Method and apparatus for allocating a control channel resource of a relay node

Method and apparatus for allocating a control channel resource of a relay node within a backhaul network subframe.

Background of the invention

<dl><dt>1. </dt><dd>Field of the Invention </dd></dl>

The present invention relates generally to wireless communications and, in particular, to a method and an apparatus for assigning a control channel of a relay node within a backhaul network subframe in a wireless communication system.

<dl><dt>2.</dt><dd> Description of the related technique </dd></dl>

Orthogonal frequency division multiplexing (OFDM) is a multi-carrier modulation technique in which a serial input symbol stream is converted into parallel symbol streams and modulated to mutually orthogonal subcarriers, that is, a plurality of subcarrier channels.

The system based on a modulation of multiple carriers was first applied to high-frequency military radios in the late 1950s, and the OFDM scheme, which overlaps multiple orthogonal subcarriers, has been developing since the 1970s. However, there were limitations in its application to real systems due to the difficulty in performing an orthogonal modulation between multiple carriers. However, the OFDM scheme has undergone rapid development since Weinstein et al. they presented in 1971 that OFDM-based modulation / demodulation can be efficiently processed using DFT (discrete Fourier transform). In addition, as a scheme that uses a guard interval and inserts a cyclic prefix symbol (CP) into the guard interval, the negative influence of the system on multiple paths and the delay spread has been significantly reduced.

Due to such technical developments, OFDM technology is being widely applied to digital transmission technologies such as digital audio broadcast (DAB), digital video broadcast (DVB), wireless local area network (WLAN), wireless asynchronous transfer mode ( WATM), etc. That is, the OFDM scheme could not be widely used before due to its high hardware complexity, but the development of various digital signal processing technologies that include fast Fourier transform (FFT) and fast reverse Fourier transform (IFFT) It has facilitated its realization.

At the same time, an LTE-A system can include relay nodes as well as base stations (evolved node B, eNodeB or eNB) and mobile stations (user equipment or UE). A base station can allocate transmission resources for the backhaul network link between the base station and the relay node and the resources allocated for the backhaul network link are called backhaul network subframes.

Figures 1 and 2 are diagrams illustrating a principle for configuring a backhaul network subframe for relay nodes in an LTE-A system.

With reference to Figures 1 and 2, reference number 343 indicates a region in which the control channel of a relay node is transmitted. Region 343 is a resource that receives information from an upper layer signaling. The amount of resource allocated, ie the size of resource block 401 (RB), is semi-static, and the RB used in the actual transmission may change in each backhaul network subframe.

In the case where the control channel of the relay node is transmitted in the assigned control region imitating the control channel structure of an LTE system, the amount of resource for transmission is less than (but not equal to) the assigned resource and, consequently, an empty area is distributed, as indicated by reference number 331, in which no transmission occurs over the entire control channel, which results in a loss of resource. Although, in the case where the resource is semi-static allocated, the region assigned for the relay node varies with each subframe, the resource cannot easily change size and is indicated in a fixed way, so it is difficult to assign resources selectively in frequency. The frequency selective resource allocation can be performed for the data channel for transmission to other terminals within the cell as well as the retransmission resource. In the case where the retransmission resource region is previously set to a large size for this, the relay must perform a plurality of blind decodes, which results in an increase in the complexity of retransmission implementation. To perform the frequency selective resource allocation, the relay node must inform a large amount of the semi-static resource 415, which results in an increase in the number of blind decodes. In the case where the large amount of the semi-static resource is reported, the number of unnecessary blind decodes also increases especially when a transmission resource is allocated

small, which results in a degradation of efficiency.

MOTOROLA: “Relay Backhaul Design”, 3GPP DRAFT; R1-092638 - BACKHAUL DESIGN FOR RELAYS VFINAL, 3RD GENERATION PARTNERSHIP PROJECT (3GPP), MOBILE COMPETENCE CENTER; 650, ROUTE DES LUCIOLES; F-06921 SOPHIA-ANTIPOLIS CEDEX; FRANCE, no. Los Angeles United States; 20090624, 2009, XP050351128, discloses a retransmission retransmission network design. The backhaul network design involves multiplexing backhaul links for multiple relay nodes on the eNB-RN link. Semi-static assigned subframes are used for backward network data transmissions. The subframe assignment would depend on the quality of backlink network. The eNB can group the relay nodes into smaller sets and provide each set in a different subframe (or subframe set).

