KR101360394B1 - Apparatus and method for subcarrier allocation in broadband wireless communication system - Google Patents

Abstract

The present invention relates to an apparatus and method for allocating subchannels in a broadband wireless communication system using a multi-hop relay method, wherein a channel is assigned to a terminal by using channel information of a base station and a terminal link, a base station and relay station link, and a relay station and terminal link. A resource allocator for allocating data to be transmitted and data to be transmitted at two hops; a resource mapper for mapping the resource to data to be transmitted at one hop and data to be transmitted at two hops according to the resource allocation information; Including a transmitter for transmitting data, the total capacity of the system is increased, and the complexity of the subchannel allocation scheme may be reduced by using the suboptimal subchannel allocation scheme.

Multi-hop relay, half duplex, relay station, subchannel assignment

Description

Apparatus and method for subchannel allocation in broadband wireless communication system using multi-hop relay method {APPARATUS AND METHOD FOR SUBCARRIER ALLOCATION IN BROADBAND WIRELESS COMMUNICATION SYSTEM}

1 is a diagram showing the configuration of a broadband wireless communication system using a general multi-hop relay method;

2 is a diagram showing the configuration of a broadband wireless communication system using a multi-hop relay method according to the present invention;

3 is a block diagram of a base station in a broadband wireless communication system using a multi-hop relay method according to the present invention;

4 is a diagram illustrating a subchannel allocated to a base station of a broadband wireless communication system using a multi-hop relay method according to the present invention;

5 is a block diagram of a relay station in a broadband wireless communication system using a multi-hop relay method according to the present invention;

6 is a diagram illustrating a subchannel allocated to a relay station of a broadband wireless communication system using a multi-hop relay method according to the present invention;

7 is a block diagram of a terminal in a broadband wireless communication system using a multi-hop relay method according to the present invention;

8 is a diagram illustrating a subchannel allocated to a terminal of a broadband wireless communication system using a multi-hop relay method according to the present invention;

9 is a diagram illustrating a subchannel allocation procedure in a broadband wireless communication system using a multi-hop relay method according to an embodiment of the present invention;

10 is a diagram illustrating an operation procedure of a base station in a broadband wireless communication system using a multi-hop relay method according to an embodiment of the present invention;

11 is a diagram illustrating an operation procedure of a relay station in a broadband wireless communication system using a multi-hop relay method according to an embodiment of the present invention;

12 is a diagram illustrating an operation procedure of a terminal in a broadband wireless communication system using a multi-hop relay method according to an embodiment of the present invention; and

FIG. 13 is a diagram illustrating a performance graph of a broadband wireless communication system using a multi-hop relay method according to an exemplary embodiment of the present invention. FIG.

The present invention relates to a broadband wireless communication system using a multi-hop relay method, and more particularly, to an apparatus and method for allocating subchannels for maximizing transmission capacity in a broadband wireless communication system using the multi-hop relay method.

Due to the rapid growth of the wireless mobile communication market, various multimedia services are required in a wireless environment. Therefore, the fourth generation mobile communication system is provided with cells of very small radius in order to enable high speed communication and to accommodate more traffic. While such wireless networks must be distributed and controlled, they must be able to actively respond to environmental changes, such as the addition of new base stations. For the reasons described above, the 4G mobile communication system requires the configuration of an autonomous adaptive wireless network.

In order to implement the autonomous adaptive wireless network required in the 4th generation mobile communication system, a research on a wireless communication system using a multi-hop relay method using a relay station which relays a signal between a base station and a terminal is being conducted.

That is, the broadband wireless communication system using the multi-hop relay method can quickly reconfigure the network in response to changes in the surrounding environment by using the relay station, and can operate the entire wireless network more efficiently. In addition, the multi-hop relay scheme may provide a wireless channel having a better channel state by providing a relay station between the base station and the terminal to configure a multi-hop relay path through the relay station. In addition, the broadband wireless communication system can provide a high-speed data channel to terminals in a region that cannot communicate with the base station, such as a shaded region, by using the multi-hop relay path, thereby expanding a cell area. .

1 illustrates a configuration of a broadband wireless communication system using a general multi-hop relay method.

As shown in FIG. 1, the base station 100 connects directly with a terminal included in a service area. On the other hand, the base station 100 is located outside the service area or outside the service area and connects to the relay link through the terminal (120, 130, 140) having a poor channel state through the relay station 110.

That is, the base station 100 is located in a shaded area where shielding is severe due to the outside of a service area or a building, so that the relay station 110 is better used for the terminals 120, 130, and 140 having poor channel conditions. A channel can be provided. In this case, the RS may be operated by an amplify and forward method of simply amplifying and retransmitting a received signal and a decode and forward method of demodulating and decoding a received signal, and then modulating and encoding and transmitting the received signal again. have.

