KR101080964B1 - Method of allocating data burst in OFDMA radio access system - Google Patents

Abstract

The present invention relates to a data burst allocation method in an OFDMA radio access system for solving a problem in which an error occurs in the middle when an allocation of data bursts is cumulative in an OFDMA radio access system and subsequent errors also occur in the subsequent allocation positions of the bursts. It is about. In the OFDMA radio access system according to the present invention, a data burst allocation method includes a frequency axis for a data burst for at least two MSSs in an orthogonal frequency division multiplexing access (OFDMA) radio access system. Alternatively, in the method of sequentially accumulating on the time axis, the location information of the data burst is included in a specific message transmitted to the at least two terminals to allocate the data burst.

OFDMA, data burst, HARQ MAP, DL-MAP, UL-MAP

Description

Method of Allocating Data Burst in OPDMA Radio Access System {Method of allocating data burst in OFDMA radio access system}

1 illustrates a conceptual configuration of an OFDM modulator.

2 shows the configuration of a data frame in a conventional OFDMA wireless communication system.

3 illustrates a data frame according to HARQ MAP.

4A and 4B are diagrams for explaining an example of a method of allocating data bursts cumulatively according to the related art.

5 and 6 are views for explaining a preferred embodiment of the present invention.

The present invention relates to an OFDMA radio access system. More specifically, the present invention provides data in an OFDMA radio access system for solving a problem in which an error occurs in the middle when an allocation of data bursts is cumulative in an OFDMA radio access system and subsequent errors also occur in an allocation position of a burst. Burst allocation method.

Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiplexing (OFDMA) scheme is being actively studied as a method suitable for high-speed data transmission in wired and wireless channels. In the OFDM method, since a plurality of carriers having mutual orthogonality are used, frequency utilization efficiency is increased, and a process of modulating and demodulating the plurality of carriers at the transceiver stage is performed by performing an Inverse Discrete Fourier Transform (IDFT) and a Discrete Fourier Transform (DFT), respectively. The same result can be achieved at high speed using Inverse Fast Fourier Transform (IFFT) and Fast Fourier Transform (FFT).

The principle of OFDM divides a high speed data stream into a plurality of low speed data streams and transmits them simultaneously using a plurality of subcarriers, thereby increasing symbol duration to multi-path delay spread. It is to reduce relative dispersion in the time domain. Transmission of data by the OFDM scheme is based on transmission symbols.

Modulation and demodulation in the OFDM scheme can be processed collectively for all subcarriers using a Discrete Fourier Transform (DFT), so it is not necessary to design a demodulator for each individual subcarrier.

1 shows a conceptual configuration of an OFDM modulator. As shown in Fig. 1, serially input data streams are converted into parallel data streams as many as subcarriers, and each parallel data stream is inverse discrete Fourier transform. Inverse Fast Fourier Transform (IFFT) is used for high speed data processing. The inverse discrete Fourier transformed data is converted back into serial data and transmitted through frequency conversion, and the receiving side receives the signal and demodulates the reverse process.

2 shows a configuration of a data frame in a conventional OFDMA wireless communication system. In FIG. 2, the horizontal axis is a time axis and is represented by a symbol unit, and the vertical axis is a frequency axis and is represented by a subchannel unit. The subchannel means a bundle of a plurality of subcarriers. Specifically, in the OFDMA physical layer, active carriers are divided into groups and transmitted to different receivers for each group. The group of carriers transmitted to such a receiver is called a subchannel. In this case, carriers constituting each subchannel may be adjacent to each other or spaced at equal intervals.

The slot assigned to each user is defined by a data region in two-dimensional space, as shown in FIG. 2, which is a set of consecutive subchannels allocated by bursts. . One data area in OFDMA is shown as a rectangle determined by time coordinates and subchannel coordinates, as shown in FIG. Such a data area may be allocated to an uplink of a specific user or a base station may transmit the data area to a specific user in downlink.

In the prior art of the OFDM / OFDMA wireless communication system, the base station allocates a data area to be transmitted through DL-MAP (DL-MAP) when there is data to be transmitted to the terminal. The terminal receives data through the allocated area (DL burst # 1 to # 5 in FIG. 2).

In FIG. 2, a downlink subframe starts with a preamble used for synchronization and equalization in the physical layer, and then a broadcast form defining positions and uses of bursts allocated to downlink and uplink. The structure of the entire frame is defined through a DL MAP (DL-MAP) message and an UL MAP (UL-MAP) message.