LG ELECTRONICS: “Resource Allocation and Downlink Control Channel Structure for Relay Backhaul Link”, 3GPP DRAFT; R1-092115 LGE_BACKHAUL RESOURCE ALLOCATION, 3RD GENERATION PARTNERSHIP PROJECT (3GPP), MOBILE COMPETENCE CENTER; 650, ROUTE DES LUCIOLES; F-06921 SOPHIA-ANTIPOLIS CEDEX; FRANCE, no. San Francisco, United States; 20090428, 2009, XP050339560, discloses a dynamic resource allocation scheme, and discloses the dynamic planning of a backhaul network resource for communication between a macro-eNB and a relay node.

Summary of the invention

Aspects of the invention are defined in the independent claims. The dependent claims define advantageous embodiments.

In order to solve the problems of the prior art, The present invention provides a method and apparatus for allocating control channel resources for a relay node within a retransmission network subframe in a wireless communication system that can divide a resource region for transmission of the relay node into Multiple resource groups and allocate resources from the same resource group to relay nodes in the same transmission mode to reduce the number of blind decodes.

In addition, the present invention provides a method and apparatus for allocating control channel resources for a relay node within a retransmission network subframe in a wireless communication system that can reduce the number of blind decodes in the relay node. and maximize frequency diversity gain and selective frequency gain among resource groups.

In addition, the present invention provides a method and apparatus for allocating control channel resources for a relay node within a backhaul subframe in a wireless communication system that can support the two resource groups in which it is performed. interlacing between control channels and resource groups in which no interlacing is performed.

Brief description of the drawings

The above and other objectives, characteristics and advantages of the present invention will become more apparent from the following detailed description together with the accompanying drawings, in which:

Figures 1 and 2 are diagrams illustrating a principle for configuring a backhaul network subframe for relay nodes in an LTE-A system;

Figure 3 is a diagram illustrating a subframe structure for use in a long-term evolution (LTE) system to which the present invention is applied;

Fig. 4 is a diagram illustrating a principle of operation of a relay in an LTE-A system according to an embodiment of the present invention;

Figure 5 is a diagram illustrating a principle of allocating control channel resources of a relay in a wireless communication system according to a first embodiment of the present invention;

Figure 6 is a diagram illustrating a principle of a resource allocation rule for relay control channel resource groups according to a second embodiment of the present invention;

Figure 7 is a flow chart illustrating a method of transmitting resource allocation information of a base station according to an embodiment of the present invention;

Figure 8 is a flow chart illustrating a method of receiving resource allocation information from a relay according to an embodiment of the present invention;

Figure 9 is a block diagram illustrating a configuration of a base station according to an embodiment of the present invention;

Figure 10 is a block diagram illustrating a configuration of a relay to receive resource allocation information according to an embodiment of the present invention; and

Fig. 11 is a diagram illustrating a principle for assigning control channel resource groups to retransmitters according to the first embodiment of the present invention.

Detailed description of embodiments of the present invention

Embodiments of the present invention are described in detail with reference to the accompanying drawings. The same reference numbers are used in all drawings to refer to the same or similar parts. The detailed description of widely known functions and structures incorporated herein may be omitted to avoid confusing the content of the present invention.

The terms and words used in the specification and the claims should be considered selected concepts as the best method to illustrate the present invention, and should be interpreted as having meanings and concepts adapted to the scope of the present invention to understand the technology of the present invention. . Therefore, the embodiments described in the specification and the constructions illustrated in the drawings do not represent all the technical variations of the present invention. Therefore, it should be understood that various modifications can be substituted.

Hereinafter, the channel and resource dedicated to a relay node are called the R channel and the R resource.

Although the following description refers to LTE and LTE-A systems, the present invention can be applied to other types of wireless communication systems in which the base station performs the planning.

OFDM, although similar to conventional frequency division multiplexing (FDM), can obtain optimal transmission efficiency during high-speed data transmission while maintaining orthogonality between multiple tones. In addition, the OFDM scheme can obtain optimum transmission efficiency during high-speed data transmission because it has a high frequency utilization efficiency and is robust against multipath fading.

Since the OFDM superimposes the frequency spectra of the subcarriers, has a high frequency utilization efficiency, is robust against selective frequency fading, it can reduce an effect of inter-symbol interference (ISI) with the use of a guard interval , you can design a simple equalizer hardware, and it is robust against impulsive noises. Therefore, the OFDM scheme is used for various communication systems.

In wireless communications, high quality and high speed data services are generally hampered by channel environments. In wireless communications, channel environments undergo frequent changes not only due to additive Gaussian white noise (AWGN) but also to the variation in power of the received signals, caused by a fading phenomenon, shading, a Doppler effect caused by the movement of a terminal and a frequent change in a terminal speed, interference by other users or multipath signals, etc. Therefore, to support high-quality and high-speed data services in wireless communications, there is a need to efficiently overcome the aforementioned factors.

