JP5284770B2 - Base station and downlink burst area allocation method - Google Patents

Description

  The present invention relates to a base station in WiMAX (Worldwide Interoperability for Microwave Access) that performs multiple access communication with a plurality of communication terminals using a plurality of subcarriers defined by an OFDM (Orthogonal Frequency Division Multiplexing) scheme, and the base station The present invention relates to a method for assigning a downlink burst area in FIG.

  Conventionally, various techniques relating to wireless communication have been proposed. For example, Patent Literature 1 discloses a wireless communication technique called WiMAX, which performs communication using an OFDMA (Orthogonal Frequency Division Multiple Access) method.

  In WiMAX, various methods are defined as subchannel arrangement methods. Among them, in downlink PUSC (Partial Usage of Subchannels) applied in downlink communication, a plurality of major groups each defined by a plurality of subchannels are defined.

  On the other hand, in WiMAX, a downlink burst region for transmitting user data is allocated in a downlink subframe used when a signal is transmitted from a base station to a communication terminal. When a base station having an array antenna adopts downlink PUSC as a subchannel arrangement method in the downlink burst region and performs signal forming to control the directivity of the array antenna and transmits a signal to a communication terminal, a major group It is necessary to allocate the downlink burst area in the downlink subframe in units.

  Also, in WiMAX, it is necessary to allocate a downlink burst region in a downlink subframe so as to be rectangular on the OFDM symbol (time) -subchannel plane, with the horizontal axis representing the OFDM symbol and the vertical axis representing the subchannel. is there.

  Further, in WiMAX, it is necessary to allocate a downlink burst region in a downlink subframe in units called “slots” configured by one subchannel and at least one OFDM symbol.

JP 2008-48236 A

  As described above, in WiMAX, there are various restrictions when allocating a downlink burst area in a downlink subframe. Therefore, in a plurality of slots constituting the downlink burst area, slots that are not used for user data transmission. There may be many. Therefore, there are cases where radio resources cannot be used efficiently.

  Therefore, the present invention has been made in view of the above-described points, and an object thereof is to provide a technique capable of suppressing the number of unused slots in the downlink burst region.

In order to solve the above problems, a base station according to the present invention uses WiMAX (Worldwide Interoperability for Microwave Access) that performs multiple access communication with a plurality of communication terminals using a plurality of subcarriers in an OFDM (Orthogonal Frequency Division Multiplexing) scheme. A burst region allocating unit for allocating at least one downlink burst region in a downlink subframe defined on the time-subchannel plane, and the burst region allocating unit allocated in the downlink subframe A transmission unit that transmits data using a downlink burst region, wherein the plurality of subcarriers are divided into a plurality of subchannels, the plurality of subchannels are divided into a plurality of major groups, and one subchannel is provided. And at least one OFDM symbol form a slot, and the burst region is The allocating unit allocates the downlink burst region in the downlink subframe in units of slots and in units of major groups so that the downlink burst region is rectangular on the time-subchannel plane, and the burst region allocating unit is in the downlink subframe. a plurality of reference values is defined to be used when allocating downlink burst area, the plurality of reference values, each of which constitutes a plurality of measure group subchannel or numbers are consecutive constituting one measure group match the number of sub-channels, are determined in such a more mutually different values, the burst region allocating unit is a reference value in which one of certain of said plurality of reference values, one downlink The remainder when dividing the number of slots required to transmit data in the burst area by a certain reference value When a reference value that is zero exists between the plurality of reference values, at least one major that is configured by the same number of subchannels as the reference value that has a remainder of zero among the plurality of major groups. When one downlink burst region is allocated in a downlink subframe so as to occupy only a group, and there is no reference value between the plurality of reference values where the remainder is zero, among the plurality of reference values A reference value that is obtained by subtracting the remainder when the necessary number of slots is divided by the reference value from the value of the reference value. The one downlink burst region is allocated in the downlink subframe so as to occupy only at least one major group composed of the same number of subchannels as the value.

  Also, in one aspect of the base station according to the present invention, the burst area allocation unit is a reference value of the plurality of reference values, and is a slot necessary for transmitting data in one downlink burst area When there are a plurality of reference values between the plurality of reference values when the number is divided by a certain reference value, the number of subchannels is the same as the largest reference value. The one downlink burst region is allocated in the downlink subframe so as to occupy only at least one major group, and when there is no reference value between the plurality of reference values, the remainder is zero. A reference value among reference values, and a value obtained by subtracting the remainder when the necessary number of slots is divided by the reference value from the reference value is the plurality of reference values When there are a plurality of reference values that are the smallest among the plurality of reference values, it occupies only at least one major group composed of the same number of subchannels as the largest reference value. The one downlink burst region is allocated in the downlink subframe.

