WO2011002263A2 - Method and apparatus for receiving control information of relay station in wireless communication system including relay station - Google Patents

Abstract

A method for receiving control information of a relay station in a wireless communication system including the relay station comprises the steps of: receiving resource allocation information from a base station; and receiving backhaul downlink control information from the base station in wireless resources which the resource allocation information indicates, wherein the resource allocation information includes an OFDM symbol for transmitting access downlink control information from the relay station to a relay station terminal in a time domain with respect to a sub-frame including a plurality of OFDM symbols and at least one or more OFDM symbols positioned after a guard period, and indicates the wireless resources including resource element groups separated to a frequency domain with a constant interval in one or more OFDM symbols.

Description

Method and apparatus for receiving control information of relay station in wireless communication system including relay station

The present invention relates to wireless communication, and more particularly, to a method and apparatus for a relay station to receive control information from a base station in a wireless communication system including a relay station.

The International Telecommunication Union Radio communication sector (ITU-R) is working on the standardization of International Mobile Telecommunication (IMT) -Advanced, the next generation of mobile communication systems after the third generation. IMT-Advanced aims to support Internet Protocol (IP) -based multimedia services at data rates of 1 Gbps in stationary and slow motions and 100 Mbps in high speeds.

3rd Generation Partnership Project (3GPP) is a system standard that meets the requirements of IMT-Advanced. Long Term Evolution is based on Orthogonal Frequency Division Multiple Access (OFDMA) / Single Carrier-Frequency Division Multiple Access (SC-FDMA) transmission. LTE-Advanced is being prepared. LTE-Advanced is one of the potential candidates for IMT-Advanced. The main technologies of LTE-Advanced include relay station technology.

A relay station is a device for relaying a signal between a base station and a terminal, and is used to expand cell coverage and improve throughput of a wireless communication system.

In the wireless communication system including the relay station, a signal transmission method between the base station and the relay station is currently being studied. It is problematic to use the signal transmission method between the base station and the terminal as it is for signal transmission between the base station and the relay station.

In the time domain, the RS may not be able to transmit or receive a signal over one subframe. Since the relay station usually relays signals to a plurality of terminals, frequent reception mode and transmission mode switching occurs. In addition, the RS may receive a signal from the BS or transmit a signal to the RS in the same frequency band. Alternatively, the relay station may receive a signal from the relay station terminal or transmit a signal to the base station in the same frequency band. In the switching between the reception mode and the transmission mode, a predetermined time period in which the relay station does not transmit or receive a signal to prevent inter-signal interference and stabilize the operation between the reception mode section and the transmission mode section (hereinafter referred to as guard time). Is called).

In addition, the RS may need to transmit control information in order to prevent the RS from taking unnecessary data reception operations in a subframe receiving a signal from the BS.

Due to the constraints described above, it is difficult for a relay station to apply a conventional method of receiving control information between base stations and terminals. What is needed is a method and apparatus for a relay station to receive control information in a backhaul link between a relay station and a base station.

The present invention provides a method and apparatus for receiving control information of a relay station in a wireless communication system including the relay station.

In a wireless communication system including a relay station according to an aspect of the present invention, a method for receiving control information of a relay station includes receiving resource allocation information from a base station; And receiving backhaul downlink control information from the base station in a radio resource indicated by the resource allocation information, wherein the resource allocation information is a relay station terminal in the time domain for a subframe including a plurality of OFDM symbols. And an OFDM symbol for transmitting access downlink control information to the at least one OFDM symbol and a resource element group spaced at regular intervals from the at least one OFDM symbol in the frequency domain. It is characterized by indicating the resource.

The relay station according to another aspect of the invention the RF unit for transmitting and receiving radio signals; And a processor connected to the RF unit, wherein the processor receives resource allocation information from a base station and receives backhaul downlink control information from the base station in a radio resource indicated by the resource allocation information, wherein the resource allocation information is received. Is an OFDM symbol in which a relay station transmits access downlink control information to a relay terminal in a time domain for a subframe including a plurality of OFDM symbols, and at least one or more OFDM symbols located after a guard interval, and the at least one or more symbols It is characterized by indicating a radio resource including resource element groups spaced at regular intervals from the OFDM symbol to the frequency domain.

In a wireless communication system including a relay station, the relay station can reliably receive backhaul downlink control information such as ACK / NACK or information on the number of OFDM symbols in the control region from the base station.

1 shows a wireless communication system including a relay station.

2 shows a link present in a wireless communication system.

3 is a diagram conceptually showing a functional module of a relay station.

4 shows a radio frame structure of 3GPP LTE.

5 is an exemplary diagram illustrating a resource grid for one downlink slot.

6 shows a structure of a downlink subframe.

7 shows a structure of an uplink subframe.

8 shows an example of a timing relationship between an uplink radio frame and a downlink radio frame.

9 is a diagram illustrating a configuration of a subframe in which a relay station receives a signal from a base station.

10 shows an uplink HARQ applied to a backhaul link.

11 is a block diagram illustrating an example of a R-PHICH transmission process.

12 shows an example of an R-PDCCH structure.

FIG. 13 shows an example of resource mapping of an R-PHICH in the R-PDCCH structure described with reference to FIG. 12.

14 is a simplified example of resource mapping of the R-PHICH shown in FIG. 13.

15 and 16 illustrate other examples of resource mapping of the R-PHICH in the R-PDCCH structure described with reference to FIG. 12.

17 shows an example in which an R-PHICH region is allocated separately from an R-PDCCH region.

18 shows an example of resource mapping of an R-PCFICH in the R-PDCCH structure described with reference to FIG. 12.

19 shows another example of an R-PDCCH structure.

20 to 22 illustrate examples of resource mapping of the R-PHICH in the R-PDCCH structure described with reference to FIG. 19.