When the relay station of the broadband wireless communication system using the multi-hop relay method uses the amplification transmission method, the relay station should have the same frequency band for receiving each data stream and transmitting frequency band. If the transmission frequency band and the reception frequency band of the broadband wireless communication system are allocated differently, the relay station should have the same number of reception frequency bands and transmission frequency bands. Therefore, the relay station using the amplified transmission scheme restricts the degree of freedom in frequency utilization, thereby reducing the frequency usage efficiency.

In addition, when the RS uses a decoding transmission scheme, the RS receives a signal encoded by a long channel code from a plurality of user streams at once through a plurality of subchannels. Subsequently, the RS decodes the signal encoded with the long channel code, encodes the short coded channel code for each user data stream, and transmits the same to the MS using a plurality of subchannels. In this case, the RS in the decoding transmission method must match the number of subchannels allocated to the BS and the RS link and the number of subchannels allocated to the RS and the UE link. Therefore, the RS of the decoding transmission method can improve the frequency use efficiency by guaranteeing the degree of freedom in frequency utilization.

However, when the broadband wireless communication system using the multi-hop relay method uses the relay station, the base station transmits a signal to the terminal in two hops through the relay station. In contrast, the terminal also transmits a signal to the base station through the relay station in two hops. In this case, the broadband wireless communication system needs to allocate a subchannel to the base station, the relay station link, and the relay station and the terminal link, respectively, which causes a problem that the frequency use efficiency is reduced by half.

Accordingly, an object of the present invention to solve the above problems is to provide an apparatus and method for improving the frequency efficiency by using the half duplex method in a broadband wireless communication system using a multi-hop relay method.

Another object of the present invention is to provide a subchannel allocation apparatus and method for optimizing a transmission capacity when using a half duplex scheme in a broadband wireless communication system using a multi-hop relay scheme.

According to a first aspect of the present invention for achieving the above objects, a base station apparatus of a broadband wireless communication system using a multi-hop relay method, using the channel information of the base station and the terminal link, the base station and relay station link, the relay station and the terminal link A resource allocator for allocating data of data to be transmitted in one hop and data to be transmitted in two hops to the terminal; and mapping the resource to data to be transmitted in one hop and data to be transmitted in two hops according to the resource allocation information. And a transmitter for transmitting the resource-mapped data.

According to a second aspect of the present invention, a method of operating a base station in a broadband wireless communication system using a multi-hop relay method includes a base station and a terminal link, a base station and relay station link, and a relay station and terminal link to channel information to the terminal. Allocating resources of data to be transmitted in one hop and data to be transmitted in two hops; and a first frame including data to be transmitted in one hop to the terminal and data to be transmitted in two hops through the relay station according to the resource allocation information. And a second frame including data to be transmitted in one hop to the terminal according to the resource allocation information.

According to a third aspect of the present invention, a terminal apparatus of a broadband wireless communication system using a multi-hop relay system includes: a resource allocation information confirmation unit for confirming resource allocation information received from a base station; and the base station according to the resource allocation information. It characterized in that it comprises a receiving unit for receiving data transmitted in one hop from, and data transmitted in two hops through the relay station.

According to a fourth aspect of the present invention, a method of operating a terminal in a broadband wireless communication system using a multi-hop relay method includes: checking resource allocation information received from a base station; And receiving data transmitted in one hop and data transmitted in two hops through the relay station.

According to a fifth aspect of the present invention, a broadband wireless communication system for supporting a multi-hop relay service allocates resources according to channel information of links between a base station, a terminal, and a relay station to one terminal to the terminal through a first frame. A base station transmitting data to be transmitted in two hops through the relay station and data to be transmitted, and transmitting data to be transmitted in one hop to the terminal using a second frame; and the base station through the first frame according to the resource allocation information. A relay station receiving data from the base station and transmitting the received data to the terminal through the second frame, and data transmitted from the base station through the first frame and the second frame to one hop according to the resource allocation information; And a terminal receiving data transmitted in two hops through the relay station through the second frame. It is characterized in that comprises.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Hereinafter, a description will be given of a subchannel allocation technique for maximizing transmission capacity in a broadband wireless communication system using a multi-hop relay method. In the following description, a wideband wireless communication system using an Orthogonal Frequency Division Multiple Access method is described as an example, but the same may be applied to a wideband wireless communication system having another communication method.

Hereinafter, the broadband wireless communication system is a half duplex scheme in which a signal transmitted to the terminal is transmitted in one hop or two hops according to the channel state of the base station, the terminal link, the base station, the relay station link, and the relay station and the terminal link. Use Here, it is assumed that a signal transmitted in two hops in the half duplex method uses a decode and forward method in the RS.