In the OFDM, the modulation signals are located in the two-dimensional time and frequency resources. Resources in the time domain are divided into different OFDM symbols, and are orthogonal to each other. The resources in the frequency domain are divided into different tones, and are also orthogonal to each other. That is, the OFDM scheme defines a minimum unit resource by designating a particular OFDM symbol in the time domain and a particular tone in the frequency domain, and the unit resource is called a resource element (RE). Since the different REs are orthogonal to each other, signals transmitted in different REs can be received without causing interference with each other.

A physical channel is a channel defined in the physical layer to transmit modulation symbols obtained by modulating one or more encoded bit sequences. In a system of multiple access by orthogonal frequency division (OFDMA) a plurality of physical channels can be transmitted depending on the use of the information sequence

or receiver The transmitter and receiver negotiate the RE in which a physical channel is transmitted, and this process is called mapping.

The LTE system is a communication system that uses OFDM on the downlink, and multiple carrier frequency division multiple access (SC-FDMA) on the uplink. The LTE-A system is an advanced LTE system that supports wider bandwidth by adding two or more carriers of LTE components.

Figure 3 is a diagram illustrating a subframe structure for use in a long-term evolution (LTE) system to which the present invention is applied.

With reference to Figure 3, the resources are composed of a plurality of resource blocks (RB) in the LTE bandwidth, and an RB 109 (or 113) is defined as 12 tones in the frequency domain and 14 or 12 OFDM symbols in the time domain and is a basic unit of resource allocation. A subframe 105 is 1 ms long and consists of two consecutive time slots 103. The subframe consisting of 14 OFDM symbols is called a normal cyclic prefix (CP) subframe and the subframe consisting of 12 OFDM symbols is called an extended CP subframe.

The reference signals 119 (RS) are signals negotiated between the mobile terminal and the base station for the mobile terminal to estimate the channel. The RS 119 can carry the information on the number of antenna ports, for example, 0, 1, 2 and 3. In the case where the number of antenna ports is greater than 1, multiple antennas are used. Although the absolute position of the RE for RS 119 in the frequency domain varies depending on the cell, the interval between RS 119 is maintained regularly. That is, the RS 119 of the same antenna port maintains a distance of 6 RE, and the reason why the absolute position of the RS 119 varies is to avoid the collision of the RS of different cells.

At the same time, the control region is located at the beginning of the subframe. In Figure 3, reference number 117 indicates the control region (ie, PDCCH). The control region may be configured along the OFDM symbols at the beginning of a subframe. In this case, L can have a value of 1, 2 or 3. In the case where the amount of the control information is small so that an OFDM symbol is sufficient to transmit the control information, only one OFDM symbol is used at the beginning of the subframe to transmit the control information ( L = 1), and the remaining 13 OFDM symbols are used to transmit data. The L value is used as basic information for demapening in the receiver and, therefore, if it is not received, the receiver cannot recover the control channel. In multimedia broadcasting over a single frequency network (MBSFN), the value of L is 2. In this case, the MBSFN is a channel for transmitting broadcast information. If the subframe indicates broadcast information, the LTE terminal receives in the control region but not in the subframe data region.

The reason why the control signaling is transmitted at the beginning of the subframe is for the terminal to determine if the subframe is destined for it and, consequently, to determine whether to receive the data channel (i.e., the shared channel Physical downlink (PDSCH)). If it is determined that there is no data channel destined for the terminal, the terminal may enter a sleep mode and save energy.

The LTE standard specifies three downlink control channels: physical channel control format indicator (PCFICH), physical channel hybrid ARQ indicator (PHICH) and packet data control channel (PDCCH); and these control channels are transmitted in group units 111 of resource elements (REG) within the control region 117.

The PCFICH is the physical channel for transmitting the control channel format indicator (CCFI) to the terminal. The CCFI is 2 bits long and indicates the number of symbols that occupy the control region in a subframe "L". Since a terminal can recognize the number of symbols in the control region based on the CCFI, the PCFICH must be the first channel to be received in a subframe except when the downlink resource is assigned persistently. Since it is impossible to know the value of L before receiving the PCFICH, the PCFICH is always mapped with the first OFDM symbol of each subframe. The PCFICH is in 4 resource groups formed by equitably separating 16 subcarriers in the frequency.

The PHICH is the physical channel for transmitting downlink ACK / NACK. The PHICH is received by the terminal that is transmitting data on the uplink. Therefore, the PHICH number is in proportion to the number of terminals that transmit on the uplink. The PHICH is transmitted in the first OFDM symbol (LPHICH = 1) or three OFDM symbols (LPHICH = 3) in the control region. The PHICH configuration information (channel number, LPHICH) is disseminated through the primary broadcast channel (PBCH) so that all terminals acquire the information in their initial connection to the cell. In addition, the PHICH is transmitted in a predetermined position per cell such as the PCFICH so that the terminals can acquire the PHICH configuration information by receiving the PBCH when the terminal is connected to the cell independently of other control channel information.