23 and 24 illustrate examples in which the R-PHICH region is separately allocated from the R-PDCCH region described with reference to FIG. 19.

FIG. 25 shows an example in which an R-PCFICH is allocated to the first OFDM symbol of the R-PDCCH region described with reference to FIG. 23 or 24.

Fig. 26 is a block diagram showing a base station and a relay station.

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be used in various wireless communication systems. CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16e (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA), and the like. UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) long term evolution (LTE) is part of an Evolved UMTS (E-UMTS) using E-UTRA, and employs OFDMA in downlink and SC-FDMA in uplink. LTE-Advanced (LTE-A) is the evolution of 3GPP LTE. In the following description, for clarity, 3GPP LTE / LET-A will be described as an example, but the technical spirit of the present invention is not limited thereto.

1 shows a wireless communication system including a relay station.

Referring to FIG. 1, a wireless communication system 10 including a relay station includes at least one base station 11 (eNodeB, eNB). Each base station 11 provides a communication service for a particular geographic area 15, commonly referred to as a cell. The cell can be further divided into a plurality of areas, each of which is called a sector. One or more cells may exist in one base station. The base station 11 generally refers to a fixed station communicating with the terminal 13, and includes a base station (BS), a base transceiver system (BTS), an access point, an access network (AN), and the like. It may be called in other terms. The base station 11 may perform functions such as connectivity, management, control, and resource allocation between the relay station 12 and the terminal 14.

Relay Node (RN, 12) refers to a device for relaying a signal between the base station 11 and the terminal 14, and may be referred to as other terms such as a relay station, a repeater, a relay, and the like. Can be. As a relay method used by the relay station, any method such as AF and ADF may be used, and the technical spirit of the present invention is not limited thereto.

Terminals 13 and 14 may be fixed or mobile, and may include a mobile station (MS), a user terminal (UT), a subscriber station (SS), a wireless device, and a personal digital assistant (PDA). ), A wireless modem, a handheld device, and an access terminal (AT). Hereinafter, a macro terminal (Mac-UE, Ma-UE, 13) is a terminal that communicates directly with the base station 11, the relay station terminal (RN-UE, 14) refers to a terminal that communicates with the relay station. Even in the macro terminal 13 in the cell of the base station 11, it is possible to communicate with the base station 11 via the relay station 12 in order to improve the transmission rate according to the diversity effect.

2 shows a link present in a wireless communication system.

As shown in FIG. 2, in a wireless communication system 10 including a relay station, a link between the base station 11 and the relay station 12 and a link between the relay station 12 and the relay station terminal 14 exist. In addition, although not shown in the drawings, a link between the base station and the macro terminal also exists. Hereinafter, for convenience, the link between the base station 11 and the relay station 12 will be referred to as a backhaul link. The backhaul link may be divided into a backhaul downlink (B-DL) and a backhaul uplink (B-UL). The backhaul downlink means communication from the base station 11 to the relay station 12, and the backhaul uplink means communication from the relay station 12 to the base station 11.

The link between the relay station 12 and the relay station terminal 14 will be referred to as an access link. The access link may be divided into an access downlink (A-DL) and an access uplink (A-UL). Access downlink means communication from the relay station 12 to the relay station terminal 14, and access uplink means communication from the relay station terminal 14 to the relay station 12.

The link between the base station 11 and the macro terminal 13 will be referred to as a macro link. The macro link may be divided into a macro downlink and a macro uplink. A macro downlink (M-DL) means communication from the base station 11 to the macro terminal 13, and a macro uplink , M-UL) means communication from the macro terminal 13 to the base station 11.

The wireless communication system 10 including the relay station is a system supporting bidirectional communication. Bidirectional communication may be performed using a time division duplex (TDD) mode, a frequency division duplex (FDD) mode, or the like. TDD mode uses different time resources in uplink transmission and downlink transmission. The FDD mode uses different frequency resources in uplink transmission and downlink transmission. When the FDD mode is applied, the same frequency band may be used in the backhaul downlink and the access downlink, and the same frequency band may be used in the backhaul uplink and the access uplink.

3 is a diagram conceptually showing a functional module of a relay station.

Referring to FIG. 3, the RS should be able to receive a signal from a base station in a backhaul downlink and perform OFDMA signal processing through a fast fourier transform (FFT). In addition, the RS should be able to receive the signal from the RS in the access uplink and perform OFDMA signal processing through the FFT. The two processes can be performed simultaneously.

The relay station should be able to transmit signals to the base station through DFT-s-OFDMA (SC-FDMA) signal processing in the backhaul uplink. In addition, the RS must be able to transmit a signal to the RS through DFT-s-OFDMA (SC-FDMA) signal processing in the access downlink. The two processes can be performed simultaneously.

However, it is assumed that it is difficult for the relay station to receive a signal from the relay station terminal in the access uplink and transmit a signal to the base station in the backhaul uplink. In addition, it is assumed that it is difficult for the relay station to receive a signal from the base station in the backhaul downlink and to transmit the signal to the relay station terminal in the access downlink.

4 shows a radio frame structure of 3GPP LTE.

Referring to FIG. 4, a radio frame consists of 10 subframes, and one subframe consists of two slots. One subframe may have a length of 1 ms, and one slot may have a length of 0.5 ms. The time taken for one subframe to be transmitted is called a transmission time interval (TTI). TTI may be a minimum unit of scheduling.