The DL-MAP message defines the usage allocated per burst for the downlink interval in the burst mode physical layer, and the UL-MAP message defines the usage of the burst allocated for the uplink interval. Information element (IE) constituting DL-MAP is based on Downlink Interval Usage Code (DIUC), Connection ID (CID), and location information (subchannel offset, symbol offset, number of subchannels, number of symbols) of burst. Downlink traffic intervals are divided at the user end. On the other hand, the information elements constituting the UL-MAP message is determined by the Uplink Interval Usage Code (UIUC) for each CID (Connection ID), the location of the interval is defined by the 'duration'. Here, the use of each section is determined according to the UIUC value used in the UL-MAP, and each section starts at a point separated from the previous IE starting point by the 'duration' defined in the UL-MAP IE.

Downlink Channel Descriptor (DCD) messages and Uplink Channel Descriptor (UCD) messages are physical layer-related parameters to be applied in burst periods allocated to downlink and uplink, respectively, such as modulation type and FEC code type. It includes. In addition, it defines the necessary parameters (for example, K, R values of the R-S Code, etc.) according to various types of forward error correction codes. Such parameters are given by a burst profile defined for each Uplink Interval Usage Code (UIUC) and Downlink Interval Usage Code (DIUC) in UCD and DCD, respectively.

In the OFDMA communication system, the burst allocation scheme may be classified into a general MAP scheme and an HARQ scheme according to whether or not the HARQ scheme is supported.

In the downlink, a burst allocation scheme in a general MAP teaches a rectangular shape consisting of a time axis and a frequency axis, as shown in FIG. That is, it teaches the start symbol number (symbol offset), the start subchannel number (subchannel offset), the number of symbols used and the number of subchannels (No. OFDMA symbols, No. Subchannels) used. Uplink uses a method of assigning the symbol axis in sequence so that the burst of uplink can be allocated by only teaching the number of symbols used.

3 shows a data frame according to HARQ MAP. Unlike the general MAP, the HARQ MAP uses a scheme in which uplink and downlink are sequentially assigned to subchannel axes. HARQ MAP only tells the length of the burst. This method allocates bursts sequentially, as shown in FIG. The start position of the burst is the position where the previous burst ended and occupies radio resources by the length allocated from the start position. The method described below relates to a method of assigning bursts cumulatively along the frequency axis, and the method of assigning bursts along the time axis also follows the same principle.

In addition, in the HARQ MAP, the MAP message may be divided into several pieces (see FIG. 3: HARQ MAP # 1, # 2, ..., #N) so that each MAP message may have any burst information. For example, MAP message # 1 may include burst # 1, MAP message # 2 may include burst # 2, and MAP message # 3 may include information of bursts # 3 to # 5.

4A and 4B are diagrams for explaining an example of a method of allocating data bursts cumulatively according to the related art. In FIG. 4, MAP message # 1 includes allocation information for bursts # 1 and # 2, and MAP message # 2 includes allocation information for bursts # 3, # 4 and # 5. MSS # 1 knows the size and location of the burst by looking at the information of burst # 1 in the contents of MAP message # 1. MSS # 2 knows the location of the burst by reading the 'duration' of burst # 1 of the contents of MAP message # 1. MSS # 3 calculates the 'duration' sum of bursts # 1 and # 2 of MAP message # 1 and finds the location of the burst. In this way, you can tell the location of all bursts sequentially.

In the prior art as described above, each mobile subscriber station (MSS) must also read MAP messages transmitted to other MSSs in order to know the location and size of data bursts allocated to them, and accumulate all 'duration' values therein. do. If any of the previous MAP messages fail during this process, the exact location of the burst assigned to it cannot be determined. For example, in FIG. 2, when an error occurs in MAP message # 1, the location of bursts allocated to MSS # 1 to # 5 as well as MSS # 3 to # 5 may be unknown.

The present invention has been made to solve the problems of the prior art as described above, an object of the present invention is to configure a message for allocating a data burst to the terminal independently of the other messages by the terminal is assigned to itself and uplink and The present invention provides a method for allocating data bursts in an OFDMA radio access system that can reduce the trouble and the possibility of confirming all previous messages to locate downlink data bursts.

In one aspect of the present invention, a data burst allocation method in an OFDMA radio access system according to the present invention includes a data burst for at least two mobile subscriber stations (MSSs) in an orthogonal frequency division multiplexing access (OFDMA) radio access system. A method of sequentially accumulating a data burst on a frequency axis or a time axis and assigning the data burst includes location information of the data burst in a specific message transmitted to the at least two terminals to allocate the data burst. do.