2 is a block diagram of a broadband wireless communication system using a multi-hop relay method according to the present invention.

As shown in FIG. 2, the base station 200 transmits data through the 1-hop link to the terminal 250 having a good channel condition. In addition, the base station 200 transmits data through the relay stations 210, 220, 230 to the terminal having a poor channel condition.

If the channel condition of the terminal 1 240 is good, the base station 200 transmits a part of transmission data to the terminal 1 240 through a 1-hop link, and the remaining data is transmitted through the relay station 1 210. It transmits to the terminal 1 240 on a hop link. Here, the broadband wireless communication system includes data transmitted from the base station 200 to the terminal or the relay station through the 1-hop link by using the j-th frame. In addition, the broadband wireless communication system transmits data transmitted from the base station 200 to the terminal through a 1-hop link using the (j + 1) th frame, and the relay stations 210, 220, and 230 transmit the data to the terminals. Data to be transmitted to (240, 260). In this case, the j th frame and the (j + 1) th frame are divided into frequency resources or time resources.

Hereinafter, a description will be given of a block configuration of a base station, a relay station, and a terminal when the broadband wireless communication system uses a half duplex scheme.

3 is a block diagram of a base station in a broadband wireless communication system using a multi-hop relay method according to the present invention.

As shown in FIG. 3, the base station includes an encoder 301, a modulator 303, a resource mapper 305, a resource allocator 307, a feedback receiver 309, an OFDM modulator 311, and an RF processor ( 313).

The encoder 301 encodes and outputs data to be transmitted to a terminal or relay station according to a predetermined code rate. The modulator 303 modulates and outputs data provided from the encoder 301 according to a predetermined modulation scheme.

The resource mapper 305 allocates a corresponding subchannel to data provided from the modulator 303 according to the subchannel allocation information provided from the resource allocator 307. For example, the resource mapper 305 allocates a subchannel for the data to be transmitted according to the subchannel allocation information provided from the resource allocator 307 as shown in FIG. 4.

4 illustrates a subchannel allocated to a base station of a broadband wireless communication system using a multi-hop relay method according to the present invention.

As shown in FIG. 4, the base station distinguishes data to be transmitted in one hop and data to be transmitted in two hops. In addition, the data to be transmitted in the first hop is divided into data to be transmitted in the j-th frame and data to be transmitted in the (j + 1) th frame, and each data is encoded by the encoder 301 and the modulator 303. Thereafter, the resource mapper 305 transmits data to the first hop included in the j th frame and the (j + 1) th frame included in the j th frame according to the subchannel allocation information provided from the resource allocator 307. Subchannels of data to be transmitted in one hop and data to be transmitted in two hops are allocated.

The resource allocator 307 transmits data such that the capacity for transmitting data is optimal using channel information of the base station and the relay station link, the base station and the terminal link, and the relay station and the terminal link provided from the feedback receiver 309. Allocates subchannels for

The feedback receiver 309 collects channel information of the base station and the relay station link, the base station and the terminal link, and the relay station and the terminal link received from the relay station and the terminal, and provides them to the resource allocator 307.

The OFDM modulator 311 outputs sample data (OFDM symbols) by performing an inverse fast Fourier transform on the data provided from the resource mapper 305.

The RF processor 313 converts the baseband signal provided from the OFDM modulator 311 into an RF (Radio Frequency) signal and transmits the same through an antenna.

5 is a block diagram of a relay station in a broadband wireless communication system using a multi-hop relay method according to the present invention.

As illustrated in FIG. 5, the RS includes a receiver 500, a transmitter 520, and a resource allocation information checker 530.

The resource allocation information checking unit 530 checks and stores the resource allocation information provided from the base station. That is, the resource allocation information checking unit 530 checks the resource allocation information and transmits resource allocation information of the data received from the base station to the receiving terminal 500. In addition, the resource allocation information checking unit 530 checks the resource allocation information and transmits resource allocation information to transmit data to the terminal to the transmitting end 520.

The receiver 500 includes an RF processor 501, an OFDM demodulator 503, a resource demapper 505, a demodulator 507, a decoder 509, and a channel estimator 511.

The RF processor 501 converts a radio frequency (RF) signal received through an antenna into a baseband analog signal. The OFDM demodulator 503 performs fast Fourier transform on the sample data provided from the RF processor 501 and outputs data in the frequency domain.

The resource demapper 505 detects data corresponding to the relay station in a frame received according to the resource allocation information of the relay station provided from the resource allocation information checking unit 530.

The demodulator 507 demodulates and outputs data provided from the resource demapper 505 according to a predetermined modulation scheme. The decoder 509 decodes the data provided from the demodulator 507 according to the code rate to restore the data.