One slot may include a plurality of orthogonal frequency division multiplexing (OFDM) symbols in the time domain. The OFDM symbol is used to represent one symbol period since 3GPP LTE uses OFDMA in downlink and may be called another name. For example, when SC-FDMA is used as an uplink multiple access scheme, it may be referred to as an SC-FDMA symbol. One slot includes 7 OFDM symbols as an example, but the number of OFDM symbols included in one slot may vary according to the length of a cyclic prefix (CP). According to 3GPP TS 36.211 V8.5.0 (2008-12), one subframe includes 7 OFDM symbols in a normal CP and one subframe includes 6 OFDM symbols in an extended CP. The structure of the radio frame is only an example, and the number of subframes included in the radio frame and the number of slots included in the subframe may be variously changed. Hereinafter, the symbol may mean one OFDM symbol or one SC-FDMA symbol.

The structure of the radio frame described with reference to FIG. 4 is 3GPP TS 36.211 V8.3.0 (2008-05) "Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)" See sections 4.1 and 4.

5 is an exemplary diagram illustrating a resource grid for one downlink slot.

In a radio frame used in FDD or TDD, one slot includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols in the time domain and includes a plurality of resource blocks (RBs) in the frequency domain. . The resource block includes a plurality of consecutive subcarriers in one slot in resource allocation units.

Referring to FIG. 5, one downlink slot includes 7 OFDM symbols and one resource block includes 12 subcarriers in a frequency domain, but is not limited thereto. The subcarriers in the RB may have an interval of, for example, 15 KHz.

Each element on the resource grid is called a resource element, and one resource block includes 12 × 7 resource elements. The number N ^DL of resource blocks included in the downlink slot depends on the downlink transmission bandwidth set in the cell. The resource grid described in FIG. 5 may also be applied to uplink.

6 shows a structure of a downlink subframe.

Referring to FIG. 6, a subframe includes two consecutive slots. In the subframe, the first 3 OFDM symbols of the first slot are a control region to which a physical downlink control channel (PDCCH) is allocated, and the remaining OFDM symbols are a data region to which a physical downlink shared channel (PDSCH) is allocated. )to be. In addition to the PDCCH, the control region may be allocated a control channel such as a physical control format indicator channel (PCFICH) and a physical HARQ indicator channel (PHICH). The UE may read the data information transmitted through the PDSCH by decoding the control information transmitted through the PDCCH. Here, the control region includes only 3 OFDM symbols, and the control region may include 2 OFDM symbols or 1 OFDM symbol. The number of OFDM symbols included in the control region in the subframe can be known through the PCFICH. The PHICH carries information indicating whether reception of the uplink data transmitted by the UE is successful.

The control region is composed of logical CCE columns that are a plurality of CCEs. The CCE column is a collection of all CCEs constituting the control region in one subframe. The CCE corresponds to a plurality of resource element groups (REGs). For example, the CCE may correspond to 9 resource element groups. Resource element groups are used to define the mapping of control channels to resource elements. For example, one resource element group may consist of four resource elements.

A plurality of PDCCHs may be transmitted in the control region. The PDCCH carries control information such as scheduling assignment. The PDCCH is transmitted on an aggregation of one or several consecutive control channel elements (CCEs). The format of the PDCCH and the number of bits of the PDCCH are determined according to the number of CCEs constituting the CCE group. The number of CCEs used for PDCCH transmission is called a CCE aggregation level. In addition, the CCE aggregation level is a CCE unit for searching for a PDCCH. The size of the CCE aggregation level is defined by the number of adjacent CCEs. For example, the CCE aggregation level may be an element of {1, 2, 4, 8}.

Control information transmitted through the PDCCH is referred to as downlink control information (DCI). DCI includes uplink scheduling information, downlink scheduling information, system information, system information, uplink power control command, control information for paging, control information for indicating a random access response, etc. It includes.

The DCI format includes format 0 for PUSCH scheduling, format 1 for scheduling one physical downlink shared channel (PDSCH) codeword, and format 1A for compact scheduling of one PDSCH codeword. Format 1B for simple scheduling of rank-1 transmission of a single codeword in spatial multiplexing mode, format 1C for very simple scheduling of downlink shared channel (DL-SCH), format for PDSCH scheduling in multi-user spatial multiplexing mode 1D, format 2 for PDSCH scheduling in closed-loop spatial multiplexing mode, format 2A for PDSCH scheduling in open-loop spatial multiplexing mode, TPC of 2-bit power regulation for PUCCH and PUSCH Transmission power control) format 3, and format 3A for transmission of 1-bit power control TPC commands for PUCCH and PUSCH.

7 shows a structure of an uplink subframe.

Referring to FIG. 7, an uplink subframe is allocated a control region to which a physical uplink control channel (PUCCH) carrying uplink control information is allocated in a frequency domain and a physical uplink shared channel (PUSCH) carrying user data. It can be divided into data areas.

The PUCCH for one UE is allocated to a resource block (RB) pair (51, 52) in a subframe, and the RBs 51 and 52 belonging to the RB pair occupy different subcarriers in each of two slots. do. This is said that the RB pair allocated to the PUCCH is frequency hopping at the slot boundary.

PUCCH may support multiple formats. That is, uplink control information having different numbers of bits per subframe may be transmitted according to a modulation scheme. For example, when using Binary Phase Shift Keying (BPSK) (PUCCH format 1a), uplink control information of 1 bit can be transmitted on PUCCH, and when using Quadrature Phase Shift Keying (QPSK) (PUCCH format 1b). 2 bits of uplink control information can be transmitted on the PUCCH. In addition to the PUCCH format, there are Format 1, Format 2, Format 2a, Format 2b, and the like (3GPP TS 36.211 V8.2.0 (2008-03) "Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); See Section 5.4 of “Physical Channels and Modulation (Release 8)”.

 8 shows an example of a timing relationship between an uplink radio frame and a downlink radio frame.