PDCCH 117 is the physical channel for transmitting data channel assignment information or energy control information. The PDCCH can be transmitted with different channel coding rates depending on the channel condition of the target terminal. Since phase shift modulation is always used in

Quadrature (QPSK) for PDCCH transmissions, changing the channel encoding rate requires changing the amount of resource for a PDCCH. When the terminal channel condition is good, a high channel coding rate is used to save the resource. On the other hand, when the terminal channel condition is bad, a low channel coding rate is used to increase the probability of reception at the terminal even at the expense of large amounts of resources. The amount of resource for each PDCCH is determined in unit of control channel element (CCE). Each CCE is composed of 5 groups 111 of resource elements (REG). To ensure diversity, the PDCCH REGs are arranged in the control region after interlacing has been performed.

To multiplex various ACK / NACK signals, a code division multiplexing (CDM) technique is applied to the PHICH. In a single REG 111 8 PHICH signals are multiplexed into 4 parts of real number and 4 parts of imaginary number by means of the CDM technique and repeated as much as NPHICH so that they are distributed in the frequency domain to obtain a gain of frequency diversity. By using REG 111 of NPHICH, it is possible to form the 8 or less PHICH signals. To form more than 8 PHICH it is necessary to use another REG 111 of NPHICH.

After allocating resources for the PCFICH and PHICH, a scheduler determines the value of L, maps the physical channels with the REG 111 of the assigned control region 117 based on the value of L, and interlaces to obtain a diversity gain of frequency. Interlacing is performed in the total REG 111 of subframe 105 determined by the value of L in REG units in the control region 117. The interleaver output in the control region 117 can prevent inter-cell interference (ICI) caused by using the same interleaver for the cells and obtain the diversity gain by distributing the REG 111 of the control region 117 by one or more symbols. In addition, it is guaranteed that the REG 111 that form the same control channel are distributed uniformly by the symbols per control channel.

Recently an investigation has been carried out on the LTE-A system as an advanced LTE system. Particularly, the investigation has focused on the extension of coverage with retransmitters that eliminate shadow zones in the cell and wireless recoil network to connect the base stations with the relay that operates in the same way as the base station.

Figure 4 is a diagram illustrating a principle of operation of a relay in an LTE-A system according to an embodiment of the present invention.

With reference to Figure 4, the relay 203 receives data transmitted from the base station 201 and forwards the data to the terminal 205. There may be multiple communication links in the cell that has a relay node.

The base station 201 and the terminal 207 are connected through a link 209, and the relay node 203 and the terminal 205 are connected through a link C 213. Since the relay node 203 is considered a base station in In view of terminal 205, link A 209 and link C 213 can be considered to be in the same transmission region as indicated by reference number 219.

The base station 201 and the relay 203 are connected through a link B 211, and the link B 211 is used to transmit the data destined to the terminal 205 connected to the relay 203 or exchange upper layer signaling between the base station 201 and the 203 relay.

Reference numbers 215 and 217 indicate the subframes that carry the data transmitted from the base station 201 to the terminal 205 by the relay 203. The subframes indicated by reference number 215 show the region in which the base station 201 transmits data to the relay 203 and the terminal 207, and the frames indicated by the reference number 217 show the region in which the relay node 203 transmits data to terminal 205 or receives data from base station 201. Subframes indicated by reference number 219 show the region in which terminal 207 connected to base station 201, or terminal 205 connected to relay 203, receives data from base station 201 or relay 203, respectively.

Reference number 221 indicates a backhaul network subframe transmitted over the backhaul link. The backhaul network subframe can be used to carry data transmitted to the relay node 203 and to the terminal 207 connected to the base station 201 or dedicated to the transmission of backhaul network data.

Reference number 235 indicates a resource region assigned for backhaul transmission. The base station 201 transmits the control channel 225 in each subframe, and the relay 203 also transmits the control channel in the same manner. The relay 203 cannot transmit and receive data simultaneously. Therefore, when the relay 203 transmits the control channel, it cannot receive the control channel information transmitted by the base station 201. The base station 201 transmits the data to the relay 203 in the

region 235 of the backhaul subframe after transmission of the control channel so that the relay 203 receives the information from the corresponding region. After transmission in the data channel region 235 it is necessary to change from transmission to reception. Therefore, an empty region 229 is required.

A description is now made of the method for a base station to allocate resources to a relay in a wireless broadband communication system.