The base station according to the present invention is a WiMAX (Worldwide Interoperability for Microwave Access) base station that performs multiple access communication with a plurality of communication terminals using a plurality of subcarriers in an OFDM (Orthogonal Frequency Division Multiplexing) scheme. A burst region allocation unit that allocates at least one downlink burst region in a downlink subframe defined on a time-subchannel plane, and a downlink burst region allocated by the burst region allocation unit in the downlink subframe. A plurality of subcarriers divided into a plurality of subchannels, the plurality of subchannels divided into a plurality of major groups, one subchannel and at least one OFDM A slot is composed of symbols, and the burst area allocating unit -The downlink burst area is allocated in the downlink subframe in slot units and major group units so that the downlink burst area is rectangular on the subchannel plane, and the burst area allocation unit allocates the downlink burst area in the downlink subframe. a plurality of reference values is defined to be used when allocating the plurality of reference values, respectively, the number of sub carriers constituting the plurality of measure group subchannel or numbers are consecutive constituting one measure group And the burst area allocating unit is a reference value of the plurality of reference values, and a multiple of the reference value is one. A reference value that matches the number of slots required for transmitting data in the downlink burst region is between the plurality of reference values. If there is a sub-frame, the one sub-burst burst region is allocated to the sub-frame so as to occupy only at least one major group composed of the same number of sub-channels as the corresponding reference values among the plurality of major groups. And the matching reference value does not exist between the plurality of reference values, the reference value is a reference value of the plurality of reference values that is greater than the required number of slots and The difference between the closest multiple of the reference value and the required number of slots occupies at least one major group composed of the same number of subchannels as the reference value that is the smallest among the plurality of reference values. The one downlink burst region is allocated in the downlink subframe.

  Also, in one aspect of the base station according to the present invention, the burst area allocation unit is a reference value of the plurality of reference values, and a multiple of the reference value is data in one downlink burst area. When there are a plurality of reference values that match the number of slots required for transmitting the reference value among the plurality of reference values, at least one of the sub-channels configured with the same number of subchannels as the largest reference value among them A reference from among the plurality of reference values when the one downlink burst region is allocated in a downlink subframe so as to occupy only a major group, and the corresponding reference value does not exist between the plurality of reference values. And the difference between the multiple of the certain reference value that is greater than and closest to the required number of slots and the required number of slots is the largest among the plurality of reference values. When there are a plurality of reference values that become smaller between the plurality of reference values, the single reference group is occupied so as to occupy at least one major group composed of the same number of subchannels as the largest reference value. A downlink burst area is allocated in a downlink subframe.

The downlink subburst area allocation method according to the present invention is a WiMAX (Worldwide Interoperability for Microwave Access) that performs multiple access communication with a plurality of communication terminals using a plurality of subcarriers in an OFDM (Orthogonal Frequency Division Multiplexing) scheme. In the base station, the plurality of subcarriers are divided into a plurality of subchannels, the plurality of subchannels are divided into a plurality of major groups, and one subchannel and A slot is composed of at least one OFDM symbol, and the downlink burst region is allocated in the downlink subframe in slot units and major group units so as to be rectangular on the time-subchannel plane, and in the downlink subframe. Multiple used when downlink burst area is allocated Reference values are determined in the plurality of reference values, respectively, match the number of sub carriers constituting the plurality of measure group subchannel or numbers are consecutive constituting one measure group and different from each other A certain reference value of the plurality of reference values, and the number of slots required to transmit data in one downlink burst region is divided by the certain reference value. When a reference value with a remainder of zero is present between the plurality of reference values, the plurality of major groups are configured by the same number of subchannels as the reference value with a remainder of zero. The one downlink burst region is allocated in the downlink subframe so as to occupy only at least one major group, and a reference value in which the remainder is zero is the plurality of references. If there is no value between the values, a reference value of the plurality of reference values, and the remainder when the necessary number of slots is divided by the reference value is subtracted from the value of the reference value. The one downlink burst region is included in the downlink subframe so that the obtained value occupies only at least one major group composed of the same number of subchannels as the smallest reference value among the plurality of reference values. assign.