Referring to FIG. 8, the uplink frame #i in the UE is ((N _TA + N _TAoffset ) x T _s ) (where 0 ≦ N _TA ≦ 20512, where N _TAoffset is an FDD frame) compared to the downlink frame #i. 0, in the case of the TDD frame 624) may be transmitted earlier. Here, Ts may be 1 / (15000 x 2048) seconds. The timing relationship between the uplink radio frame and the downlink radio frame is 3GPP TS 36.213 V8.6.0. See section 4.2.3.

The present invention will now be described. In a wireless communication system including a relay station, the relay station receives resource allocation information for the backhaul downlink from the base station. The resource allocation information may be transmitted through a higher layer signal such as a physical layer signal or a radio resource control (RRC) message. The relay station receives the backhaul downlink control information from the base station in the radio resource indicated by the resource allocation information. The radio resource indicated by the resource allocation information is an OFDM symbol in which a relay station transmits access downlink control information to a relay station terminal in a time domain for a subframe including a plurality of OFDM symbols, and is located after a guard interval required for transmitting and receiving switching of the relay station. It includes at least one OFDM symbol. In this case, a resource element group (REG) spaced at regular intervals in the frequency domain from the at least one OFDM symbol may be included, and backhaul downlink control information may be transmitted through the resource element group. The backhaul downlink control information may be ACK / NACK for backhaul uplink data transmitted from the relay station to the base station, and the number of OFDM symbols to which backhaul downlink control information transmitted to the relay station is allocated. It may include information on the transmitted frequency band. The present invention will be described in detail below.

9 is a diagram illustrating a configuration of a subframe in which a relay station receives a signal from a base station.

Referring to FIG. 9, a subframe 400 in which a relay station receives a signal from a base station includes an access control signal region 410, a guard interval 1 420, a guard interval 2 430, and a backhaul region. 440).

The access control signal area 410 is a radio resource area in which the relay station transmits a control signal to the relay station terminal. The control signals transmitted from the relay station to the relay terminal may inform the relay terminal that the access downlink data will not be transmitted, thereby serving to prevent the relay station from taking unnecessary data reception operations. When the RS covers radio resource management (RRM) and operates by being given an individual cell ID, such a control signal should be transmitted in the first predetermined number of OFDM symbols of all access downlink subframes in order to provide backward compatibility to the RS. can do. The control signal may include a PCFICH, PDCCH, PHICH signal and the like. The access control signal region 410 may include 1 to 3 OFDM symbols.

The RS transmits a control signal to the UE through the access control signal region 410 in a subframe set as a subframe receiving a signal from the BS, and then, from the BS in the backhaul region 440 after the guard interval 1 420. It can receive a signal. That is, the relay station may control the access control signal region 410 and the backhaul region in a time division multiplexing (TDM) manner to prevent transmission and reception of signals on the same radio resource, that is, the same frequency (same IFFT / FFT region) on the backhaul link and the access link. 440 may be operated separately.

Guard period 1 (420) and guard period 2 (430) is an operation stabilization time required for switching between reception and transmission of a signal at the relay station, which is a kind of transition time. The guard period 1 420 and the guard period 2 430 may be time intervals of one symbol interval or less. Guard period 2 (430) may be included only when necessary.

The relay station may receive a signal from the base station through the backhaul area 440 as described above. Unlike the terminal, the relay station can receive a signal from the base station using only some OFDM symbols in the subframe. In this case, it is a question of how the relay station configures a control channel for receiving control information from the base station.

First, terms are defined for convenience of description. Hereinafter, the R-PDCCH means a control channel through which the base station transmits backhaul downlink control information to the relay station. R-PHICH refers to a channel through which the base station transmits ACK / NACK for backhaul uplink data to the relay station. The R-PCFICH refers to a channel in which the base station informs the relay station of the number of OFDM symbols of the R-PDCCH or in addition, informs the frequency band and the DCI format in which the R-PDCCH is transmitted. The R-PDSCH means a data channel through which the base station transmits backhaul downlink data to the relay station. The macro PDCCH refers to a control channel through which the base station transmits downlink control information to the macro terminal, and the access PDCCH refers to a control channel through which the relay station transmits access downlink control information to the RS. The R-PDCCH region / band means a radio resource region / frequency band through which the R-PDCCH is transmitted. The R-PHICH region / band means a radio resource region / frequency band through which the R-PHICH is transmitted, and the R-PCFICH region / band means a radio resource region / frequency band through which the R-PCICH is transmitted. The R-PUSCH means a data channel through which the relay station transmits backhaul uplink data to the base station.

A wireless communication system including a relay station may support uplink or downlink hybrid automatic repeat request (HARQ) on a backhaul link.

10 shows an uplink HARQ applied to a backhaul link.

The base station receiving the backhaul uplink data 110 on the R-PUSCH from the relay station transmits the ACK / NACK signal 111 on the R-PHICH after a predetermined subframe has elapsed. The ACK / NACK signal 111 becomes an ACK signal when the backhaul uplink data 110 is successfully decoded, and becomes an NACK signal when decoding of the backhaul uplink data 110 fails. When the NACK signal is received, the RS may transmit retransmission data 120 for the backhaul uplink data 110 until ACK information is received or up to a maximum number of retransmissions. The base station may transmit the ACK / NACK signal 121 for the retransmission data 120 on the R-PHICH.

Hereinafter, the R-PHICH will be described.

11 is a block diagram illustrating an example of a R-PHICH transmission process.

The base station transmits ACK / NACK for the stream received from the relay station through the R-PUSCH through the R-PHICH. The base station codes 1 bit ACK / NACK into 3 bits using a repetition code having a code rate of 1/3 (S130). The coded ACK / NACK is modulated by a Binary Phase Key-Shifting (BPSK) scheme to generate three modulation symbols (S131). The modulation symbol is spread using spreading factor SF = 4 in the normal CP structure and SF = 2 in the extended CP structure (S132). An orthogonal sequence may be used when spreading the modulation symbols, and the number of orthogonal sequences used is SF * 2 to apply I / Q multiplexing. R-PHICHs spread using SF * 2 orthogonal sequences may be defined as one R-PHICH group. Layer mapping is performed on the spread symbols (S133). The layer mapped symbols are resource mapped and transmitted (S134).