The channel estimator 511 estimates the channel of the base station and the relay station link using the received signal provided from the RF processor 501 and feeds back the channel information to the base station.

The transmitter 520 includes an encoder 521, a modulator 523, a resource mapper 525, an OFDM modulator 527, and an RF processor 529.

The encoder 521 receives data to be transmitted from the receiver 500 to the terminal, encodes the data according to a predetermined code rate, and outputs the encoded data. The modulator 523 modulates the data provided from the encoder 521 according to a predetermined modulation scheme and outputs the modulated data.

The resource mapper 525 allocates a corresponding subchannel to data provided from the modulator 523 according to the subchannel allocation information provided from the resource allocation information checking unit 530. For example, the resource mapper 525 allocates a subchannel for the data to be transmitted according to the subchannel allocation information provided from the resource allocation information checking unit 530 as shown in FIG. 6.

6 shows a subchannel allocated to a relay station of a broadband wireless communication system using a multi-hop relay method according to the present invention.

As shown in FIG. 6, the RS encodes data confirmed by the receiver 500 by the encoder 521 and the modulator 523. Thereafter, the resource mapper 525 allocates the subchannel of the (j + 1) th frame based on the subchannel allocation information provided from the resource allocation information checking unit 530 to the data provided from the modulator 523. do.

The OFDM modulator 527 outputs sample data (OFDM symbols) by performing inverse fast Fourier transform on the data provided from the resource mapper 525.

The RF processor 529 converts the baseband signal provided from the OFDM modulator 527 into a radio frequency (RF) signal and transmits the same through an antenna.

7 is a block diagram of a terminal in a broadband wireless communication system using a multi-hop relay method according to the present invention.

As shown in FIG. 7, the terminal includes an RF processor 701, an OFDM demodulator 703, a resource demapper 705, a demodulator 707, a decoder 709, and a channel estimator 711. do.

The RF processor 701 converts a radio frequency (RF) signal received through an antenna into a baseband analog signal. The OFDM demodulator 703 outputs data in the frequency domain by fast Fourier transforming the sample data provided from the RF processor 701.

The resource demapper 705 detects data corresponding to the terminal in a frame received according to the resource allocation information provided from the base station. For example, the resource demapper 705 detects data corresponding to the terminal in the j th frame and the (j + 1) th frame as shown in FIG. 8. Here, although not shown, the resource demapper 705 is provided with the resource allocation information from a resource allocation information checking unit for checking and storing the resource allocation information provided from the base station.

8 illustrates a subchannel allocated to a terminal of a broadband wireless communication system using a multi-hop relay method according to the present invention.

As illustrated in FIG. 8, the resource demapper 705 receives data provided from the base station and the relay station through the j th frame and the (j + 1) th frame according to the resource allocation information provided from the base station. Check it.

The demodulator 707 demodulates and outputs data provided from the resource demapper 705 according to a predetermined modulation scheme. The decoder 709 decodes the data provided from the demodulator 707 according to the code rate to restore the data.

The channel estimator 711 estimates a channel of a base station, a terminal link, a relay station, and a terminal link by using the received signal provided from the RF processor 701 and feeds back the channel information to the base station.

As described above, the base station allocates a subchannel for transmitting data such that the capacity for transmitting data is optimal using channel information of the base station and the relay station link, the base station and the terminal link, and the relay station and the terminal link. In this case, the base station allocates a subchannel so that the transmission capacity is optimal by using Equation 1 below.

는 기지국과 i번째 중계국의 n번째 부채널의 채널 이득(1 ≤i≤M) 또는 상기 기지국과 (i-M)번째 단말의 n번째 부채널의 채널 이득((M+1)≤i≤(M+K))을 나타내고, 상기

는 j번째 프레임에서 n번째 부채널을 i번째 중계국 또는 단말이 사용하는지를 나타내며, 상기

는 (j+1)번째 프레임에서 n번째 부채널을 m번째 기지국(m=0) 또는 중계국(m=1, …,M)이 k번째 단말 사이에 할당되었는지를 나타낸다. 또한, 상기

는 m번째 중계국과 k번째 단말 사이의 n번째 부채널의 채널 이득을 나타내고, 상기 R_m ⁽¹⁾는 상기 m번째 중계국에서 N개의 OFDM 부채널을 사용하여 수신 가능한 데이터 양을 나타내며, 상기 R_m ⁽²⁾는 상기 m번째 중계국에서 N개의 OFDM 부채널을 사용하여 송신 가능한 데이터 양을 나타낸다.Here, N represents the number of OFDM subchannels, M represents the number of relay stations, and K represents the number of terminals. In addition,

Is the channel gain of the nth subchannel of the base station and the i-th relay station (1 ≦ i ≦ M) or the channel gain of the nth subchannel of the base station and the (iM) th terminal ((M + 1) ≦ i ≦ (M +). K)), and

Indicates whether the i th relay station or the terminal uses the n th subchannel in the j th frame.

