KR20060040905A - Apparatus and method for reducing uplink interference in time division duplexing based broadband wireless communication system - Google Patents

Abstract

The present invention relates to an apparatus and method for reducing uplink interference in a time division duplexing (TDD) based broadband wireless communication system having a multi-sector structure. In a communication method of a base station according to the present invention, a process of dividing a plurality of sectors into three groups, a process of performing uplink communication of the three groups alternately, and a specific one of the three groups may be performed. When performing uplink communication, the remaining two groups include performing downlink communication. As such, since sectors in the base station alternately perform uplink communication, there is an advantage of reducing uplink interference.

UL interference, broadcast service, multi-sector, frame

Description

Apparatus and method for reducing uplink interference in time division duplexing based broadband wireless communication system {APPARATUS AND METHOD FOR REDUCING UPLINK INTERFERENCE IN TDD-BROADBAND WIRELESS SYSTEM}             

1 shows an example of occurrence of intersector interference in a conventional three-sector cell structure.

2 illustrates a six-sector cell structure in accordance with the present invention.

3 illustrates a frame structure according to an embodiment of the present invention.

4 is a diagram illustrating an initial negotiation procedure between a base station and a terminal according to an embodiment of the present invention.

5 is a diagram illustrating a frame structure for providing a broadcast service according to an embodiment of the present invention.

6 illustrates an example in which a terminal belonging to an uplink period receives a broadcast service from another area when using a frame structure according to the present invention.

FIG. 7 illustrates a procedure for a base station to determine a sector-by-sector communication direction at a specific time in a TDD-based broadband communication system having a multi-sector structure according to an embodiment of the present invention.

8 is a diagram illustrating a procedure for a terminal to determine a communication direction at a specific time in a TDD-based wideband communication system having a multi-sector structure according to an embodiment of the present invention.

9 is a view showing a transmission and reception structure of a terminal in a TDD-based broadband communication system according to an embodiment of the present invention.

10 is a graph showing a change in SINR value according to the number of terminals for each sector obtained through simulation.

The present invention relates to an apparatus and a method for reducing uplink interference in a broadband wireless communication system. In particular, the present invention relates to an uplink in an Orthogonal Frequency Multiple Access (OFDMA) communication system based on TDD having a multi-sector structure. An apparatus and method for performing uplink communication with sectors staggered to reduce link interference.

In general, in the 4th Generation communication system, which is the next generation communication system, active research is being conducted to provide users with services having various Quality of Service (QoS) having a transmission rate of about 100 Mbps. Currently, 3rd Generation communication systems generally support transmission rates of about 384 Kbps in outdoor channel environments with relatively poor channel environments, and up to 2Mbps in indoor channel environments with relatively good channel environments. do.

Meanwhile, wireless local area network (LAN) systems and wireless metropolitan area network (MAN) systems generally support transmission rates of 20 Mbps to 50 Mbps. However, the wireless MAN system is suitable for supporting high-speed communication services because of its wide coverage and high-speed transmission, but it does not consider the mobility of a user, that is, a subscriber station. . Therefore, in the 4G communication system, research is being actively conducted in the form of ensuring mobility and QoS in a wireless LAN system and a wireless MAN system that guarantee a relatively high transmission speed.

An orthogonal frequency division multiple access (OFDM) scheme and an orthogonal frequency division multiple access (OFDMA) scheme are applied to a physical channel of the wireless MAN system. and Electronics Engineers) 802.16 communication system, that is, the IEEE 802.16 OFDM / OFDMA communication system realizes high-speed data transmission by transmitting a physical channel signal using a plurality of sub-carriers.

On the other hand, in recent years, a system having a frequency reuse of 1 is commonly used to increase spectral efficiency in a cellular network. Here, the frequency reuse of 1 means that all base stations in the system can use the same radio resource at the same time. In other respects, however, an increase in the frequency reuse rate causes an increase in the effective interference signal, thereby reducing the capacity of the entire system. Therefore, in implementing a system with frequency reuse of 1, appropriate measures are needed to reduce the influence of interference occurring between adjacent cells or sectors. In particular, in the case of uplink, performance deterioration due to interference is very large when a terminal using a non-directional antenna exists in a boundary region of a cell or sector.