The above-described process will be described using equations. The R-PHICH transmits HARQ ACK / NACK according to the R-PUSCH transmission. In this case, a plurality of R-PHICHs mapped to resource elements of the same set form an R-PHICH group, and each R-PHICH in the R-PHICH group may be distinguished by different orthogonal sequences. . The N _PHICH ^{group, which} is the number of R-PHICH groups in the FDD system, may be constant in all subframes and may be determined by Equation 1.

In Equation 1, Ng is transmitted from a higher layer through a PBCH (Physical Broadcast Channel), and may be Ng / {1 / 6,1 / 2,1,2}. The PBCH carries system information necessary for the relay station to communicate with the base station. N _RB ^DL is a backhaul downlink bandwidth configuration expressed as a multiple of N _sc ^{RB which} is a size of a resource block in a frequency domain. The R-PHICH group index n _PHICH ^group is an integer of any one of 0 to N _PHICH ^group -1.

The resource used for the R-PHICH is based on the smallest PRB index when the resource allocation of the R-PUSCH and the cyclic shift value of the DMRS (Demodulation Reference Signal) transmitted by the backhaul UL grant transmitted by the base station to the relay station. Can be determined. The resource to which the R-PHICH is mapped (hereinafter referred to as R-PHICH resource) may be expressed as an index pair (n _PHICH ^group , n _PHICH ^seq ), n _PHICH ^group is an R-PHICH group index, and n _PHICH ^seq is the R-PHICH group Represents an orthogonal sequence index. The (n _PHICH ^group , n _PHICH ^seq ) may be determined by Equation 2.

The n _DMRS may be determined based on a DMRS Cyclic Shift for DMRS field in the DCI format in the R-PDCCH _transmitted by the base station to the RS.

In Equation 2, N _SF ^PHICH is a spreading factor (SF) used for a modulation symbol. I _{PRB_RA} ^lowest_index is the smallest PRB index among PRBs of slots in which an R-PUSCH corresponding to the corresponding R-PHICH is transmitted. I _PHICH is a value of zero or one.

Orthogonal sequences used in the R-PHICH can be determined by Table 1. The orthogonal sequence used may vary depending on the n _PHICH ^seq value or the CP structure.

Sequence index (n PHICH seq )	Orthogonal Sequence
	Normal CP (N SF PHICH = 4)	Extended CP (N SF PHICH = 2)
0	[+1 +1 +1 +1]	[+1 +1]
One	[+1 -1 +1 -1]	[+1 -1]
2	[+1 +1 -1 -1]	[+ j + j]
3	[+1 -1 -1 +1]	[+ j -j]
4	[+ j + j + j + j]	-
5	[+ j -j + j -j]	-
6	[+ j + j -j -j]	-
7	[+ j -j -j + j]	-

The R-PHICH resource may be mapped to a resource element in various ways according to the structure of the R-PDCCH.

12 shows an example of an R-PDCCH structure.

Referring to FIG. 12, the R-PDCCH region includes OFDM symbols constituting the access control signal region in the time domain and N OFDM symbols (N is a natural number of 1 or more) after the guard period. The R-PDCCH region may exist throughout the system band in the frequency domain. The R-PDCCH region may also be used by the base station to transmit downlink data to the macro terminal.

As such, when the R-PDCCH region is configured, the R-PHICH may be allocated to Q OFDM symbols. That is, the duration of the R-PHICH may be a Q OFDM symbol. Here, Q is generally a natural number less than or equal to N, and may be a natural number greater than N. For example, when Q is less than or equal to N, the R-PHICH indicates that it is transmitted in the R-PDCCH region. When the R-PDCCH region is very limitedly allocated, the R-PHICH may be allocated to OFDM symbols outside the R-PDCCH region, in which case Q may be greater than N.

The R-PHICH may be mapped and transmitted to M resource elements determined by a rule capable of providing frequency diversity in a fixed position or system band in the R-PDCCH region. Here, M may be 12, for example. M resource elements may be defined as resource element groups (REGs) of P (P may be 3, for example, M). One REG includes four resource elements and may also be referred to as quadruplet (in the following embodiment, an example in which backhaul downlink control information is allocated to the REG is described, but this is not a limitation. For example, the backhaul downlink control information may be allocated to a sub-REG (eg, composed of three resource elements) including a smaller number of resource elements than the REG. P REGs may be allocated as uniformly as possible to Q OFDM symbols included in the R-PHICH interval.

FIG. 13 shows an example of resource mapping of an R-PHICH in the R-PDCCH structure described with reference to FIG. 12.

Referring to FIG. 13, the R-PHICH interval Q may be one. The OFDM symbol to which the R-PHICH is allocated is denoted by OFDM symbol #i (i is a natural number determined according to N and a guard interval). The case where the number of resource elements to which an R-PHICH is allocated is M = 12 and the number of REGs is P = 3 is illustrated. In this case, four resource elements consecutive in the frequency domain form one REG except for a resource element to which a reference signal can be arranged or a resource element to which an R-PCFICH can be allocated (not shown). These REGs are arranged at the most uniform intervals in the frequency domain. Each REG is assigned an R-PHICH.

14 is a simplified example of resource mapping of the R-PHICH shown in FIG. 13. In the following drawings, resource mapping is indicated by simplifying the process as shown in FIG. 14.

15 and 16 illustrate other examples of resource mapping of the R-PHICH in the R-PDCCH structure described with reference to FIG. 12.