First realization

Fig. 5 is a diagram illustrating a principle for allocating control channel resources of a relay in a wireless communication system according to a first embodiment of the present invention.

In this embodiment, when the retransmitter backhaul network subframe control channel resources are allocated, the base station divides the resource region for the relay into a plurality of resource groups and allocates the same resource group to retransmitters that they work in the same transmission mode to reduce the number of blind decoding attempts. At this time, the base station allocates resources to the relay in advance and informs the relay of the resource group and transmission mode currently used to reduce the number of blind decoding attempts and maximize frequency diversity gain and frequency selective gain. between the groups In addition, the base station supports the group in which the interlacing is performed and the group in which no interlacing is performed.

In relation to Figure 5, the resource allocation method according to the first embodiment of the present invention informs the relay of the resources allocated for the relay in the cell in the form of a plurality of resource groups instead of a single group of resources. resources.

In the conventional resource allocation method for transmission relay control channel as depicted in Figure 2, the entire resource region is informed. To allocate resources in a frequency selective manner in the conventional method, the base station must allocate large amounts of resources across the entire bandwidth 401 in advance. Therefore, it is difficult to perform frequency selective resource allocation and frequency diversity resource allocation.

In the resource allocation method according to the present invention, the base station segments the entire resource region into a plurality of resource groups and informs the relay of the resource group currently used as shown in Figure 5, as opposed to conventional resource allocation method in which the entire resource region is treated as a single resource, as shown in Figure 2.

In Figure 5, reference numbers 519, 521, 523 and 525 indicate the semi-static resource groups that are obtained by dividing the single resource. Resource groups are regions in which the relay PDCCH (R-PDCCH) is transmitted, and the relay attempts blind decodes with respect to the R-PDCCH in the resource group assigned to it, resulting in a reduction of the number of blind decodes. That is, the relay performs blind decoding in such a way that a group of resources (one of groups 519, 521, 523 and 525 of resources) is assigned to the relay in advance, in which there is its own relay control channel. and searches for its retransmission control channel in the selected resource group region to reduce the number of blind decoding attempts. The relay can be assigned one or more resource groups.

For example, assuming that a total of 32 physical resource blocks (PRB) are indicated, if the resource is used as a single group as shown in Figure 2, the number of blind decoding attempts is 32 + 16 + 8 + 4 = 60 Instead, if the resource is divided into 4 groups as shown in Figure 5 according to an embodiment of the present invention, the number of blind decoding attempts is 8 + 4 + 2 + 1 = 15. This is because the resource allocation method of the present invention allocates a small resource group per relay so that the relay searches only for the resource group assigned for its control channel with blind decodes.

To perform blind decoding in this way, the relay must know the total number of resource groups and the index and size of each resource group. Therefore, the base station informs the relay of the resource group information, ie the number of resource groups and the index and size of each resource group by means of the upper layer signaling. The resource group information may be transmitted in the form of information on all the resource groups by means of the system information or in the form of information on the resource group assigned to each relay by means of radio resource control signaling ( RRC).

Tables 1 and 2 show configurations of resource group information reported to the relay according to an embodiment of the present invention. Table 1 is a system information message format that carries the resource information, and Table 2 shows an RRC signaling message format that carries the

resource information

Table 1

R-PDCCH configuration {Semi-static resource group {

NumberOfResourceGroup 1, .., N {ResourceAllocation 1, ResourceAllocation 2,… ResourceAllocation N,}

} } }

Table 1 shows the case in which the resource is divided into N resource groups. The group information of

5 resources are transmitted to the relay by means of the upper layer signaling so that the relay is notified of the number of resource groups and the sizes of individual resource groups. The upper layer signaling can be done with a system information block 2 (SIB2). In the case of using system information, the base station is needed to inform the relay only of the resource group index that the relay must use to acquire the resource configuration information in the RRC signaling. If

10 in which the resource group information is not transmitted in the system information, the base station must send the information about the resource that the relay should use in the RRC signaling along with the configuration information. Table 2 shows the information by resource group when the resource group information is transmitted in RRC signaling.

Table 2

Semi-static resource group configuration {

Semi-static resource group { ResourceAllocation information, Interleaver on / off CRS or DRS DM RS port index (if DRS is used)

} }

As shown in Table 2, the resource group information includes the resource allocation information, the information on the multiplexed control channels in the assigned resource and the information related to the reference signal such as the signal type reference. This is because the relays

operating in the same mode of transmission are assigned to the same group of resources and the control channels can be interwoven. The resource allocation information informs the relay of the resource region in which the relay receiving the information attempts to demodulate the control channel between the resources carried by all the control channels. This region can receive information from a PRB index or a set of PRB. This will be further described with reference to the resource allocation method in a second embodiment as shown in Figure 6. The relay can also verify if its control channel is multiplexed with the control channels of other relays by referring to the information of on (off) / off (off) of the interleaver. If the interleaver is activated, the relay begins to receive the information with the recognition that its control channel is interlaced with the control channels of other relays. In addition, the relay receives information about the type of the reference signal used to demodulate the control channel intended for it. It is noted that all retransmitters that received the same group resource information receive the control channel using the same reference signal (RS). That is, if a specific resource group is assigned to a relay, this means that retransmitters assigned to the same resources use the same interleaving scheme and reference signal. In other words, retransmitters that operate in the same transmission mode (if using an interlaced and type of reference signal) are assigned to the same resource group.