Denotes whether the m-th base station (m = 0) or the relay station (m = 1, ..., M) is allocated between the k-th terminals in the (j + 1) th frame. In addition,

Is the channel gain of the n-th subchannel between the m-th relay station and the k-th terminal, and R _m ⁽¹⁾ represents the amount of data that can be received using N OFDM subchannels at the m-th relay station, and R _m ⁽²⁾ shows the amount of data that can be transmitted using N OFDM subchannels in the mth relay station.

)과 j번째 프레임을 이용하여 K개의 단말로 1홉으로 전송하는 데이터 량(

) 및 (j+1)번째 프레임을 이용하여 K개의 단말로 1홉으로 전송하는 데이터 량(

)의 합이 최대가 되도록 자원(부채널)을 할당한다.As shown in Equation 1, the base station transmits data through M relay stations to K terminals.

) And the amount of data transmitted in one hop to K terminals using the j th frame (

) And amount of data transmitted in one hop to K terminals using the (j + 1) th frame (

Allocate resources (subchannels) so that the sum of

However, when the base station performs the optimal resource allocation using Equation 1, the complexity of the base station and the terminal link, the base station and the terminal link, and the channel information of the relay station and the terminal link must be searched. Therefore, the base station will be described a method for optimizing the sub-channel allocation while reducing the complexity as shown in FIG.

9 illustrates a subchannel allocation procedure in a broadband wireless communication system using a multi-hop relay method according to an exemplary embodiment of the present invention.

Referring to FIG. 9, in step 901, the base station determines whether feedback information is received from the relay stations and terminals. That is, the base station determines whether a feedback signal including channel information of the base station and the relay station link, the relay station and the terminal link, and the base station and the terminal link is received from the relay stations and the terminals.

When the feedback signal is received, the base station proceeds to step 903 and checks the channel information of the base station and the relay station link, the relay station and the terminal link, and the base station and the terminal link in the feedback signal.

In step 905, the base station allocates a subchannel of the j-th frame using channel information of the base station, the relay station link, and the base station and the terminal link. For example, the base station allocates the n-th subchannel of the j-th frame to a link having the largest transmission amount among the base station, the relay station link, and the base station and the terminal link as shown in Equation 2 below. The base station allocates all subchannels of the j-th frame to a link having the largest transmission amount by using Equation 2 below. In this case, since a subchannel allocated to each link is selected and assigned to a link having the largest transmission amount for each subchannel, a plurality of subchannels can be allocated to one link.

는 상기 기지국과 i번째 중계국의 n번째 부채널의 채널 이득(1 ≤i≤M) 또는 상기 기지국과 (i-M)번째 단말의 번째 부채널의 채널 이득((M+1)≤i≤(M+K))을 나타내고, 상기

는 j번째 프레임에서 n번째 부채널을 i번째 중계국 또는 단말이 사용하는지를 나타낸다.Here, M represents the number of the relay station, and K represents the number of the terminal. In addition,

Is the channel gain of the nth subchannel of the base station and the i-th relay station (1 ≦ i ≦ M) or the channel gain of the first subchannel of the base station and (iM) th terminal ((M + 1) ≦ i ≦ (M +). K)), and

Indicates whether the i-th RS or the UE uses the n-th subchannel in the j-th frame.

After allocating the subchannel of the j-th frame, the base station proceeds to step 907 to measure the amount of data R _m ⁽¹⁾ transmitted from the base station to each relay station.

In step 909, the base station allocates the subchannel of the (j + 1) th frame by using channel information of the base station, the terminal link, the relay station, and the terminal link. For example, the base station allocates the n-th subchannel of the (j + 1) th frame to the link having the largest transmission amount among the base station, the terminal link, the relay station, and the terminal link as shown in Equation 3 below. The base station allocates all subchannels of the (j + 1) th frame to a link having the largest transmission amount by using Equation 3 below. In this case, since a subchannel allocated to each link is selected and assigned to a link having the largest transmission amount for each subchannel, a plurality of subchannels can be allocated to one link.

는 (j+1)번째 프레임에서 n번째 부채널을 m번째 기지국(m=0) 또는 중계국(m-1, …,M)이 k번째 단말 사이에 할당되었는지를 나타내고, 상기

는 m번째 중계국과 k번째 단말 사이의 n번째 부채널의 채널 이득을 나타낸다.Here, M represents the number of the relay station, and K represents the number of the terminal. In addition,

Indicates whether the nth subchannel in the (j + 1) th frame is allocated between the mth base station (m = 0) or the relay station (m-1, ..., M) between the kth terminals.