In detail, FIG. 15 illustrates a case where the R-PHICH interval Q is 2, that is, the R-PHICH is allocated to OFDM symbol #i and OFDM symbol # (i + 1). In this case, REGs to which an R-PHICH is allocated may be arranged at uniform intervals in the frequency domain, and two REGs may be allocated to OFDM symbol #i and one REG may be allocated to OFDM symbol # (i + 1) in the time domain. (This is not a limitation and conversely, one REG may be allocated to OFDM symbol #i and two REGs may be allocated to OFDM symbol # (i + 1)).

FIG. 16 illustrates a case where an R-PHICH interval Q is 3, that is, an R-PHICH is allocated to an OFDM symbol #i, an OFDM symbol # (i + 1), and an OFDM symbol # (i + 2). In this case, REGs to which an R-PHICH is allocated are arranged at equal intervals without overlapping in the frequency domain, and in the time domain, OFDM symbols #i, OFDM symbols # (i + 1) and OFDM symbols # (i + 2), respectively. One REG is assigned to. In FIG. 16, when the OFDM symbol index increases, the position on the frequency of the REG also increases, but this is not a limitation. The REGs of the respective OFDM symbols may be allocated in a structure arranged at positions as far apart as possible without overlapping in the frequency domain.

The R-PHICH period may be defined as OFDM symbols equal to or less than the number of OFDM symbols in the R-PDCCH region, but in exceptional cases, may be defined as OFDM symbols larger than the number of OFDM symbols in the R-PDCCH region. For example, the information amount of the R-PDCCH is not large, when the ACK / NACK bit site for the backhaul uplink transmission is large and reliable transmission is required.

Accordingly, the R-PHICH interval may be independently set regardless of the number of OFDM symbols in the R-PDCCH region. That is, the R-PHICH interval may include an OFDM symbol of the R-PDSCH region. In this case, the R-PHICH resource included in the R-PDSCH region may be set using puncturing or rate matching. The RS or the macro terminal may perform blind decoding without knowing whether to allocate R-PHICH resources in the R-PDSCH region or the PDSCH region. Alternatively, the base station informs the relay station, the macro terminal whether the R-PHICH resource is allocated to the R-PDSCH region or the PDSCH region, and / or the location of the R-PHICH resource as an L1 / L2 signal, or a radio resource control (RRC) message. The cell-specific higher layer signal may be informed in advance. In this case, the RS or the UE may decode only signals received from resource elements excluding R-PHICH resources in the R-PDSCH region or the PDSCH region.

17 shows an example in which an R-PHICH region is allocated separately from an R-PDCCH region.

Referring to FIG. 17, the R-PHICH region includes R OFDM symbols (R is a natural number of 1 or more) following the R-PDCCH region in the time domain, and may be set to the same frequency band as the R-PDCCH band in the frequency domain. Can be.

The method of allocating the REG in the R-PHICH region including the R OFDM symbols may be similarly applied to the method described with reference to FIGS. 14 to 16. That is, when R = 1, the method of FIG. 14, R = 2, and the method of FIG. 16 may be applied.

Alternatively, the sum of the R-PDCCH interval and the R-PHICH interval may be fixed to S, that is, S OFDM symbols or limited to S or fewer OFDM symbols. This method makes it possible to stably allocate resources for an R-PDSCH region or a PDSCH region for a relay station or a macro terminal. Information on R-PHICH resource allocation

1. It may be transmitted through a dedicated physical channel in the R-PDCCH region or included in the DCI format of a cell-specific R-PDCCH. Or, it may be included in the DCI format of the UE-specific PDCCH and defined and may transmit information on the R-PHICH resource allocation.

2. Information on the R-PHICH resource allocation may inform the RS through a higher layer signal such as an RRC message. The RRC message may be a cell specific message or a relay station specific message. When the information on the R-PHICH resource allocation is informed through the RRC message, the R-PHICH region may be defined as an OFDM symbol earlier than the R-PDCCH region.

A subcarrier or resource block (for example, including 12 subcarriers) that is not used for R-PHICH transmission among subcarrier resources on R OFDM symbols in the R-PHICH region may be used for data transmission to a relay station or a macro terminal.

18 shows an example of resource mapping of an R-PCFICH in the R-PDCCH structure described with reference to FIG. 12.

The generation of the signal transmitted in the R-PCFICH may be, for example, as follows. The information bits to be transmitted through the R-PCFICH in one subframe are b (0),... , b31, the information bits may be scrambled by a cell specific sequence. Scrambled information bits

In this case, the scrambled information bits may be generated as follows.

C (i) in Equation 3 may be given by the following equation.

In Equation 4, N _C = 1600 and the first m-sequence is initialized to x1 (0) = 1, x1 (n) = 0, n = 1,2, ..., 30. The second m-sequence is determined based on the application of the sequence. The scrambled information bits are modulated in a QPSK scheme to generate modulation symbols. Modulation symbols are represented by d (0), ..., d (15). The modulation symbols are mapped to resource elements through layer mapping and precoding.

If the R-PDCCH structure of the subframe is set to the TDM scheme as described in FIG. 12, the R-PCFICH is applied to a rule that can provide frequency diversity within a fixed position or system band in the R-PDCCH region. Z may be mapped and transmitted to the resource elements determined by. Here, Z may be for example 16.

Information transmitted through the R-PCFICH is called a relay node-control format indicator (R-CFI). The R-CFI includes the number of OFDM symbols (that is, the size of the control region) used for transmission of control channels in a subframe. In addition to this, information about a frequency band in which the R-PDCCH is transmitted and a DCI format may be included. R-CFI is information that the relay station needs to know before monitoring the R-PDCCH. Accordingly, the relay station may first monitor the R-PDCCH after receiving the R-CFI on the R-PCFICH.