Fig. 11 is a diagram illustrating a principle for assigning control channel resource groups to retransmitters according to the first embodiment of the present invention.

In relation to Figure 11, if the resource is fully configured previously as indicated by reference number 1101, the resource is divided into a plurality of resource groups as indicated by reference number 1102. At this time , the resource is divided depending on the appropriate transmission mode for individual groups determined by the base station. Relayers 1103 are grouped into relay groups 1104, 1105 and 1106 in association with the resource group. At this time, a group can be composed of one or more relays, and a relay can be included in multiple groups. A group of retransmitters is formed with relays that operate in the same transmission mode.

Once relay groups are formed, each group of relays is assigned a resource group. Each relay group is assigned a search space for blind decoding in the assigned resource group. Individual search spaces are mapped with corresponding resource groups as indicated by reference numbers 1108, 1111 and 1114. At this time, relays belonging to the same group have the same search space or respective search spaces.

Each resource group is allocated according to the transmission mode of the relay control channel. The relay assigned to the resource group indicated by reference number 1105 can be configured with a dedicated RS (DRS) as indicated by reference number 1110 without interlacing as indicated by reference number 1109. The relay assigned to the resource group indicated by reference number 1106 can be configured with a common RS (CRS) as indicated by reference number 1113 without interlacing as indicated by reference number 1112. The relay assigned to the resource group indicated by reference number 1104 can be configured with CRS as indicated by reference number 1116 and with interlacing as indicated by reference number 1115. In this case, interlacing includes interlacing of the REG level, interlacing of the CCE level and interlacing of the PRB level.

Second embodiment

As described above, in the case where the resource is divided into a plurality of resource groups that must be allocated for relay control channels, the physical resources mapped with the virtual resources of groups 511, 513, 515 and 517 Figure 5 can be arranged by consecutive physical resource blocks (PRBs) or PRBs distributed in the system bandwidth. A description is now made of the resource allocation rule for mapping virtual resources with physical resources.

Fig. 6 is a diagram illustrating a principle of a resource allocation rule for relay control channel resource groups according to a second embodiment of the present invention.

Reference numbers 601, 603, 605 and 607 indicate resource groups for transmitting the relay control channels. In this case, each resource group can be an RB or an RBG.

As mentioned earlier, the base station transmits the resource group information through the upper layer signaling. The base station also transmits the resource allocation rule by upper layer signaling. The resource allocation rule is the rule for mapping virtual resources with

physical resources.

The relay processes the signal from its relay control channel based on the resource group information received in advance. In this embodiment, when the relay performs blind decoding on the control channel signal, the number of blind decoding attempts is significantly reduced.

The retransmission control channel received includes information about the virtual resource (one of 609, 613 and 617). This information can be the index of the virtual resource assigned to the relay. If the virtual resource index is acquired, the relay can recognize the actual transmission resources (611, 615 and 619) assigned to it according to the resource allocation rule received in advance by means of the upper layer signaling. The resource allocation rule includes individual resource allocation sub-rules as indicated by reference numbers 609 and 611, 613 and 615, and 617 and 619; These sub-rules are called first, second and third rules to simplify the explanation.

The first rule is described with reference to the part indicated by reference numbers 609 and 611. The first rule is designed considering terminal multiplexing in the cell and resource allocation in units of RB groups (RBG). According to the first rule, the actual resources allocated to virtual resources are mapped on contiguous frequencies. This mapping scheme is efficient in the case where the frequency selectivity of the relay control channels or the terminal channels is very high.

The second rule is described with reference to the part indicated by reference numbers 613 and 615. The second rule is designed considering frequency diversity and resource allocation in RBG units. In the case where the frequency selectivity is not high, it is advantageous to distribute the allocated resources throughout the bandwidth in view of diversity gain and uniformity of interference between cells. In the second rule, the resources allocated in a resource group are distributed far enough in the frequency domain.

