates RS-CQICH_Alloc_IE.

Table 13 shows an example of the REP-RSDetect-RSP message.

Extended UIUC  ( hexadecimal ) Usage 00 Power_control_IE 01 Mini-subchannel_allocation_IE 02 AAS_UL_IE 03 CQICH_Alloc_IE 04 UL Zone IE 05 PHYMOD_UL_IE 06 MIMO_UL_Basic_IE 07 UL-MAP_Fast_Tracking_IE 08 UL_PUSC_Burst_Allocation_in_Other_Segment_IE 09 Fast_Ranging_IE 0A ULAllocation Start IE 0B RS-Detect_MS_IE 0C RS-CQICH_Alloc_IE 0D -0F Reserved

Table 14 shows an example of the RS-Detect MS IE format.

Syntax Size Notes RS-Detect_MS_IE () { Extended UIUC 4 bits CQICH = 0x0B Length 4 bits Length of the message in bytes (variable). N_CID 7 bits Numbers of MS Basic CIDs. Fast FeedBack Channel configuration included 1bits Fast FeedBack Channel If (Fast FeedBack Channel configuration included == 1) { OFDMA symbol offset 8 bits Subchannel offset 7bits No.OFDMA symbols 7bits No.subchannels 7bits } For (i = 0; i <N_CID; i ++) { CID 16 bits MS Basic CID may be detected by RS in the current frame. Frame_Num Frame number Allocation_Offset 6 bits Index to the Fast Feedback channel region Report type 1 bits 0: report for CINR
1: report for RSSI } Padding variable Number of bits required to align to byte length, shall be set to zero. }

Table 15 shows an example of the RS-CQICH_Alloc_IE format.

Syntax Size Notes RS-CQICH_Alloc_IE () { Extended UIUC 4 bits CQICH = 0x0C Length 4 bits Length of the message in bytes (variable). OFDMA symbol offset 8 bits Subchannel offset 7 bits No. OFDMA symbols 7 bits No. Subchannels 7 bits N_CID 7 bits Number of MS Basic CIDs For (i = 0; i <N_CID; i ++) { CID MS Basic CID Quality Allocation offset For RS-MS quality
Index to the RS-CQICH alloc channel region Report type 1 bit 0: report for CINR
1: report for RSSI If (report type == 0) { Channel quality } Else if (report type == 1) { Channel quality } } Padding variable Number of bits required to align to byte length, shall be set to zero. }

Table 16 shows an example of the REP-RSDetect-REQ message.

Syntax Size Notes REP-RSDetect_REQ () { Management message type 8 bits N_CID 7 bits Number of MS Basic CIDs. For (i = 0; i <N_CID; i ++) { CID 16 bits MS Basic CID may be detected by RS in the current frame. Report type 1 bit 0: report for CINR
1: report for RSSI } }

Table 17 shows an example of the REP-RSDetect-RSP message.

Syntax Size Notes REP-RSDetect_RSP () { Management message type 8 bits Number of MS 7 bits Numbers of MSs. For (i = 0; i <Number of MS; i ++) { CID 16 bits MS CID may be detected by RS in the current frame. Report type 1 bit 0: report for CINR
1: report for RSSI If (report type == 0) { Channel quality } Else if (report type == 1) { Channel quality } } } }

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.

The present invention has the effect that, in a broadband wireless access system, the base station determines the direct communication or the relay communication with the mobile station and increases the throughput by controlling the same.

Claims (10)

In the relay communication control method applied to a broadband wireless access system having a relay station, Broadcasting, by a base station, an uplink map (UL-MAP) message for allocating a channel for a terminal; Receiving a ranging request message for periodic ranging from the terminal through the allocated channel; Acquiring, by the base station, first channel state information between the base station and the terminal based on the ranging request message; Receiving, by the base station, a report message including second channel state information between the relay station and the terminal from the relay station; Comparing the first channel state information between the base station and the terminal and the second channel state information between the relay station and the terminal; And According to the comparison result, the base station includes a step of performing a direct communication with the terminal or relay communication with the relay station, And the second channel state information is obtained by monitoring the channel allocated to the terminal by the relay station. The method of claim 1, The second channel state information may be represented by one of a carrier to interface ratio (CINR) or a received signal strength indication (RSSI). The method of claim 1, The first channel state information between the base station and the terminal, And obtaining from the base station through the ranging request message transmitted by the ranging method indicated in the UL-MAP message. The method of claim 1, If the first channel state information between the base station and the terminal is better than the second channel state information between the relay station and the terminal, the base station performs direct communication with the terminal. Control method. The method of claim 1, In case the second channel state information between the relay station and the terminal is better than the first channel state information between the base station and the terminal, the base station performs relay communication through the relay station. Communication control method. A base station supporting a relay communication control method applied to a broadband wireless access system having a relay station, the base station comprising: Broadcasting, by the base station, an uplink map (UL-MAP) message for allocating a channel for the terminal; Receiving a ranging request message for periodic ranging from the terminal through the allocated channel; Acquiring, by the base station, first channel state information between the base station and the terminal based on the ranging request message; Receiving, by the base station, a report message including second channel state information between the relay station and the terminal from the relay station; Comparing the first channel state information between the base station and the terminal and the second channel state information between the relay station and the terminal; And According to the comparison result, the base station is configured to perform a step of performing a direct communication with the terminal or relay communication with the relay station, And wherein the second channel state information is obtained by monitoring the channel assigned to the terminal by the relay station. The method of claim 6, The second channel state information, A base station characterized by one of a carrier to interface ratio (CINR) or Received Signal Strength Indication (RSSI). The method of claim 6, The first channel state information between the base station and the terminal, The base station, characterized in that obtained by the base station via the ranging request message transmitted by the ranging method indicated in the UL-MAP message. The method of claim 6, The base station performs direct communication with the terminal when the first channel state information between the base station and the terminal is better than the second channel state information between the relay station and the terminal. . The method of claim 6, When the second channel state information between the relay station and the terminal is better than the first channel state information between the base station and the terminal, the base station performs relay communication through the relay station, Base station.

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