When the number of bits of the R-CFI is Y bits, when Y is 3 bits or less, coding combined with a repetition code may be applied to a simplex code. If Y is greater than 3 bits, block coding or tail-biting convolution coding, such as Reed-Muller coding, may be applied. In this process, Z modulation symbols can be generated by performing QPSK modulation on 2 * Z length coded bits. Z modulation symbols are mapped to resource elements and transmitted. The R-PCFICH may be allocated to the first OFDM symbol of the R-PDCCH region and transmitted.

Referring to FIG. 18, the R-PCFICH is allocated to Z / 4 quadruplets or REGs and transmitted. For example, when Z = 16, four quadruplets are allocated and transmitted. The quadruplet REG may be configured of four resource elements consecutive in the frequency domain among the remaining resource elements except for a resource element in which a reference signal may be placed. The R-PCFICH may be allocated in preference to the R-PHICH.

In the OFDM symbol in which the R-PCFICH is transmitted, quadruplets may be allocated at even intervals in the frequency domain.

19 shows another example of an R-PDCCH structure.

Referring to FIG. 19, the R-PDCCH region includes OFDM symbols constituting the access control signal region in the time domain and N OFDM symbols (N is a natural number of 1 or more) after the guard period. The R-PDCCH region may exist in some bands of the system band in the frequency domain. The R-PDCCH region may also be used by the base station to transmit downlink data to the macro terminal. That is, FIG. 19 is a case where the R-PDCCH band is limited to a part of the system band unlike the R-PDCCH structure described with reference to FIG. 12.

As such, when the R-PDCCH region is configured, the R-PHICH may be allocated to Q OFDM symbols. That is, the duration of the R-PHICH may be a Q OFDM symbol. Here, Q is generally a natural number less than or equal to N, and may be a natural number greater than N. For example, when Q is less than or equal to N, the R-PHICH indicates that it is transmitted in the R-PDCCH region. When the R-PDCCH region is very limitedly allocated, the R-PHICH may be allocated to OFDM symbols outside the R-PDCCH region, in which case Q may be greater than N.

The R-PHICH may be mapped and transmitted to M resource elements determined by a rule capable of providing frequency diversity in a fixed position or system band in the R-PDCCH region. Here, M may be 12, for example. M resource elements may be defined as resource element groups (REGs) of P (P may be 3, for example, M). One REG includes four resource elements and may be referred to as a quadruplet. P REGs may be allocated as uniformly as possible to Q OFDM symbols included in the R-PHICH interval.

20 to 22 illustrate examples of resource mapping of the R-PHICH in the R-PDCCH structure described with reference to FIG. 19. That is, FIG. 20 to FIG. 22 have a different frequency band than that of FIGS. 14 to 16.

Referring to FIG. 20, the R-PHICH interval Q may be one. The OFDM symbol to which the R-PHICH is allocated is denoted by OFDM symbol #i (i is a natural number determined according to N and a guard interval). The case where the number of resource elements to which an R-PHICH is allocated is M = 12 and the number of REGs is P = 3 is illustrated. In this case, four resource elements consecutive in the frequency domain form one REG except for a resource element to which a reference signal can be arranged or a resource element to which an R-PCFICH can be allocated. These REGs are arranged at the most uniform intervals in the frequency domain. Each REG is assigned an R-PHICH.

21 illustrates a case where the R-PHICH interval Q is 2, that is, the R-PHICH is allocated to OFDM symbol #i and OFDM symbol # (i + 1). In this case, REGs to which an R-PHICH is allocated may be arranged at uniform intervals in the frequency domain, and two REGs may be allocated to OFDM symbol #i and one REG may be allocated to OFDM symbol # (i + 1) in the time domain. (This is not a limitation and conversely, one REG may be allocated to OFDM symbol #i and two REGs may be allocated to OFDM symbol # (i + 1)).

22 shows a case where the R-PHICH interval Q is 3, that is, the R-PHICH is allocated to OFDM symbol #i, OFDM symbol # (i + 1), and OFDM symbol # (i + 2). In this case, REGs to which an R-PHICH is allocated are arranged at equal intervals without overlapping in the frequency domain, and in the time domain, OFDM symbols #i, OFDM symbols # (i + 1) and OFDM symbols # (i + 2), respectively. One REG is assigned to. 22 illustrates a case in which the position on the frequency of the REG also increases when the OFDM symbol index increases, but this is not a limitation. The REGs of the respective OFDM symbols may be allocated in a structure arranged at positions as far apart as possible without overlapping in the frequency domain.

23 and 24 illustrate examples in which the R-PHICH region is separately allocated from the R-PDCCH region described with reference to FIG. 19.

23 and 24, the R-PHICH region includes R OFDM symbols (R is a natural number of 1 or more) following the R-PDCCH region in the time domain. 23 illustrates an example in which the R-PHICH region is set to the same frequency band as the R-PDCCH band in the frequency domain, and FIG. 24 illustrates an example in which the R-PHICH region is set to a frequency band larger than the R-PDCCH band.

The method of allocating the REG in the R-PHICH region including the R OFDM symbols may be similarly applied to the method described with reference to FIGS. 20 to 22. In other words, when R = 1, the method of FIG. 20, R = 2, and the method of FIG. 22 may be applied.

In FIGS. 23 and 24, the sum of the R-PDCCH interval and the R-PHICH interval may be fixed to S, that is, S OFDM symbols or limited to S or fewer OFDM symbols. This method makes it possible to stably allocate resources for an R-PDSCH region or a PDSCH region for a relay station or a macro terminal. Information on R-PHICH resource allocation

1. It may be transmitted through a dedicated physical channel in the R-PDCCH region or included in the DCI format of a cell-specific R-PDCCH. Or, it may be included in the DCI format of the UE-specific PDCCH and defined and may transmit information on the R-PHICH resource allocation.