Denotes the channel gain of the n th subchannel between the m th relay station and the k th terminal.

After allocating the subchannel of the (j + 1) th frame, the base station proceeds to step 911 to measure the amount of data R _m ⁽²⁾ transmitted by the relay stations to the terminals.

In step 913, the base station determines whether the amount of data R _m ⁽¹⁾ received by the relay stations is similar to the amount of data R _m ⁽²⁾ transmitted by the relay station to the terminal. The difference between R _m ⁽¹⁾ and R _m ⁽²⁾ is compared with a preset reference value.

If the amount of data received and the amount of data transmitted by the relay stations are similar (| R _m ⁽¹⁾ -R _m ⁽²⁾ | <reference value), the base station terminates the present algorithm.

On the other hand, if the amount of data received and the amount of data transmitted by the relay stations are different (| R _m ⁽¹⁾ -R _m ⁽²⁾ | ≥ reference values), the base station proceeds to step 915 from the base station among the relay stations. The relay station RS _k having the largest difference between the amount of data received and the amount of data transmitted to the terminal is selected.

In step 917, the base station compares the amount of data received by the selected relay station with the amount of data transmitted.

If the received data amount of the relay station is greater than the transmitted data amount (R _m ⁽¹⁾ > R _m ⁽²⁾ ), the base station proceeds to step 919 in which the base station and the selected relay station link are allocated to the base station. Select the subchannel with the smallest data transmission rate among the channels.

After the subchannel having the smallest data transmission amount is selected, the base station proceeds to step 921 in which the link having the largest transmission rate is excluded, except for a link allocated to the currently selected subchannel among the base station and relay station link and the base station and terminal link. Reassigns the selected subchannel to. In step 913, the base station determines whether the amount of data R _m ⁽¹⁾ received by the relay stations is similar to the amount of data R _m ⁽²⁾ transmitted by the relay station to the terminal. To compare the difference between R _m ⁽¹⁾ and R _m ⁽²⁾ and a predetermined reference value.

On the other hand, if the amount of data transmitted by the RS is greater than the received data amount (R _m ⁽¹⁾ < R _m ⁽²⁾ ), the base station proceeds to step 923 in which the base station and the selected relay station are allocated to the link. Select the subchannel with the smallest data transmission rate among the channels.

After the subchannel having the smallest data transmission amount is selected, the base station proceeds to step 925 to remove the selected subchannel in the link having the largest transmission rate, except for the link currently allocated to the selected subchannel among the relay station and the terminal link. Reallocate. In step 913, the base station determines whether the amount of data R _m ⁽¹⁾ received by the relay stations is similar to the amount of data R _m ⁽²⁾ transmitted by the relay station to the terminal. To compare the difference between R _m ⁽¹⁾ and R _m ⁽²⁾ and a predetermined reference value.

As described above, when the base station allocates an optimal subchannel, channel information of only ((number of MSs + 1) × (number of RSs + 1)-1) × (number of OFDM subchannels) is required. That is, the amount of information fed back by the relay stations and the terminals to the base station increases.

Accordingly, the terminal receives data only from one relay station having the best average channel state among the relay stations. In this case, since the base station needs channel information of (2 × (number of MSs) + (number of RSs)) × (OFDM subchannels), the information fed back by the relay stations and terminals can be reduced.

10 is a flowchart illustrating an operation procedure of a base station in a broadband wireless communication system using a multi-hop relay method according to an exemplary embodiment of the present invention.

Referring to FIG. 10, first, the base station determines whether feedback information is received from the relay stations and terminals in step 1001. That is, the base station determines whether a feedback signal including channel information of the base station and the relay station link, the relay station and the terminal link, and the base station and the terminal link is received from the relay stations and the terminals.

When the feedback signal is received, the base station proceeds to step 1003 and allocates subchannels of the base station, the relay station, and the terminal as shown in FIG. 9 by using channel information of each link included in the feedback signal.

After allocating the subchannel, the base station proceeds to step 1005 and transmits the subchannel allocation information to the relay station and the terminal.

In step 1007, the base station configures a frame to be transmitted to the relay station and the terminal according to the subchannel allocation information. For example, the base station distinguishes data to be transmitted in one hop and data to be transmitted in two hops. In addition, the data to be transmitted in the first hop is divided into data to be transmitted in the j-th frame and data to be transmitted in the (j + 1) th frame. Subsequently, the base station performs subchannels of data to be transmitted in one hop included in the jth frame, data to be transmitted in one hop included in the (j + 1) th frame and data to be transmitted in two hops according to the subchannel allocation information. Allocate

Thereafter, the base station terminates the present algorithm.

