KR20080032825A - Apparatus and method for communicating control information in broadband wireless access communication system - Google Patents

Abstract

A control information communication device in a broadband wireless access system and a method thereof are provided to transmit a compressed control message(map message) if control information on a random CID(Connection Identifier) is the same as existing control information, thereby reducing size of the control information(map). A base station performs a resource scheduling process for the current frame(401). The base station confirms scheduling information(403), and checks whether existing scheduling information for each CID is the same as the current scheduling information(405). If so, the base station generates a compressed map message which includes CID information only for corresponding bursts(407). The base station generates and broadcasts map bursts which include map messages for the bursts(413).

Description

Control information communication apparatus and method in broadband wireless access system {APPARATUS AND METHOD FOR COMMUNICATING CONTROL INFORMATION IN BROADBAND WIRELESS ACCESS COMMUNICATION SYSTEM}

1 illustrates a frame structure of a typical IEEE 802.16 series system.

2 is a diagram illustrating a configuration of a base station in a broadband wireless access system according to an embodiment of the present invention.

3 is a diagram illustrating a configuration of a terminal in a broadband wireless access communication system according to an embodiment of the present invention.

4 is a diagram illustrating an operation procedure of a base station in a broadband wireless access system according to an embodiment of the present invention.

5 is a diagram illustrating an operation procedure of a terminal in a broadband wireless access system according to an embodiment of the present invention.

The present invention relates to a frame communication apparatus and method in a broadband wireless access system, and more particularly, to an apparatus and method for reducing the size of control information in a broadband wireless access system.

Today, many wireless communication technologies have been proposed as candidates for high speed mobile communication. Among them, orthogonal frequency division multiplexing (OFDM) is recognized as a candidate technology for the next generation of wireless communication. have. The OFDM technology is expected to be used in most of the fourth generation wireless communication technologies expected around 2010, and the OFDM6 is also adopted as a standard in the 802.16 series Wireless Metropolitan Area Network (WMAN), which is now called the 3.5 generation technology.

Among the 802.16 working group, wireless communication standards are represented by 802.16d and 802.16e, and the two standards are divided into single carrier, OFDM, and orthogonal frequency division multiple access (OFDMA) standards. .

In order to freely allocate uplink / downlink in various forms in the OFDM-based broadband wireless access system, the base station transmits information describing resource allocation of uplink / downlink every frame. In the IEEE 802.16 series system, the MAP message plays this role.

Figure 1 shows the frame structure of a typical IEEE 802.16 series system.

As shown, a frame is composed of one downlink (DL) frame and one uplink (UL) frame. The downlink frame is a section in which the base station transmits data to the terminals, and the uplink frame is a section in which several terminals transmit data to the base station in a predetermined area.

The downlink frame consists of a preamble, a frame control header (FCH), a downlink (DL) MAP, an uplink (UL) MAP, and a downlink data burst. The uplink frame is composed of a control region and an uplink data burst region. The downlink preamble is used for initial synchronization acquisition and cell search of the UE, and the FCH includes information describing the basic configuration of the frame. The DL MAP includes information for indicating an area of downlink data bursts, and the UL MAP includes information for indicating a structure of an uplink frame.

The control region of the uplink frame includes a ranging region, a CQICH region, an ACKCH region, a sounding region, and the like. The ranging area is an area where the terminal can raise a code without allocation of a base station. The ranging area is used for initial network access, handoff request, resource allocation, and the like. The CQICH region is a region for the UE to report the downlink channel status. The ACKCH region is an area for reporting whether the downlink data burst has been successfully received. The sounding region is a region in which a sounding signal for uplink channel estimation is transmitted.

In general, the frame configuration is determined by the base station, the terminal can know the frame structure and allocation information by receiving the DL MAP and UL MAP of the downlink frame transmitted by the base station for each frame. Herein, information elements (IE) constituting the MAP correspond to one data burst. That is, even if the data burst transmits a small amount of data, the corresponding MAP IE must exist. Table 1 below shows DL-MAP IE, and Table 2 shows UL-MAP IE. The detailed description of each field is specified in the standard specification, so the detailed description will be omitted here.

field Size (bit) DIUC 4 N_CID 8 CIDs (N) 16 * N OFDMA symbol offset 8 Subchannel offset 6 boosting 3 No.OFDMA symbols 7 No. Subchannels 6 repetition coding indication 2

field Size (bit) CID 16 UIUC 4 if UIUC == 12    OFDMA symbol offset 8    Subchannel offset 7    No. OFDMA symbols 7    No. Subchannels 7    Ranging Method 2    reserved One if UIUC == 14    CDMA_Allocation_IE 32 If UIUC == 15    Extended UIUC dependent IE Variable else    Duration 10    repetition coding indication 2

In the above-described frame structure, transmission units in the frequency and time domains are subchannels and symbols, respectively. As described above, in the OFDM-based broadband wireless access system, downlink bursts and uplink bursts within a frame can be allocated in at least one subchannel and one symbol unit, thereby maximizing the degree of freedom in frame configuration. However, as the degree of freedom increases, the control information to be sent increases, and when the data of several users are mixed in the frame, the control information to inform the user through DL-MAP and UL-MAP acts as a significant overhead. do.