A typical method for reducing interference effects between adjacent cells or sectors is spread spectrum such as code division multiple access (CDMA) and frequency hopping. The CDMA technology is a type of interference averaging technique that distributes the influence of narrowband interference signals to the entire band through spreading the spectrum, and thus is 10 to 20 times larger than that of the existing analog communication technology, Advanced Mobile Phone Service (AMPS). Capacity could be increased. In this context, in order to construct a system having a frequency reuse of 1, a method for reducing interference between neighboring base stations becomes a key issue.

Meanwhile, in the IEEE 802.16 OFDM / OFDMA communication system (hereinafter, collectively referred to as an "OFDMA communication system"), different subcarriers are used for each subchannel of each cell through permutation to probabilistic resource collisions. The proposal is to reduce the cost. However, such a method also has a problem in that the collision probability increases as the occupancy rate of the radio resource increases, thereby degrading performance. This problem is not a problem because the path attenuation according to the distance is large between base stations more than 2 ^nd tier apart, but performance degradation due to interference signals from adjacent base stations located in positions facing each other in the main beam direction may be severe. Can be.

In addition, in the uplink, when the terminal exists in the boundary region of the sector in the base station, the antenna gain is reduced because the terminal is greatly deviated from the main lobe direction of the base station antenna, as well as the shadow due to the feature. The received signal quality between the terminal and the base station may be worse. In this case, even though power control is performed in the uplink, the UE determines that the received signal quality is poor, and thus transmits a cone interference signal to a neighboring sector.

1 shows an example of occurrence of intersector interference in a conventional three-sector cell structure. In the figure, it is assumed that terminal MS1 is provided with service from sector b.

As shown, since the terminal MS1 is located at the boundary region of the sector, when the terminal transmits a signal in the uplink, the terminal MS1 receives the signal of the terminal MS1 even in a neighboring sector. In this case, since the distance between the sector a and the MS1 is relatively close, the signal of the terminal MS1 may have a greater influence than the interference signal received from the terminal existing in the adjacent cell (base station).

As described above, in a cellular system having a frequency reuse of 1, interference that is practically effective is caused by interference between a cell at a position facing in the main beam direction of a sector antenna and a terminal located at an intersector boundary. Interference. In other words, there is a need for a scheme for removing such uplink interference in a TDD-OFDMA communication system having a multi-sector structure.

Accordingly, an object of the present invention is to provide an apparatus and method for performing uplink communication in which sectors are staggered with each other in order to reduce uplink interference in a TDD-based broadband communication system having a multi-sector structure.

Another object of the present invention is to provide a frame structure for reducing uplink interference in a TDD-based broadband communication system having a multi-sector structure.

Another object of the present invention is to provide an apparatus and method for efficiently providing a broadcast service in a TDD-based broadband communication system having a multi-sector structure.

According to a first aspect of the present invention for achieving the above object, a communication method of a base station in a time division duplexing (TDD) -based broadband wireless communication system having a multi-sector structure, to divide the plurality of sectors into three groups A process of performing uplink communication with the three groups alternately, and a process of performing downlink communication with the other two groups when a specific one of the three groups performs uplink communication Characterized in that it comprises a.

According to a second aspect of the present invention, a plurality of sectors in a base station are divided into three groups, and the three groups are alternately selected to perform uplink communication, and a specific group may perform uplink communication. In the broadband wireless communication system in which the remaining groups perform downlink communication, a communication method of a terminal includes: receiving, from a base station, a message including timing information about a downlink period and an uplink period of a sector to which the terminal belongs; Performing switching between downlink and uplink according to the timing information extracted from the received message, checking whether a broadcast service should be received in the uplink period, and receiving the broadcast service In this case, the method includes switching to downlink to receive a broadcast service from an adjacent base station. It is characterized by.