11 is a flowchart illustrating an operation procedure of a relay station in a broadband wireless communication system using a multi-hop relay method according to an exemplary embodiment of the present invention.

Referring to FIG. 11, first, the RS checks subchannel allocation information received from the BS in step 1101.

In step 1103, the RS checks whether a signal is received from the BS.

If the signal is received, the RS proceeds to step 1105 to estimate a channel of the received signal and feeds back channel information of the base station and RS link to the base station.

Thereafter, the RS proceeds to step 1107 to restore data transmitted from the BS to the RS in the j th frame received from the BS according to the subchannel allocation information.

After reconstructing the data, the RS proceeds to step 1109 and allocates a subchannel of the (j + 1) th frame to the reconstructed data according to the subchannel allocation information for transmitting the reconstructed data to the terminal. do. Thereafter, the RS transmits the (j + 1) th frame to the UE.

The relay station then terminates this algorithm.

12 illustrates an operation procedure of a terminal in a broadband wireless communication system using a multi-hop relay method according to an embodiment of the present invention.

Referring to FIG. 12, first, in step 1201, the terminal checks subchannel allocation information received from the base station.

In step 1203, the terminal determines whether a signal is received from the base station and the relay station.

If the signal is received, the terminal proceeds to step 1205 to estimate the channel of the received signal to check the channel information of the base station and the relay station link, the relay station and the terminal link. Thereafter, the terminal feeds back channel information of the base station, the relay station link, and the relay station and the terminal link to the base station.

In step 1207, the terminal restores the data transmitted by the base station and the relay station in the jth frame and the (j + 1) th frame received from the base station and the relay station according to the subchannel allocation information.

Thereafter, the terminal ends the algorithm.

13 illustrates a performance graph of a broadband wireless communication system using a multi-hop relay method according to an embodiment of the present invention. In the following description, in FIG. 13B, the horizontal axis represents a type of subchannel allocation scheme, and the vertical axis represents a performance gain (sum rate).

As shown in (a) of FIG. 13 with reference to FIG. 13, when four relay stations are located around one base station and 10 terminals are located at a cell edge, the performance of the subchannel allocation scheme according to the present invention is improved. Measure

As shown in (b) of FIG. 13, in the environment as shown in (a) of FIG. 13, system 1 does not utilize a relay station, and the terminal communicates with only one relay station to which it depends. No. 2 system, the third system in which the terminal communicates with the relay station to which the terminal is dependent 1 or 2 hops, the terminal according to another embodiment of the present invention with the M relay stations It shows the performance of system 4 to communicate freely with one hop or two hops. That is, the third system is a system in which the terminal is configured to receive data only from one relay station having the best average channel state among the relay stations in order to reduce the amount of feedback.

System 2 increases the sum rate of 65.4% compared to System 1, and System 3 increases the sum of 25.8% compared to System 2. In addition, the fourth system increases the total capacity of 0.64% compared to the third system. Accordingly, when subchannels are allocated in accordance with the present invention, it indicates that the performance of the broadband wireless communication system is improved.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but is capable of various modifications within the scope of the invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, in a broadband wireless communication system using a multi-hop relay method, a base station transmits data in one or two hops to a terminal according to a channel state of each link, thereby increasing the total capacity of the broadband wireless communication system. There is an advantage to this. The base station has an advantage of reducing the complexity of the subchannel allocation scheme using a suboptimal subchannel allocation algorithm.

Claims (22)