In particular, certain services such as VoIP have a characteristic that small packets are periodically generated. In this case, an overhead in which the amount of control information (MAP information) becomes larger than the amount of traffic actually transmitted may occur. In the worst case, the MAP overhead causes a very small amount of resources that can be allocated for real traffic, resulting in a low throughput of the system.

Accordingly, an object of the present invention is to provide an apparatus and method for reducing the size of control information in a broadcast broadband wireless access system.

Another object of the present invention is to provide an apparatus and method for reducing MAP overhead in a broadband wireless access system.

According to an aspect of the present invention for achieving the above object, in the base station apparatus in the broadband wireless access system, a storage unit for storing the scheduling information of the previous frame, a scheduler for performing resource scheduling for this frame, and the scheduler And a control information generation unit for comparing the current scheduling information from the previous scheduling information with the previous scheduling information stored in the storage unit and generating a compressed resource allocation message when the scheduling information is the same.

According to another aspect of the present invention, in a terminal device in a broadband wireless access system, a storage unit for managing burst information required for communication, and decoding control information received in this frame, and compressing the terminal in the control information. And a decoding unit for storing burst information of a previous frame in the storage unit and a controller for controlling downlink and uplink communication using the burst information stored in the storage unit when the resource allocation message exists. .

According to still another aspect of the present invention, in a communication method of a base station in a broadband wireless access system, a process of performing resource scheduling for this frame, a process of comparing the current scheduling information and previous scheduling information stored in a storage unit; And generating a compressed resource allocation message when the scheduling information is the same.

According to still another aspect of the present invention, in a communication method of a terminal in a broadband wireless access system, a process of decoding control information received in this frame and a compressed resource allocation message for the terminal in the control information exist The method may include storing burst information of a previous frame in a storage unit and performing downlink and uplink communication using the burst information stored in the storage unit.

Hereinafter, the operating principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

Hereinafter, a scheme for reducing control information size in a broadband wireless access system will be described.

The broadband wireless access system is, for example, a communication system using Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA). That is, the following description will be given using a broadband wireless access communication system using multiple carriers as an example, but the present invention can be equally applied to a wireless communication system using another access method.

2 illustrates a configuration of a base station in a broadband wireless access system according to an embodiment of the present invention.

As shown, the scheduler 200, the scheduler information storage 202, the MAP generator 204, the encoder 206, the modulator 208, the resource mapper 210, the OFDM modulator 212, the DAC ( Digital to Analog Converter (214) and RF (Radio Frequency) transmitter 216.

Referring to FIG. 2, first, the scheduler 200 performs resource scheduling using channel information (CQI information) for each terminal fed back through a feedback channel (eg, CQI channel), and performs the scheduling information (resource allocation information, Control information, etc.) to the MAP generator 204.

The MAP generator 204 generates MAP information (DL MAP / UL MAP) according to the scheduling information received from the scheduler 200. Here, the scheduling information may be OFDMA symbol offset, subchannel offset, boosting information, number of OFDMA symbols, number of subchannels, repetitive coding indicators, and the like for each burst.

According to the present invention, the MAP generator 204 compares the burst information received from the scheduler 200 with the existing burst information stored in the scheduling information storage unit 202 based on a connection identifier. At this time, if the existing burst information for any connection identifier and the burst information determined through this scheduling is different, the MAP generator 204 is the burst information received from the scheduler 200, the scheduling information storage unit 202 In the MAP message, and a general MAP message (MAP IE) is created using the burst information. Here, the general MAP message has a form as shown in Table 1 when the downlink, and has a form as shown in Table 2 when the uplink.

If the existing burst information for any connection identifier and the burst information determined through this scheduling are the same, the MAP generator 204 creates a compressed MAP message according to the present invention. In this case, the compressed MAP message may have the form of an extended MAP IE defined by the IEEE 802.16 standard.