According to a fourth aspect of the present invention, a plurality of sectors in a base station are divided into three groups, and the three groups are alternately selected to perform uplink communication, and a specific group may perform uplink communication. In the broadband wireless communication system in which the remaining groups perform downlink communication, the terminal apparatus analyzes a duplexer in charge of switching between transmission and reception, and a message received from the base station to analyze timing information of the downlink period and the uplink period. And a controller for controlling a switching operation of the duplexer based on timing information and broadcast service reception from the control message processor.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, if it is determined that the detailed description of the related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In the following description, specific details such as the number of sectors in a base station, a grouping method of sectors, a number of groups, and the like are shown to help a more general understanding of the present invention. It will be apparent to those skilled in the art that these inventions may be readily practiced without these specific details and by modifications thereof.

Hereinafter, a method for performing uplink communication in which sectors are staggered with each other in order to reduce uplink interference in a time division multiplexing (TDD) based broadband communication system having a multi-sector structure will be described. Specifically, a frame structure for performing uplink communication in which sectors deviate from each other, an uplink / downlink switching scheme according to a new frame structure, and a broadcast service method for efficiently using a new frame structure will be described.

2 illustrates a six-sector cell structure according to the present invention.

Referring to FIG. 2, six sectors in a base station (or cell) are divided into three regions {a, d}, {b, e}, and {c, f}, and for convenience, the region {a, d} is referred to as 'A'. In this case, the region (b, e} is defined as the 'B' region, and the region {c, f} is defined as the 'C' region, in which antennas of the same region in each base station face in opposite directions and are located in the same region. The sectors belonging to each other simultaneously perform uplink or downlink communication, for example, if the A areas (a, b sectors) are uplink periods, the remaining B and C areas (b, c, e, f sectors) are downlink periods. That is, three regions alternately perform uplink communication, and when a specific one of the three regions performs uplink communication, the remaining two regions perform downlink communication.

3 illustrates a frame structure according to an embodiment of the present invention. In the drawing, the horizontal axis represents a time domain, and the vertical axis represents a spatial region divided by sectors.

As described above, when two sectors out of six sectors per base station are grouped into one area, three areas are defined in one base station. As shown, sectors a and sector d are collectively defined as region A, sectors b and sector e are collectively defined as region B and sectors c and sector f are collectively defined as region C. Here, two sectors of the same area form beams in opposite directions to each other. The three regions alternately perform uplink communication. This may reduce the amount of uplink interference by 1/3. At this time, if the length of the uplink and downlink frame in each area is the same, the downlink and uplink ratio is 2: 1. In the frame structure according to the present invention, although the resource use opportunity in the uplink is reduced as a whole, the frequency reuse in the entire period is maintained at 1 since the use opportunity of the resource increases in the downlink period.

As described above, according to the present invention, since the switching scheme between uplink and downlink is different for each sector, when the UE enters a different area at the time of initial system connection or through handover, Timing information should be obtained from the base station.

4 illustrates an initial negotiation procedure between a base station and a terminal according to an embodiment of the present invention. According to the present invention, the terminal acquires uplink / downlink timing information of the region to which it belongs through an initial basic capability negotiation procedure.

Referring to FIG. 4, first, upon initial system access, the UE acquires a base station having the best signal quality through discovery and acquires synchronization through a downlink control symbol from the obtained base station (step 401). .

Thereafter, the terminal transmits a ranging request signal (RNG-REQ: ranging request) to the base station for uplink time offset and power control (step 403), and the base station transmits a response signal (RNG-) to the ranging request signal. RSP: ranging-response) is transmitted to the terminal (step 405). The response signal (RNG-RSP) may include information for adjusting uplink time offset of the terminal and power control information.

Thereafter, the terminal transmits a subscriber basic capability request signal (SBC-REQ) to the base station to negotiate the basic capability (step 407), and the base station transmits a response signal to the subscriber basic capability request signal (step S407). SBC-RSP: transmits a subscriber basic capability-response) to the terminal (step 409). The subscriber capability request signal (SBC-REQ) may include information on the basic capability of the subscriber (MAC version, hybrid ARQ support, etc.). In addition, according to the present invention, the response signal SBC-RSP includes uplink / downlink timing information of a sector to which the current UE belongs. After negotiating the basic capability, the terminal finally enters the network (step 411).