The third rule is described with reference to the part indicated by reference numbers 617 and 619. The third rule is designed considering frequency diversity, the allocation of virtual resources in RBG units and the mapping of virtual resources with resources. physicists in units of RB. Although virtual resources are allocated in RBG units as indicated by reference number 617, virtual resources are mapped with physical resources in the RBG in RB units. The third rule is robust against interference and advantageous for multiplexing planned terminal data because it can obtain a higher frequency diversity gain compared to the second rule.

Consecutive resources can be allocated to retransmitters that use beam shaping and / or spatial multiplexing techniques to exploit the frequency selective feature. Distributed resources can be used for diversity transmission using the normal reference signal. In this way, the system can allocate resources considering the frequency characteristic of the retransmission channel and the reference signal

or the mode of transmission. By performing multiplexing (interlacing) in the assigned resources of control channels in the same group of resources, it is possible to guarantee the diversity of the control channels. Interlocking of control channels can be performed using a REG level interleaver as explained in the first embodiment.

The method of configuring a plurality of resource groups for resource allocation to relay nodes and signaling the resource allocation rule to map resources in the individual resource group, the control channel, and the transmission mode to transmit / receive resource group information, described above in this document. A method of reducing the number of blind decoding attempts to reduce the data overload of the resource group information is described hereinafter. The resource group indicator includes the indexes of the resource groups assigned to individual relays, and each relay can reduce the number of blind decoding attempts to search for its group indicator using the resource group indicator.

Third embodiment

In a third embodiment of the present invention, a physical channel of retransmission control format indicator (RPCFICH) is used to transmit the resource group indicator. The R-PCFICH is transmitted in a fixed position and, if the semi-static resource group is divided as described in the first embodiment, the R-PCFICH can be transmitted in predetermined positions according to the number of the semi-static resource groups. That is, when the R-PDCCH is received in the initial connection process, there are positions to transmit the R-PCFICH in individual resource groups, and the relay performs blind decodes in the regions that carry the R-PCFICH instead of the Relay control channel regions of all resource groups. In this way, the relay performs a demodulation in the number of resource groups that receive the value of R-PCFICH. The R-PCFICH carries the index that indicates the resource group that includes the control channel of the

relay In this way, the relay can reduce the number of blind decoding attempts to find the resource group assigned for its relay control channel.

Fourth realization

In a fourth embodiment, a common relay control channel, ie common R-PDCCH, is used to implement a method to indicate a group of dynamic resources. In this case, the relay must receive the common R-PDCCH transmitted by the base station in addition to the specific relay control channel. In this common control channel, the index of the resource group used in the following retransmission network subframe of the corresponding relay is transmitted. Since the resource group to be used in the following backhaul network subframe is recognized upon receipt of the common R-PDCCH, the relay can reduce the number of blind decoding attempts.

A description is now made of a method for a base station to transmit the resource allocation information. Figure 7 is a flow chart illustrating a method of transmitting resource allocation information of a base station according to an embodiment of the present invention.

In relation to Figure 7, the base station configures the information on the resource groups considering a number of retransmitters in the cell and the channel conditions between the base station and the retransmitters in step 703. Next, the base station selects RB or RBG to be assigned in the individual semi-static resource groups in step 705. A selection procedure of this type is carried out with one of the three resource allocation rules described with reference to Figure 6. Next, the base station transmits the resource group information, the resource allocation information by group and the transmission channel mode information to the retransmitters by means of the upper layer signaling in step 707.

In the case of using the resource group indicator indicating the semi-static resource allocation group mapped with the resource assigned to the corresponding relay, the base station transmits the resource group indicator indicating the resource group that uses the subframe of Current backhaul network in the R-PCFICH or R-PDCCH in step 709. In the case where the resource group indicator is not used, step 709 is skipped.

In this case, the resource groups are updated over a long interval and the resource group indicator in each backhaul network subframe is updated.

A description is now made of a method for a relay to receive resource allocation information. Figure 8 is a flow chart illustrating a method of receiving resource allocation information from a relay according to an embodiment of the present invention.

In relation to Figure 8, the relay receives the resource group information to transmit the relay control channel, the resource allocation rule that indicates how to map with the virtual resources of the relay control channel with the physical resources, and the transmission mode of the control channel in advance by means of the upper layer signaling in step 803. In step 807, the relay receives the control channel based on the resource group information and the control channel transmission mode information acquired in step 803.

In the case of using the resource group indicator, the relay verifies if the current subframe is a backhaul network subframe and, if so, verifies the resource group indicator and selects the resource group to attempt to receive its channel of control in the current subframe using the resource group indicator in step 805. The resource group indicator can be received in the R-PCFICH or the common R-PDCCH.

Next, the relay performs a blind decoding in the relay control channels using the resource group information or the resource group indicator in step 807. In the case of using the resource group indicator, the relay searches for the resource group indicated by the resource group indicator and finds its relay control channel by blindly decoding the resource group found.