For example, the compressed MAP message may have a form as shown in Table 3 when it is downlink, and may have a form as shown in Table 4 when it is uplink.

field Size (bit) DIUC = 15 (extended DIUC) 16 Extended DIUC 4 length 4 N_CID 4 CIDs (N) 16 * 4

field Size (bit) CID 16 UIUC = 15 (extended UIUC) 4 Extended UIUC 4 length 4

Referring to Table 3, the downlink compressed MAP message is a field in which a code indicating that an extended DL-MAP_IE is recorded (DIUC = 15), a field in which an extended DIUC value is recorded (extended DIUC), a length field (length), and a CID. The number N_CID is recorded, and the plurality of CIDs are recorded. Here, the length field is set to the sum of the N-CID field size and the CIDs field size. The field in which the extended DIUC value is recorded may be set to one of values of O9, OA, OC, and OE not used in the current standard.

Referring to Table 4, the uplink compressed MAP message is a field in which a CID is recorded (CID), a field in which a code indicating a coded extension UL-MAP_IE is recorded (UIUC = 15), and a field in which an extended UIUC value is recorded (Extended UIUC). And a length field. Here, the length field is set to the size of the data to be attached later. The field in which the extended UIUC value is recorded may be set to one of values of OB, OC, OD, OE, and OF not used in the current standard.

As described above, when the existing burst information and the burst information obtained through this scheduling are the same, the present invention creates a MAP message including only the connection identifier for the corresponding burst. When the terminal receives the compressed MAP message according to the present invention, the terminal performs communication using information of the previously received MAP message.

The transmission / reception controller 218 controls the overall operation of downlink communication and uplink communication using the scheduling information stored in the scheduling information storage unit 202. For example, the downlink burst is mapped to the corresponding resource (or region) according to the scheduling information and transmitted, and the operation for receiving the uplink burst in the corresponding resource is controlled. Since the operation of configuring and transmitting a downlink frame and receiving an uplink frame according to the scheduling information is already known, a detailed description thereof will be omitted.

The encoder 206 encodes the information bit stream from the MAP generator 204 to generate code symbols. For example, the encoder 206 uses an encoder using a convolutional code (CC), an encoder using a block turbo code (BTC), and a convolutional turbo code (CTC). And an encoder using a zero tailing convolutional code (ZT-CC). The modulator 208 modulates the code symbols from the encoder 206 in a predetermined modulation scheme to generate modulation symbols. Since the MAP information is information that all terminals should receive, it is assumed that the MAP information is coded and modulated using a robust modulation scheme (eg, QPSK, R = 1/2, Repetition = 6). .

The resource mapper 210 maps the data from the modulator 208 to a predetermined resource (eg, a preceding section of the frame) and outputs the data. The OFDM modulator 212 OFDM modulates the resource mapped data from the resource mapper 210 to generate an OFDM symbol. In this case, the OFDM modulation includes an Inverse Fast Fourier Transform (IFFT) operation, Cyclic Prefix (CP) insertion, and the like.

A digital to analog converter (DAC) 214 converts sample data from the OFDM modulator 212 into an analog signal and outputs the analog signal. The RF transmitter 216 converts the baseband signal from the DAC 312 into a radio frequency (RF) signal and transmits the same through an antenna. The terminals receiving the MAP information thus transmitted receive forward data from the base station according to the MAP information, and transmit reverse data to the base station.

In the above-described embodiment, it is assumed that the general MAP message is initially transmitted when the burst information is changed. However, the general MAP message may be periodically transmitted in case the general MAP message is lost. At this time, the transmission period is set to a long period when the channel is good for the connection identifier, and a short period when the channel is not good.

3 shows the configuration of a terminal in a broadband wireless access communication system according to an embodiment of the present invention.

As shown, RF receiver 300, ADC 302, OFDM demodulator 304, MAP extractor 306, demodulator 308, decoder 310, MAP decoder 312, burst information storage unit 314 And a transmit / receive controller 316.

Referring to FIG. 3, the RF receiver 300 converts an RF signal received from a base station into a baseband signal and outputs the baseband signal. The ADC 302 converts the baseband analog signal from the RF processor 300 into digital sample data and outputs the digital sample data. The OFDM demodulator 304 OFDM demodulates the sample data from the ADC 302 and outputs subcarrier values. In this case, the OFDM demodulation means a CP removal, a Fast Fourier Transform (FFT) operation, or the like.

The MAP extractor 306 extracts and outputs MAP bursts received in a predetermined region within a frame from data from the OFDM demodulator 304. The demodulator 310 demodulates and outputs the data from the MAP extractor 306 in a predetermined manner. The decoder 310 decodes data from the demodulator 310 to restore MAP information. In this case, the decoder 310 checks the CRC for the restored MAP information, and provides the MAP information to the MAP decoder 312 when the CRC check succeeds.