As described above, through the basic capability negotiation, the UE identifies which of the three areas A, B, and C belong to the sector to which the UE belongs, and downlink / uplink timing information of the corresponding area. Will be obtained. Similarly, even when the UE enters a new area through handover, timing information on the downlink / uplink may be obtained through basic capability negotiation with the corresponding target base station.

Meanwhile, in the conventional TDD frame structure, all the base stations in the system perform uplink and downlink at the same time, whereas in the frame structure according to the present invention, one region of the three regions is uplink and the remaining 2 in a specific time frame. The three regions will perform downlink communication. Such a frame structure has an advantage of providing a multicast or broadcast service with downlink at any time without distinguishing between uplink and downlink using a single frequency network (SFN) network. In other words, even if the terminal belongs to the uplink region, the broadcast service can be received through the downlink of the adjacent region.

Next, a method for simultaneously providing a real time broadcast service and a packet data service in a frame structure according to the present invention will be described in detail.

5 illustrates a frame structure for providing a broadcast service according to an embodiment of the present invention.

As shown, region A (a sector and sector d) communicates as downlink-> downlink-> uplink ..., and region B (b sector and e-sector) is uplink-> downward. Communication is performed as in Link-> Downlink ..., and C region (sector c and f-sector) is performing communication as Downlink-> Uplink-> Downlink ...

Here, looking at uplink frames (the third frame of region A, the first frame of region B, and the second frame of region C), a portion of resources are allocated to a common broadcasting service region to allocate a broadcast service and a packet. It provides data service at the same time. The remaining downlink frames are allocated to empty regions in order not to use resources corresponding to the broadcast service region.

For example, if the area A is uplink and the areas B and C are the downlink periods (the third frame period), the terminal A and the terminal that will perform the downlink communication together in the area A There may exist, only the terminal performing the downlink communication in the B and C region. Here, the terminal performing downlink communication among the terminals belonging to the area A is a terminal receiving a broadcast service. In this case, the terminal belonging to the area A and receiving the broadcast service receives the broadcast service from the adjacent B and C areas.

As described above, the terminal determines the arrangement of the uplink period and the downlink period according to the region to which it belongs. Meanwhile, in the broadcasting region of the downlink period, since each base station transmits the same data, a terminal that wants to receive a broadcasting service receives the broadcasting service through macro diversity. Therefore, even if the region to which the terminal currently belongs is an uplink section, a broadcast service can be provided through a downlink broadcasting region of another adjacent region. On the other hand, the part of the uplink section that opposes the downlink broadcast service section is to be left blank without considering the collision between resources during uplink transmission.                     

6 illustrates an example in which a terminal belonging to an uplink period receives a broadcast service from another area when using a frame structure according to the present invention. As shown, a sector area of the base station BS1 is a current uplink period, but the terminal receiving the broadcast service may receive a broadcast service from adjacent base stations BS2 and BS3 performing the downlink period at the same instant.

Next, a method for determining a sector-by-sector communication direction at a specific point in time will be described.

7 illustrates a procedure for a base station to determine a sector-by-sector communication direction at a specific time in a TDD-based broadband communication system having a multi-sector structure according to an embodiment of the present invention. The following description assumes a six sector structure. First, six sectors are divided into three regions A, B, and C. FIG. In this case, two sectors belonging to the same group form beams in opposite directions.

Referring to FIG. 7, the base station calculates the remaining value obtained by dividing the frame number N by 3 in step 701. In step 703, the base station checks whether the remaining value is '0'. The frame having the remaining value '0' may be a third frame, a sixth frame, a ninth frame, and the like from a predetermined reference. If the remaining value is '0', the base station performs uplink communication for the A area and downlink communication for the remaining B and C areas in step 709.

If the remaining value is not '0', the base station proceeds to step 705 to check whether the remaining value is '1'. The frame having the remaining value '1' may be a first frame, a fourth frame, a seventh frame, or the like. If the remaining value is '1', the base station proceeds to step 711 to perform uplink communication for the B area and to perform downlink communication for the remaining A and C areas.

If the remaining value is not '1', the base station proceeds to step 707 to check whether the remaining value is '2'. The frame having the remaining value '2' may be a second frame, a fifth frame, an eighth frame, or the like. If the remaining value is '2', the base station proceeds to step 713 to perform uplink communication for the C region and downlink communication for the remaining A and B regions.