The downlink subburst area allocation method according to the present invention is a WiMAX (Worldwide Interoperability for Microwave Access) that performs multiple access communication with a plurality of communication terminals using a plurality of subcarriers in an OFDM (Orthogonal Frequency Division Multiplexing) scheme. In the base station, the plurality of subcarriers are divided into a plurality of subchannels, the plurality of subchannels are divided into a plurality of major groups, and one subchannel and A slot is composed of at least one OFDM symbol, and the downlink burst region is allocated in the downlink subframe in slot units and major group units so as to be rectangular on the time-subchannel plane, and in the downlink subframe. Multiple used when downlink burst area is allocated Reference values are determined in the plurality of reference values, respectively, match the number of sub carriers constituting the plurality of measure group subchannel or numbers are consecutive constituting one measure group and different from each other The number of slots required to transmit data in one downlink burst area, which is a certain reference value of the plurality of reference values, and a multiple of the certain reference value is a single downlink burst area. Is present between the plurality of reference values, among the plurality of major groups, only at least one major group composed of the same number of subchannels as the matching reference values is included. When one downlink burst region is allocated in the downlink subframe so as to occupy, and the corresponding reference value does not exist among the plurality of reference values Is a reference value of the plurality of reference values, and a difference between the multiple of the reference value larger than and closest to the required number of slots and the required number of slots is the plurality of the plurality of reference values. The one downlink burst region is allocated in the downlink subframe so as to occupy only at least one major group composed of the same number of subchannels as the reference value that becomes the smallest among the reference values.

According to the present invention, respectively, match the number of sub carriers constituting the plurality of measure group subchannel or numbers are consecutive constituting one measure group, defined to be the more mutually different values A reference value that is a reference value among a plurality of reference values, and a reference value that has zero remainder when dividing the number of slots necessary for transmitting data in one downlink burst region by the reference value When there is a reference value between the reference values, the single downlink is so arranged that it occupies at least one major group composed of the same number of subchannels as the reference value for which the remainder is zero. A burst area is allocated in the downlink subframe. If there is no reference value whose remainder is zero, the reference value is a reference value among a plurality of reference values, and the remainder when the necessary number of slots is divided by the certain reference value is the reference value. The downlink burst region is divided into downlink sub-areas so that the value obtained by subtracting from the reference value occupies at least one major group composed of the same number of sub-channels as the smallest reference value among a plurality of reference values. Assigned within the frame. Therefore, the number of slots that are not used for data transmission in a plurality of slots constituting one downlink burst area can be suppressed.

  Also, according to one aspect of the present invention, when a certain reference value among a plurality of reference values is divided by the certain reference value, the number of slots necessary for transmitting data in one downlink burst region If there are multiple reference values with a remainder of zero, the one downlink burst region is set so as to occupy only at least one major group composed of the same number of subchannels as the largest reference value. Allocated in the downlink subframe. Then, when there is no reference value whose remainder is zero, a reference value of a plurality of reference values, and the remainder when the necessary number of slots is divided by the certain reference value is subtracted from the reference value. When there are multiple reference values that have the smallest value among multiple reference values, they occupy only at least one major group consisting of the same number of subchannels as the largest reference value. In this way, the one downlink burst region is allocated in the downlink subframe. Therefore, the length of one downlink burst area in the time direction can be suppressed, and another downlink burst area can be easily arranged adjacent to the one downlink burst area in the time direction. As a result, a plurality of downlink burst regions can be efficiently arranged in one downlink subframe.

Further, according to the present invention, respectively, match the number of sub carriers constituting the plurality of measure group subchannel or numbers are consecutive constituting one measure group, and determined so as to be mutually different values A reference value that is a reference value of a plurality of reference values that is equal to the number of slots required when a multiple of the reference value is transmitted in one downlink burst area. Among the plurality of major groups, the one downlink burst region is placed in the downlink sub-region so as to occupy only at least one major group composed of the same number of sub-channels as the corresponding reference value. Assigned within the frame. Then, when there is no matching reference value, the reference value is a reference value of the plurality of reference values, which is larger than the required number of slots and closest to the reference value, and the required value The one downlink burst area is allocated in the downlink subframe so that it occupies only at least one major group composed of the same number of subchannels as the reference value where the difference from the number of slots is the smallest among multiple reference values. ing. Therefore, the number of slots that are not used for data transmission in a plurality of slots constituting one downlink burst area can be suppressed.