The MAP decoder 312 decrypts the MAP information received from the decoder 310. At this time, according to the present invention, the MAP decoder 312 determines whether a compressed MAP message corresponding to the received MAP message is received. When the compressed MAP message is received, the existing burst information stored in the burst information storage unit 314 is maintained as it is, and when the general MAP message is received, the burst information stored in the burst information storage unit 314 is stored in the general MAP message. Update with information elements.

The transmission / reception controller 316 controls the overall operation of downlink communication and uplink communication using the downlink / uplink burst information stored in the burst information storage unit 314. For example, a downlink burst is received from a corresponding resource (area) according to the downlink burst information, and an operation for transmitting an uplink burst from the corresponding resource is controlled according to the uplink burst information. As such, since the operation of receiving the downlink burst and transmitting the uplink burst according to the received MAP information is already known, a detailed description thereof will be omitted.

The scheduling information storage unit 202 of FIG. 2 and the burst information storage unit 314 of FIG. 3 manage burst information for every frame. However, when several bursts are allocated to one connection identifier, there is a need for a method for maintaining the same information between the base station and the terminal. In the present invention, it is assumed that burst information obtained through a general MAP message is stored in a subchannel index order. That is, when a plurality of bursts are allocated to one CID, the plurality of burst informations are managed in subchannel index order. In this case, when a burst is newly added for one connection identifier, the base station allocates a burst to a subchannel larger than the subchannels used by the allocated bursts, and generates and transmits a general MAP message accordingly. When a general MAP message having a subchannel index larger than pre-allocated bursts is received, the terminal recognizes that a burst has been newly added, and stores and manages newly received burst information after pre-stored burst information. If the number of bursts is reduced, the base station retransmits general MAP messages for all bursts after the expired burst, and the terminal sorts and stores burst information according to the general MAP messages.

4 is a flowchart illustrating an operation procedure of a base station in a broadband wireless access system according to an embodiment of the present invention.

Referring to FIG. 4, the base station first performs resource scheduling for this frame in step 601. When the resource scheduling is completed, the base station checks the scheduling information in step 403 and checks whether the existing scheduling information and the current scheduling information are the same for each connection identifier in step 405. That is, it is checked whether the burst information and the existing burst information are the same for each connection identifier. As described above, the burst information may be an OFDMA symbol offset, a subchannel offset, boosting information, the number of OFDMA symbols, the number of subchannels, an iterative coding indicator, or the like.

If the existing burst information and the current burst information are the same for any connection identifier, the base station generates a compressed MAP message (see Tables 3 and 4) containing only the connection identifier information for the corresponding burst in step 407. On the other hand, if the existing burst information and the current burst information for any connection identifier is different, the base station updates the scheduling information for the connection identifier in step 409, the general MAP message shown in Table 1 and Table 2 in step 411 Create

As such, when MAP messages for all bursts are generated, the base station generates and broadcasts a MAP burst including MAP messages for bursts in step 413. Thereafter, the base station transmits uplink bursts according to the information recorded in the MAP burst, and receives downlink bursts.

5 illustrates an operation procedure of a terminal in a broadband wireless access system according to an embodiment of the present invention.

Referring to FIG. 5, first, a UE checks whether a MAP burst is received in step 501. When the MAP burst is received, the terminal proceeds to step 503 to check the CRC code of the received MAP burst, and determines whether the CRC code is normal. If it is determined that the CRC code is abnormal, the terminal does not operate during this frame and returns to step 501 to receive a MAP of the next frame.

If it is determined that the CRC code is normal, the terminal proceeds to step 505 to sequentially decode MAP messages of the MAP burst. In step 507, the terminal determines whether there is a MAP message with an extended DIUC / UIUC value.

If a MAP message with an extended DIUC / UIUC value is detected, the terminal proceeds to step 509 and determines whether the extended DIUC / UIUC value is a compressed MAP message. If it is specified that the compressed MAP message, the terminal proceeds to step 511 and maintains the stored burst information as it is. In other words, it is recognized that the burst information has not changed.

On the other hand, if the MAP message having a general DIUC / UIUC value is detected in step 507, or if it is determined in step 509 that the MAP message is not a compressed MAP message, the terminal proceeds to step 513 to correspond to the general MAP message Decoding is performed to obtain burst information, and the burst information is updated with the obtained information in step 515.

As such, when both information about the downlink burst and the uplink burst for the frame is obtained, the terminal receives the downlink burst according to the obtained information and transmits the uplink burst.