As described above, when a plurality of sectors are classified into three groups, the three groups alternately perform uplink communication, and when one specific group performs uplink communication, the remaining groups perform downlink communication. It is characterized by performing.

Next, a procedure for determining a communication direction for each frame section in the terminal will be described.

8 illustrates a procedure for a terminal to determine a communication direction at a specific time in a TDD-based broadband communication system having a multi-sector structure according to an embodiment of the present invention. Prior to the description, it is assumed that the terminal already knows timing information about the uplink and downlink periods through negotiation with the base station.

Referring to FIG. 8, first, in step 801, the UE checks whether a region (or sector) to which the terminal belongs is a downlink period. If the downlink period, the terminal proceeds to step 702 to receive the downlink data from the base station. At this time, if the terminal is provided with a broadcast service, the terminal receives the broadcast service from the base stations that perform downlink among the other base stations as well as the base station (or cell) to which it belongs. In this case, the terminal receives a broadcast service from various base stations through macro diversity.

If the uplink period, the terminal proceeds to step 805 to check whether to receive a broadcast service. In this case, if it is necessary to receive a broadcast service, the terminal proceeds to downlink communication in step 807 to receive a broadcast service (multicast or broadcast service) from neighboring base stations. If it is not necessary to receive the broadcast service, the terminal proceeds to step 809 to perform uplink communication.

9 shows a transmission and reception structure of a terminal in a TDD-based broadband communication system according to an embodiment of the present invention.

As shown, the terminal includes an encoder 901, an interleaver 903, a modulator 905, a subcarrier mapper 907, an IFFT operator 909, a parallel / serial converter 911, a CP adder 913, Transmitter 915, duplexer 917, receiver 919, CP remover 921, serial / parallel converter 923, FFT operator 925, subcarrier demapper 927, demodulator 929, deinterleaver 931 and the decoder 933 are comprised.

First, referring to the transmission path, the encoder 901 outputs by channel coding at a corresponding code rate in order to make the input information data robust to the wireless channel. The interleaver 903 strongly interleaves the encoded data from the encoder 901 to a burst error and outputs it. The modulator 905 modulates and outputs data from the interleaver 903 in a corresponding modulation scheme. Here, the modulation scheme may be Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (16QAM), 64QAM, or the like. The subcarrier mapper 907 submaps and outputs data from the modulator 905.

The IFFT operator 909 performs an inverse fast Fourier transform (IFFT) on the data from the subcarrier mapper 907 and outputs time sample data. The parallel / serial converter 911 converts the parallel data input from the IFFT operator 909 into serial data and outputs the serial data. The CP adder 913 is a sample output from the parallel / serial converter 911 to remove noise due to a magnetic signal (Inter Symbol Interference, hereinafter referred to as 'ISI') caused by a multipath fading phenomenon of a wireless channel. The protection section (CP: Cyclic Prefix) is inserted into the data and output.

The transmitter 915 converts the digital signal from the CP adder 207 into an analog signal, converts the analog baseband signal into a radio frequency (RF) band signal so as to be actually transmitted to the duplexer 917. Output The duplexer 917 outputs a transmission signal (uplink signal) from the transmitter 915 to the antenna ANT in a TDD scheme, and receives a reception signal (downlink signal) from the antenna ANT in the receiver 919. )                     

Next, referring to the reception path, the receiver 919 converts a signal of a high frequency band from the duplexer 917 into a baseband, and converts and outputs the baseband analog signal into time sample data. The CP remover 921 removes the guard period CP from the sample data from the receiver 919 and outputs valid data of the OFDM symbol. The serial / parallel converter 923 converts the serial data from the CP remover 921 into parallel data for input of the IFFT operator 925 and outputs the serial data. The FFT operator 925 performs Fast Fourier Transform (FFT) on the parallel data from the serial / parallel converter 923 and outputs data in the frequency domain.