  Further, according to one aspect of the present invention, a reference value among a plurality of reference values, and a multiple of the reference value is a number of slots required for transmitting data in one downlink burst region. When there are multiple matching reference values, the one downlink burst region is included in the downlink subframe so as to occupy only at least one major group composed of the same number of subchannels as the largest reference value among them. Assigned to. Then, when there is no matching reference value, a certain reference value of the plurality of reference values, which is a multiple of the reference value that is larger than and closest to the required number of slots, and the required slot When there are multiple reference values whose difference from the number is the smallest among multiple reference values, they occupy only at least one major group composed of the same number of subchannels as the largest reference value. In this way, the one downlink burst region is allocated in the downlink subframe. Therefore, the length of one downlink burst area in the time direction can be suppressed, and another downlink burst area can be easily arranged adjacent to the one downlink burst area in the time direction. As a result, a plurality of downlink burst regions can be efficiently arranged in one downlink subframe.

  FIG. 1 is a diagram showing a configuration of a wireless communication system according to an embodiment of the present invention. Moreover, FIG. 2 is a figure which shows the structure of the base station 1 with which the radio | wireless communications system which concerns on this Embodiment is provided. The wireless communication system according to the present embodiment is a system that complies with, for example, mobile WiMAX specified in IEEE 802.16e, and the base station 1 performs bidirectional wireless communication with a plurality of communication terminals 2 using the OFDMA method. Do. The base station 1 that performs communication by the OFDMA scheme can simultaneously communicate with the plurality of communication terminals 2 by individually allocating radio resources specified by the subchannel and the OFDM symbol to each of the plurality of communication terminals 2. It is possible.

  As shown in FIG. 2, the base station 1 includes a radio communication unit 10 having a radio reception unit 11 and a radio transmission unit 12, a data processing unit 14, a weight calculation unit 15, and a burst area allocation unit 16. ing. The wireless reception unit 11 and the wireless transmission unit 12 share an array antenna 13 including a plurality of antenna elements 13a as an antenna. That is, the array antenna 13 functions as a transmission antenna that transmits a radio signal to the communication terminal 2 and a reception antenna that receives a radio signal from the communication terminal 2. The base station 1 performs beam forming by weighting each of the plurality of antenna elements 13a constituting the array antenna 13 and directs the directivity by the array antenna 13 to the communication terminal 2 to be communicated. Is possible.

  The wireless reception unit 11 performs amplification processing and down-conversion on each of the signals received by the plurality of antenna elements 13a of the array antenna 13, and converts the signals received by the plurality of antenna elements 13a to baseband signals. Convert and output.

  For each communication terminal 2 to be communicated, the weight calculation unit 15 estimates the quality of the transmission path of each subcarrier assigned to the communication terminal 2 based on the known sounding signal transmitted from the communication terminal 2. The sounding signal from the communication terminal 2 is acquired by the data processing unit 14. Then, based on the estimation result, the weight calculation unit 15 assigns, for each communication carrier 2 to be communicated, a reception weight and a transmission weight applied to the array antenna 13 for each subcarrier assigned to the communication terminal 2. calculate. In the weight calculation unit 15, the reception and transmission weights are calculated by a convergence operation using, for example, an LMS (Least Mean Square) algorithm.

  For example, when 100 subcarriers are assigned as subcarriers used when a certain communication terminal 2 transmits data to the base station 1, the array antenna 13 according to the present embodiment has three antenna elements. Since it is configured by 13a, the weight calculation unit 15 calculates (100 × 3) reception weights for the communication terminal 2. Further, when 150 subcarriers are assigned as subcarriers used when data is transmitted to a certain communication terminal 2 in the base station 1, the weight calculation unit 15 sets (150 (3) Weights for transmission are calculated.

  As described above, the weight calculation unit 15 obtains each of reception and transmission by multiplying the number of antenna elements 13a constituting the array antenna 13 and the number of subcarriers assigned to the communication terminal 2. A number of weights are obtained for each communication terminal 2.