A base station apparatus of a broadband wireless communication system using a multi-hop relay method, A resource allocator for allocating data of data to be transmitted in one hop and data to be transmitted in two hops to the terminal by using channel information of the base station and the terminal link, the base station and the relay station link, and the relay station and the terminal link; A resource mapper for mapping a resource to data to be transmitted to the first hop and data to be transmitted to the second hop according to the resource allocation information; And a transmitter for transmitting the mapped data of the resource. The method according to claim 1, The resource allocator may classify data to be transmitted in one hop and data to be transmitted in two hops to the terminal through each link according to channel information of each link, and determine whether to transmit data to be transmitted in the first hop in a first frame. Device for allocating resources by dividing whether to transmit in two frames. 3. The method of claim 2, And the first frame and the second frame are divided into time resources or frequency resources. The method according to claim 1, The resource mapper maps data to be transmitted in one hop to the terminal in the first frame and data to be transmitted in two hops through the relay station according to the resource allocation information, and transmits data to be transmitted in one hop to the terminal in the second frame. Device for mapping. The method according to claim 1, And a feedback receiver for checking channel information of the base station and the terminal link, the base station and the relay station link, and the relay station and the terminal link fed back from the relay stations and the terminals. A method of operating a base station in a broadband wireless communication system using a multi-hop relay method, Allocating resources of data to be transmitted in one hop and data to be transmitted in two hops to the terminal using channel information of the base station and the terminal link, the base station and the relay station link, and the relay station and the terminal link; Configuring a first frame including data to be transmitted in one hop to the terminal and data to be transmitted in two hops through the relay station according to the resource allocation information; And constructing a second frame including data to be transmitted in one hop to the terminal according to the resource allocation information. The method according to claim 6, And identifying channel information of the base station and the terminal link, the base station and the relay station link, and the relay station and the terminal link by using the signals fed back from the relay stations and the terminals. The method according to claim 6, The first frame and the second frame, characterized in that divided into time resources or frequency resources. The method according to claim 6, The process of allocating the resource, Allocating resources of the first frame and the second frame to each link by using channel information of the base station and the terminal link, the base station and the relay station link, and the relay station and the terminal link; Comparing the amount of data transmitted to the relay station with the amount of data transmitted from the relay station to the terminal according to the resource allocation information of each link; And reallocating the resource when the difference between the amount of data transmitted to the relay station and the amount of data transmitted from the relay station is greater than a reference value. 10. The method of claim 9, The process of allocating the resource to each link, Allocating a subchannel of the first frame to a link having the largest data transmission rate among the base station and terminal links and the base station and relay station links; And allocating a subchannel of the second frame to a link having the largest data transmission rate among the base station and terminal links and the relay station and terminal links. 10. The method of claim 9, The process of reallocating the resource, When the difference between the amount of data transmitted to the relay station and the amount of data transmitted from the relay station is greater than a reference value, selecting a relay station having a largest difference between the amount of data transmitted to the relay station and the amount of data transmitted from the relay station; When the amount of data transmitted to the selected RS is greater than the amount of data transmitted from the RS, selecting a subchannel having the lowest data transmission amount among the subchannels allocated to the BS and the selected RS link; And reassigning the selected subchannel to a link having the largest data transmission rate among the base station and relay station links and the base station and terminal links. The method of claim 11, When the amount of data transmitted to the selected RS is smaller than the amount of data transmitted from the RS, selecting a subchannel having the lowest data transmission amount among the subchannels allocated to the selected RS and the terminal link; And reassigning the selected subchannel to a link having the largest data transmission rate among the relay station and the terminal links. 10. The method of claim 9, The process of reallocating the resource, And reallocating the resource until a difference between the amount of data transmitted to all the relay stations and the amount of data transmitted from the relay stations is less than or equal to a reference value. A terminal device of a broadband wireless communication system using a multi-hop relay method, A resource allocation information confirmation unit for confirming resource allocation information received from the base station; Receives data transmitted in one hop from the base station through a first frame according to the resource allocation information, receives data transmitted in one hop from the base station through a second frame and data transmitted in two hops through a relay station Apparatus comprising a receiving unit to. 15. The method of claim 14, And estimating a channel of the base station, the terminal link, the relay station, and the terminal link by using a received signal, and feeding back channel information of the base station, the terminal link, the relay station, and the terminal link to the base station. Device. delete In the operation method of a terminal in a broadband wireless communication system using a multi-hop relay method, Checking resource allocation information received from the base station; Receiving data transmitted in one hop from the base station through a first frame according to the resource allocation information; And receiving data transmitted in one hop from the base station and data transmitted in two hops through a relay station according to the resource allocation information. 18. The method of claim 17, Estimating a channel of the base station and the terminal link and the relay station and the terminal link using the received signal; And feeding back channel information of the base station and the terminal link and the relay station and the terminal link to the base station. delete A broadband wireless communication system for supporting a multi-hop relay service, Allocates resources according to channel information of links between a base station, a terminal, and a relay station, and transmits data to be transmitted in one hop to the terminal through a first frame and data to be transmitted in two hops through the relay station, and uses the second frame. A base station transmitting data to be transmitted in one hop to a terminal, A relay station which receives data from the base station through the first frame according to the resource allocation information and transmits the received data to the terminal through the second frame; And a terminal receiving data transmitted in one hop from the base station through the first frame and the second frame and data transmitted in two hops through the relay station through the second frame according to the resource allocation information. System configured. The method of claim 20, The base station allocates resources of data to be transmitted in one hop and data to be transmitted in two hops to the terminal by using channel information of the base station and the terminal link, the base station and the relay station link, and the relay station and the terminal link. Transmitting data to be transmitted in one hop to the terminal through the first frame and data to be transmitted in two hops through the relay station according to the resource allocation information, and transmitting data to be transmitted in one hop to the terminal through the second frame. System characterized in that. 21. The method of claim 20, The first frame and the second frame, characterized in that divided into time resources or frequency resources.

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