The subcarrier demapper 927 extracts and outputs subcarrier values carrying actual data from the subcarrier values from the FFT operator 925. The demodulator 929 demodulates and outputs data from the subcarrier demapper 927 in a corresponding demodulation scheme. The deinterleaver 931 deinterleaves and outputs data from the demodulator 929. The decoder 933 restores information data by channel decoding the data from the deinterleaver 931 at a code rate.

The control message processor 935 processes the control message from the base station to obtain necessary information. According to the present invention, the control message processor 935 analyzes a subscriber basic capability-response (SBC-RSP) message received from a base station, obtains timing information for downlink / uplink, and transmits the downlink / uplink to the downlink / uplink. The timing information is provided to the transmission / reception controller 937. The transmission / reception controller 937 controls the switching operation of the duplexer 917 with timing information on downlink / uplink from the control message processor 935. In this case, the transmission / reception controller 937 controls the duplexer 971 by determining not only timing information regarding the downlink / uplink but also whether a broadcast service is received by the current terminal. For example, if an uplink period is required to receive a broadcast service, the duplexer 917 is controlled to receive a downlink signal.

Then, the performance change when using the frame structure according to the present invention will be described here.

First, referring to the interference effect between adjacent cells, since uplink and downlink are simultaneously performed in the same time interval, it is necessary to consider the influence of the interference signal. For example, when the A (a, d sector) area is an uplink period, the remaining B (b, e sector) and C (c, f) areas are downlink periods. In this case, signals transmitted from the sector antennas of the B and C regions may cause interference to the sector antennas of the A region. In particular, if the beam pattern of the antenna is not correct, interference effects from other sectors co-sited in the same cell cannot be ignored. Such interference effects from different sectors between the same cells are not a problem when using smart antennas that are actively being developed.

In addition, referring to the case where the terminal is located in the boundary region of the cell, at this time, the number of the main interference sector antennas affecting the signal toward the sector antenna of the A region is four considering only 1 ^st tier. However, in this case, since the signal of the interference sector is spaced about 60 ° from the main beam direction of the sector antenna of the A region, the incident interference signal is attenuated by the antenna pattern of the base station. Nevertheless, a terminal located in an intercell boundary region may encounter an uplink service unavailable condition at any time. If a service outage is detected, a method of transmitting data through a protection channel may be considered. The guard channel is a subchannel left unused by all base stations and guarantees maximum reception SINR (Signal to Interference Noise Ratio).

On the other hand, when the region A is an uplink period and the region B is a downlink period, an interference effect of a signal transmitted from a terminal of the region A to the terminal of the region B may be considered. In this case, not only the transmission power of the terminal is lower than that of the base station, but also the altitude of the terminal is not high, so it can be assumed that various obstacles exist between the corresponding terminals in a place such as an urban area, and thus the interference effect can be eliminated to some extent. In addition, if the terminal of the area A is located in the boundary area, so that it is not easy to access the base station to which it belongs, since the corresponding terminal uses the protected channel, the interference effect on the terminal of the area B is greatly reduced.

As described above, the present invention proposes a method of dividing sectors into three groups for each cell in a TDD-based OFDMA communication system, and reducing the size of intercell interference by performing three groups of uplink communication. Doing. In addition, the present invention proposes a method for effectively serving a real-time broadcast service together with an existing packet data service by setting a common broadcasting channel in a downlink frame.                     

As described above, the present invention reduces the radio resource usage opportunity in the uplink period by one third, but there is no problem in operation since the Internet service and broadcasting service such as web browsing are more concentrated on the downlink. The transmission efficiency reduced in the uplink period is utilized in the downlink, and it can be a method for efficiently providing integrated services of broadcasting and communication in a TDD-based OFDMA communication system by using the channel as a broadcast dedicated channel through the SFN network.

Meanwhile, in the present invention, the amount of interference in the uplink is theoretically reduced to 1/3 (4.77 dB). Here, we will look through the simulation how much the actual interference size is reduced when using the frame structure according to the present invention. In the simulation, a total of seven cells are assumed considering only 1 ^st tier, and each cell is composed of six sectors. The path attenuation index according to the distance is 3.88, and the path attenuation model is applied to the ITU-R Vehicular channel model. UL power control is not applied and the antenna pattern is assumed to be ideal.