In another aspect of the present invention, a data burst allocation method in an OFDMA radio access system according to the present invention includes orthogonal frequency (OFDMA) for sequentially accumulating downlink and uplink data bursts on a frequency axis or a time axis. (Division Multiplexing Access) A terminal of a broadband wireless access system, comprising: receiving a message including location information of a data burst allocated to the terminal; Determining a location of a downlink data burst allocated to the terminal according to the location information; And acquiring data transmitted through a downlink data burst assigned to the terminal. The data burst allocation method may include: identifying a position of an uplink data burst allocated to the terminal according to the location information; And transmitting data through a general uplink data burst assigned to the terminal.

The construction, operation, and other features of the present invention will be readily understood by the preferred embodiments of the present invention described below with reference to the accompanying drawings. 5 and 6 are views for explaining a preferred embodiment of the present invention.

In FIG. 5, each MAP message for allocating downlink or uplink data bursts to UEs includes location information of the data burst called 'Start Offset'. The 'Start Offset' is information on the start position of the first burst of each MAP message (Burst # 1 in the case of MAP message # 1 and Burst # 3 in the case of MAP message # 2 in FIG. 5). Indicates the number of allocation units from which the first burst starts. That is, in FIG. 5, MSS # 1 is assigned burst # 1 as many as four allocation units starting from the first allocation unit, and MSS # 2 is assigned burst # 2 as many as 25 allocation units thereafter. # 3 is assigned burst # 3 as many as eight allocation units, starting with the twentieth allocation unit. The allocation result of the data burst for each terminal in FIG. 5 is the same as that of FIG. 4B.

In FIG. 6, the position information of the data burst included in each MAP message is represented by two-dimensional coordinate values on the data frame by giving two values of 'Symbol offset' and 'Subchannel offset'. That is, the 'Symbol offset' and 'Subchannel offset' are information about the start position of the first burst of each MAP message (burst # 1 in the case of MAP message # 1 and burst # 3 in the case of MAP message # 2 in FIG. 6). As a two-dimensional coordinate value by the time axis and the frequency axis on the data frame. Since 'Symbol offset = 4' and 'Subchannel offset = 2' in MAP message # 2, the start position of burst # 3 allocated to MSS # 3 is the same as that of FIG. 4B.

Table 1 and Table 2 show 'Start offset' in FIG. 5 and 'Symbol offset' and 'Subchannel in FIG. 5 to HARQ MAP message in order to apply the technical idea according to the present invention in the IEEE802.16d / e OFDMA system. offset 'is included.

Syntax Size (bits) Notes HARQ MAP message format () {   HARQ MAP Indicator 3 Set to 0b111   HARQ UL-MAP appended One   CRC appended One   MAP message length 9 Length of HARQ MAP in bytes   DL IE count 6 Number of DL IE in the burst   Start offset 16   For (I = 0; I <DL IE count; I ++) {     Compact DL-MAP IE () variable   }   If (Compact UL-MAP appended == 1) {     Start offset 16     While (map data remains) {       Compact UL-MAP IE () variable     }   }   if! (byte boundary) {     Padding nibble 4   } }

Symbol offset 8 Subchannel offset 8

Table 3 and Table 4 show 'Start offset' or 'Symbol offset' and 'Subchannel offset' in the form of DL-MAP_IE in the HARQ MAP message in order to apply the technical idea according to the present invention to the IEEE802.16d / e OFDMA system. If included, the format is shown. The 'Start offset' or 'Symbol offset' and 'Subchannel offset' of Tables 3 and 4 indicate the start position of the first downlink data burst in the HARQ MAP message.

Syntax Size (bits) Notes Start_Offset_Compact_DL-MAP_IE () {   DL-MAP Type = 7 3   DL-MAP sub-type 5 Extension sub type = 3   Length 4 Length of the IE in bytes   Start Offset 16 Start location of the first burst in following DL_MAP IE   Reserved 4 }

Syntax Size (bits) Notes Start_Offset_Compact_DL-MAP_IE () {   DL-MAP Type = 7 3   DL-MAP sub-type 5 Extension sub type = 3   Length 4 Length of the IE in bytes   Symbol offset 8 Start location along symbol of the first burst in following DL-MAP IE   Subchannel Offset 8 Start location along subchannel of the first burst in following DL-MAP IE   Reserved 4 }

Tables 5 and 6 show 'Start offset' or 'Symbol offset' and 'Subchannel offset' in the form of UL-MAP_IE in HARQ MAP message in order to apply the technical idea according to the present invention in the IEEE802.16d / e OFDMA system. If you include ', it indicates the format. The 'Start offset' or 'Symbol offset' and 'Subchannel offset' of Table 5 and Table 6 indicate the start position of the first uplink data burst in the HARQ MAP message.                     