2. Information on the R-PHICH resource allocation may inform the RS through a higher layer signal such as an RRC message. The RRC message may be a cell specific message or a relay station specific message. When the information on the R-PHICH resource allocation is informed through the RRC message, the R-PHICH region may be defined as an OFDM symbol earlier than the R-PDCCH region.

A subcarrier or resource block (for example, including 12 subcarriers) that is not used for R-PHICH transmission among subcarrier resources on R OFDM symbols in the R-PHICH region may be used for data transmission to a relay station or a macro terminal.

FIG. 25 shows an example in which an R-PCFICH is allocated to the first OFDM symbol of the R-PDCCH region described with reference to FIG. 23 or 24. FIG. 25 is different from the frequency band to which the R-PCFICH is allocated to FIG. 18.

Referring to FIG. 25, an R-PCFICH is allocated to Z / 4 quadruplets or REGs and transmitted. For example, when Z = 16, four quadruplets are allocated and transmitted. The quadruplet REG may be configured of four resource elements consecutive in the frequency domain among the remaining resource elements except for a resource element in which a reference signal may be placed. The R-PCFICH may be allocated in preference to the R-PHICH. In the OFDM symbol in which the R-PCFICH is transmitted, quadruplets may be allocated at even intervals in the frequency domain.

Fig. 26 is a block diagram showing a base station and a relay station.

The base station 700 includes a processor 710, a memory 720, and an RF unit 730. The processor 710 transmits resource allocation information to the relay station, and transmits backhaul downlink control information from the relay station through a radio resource indicated by the resource allocation information. The memory 720 is connected to the processor 710 to store various information for driving the processor 710. The RF unit 730 is connected to the processor 710 to transmit and / or receive a radio signal.

The relay station 800 includes a processor 810, a memory 820, and an RF unit 830. The processor 810 receives resource allocation information from the base station, and receives backhaul downlink control information from the base station in a radio resource indicated by the resource allocation information. The resource allocation information includes an OFDM symbol in which a relay station transmits access downlink control information to a relay terminal in a time domain for a subframe including a plurality of OFDM symbols, and at least one OFDM symbol located after a guard interval. A radio resource including a resource element group spaced at regular intervals in the frequency domain from at least one or more OFDM symbols. This radio resource allocation method has been described above with reference to FIGS. 12 to 25.

The memory 820 is connected to the processor 810 and stores various information for driving the processor 810. The RF unit 830 is connected to the processor 810 to transmit and / or receive a radio signal.

Processors 710 and 810 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, data processing devices, and / or converters that interconvert baseband signals and wireless signals. The memories 720 and 820 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices. The RF unit 730 and 830 may include one or more antennas for transmitting and / or receiving a radio signal. When the embodiment is implemented in software, the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function. Modules may be stored in memories 720 and 820 and executed by processors 710 and 810. The memories 720 and 820 may be inside or outside the processors 710 and 810, and may be connected to the processors 710 and 810 by various well-known means.

Although the present invention has been described above with reference to the embodiments, it will be understood by those skilled in the art that the present invention may be modified and changed in various ways without departing from the spirit and scope of the present invention. I can understand. Therefore, the present invention is not limited to the above-described embodiment, and the present invention will include all embodiments within the scope of the following claims.

Claims (9)

1. A method of receiving control information of a relay station in a wireless communication system including a relay station, the method comprising: receiving resource allocation information from a base station; And receiving backhaul downlink control information from the base station in a radio resource indicated by the resource allocation information, wherein the resource allocation information is a relay station terminal in a time domain for a subframe including a plurality of OFDM symbols. An OFDM symbol for transmitting access downlink control information to the wireless LAN and at least one OFDM symbol located after a guard interval, and including a resource element group spaced at regular intervals in the frequency domain from the at least one OFDM symbol Pointing to a resource.
2. The resource element group of claim 1, wherein the resource element group includes four resource elements, wherein the four resource elements are four resource elements contiguous in the frequency domain except for a resource element on which a reference signal can be placed. How to.
3. The method of claim 1, wherein the backhaul downlink control information is acknowledgment / not-acknowledgement (ACK / NACK) for backhaul uplink data transmitted from the relay station to the base station.
4. 4. The method of claim 3, wherein the radio resource to which the ACK / NACK is transmitted further includes a separate OFDM symbol located after the at least one OFDM symbol or includes only the separate OFDM symbol.
5. 5. The method of claim 4, wherein the frequency band in which ACK / NACK is transmitted in the separate OFDM symbol is equal to or greater than the frequency band in which backhaul downlink control information is transmitted in the at least one OFDM symbol.
6. The method of claim 3, wherein the radio resource for transmitting the ACK / NACK is transmitted in one, two or three OFDM symbols of the at least one OFDM symbol.
7. The method of claim 1, wherein the backhaul downlink control information is information on the number of OFDM symbols including backhaul downlink control information transmitted from the base station to the relay station.
8. 8. The method of claim 7, wherein the information on the number of OFDM symbols including backhaul downlink control information transmitted from the base station to the relay station is transmitted in a first OFDM symbol of the at least one OFDM symbol.
9. RF unit for transmitting and receiving a radio signal; And a processor connected to the RF unit, wherein the processor receives resource allocation information from a base station and receives backhaul downlink control information from the base station in a radio resource indicated by the resource allocation information, wherein the resource allocation information Is an OFDM symbol in which a relay station transmits access downlink control information to a relay terminal in a time domain for a subframe including a plurality of OFDM symbols, and at least one or more OFDM symbols located after a guard interval, and the at least one or more symbols A relay station for indicating a radio resource including a group of resource elements spaced at regular intervals from the OFDM symbol to the frequency domain.

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