10 is a graph showing a change in SINR value according to the number of terminals for each sector obtained through simulation. As shown, it can be seen that the proposed scheme has a higher signal-to-interference noise ratio (SINR) gain of about 2 to 4 dB compared to the conventional scheme.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present 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 those equivalent to the scope of the claims.

As described above, the present invention has an advantage of reducing uplink interference since sectors in the base station alternately perform uplink communication. In addition, there is an advantage that the broadcast service can be efficiently provided by allocating a common broadcast channel for the broadcast service in the downlink frame.

Claims (21)

A communication method of a base station in a TDD (Time Division Duplexing) based broadband wireless communication system having a multi-sector structure, Dividing the plurality of sectors into three groups; Performing uplink communication with the three groups in turn; And when one of the three groups performs uplink communication, the remaining two groups include performing downlink communication. The method of claim 1, And when there are six sectors in the base station, two sectors belonging to the same group generate beams in opposite directions to each other. The method of claim 1, The downlink frame includes a broadcasting region for a broadcast service. The method of claim 3, The broadcast service is characterized in that it is provided via a single frequency network (SFN). The method of claim 3, The uplink frame includes a blank region which is not used corresponding to the downlink broadcast service region. The method of claim 1, The timing information for the uplink period and the downlink period for each of the plurality of sectors is provided to the terminal through a message for subscriber basic capability (SBC) negotiation. The method of claim 1, The length of the uplink frame and the downlink frame, characterized in that the same. A communication method of a base station in a TDD (Time Division Duplexing) based broadband wireless communication system having a multi-sector structure, Dividing the plurality of sectors into three groups; Calculating a remaining value by dividing the frame number counted by a predetermined reference by '3'; When the remaining value is '0', a first group of the three groups performs uplink communication, and the remaining groups perform downlink communication; When the remaining value is '1', a second group of the three groups performs uplink communication, and the remaining groups perform downlink communication; And when the remaining value is '2', a third group of the three groups performs uplink communication and the remaining groups perform downlink communication. A plurality of sectors in the base station are divided into three groups, the three groups are alternately selected to perform uplink communication, and when a specific group performs uplink communication, the remaining groups perform downlink communication. In the broadband wireless communication system of the terminal, Receiving a message including timing information about a downlink period and an uplink period of a sector to which the terminal belongs from a base station; Performing switching between downlink and uplink according to the timing information extracted from the received message; Checking whether to receive a broadcast service in the uplink period; If it is necessary to receive the broadcast service, switching to downlink and receiving a broadcast service from an adjacent base station. The method of claim 9, And when there are six sectors in the base station, two sectors belonging to the same group generate beams in opposite directions to each other. The method of claim 9, The downlink frame includes a broadcasting region for a broadcast service. The method of claim 9, The uplink frame includes a blank region which is not used corresponding to a downlink broadcast service region. The method of claim 9, The message including timing information for the uplink period and the downlink period is a message for subscriber basic capability (SBC) negotiation. The method of claim 9, The length of the uplink frame and the downlink frame, characterized in that the same. A plurality of sectors in the base station are divided into three groups, the three groups are alternately selected to perform uplink communication, and when a specific group performs uplink communication, the remaining groups perform downlink communication. A terminal device in a broadband wireless communication system, A duplexer responsible for switching between transmission and reception, A control message processor that analyzes the message received from the base station and obtains timing information about the downlink period and the uplink period; And a controller for controlling the switching operation of the duplexer based on timing information from the control message processor and broadcast service reception. The method of claim 15, The controller may control the duplexer to receive a downlink signal even when the broadcast service is to be received even in the current uplink period. The method of claim 15, And when there are six sectors in the base station, two sectors belonging to the same group generate beams in opposite directions to each other. The method of claim 15, The downlink frame includes a broadcasting region for a broadcast service. The method of claim 15, The uplink frame includes a blank region which is not used corresponding to a downlink broadcast service region. The method of claim 15, And a message including timing information about the uplink period and the downlink period is a message for subscriber basic capability (SBC) negotiation. The method of claim 15, And a length of the uplink frame and the downlink frame is the same.

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