Next, the relay verifies whether the R-PDCCH was successfully received and, if so, acquires the planning information of the R-PDCCH to receive data in step 809. That is, the relay verifies the virtual resource assigned to it from its retransmission control channel and recognizes the physical channel actually assigned to it according to the resource allocation rule received in advance through the virtual resource.

A description is now made of the configuration of a base station for transmitting resource allocation information with reference to Figure 9. Figure 9 is a block diagram illustrating a configuration of a base station according to an embodiment of the present invention. .

As shown in Figure 9, the base station includes a controller 901, a resource allocator 903, an upper layer signaling generator 905, a data channel generator 907, a resource indicator generator 909, a generator 911 control channel signal and a 913 control channel generator.

Controller 901 performs the planning and allocates resources to individual relays. The controller 901 also generates the resource groups that should be indicated to the individual relays by grouping the retransmission retransmission network control channels through the resource allocator 903. In this case, the size of a resource group and the number of resource groups may vary depending on the channel conditions.

The upper layer signaling generator 905 generates information on the resource group information and the control channel transmission mode in the format described with reference to tables 1 and 2. The upper layer signaling generator 905 also generates the information about the resource allocation rule that has been assigned to the resource, whether an interleaver is used or not, and the type of reference signal used for control channel decoding.

Group resource information and transmission mode information can be transmitted through a data channel. Accordingly, the data channel generator 907 transmits the resource group information and the resource allocation rule mapped with the data channel.

When the resource group indicator described in the third and fourth embodiments is used, controller 901 controls the resource indicator generator 909 to generate the resource group indicator using the resource group information of a specific relay as a result of a planning in addition to the stages mentioned above.

The resource indicator generator 909 generates the resource indicator that is transmitted in one of the R-PCFICH and the common R-PDCCH as described above. The control channel signal generator 911 generates the control channel signal that includes the resource indicator, and the control channel generator 913 maps the control channel information that includes the resource indicator with the control channel that It must be transmitted.

Fig. 10 is a block diagram illustrating a configuration of a relay to receive resource allocation information according to an embodiment of the present invention.

As shown in Figure 10, the relay includes a control channel receiver 1001, a control channel blind decoder 1005, a data channel decoder 1007, a data channel receiver 1009 and a controller 1013.

The data channel receiver 1009 receives a data channel and extracts upper layer signaling 1011 from the data channel. The upper layer 1011 signaling includes assigned resource group information, the resource allocation rule with which virtual resources are mapped with physical resources and control channel transmission mode information. The data channel receiver 1009 also transfers the extracted resource group information and the resource allocation rule to the controller 1013.

The control channel receiver 1001 receives a channel such as the R-PCFICH and the common R-PDCCH and extracts the resource group indicator 1003 from the control channel.

The resource group indicator 1003 can be selectively included. In the case where the resource group indicator is not used, the control channel blind decoder 1005 verifies the resource group information provided by the controller 1013, searches for its resource group by performing a blind decoding and finds its R -PDCCH performing a blind decoding in the resource group found.

In the case where the resource group indicator is used, the control channel blind decoder 1005 verifies the number of resource groups and the sizes of individual resource groups using the resource group information issued by the controller 1013 and find its resource group indicated by the resource group indicator 1003. Next, the blind control channel decoder 1005 finds its retransmission control channel by performing a blind decoding in the resource group found.

After finding its own relay control channel, the blind control channel decoder 1005 verifies the position of the virtual resource assigned to the relay of the relay control channel found. Next, the blind control channel decoder 1005 receives the resource allocation rule provided by the controller 1013 and verifies the position of the physical resource assigned to the relay according to the resource allocation rule.

The data channel decoder 1007 verifies the position of the physical resource assigned to the relay by means of the control channel blind decoder 1005 and receives the data at the corresponding position of the data channel.

The configurations of the base station and the relay according to the embodiments of the present invention have been described above herein.

As described above, in the method and the control channel resource allocation apparatus for a relay node in a wireless communication system, a base station allocates a large amount of resources for the relay control channel in form of perfectly divided resource groups so that it is possible to reduce the number of blind decodes and dynamically allocate resources in each backhaul network subframe. In addition, the control channel resource allocation method and apparatus of the present invention can allocate resources to transmit data to terminals as well as the relay control channel in a frequency selective manner, which results in an improvement in all performance

10 of the system.

Although embodiments of the present invention have been described in detail hereinbefore, it should be clearly understood that the various variations and / or modifications of the basic inventive concepts taught herein may occur to those skilled in the present art. they will still be within the scope of the present invention, as defined in the appended claims.