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. For example, although the above-described embodiment describes an OFDMA-TDD based system as an example, the present invention can be easily applied regardless of a duplexing scheme such as an FDD system or a system using a mixture of TDD and FDD. Message structures can also be easily modified.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined 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, if the control information (or burst information) for any connection identifier (or user) is the same as the existing control information, by sending a compressed control message (MAP message), the control information ( There is an advantage that the size of the MAP) can be reduced. Since the downlink data burst region can be increased due to the reduction of the MAP information, the cell capacity of the system can be increased.

Claims (27)

A base station apparatus in a broadband wireless access system, A storage unit for storing scheduling information of a previous frame; A scheduler that performs resource scheduling for this frame, And a control information generation unit for comparing the current scheduling information from the scheduler with previous scheduling information stored in the storage unit and generating a compressed resource allocation message if the scheduling information is the same. The method of claim 1, And the control information generation unit compares the previous burst information with the current burst information for each user identifier, and generates the compressed resource allocation message when the burst information is the same. The method of claim 1, The resource allocation message is characterized in that the MAP message. The method of claim 1, The compressed resource allocation message, characterized in that it comprises a code and a user identifier indicating that the message is compressed. The method of claim 4, wherein And the user identifier is a connection identifier (CID). The method of claim 1, The scheduling information may include at least one of an OFDMA symbol offset, a subchannel offset, boosting information, a number of OFDMA symbols, a number of subchannels, and an iterative coding indicator. The method of claim 1, The control information generation unit, if the previous scheduling information and the current scheduling information is different, generating a general resource allocation message, characterized in that for updating the scheduling information of the storage unit with the current scheduling information. The method of claim 1, An encoder for encoding information from the control information generator, A modulator for modulating data from the encoder; A resource mapper for mapping data from the modulator to a predetermined resource; An OFDM modulator for OFDM modulating the resource mapped data from the resource mapper; And an RF transmitter for transmitting the data from the OFDM modulator by converting a signal of an RF band. A terminal device in a broadband wireless access system, A storage unit for managing burst information necessary for communication; A decoding unit for decoding control information received in this frame and storing burst information of a previous frame in the storage unit when a compressed resource allocation message for the terminal exists in the control information; And a controller for controlling downlink and uplink communications using burst information stored in the storage. The method of claim 9, The decoding unit, when there is a general resource allocation message for the terminal in the control information, characterized in that for storing the burst information extracted from the general resource allocation message to the storage unit. The method of claim 9, The resource allocation message is characterized in that the MAP message. The method of claim 9, And the compressed resource allocation message includes a code indicating a compressed message and a user identifier. The method of claim 12, And the user identifier is a connection identifier (CID). The method of claim 9, The burst information may include at least one of an OFDMA symbol offset, a subchannel offset, boosting information, a number of OFDMA symbols, a number of subchannels, and an iterative coding indicator. In the communication method of a base station in a broadband wireless access system, Performing resource scheduling for this frame, Comparing the current scheduling information with previous scheduling information stored in a storage unit; Generating a compressed resource allocation message when the scheduling information is the same. The method of claim 15, The resource allocation message is characterized in that the MAP message. The method of claim 15, The compressed resource allocation message includes a code indicating a compressed message and a user identifier. The method of claim 17, Wherein the user identifier is a connection identifier (CID). The method of claim 15, The scheduling information may include at least one of an OFDMA symbol offset, a subchannel offset, boosting information, a number of OFDMA symbols, a number of subchannels, and an iterative coding indicator. The method of claim 15, Generating a general resource allocation message when the previous scheduling information and the current scheduling information are different; And updating the scheduling information of the storage unit with the current scheduling information. The method of claim 15, Encoding and modulating control information including the resource allocation message; OFDM modulation by mapping the modulated data to a predetermined resource; And transmitting the OFDM-modulated data by converting a signal of an RF band. In a communication method of a terminal in a broadband wireless access system, Decoding the control information received in this frame, Storing burst information of a previous frame in a storage unit when there is a compressed resource allocation message for the terminal in the control information; And performing downlink and uplink communications using burst information stored in the storage unit. The method of claim 22, If there is a general resource allocation message for the terminal in the control information, further comprising storing the burst information extracted from the general resource allocation message in the storage unit. The method of claim 22, The resource allocation message is characterized in that the MAP message. The method of claim 22, The compressed resource allocation message includes a code indicating a compressed message and a user identifier. The method of claim 25, Wherein the user identifier is a connection identifier (CID). The method of claim 22, The burst information includes at least one of an OFDMA symbol offset, a subchannel offset, boosting information, a number of OFDMA symbols, a number of subchannels, and an iterative coding indicator.

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