  The data processing unit 14 performs an FFT (Fast Fourier Transform) process on each of the plurality of baseband signals output from the wireless reception unit 11, and each of the plurality of baseband signals includes a plurality of baseband signals included therein. Obtain subcarriers separately. For each subcarrier of the same frequency included in the plurality of baseband signals, the data processing unit 14 calculates the corresponding reception signal calculated by the weight calculation unit 15 for each of the subcarriers of the same frequency. A weight is set to control the phase and amplitude of each subcarrier. Then, the data processing unit 14 synthesizes the subcarriers having the same frequency after the weight setting for each subcarrier having the same frequency included in the plurality of baseband signals. Thereby, the beam of the array antenna 13 can be directed to the desired wave, and the interference wave can be removed. The data processing unit 14 performs demodulation processing or the like on each of the signals (hereinafter referred to as “combined subcarriers”) obtained by combining the subcarriers of the same frequency after the weight setting, so that the communication terminal 2 Various data such as sounding signals are reproduced.

  Further, the data processing unit 14 generates serial transmission data. The data processing unit 14 converts the generated serial transmission data into parallel transmission data, and modulates a plurality of subcarriers used for transmission with the parallel transmission data. Subcarrier groups composed of a plurality of subcarriers after the modulation are prepared for the number of antenna elements 13a. In the present embodiment, the same three subcarrier groups are prepared. For each subcarrier of the same frequency included in the plurality of subcarrier groups, the data processing unit 14 sets the corresponding transmission weight calculated by the weight calculation unit 15 for each of the subcarriers of the same frequency. Set. Then, for each of the plurality of subcarrier groups, the data processing unit 14 combines the plurality of subcarriers after weight setting included in the subcarrier group to generate a baseband signal. As a result, baseband signals are generated as many as the number of antenna elements 13 a of the array antenna 13. The data processing unit 14 outputs the generated plurality of baseband signals to the wireless transmission unit 12.

  The burst area allocation unit 16 allocates at least one downlink burst area used for transmission of user data in the downlink direction in a downlink subframe for transmitting a signal from the base station 1 to the communication terminal 2. The downlink burst area is specified by the OFDM symbol and the subchannel, and at least one user data for the communication terminal 2 is included in one downlink burst area. By assigning a downlink burst area in the downlink subframe, the base station 1 determines radio resources to be used when transmitting user data to the communication terminal 2 to be communicated.

  The burst area allocation unit 16 allocates an uplink burst area used for uplink transmission of user data in an uplink subframe for transmitting a signal from the communication terminal 2 to the base station 1. The uplink burst region is specified by the OFDM symbol and the subchannel, and user data from one communication terminal 2 is included in one uplink burst region. By assigning an uplink burst region in an uplink subframe, the base station 1 determines radio resources to be used when the communication terminal 2 to be communicated transmits user data.

  The radio transmission unit 12 performs up-conversion and amplification processing on the plurality of baseband signals input from the data processing unit 14, and then inputs the signals to the plurality of antenna elements 13a. Thereby, a radio signal is transmitted from the array antenna 13 toward the communication terminal 2 to be communicated.

  Next, the configuration of the frame 100 in mobile WiMAX will be described. FIG. 3 is a diagram illustrating a configuration example of the frame 100. In mobile WiMAX, a TDD (Time Division Duplexing) method is adopted as a duplex method between the base station 1 and the communication terminal 2. As shown in FIG. 3, one frame 100 includes a downlink subframe 101 for transmitting a signal from the base station 1 to the communication terminal 2 and an uplink subframe for transmitting a signal from the communication terminal 2 to the base station 1. Frame 102. In frame 100, TGG (Transmit Transition Gap), which is a guard time when base station 1 switches from transmission to reception, and RTG (Receive Transition), which is a guard time when base station 1 switches from reception to transmission. Gap) is provided.

  As shown in FIG. 3, each of the downlink subframe 101 and the uplink subframe 102 is expressed in two dimensions including a time axis given by the OFDM symbol number and a frequency axis given by the subchannel number. . In other words, each of the downlink subframe 101 and the uplink subframe 102 is defined on the time-subchannel plane. In the OFDMA scheme, a plurality of subcarriers are grouped into a plurality of subchannels, and the allocation of subcarriers to the communication terminal 2 is performed in units of subchannels. In the OFDMA scheme, radio resources are allocated to each communication terminal 2 in two dimensions expressed by a frequency axis and a time axis.

  In the downlink subframe 101, for example, a preamble area 101a, an FCH (Frame Control Header) area 101b, a DL-MAP (Downlink Map) area 101c, an UL-MAP (Uplink Map) area 101d, and a plurality of downlink burst areas 101e are included. Assigned. The range of each region such as preamble region 101a in downlink subframe 101 is determined by the number of subchannels and the number of OFDM symbols.