Syntax Size (bits) Notes Start_Offset_Compact_UL-MAP_IE () {   UL-MAP Type = 7 3   UL-MAP sub-type 5 Extension sub type = 3   Length 4 Length of the IE in bytes   Start Offset 16 Start location of the first burst in following Compact UL-MAP IE   Reserved 4 }

Syntax Size (bits) Notes Start_Offset_Compact_DL-MAP_IE () {   DL-MAP Type = 7 3   DL-MAP sub-type 5 Extension sub type = 3   Length 4 Length of the IE in bytes   Symbol offset 8 Start location along of the first burst in following UL-MAP IE   Subchannel Offset 8 Start location along subchannel of the first burst in following UL-MAP IE   Reserved 4 }

Table 7 shows the format when Tables 3, 4, 5 and 6 are included in the HARQ MAP message.

Syntax Size (bits) Notes HARQ MAP message format () { ···   For (I = 0; I <DL IE count; I ++) {     Compact DL-MAP IE () variable One of compact DL-MAP IE's may be Start_Offset_Compact_DL-MAP_IE ()   } ···   If (Compact UL-MAP appended == 1) {     While (map data remains) {       Compact UL-MAP IE () variable One of compact UL-MAP IE's may be Start_Offset_Compact_UL-MAP_IE ()     }   }

The terminal receives a MAP message including location information of a downlink or uplink data burst allocated to the terminal, identifies a location of the downlink or uplink data burst from the location information, and determines the downlink data burst. Acquire the data transmitted through the, and transmits the data through the uplink data burst.

In the prior art, each terminal must also read the MAP message transmitted to the other terminal in order to know the location and size of the data burst assigned to it, and since the 'duration' values in all of them must be cumulatively calculated, the previous MAP message in the process. If any one of the errors occurs, it is impossible to determine the exact location of the burst assigned to it, whereas in the present invention, each terminal is different in order to determine the location and size of the downlink or uplink data burst assigned to it. It is not necessary to read the MAP message delivered to the terminal, only the MAP message delivered to the terminal needs to be read.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

According to the data burst allocation method in the OFDMA radio access system according to the present invention, a message for allocating a data burst to a terminal is configured independently of other messages to determine the positions of uplink and downlink data bursts allocated to the terminal. In order to reduce the trouble and the possibility of error, all previous messages must be checked.

Claims (15)

A method of sequentially accumulating and assigning data bursts for at least two mobile subscriber stations (MSSs) on a frequency axis or a time axis in an orthogonal frequency division multiplexing access (OFDMA) wireless access system, Location information of the data burst is included in a specific message transmitted to the at least two terminals to allocate the data burst, The location information of the data burst is characterized in that the location information of the first data burst included in the message, How to allocate data bursts. delete The method of claim 1, And sequentially assigning the data bursts on the frequency axis and sequentially assigning the data bursts, wherein the position information is a cumulative value from the first allocation unit to the frequency axis. The method of claim 1, And sequentially assigning the data bursts on the time axis and assigning the data bursts, wherein the position information is a cumulative value from the first allocation unit to the time axis. The method of claim 1, And the position information is a two-dimensional coordinate value of a frequency axis and a time axis from a first allocation unit. The method according to claim 1 or 3 to 5, wherein The message is a data burst allocation method, characterized in that the HARQ MAP message. The method of claim 6, The location information is a burst data allocation method, characterized in that included in the information element (IE) form in the HARQ MAP message. A terminal of an orthogonal frequency division multiplexing access (OFDMA) broadband wireless access system in which downlink and uplink data bursts are accumulated and allocated sequentially on a frequency axis or a time axis, Receiving a message including location information of a data burst allocated to the terminal; Determining a location of a downlink data burst allocated to the terminal according to the location information; And Acquiring data transmitted through a downlink data burst allocated to the terminal; The location information is characterized in that the location information of the first data burst included in the message, How to allocate data bursts. The method of claim 8, Determining a location of an uplink data burst allocated to the terminal according to the location information; And And transmitting data through a general uplink data burst assigned to the terminal. delete 10. The method according to claim 8 or 9, And sequentially assigning the data bursts on the frequency axis and sequentially assigning the data bursts, wherein the position information is a cumulative value from the first allocation unit to the frequency axis. 10. The method according to claim 8 or 9, And sequentially assigning the data bursts on the time axis and assigning the data bursts, wherein the position information is a cumulative value from the first allocation unit to the time axis. 10. The method according to claim 8 or 9, And the position information is a two-dimensional coordinate value of a frequency axis and a time axis from a first allocation unit. 10. The method according to claim 8 or 9, The message is a data burst allocation method, characterized in that the HARQ MAP message. The method of claim 14, The location information is a burst data allocation method, characterized in that included in the information element (IE) form in the HARQ MAP message.

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