  On the other hand, in the uplink subframe 102, for example, a ranging area 102a, a CQICH area 102b, an ACK area 102c, a sounding zone 102d, and a plurality of uplink burst areas 102e are allocated. Similar to the downlink subframe 101, the range of each region such as the ranging region 102a in the uplink subframe 102 is determined by the number of subchannels and the number of OFDM symbols.

  In the preamble area 101a, a signal necessary for the communication terminal 2 to synchronize with the base station 1 is included. The FCH region 101b includes a DL-MAP message length (to be described later) in the DL-MAP region 101c, a DLFP (Downlink Frame Prefix) indicating the error correction code scheme used therein and the number of repetitions of the repetition code, and the like. It is done. The communication terminal 2 demodulates the DL-MAP message according to the contents of DLFP.

  At least one communication terminal 2 can be assigned to each of the plurality of downlink burst areas 101e by the DL-MAP message 101c, and user data to the corresponding communication terminal 2 is stored in each downlink burst area 101e. Included. In the downlink subframe 101 of FIG. 3, five downlink burst areas 101e from # 1 to # 5 are arranged. The time zone (OFDM symbol) and subchannel occupied by the downlink burst region 101e on the time-subchannel plane are radio resources allocated to the communication terminal 2 associated with the downlink burst region 101e.

  The DL-MAP area 101c includes a DL-MAP message indicating radio resource allocation to each communication terminal 2 that performs communication in the downlink subframe 101 to which the DL-MAP area 101c belongs. The DL-MAP message includes information such as which area each downlink burst area 101e is assigned in the downlink subframe 101 and which communication terminal 2 is assigned to each downlink burst area 101e. It is. Therefore, by the DL-MAP message, the communication terminal 2 that performs communication in the downlink subframe 101 to which the DL-MAP message belongs, the subchannel that is used when communicating with the communication terminal 2, and the time during which communication is performed with the communication terminal 2 A band is specified. Each communication terminal 2 knows which subchannel is used in which time zone (OFDM symbol) the data addressed to itself is transmitted from the base station 1 by analyzing the content of the DL-MAP message. Can do. As a result, each communication terminal 2 can appropriately receive data addressed to itself from the base station 1.

  The UL-MAP area 101d includes a UL-MAP message indicating radio resource allocation to each communication terminal 2 to be communicated in the uplink subframe 102 following the downlink subframe 101 to which the UL-MAP area 101d belongs. In the UL-MAP message, to which uplink burst area 102e is assigned in the uplink subframe 102, which communication terminal 2 is assigned to each uplink burst area 102e in the uplink subframe 102. It contains information such as Therefore, the communication terminal 2 that performs communication in the uplink subframe 102 following the downlink subframe 101 to which the UL-MAP message belongs, the subchannel used when communicating with the communication terminal 2, and the communication terminal 2 and the time zone for communication are specified. Each communication terminal 2 can know which sub-channel should be used for transmitting data addressed to the base station 1 by analyzing the content of the UL-MAP message.

  A different communication terminal 2 is assigned to each of the plurality of uplink burst regions 102e in the uplink subframe 102 by the UL-MAP message, and the corresponding communication terminal 2 transmits to each uplink burst region 102e. User data is included. In the uplink subframe 102 of FIG. 3, four uplink burst regions 102e from # 1 to # 4 are allocated. The time zone (OFDM symbol) and subchannel occupied by the uplink burst region 102e on the time-subchannel plane are radio resources allocated to the communication terminal 2 associated with the uplink burst region 102e.

  The ranging area 102a includes a band request and a signal for performing ranging. The CQICH region 102b includes channel quality information. The ACK area 102c includes ACK (Acknowledgement) or NACK (Negative Acknowledgement) for HARQ (Hybrid Automatic Repeat Request) from the base station 1.

  The sounding zone 102d includes a known sounding signal used when the weight calculation unit 15 of the base station 1 calculates the weight applied to the array antenna 13. All subchannels, that is, all subcarriers are allocated to the sounding zone 102d. The plurality of subchannels allocated to the sounding zone 102d are allocated so as not to overlap with the plurality of communication terminals 2 communicating with the base station 1 in the uplink subframe 102 to which the sounding zone 102d belongs. Each communication terminal 2 that communicates with the base station 1 in the uplink subframe 102 transmits a sounding signal to the base station 1 using the assigned subchannel. When there is one communication terminal 2 that communicates with the base station 1 in the uplink subframe 102, all the subchannels are assigned to the one communication terminal 2, and the one communication terminal 2 A sounding signal is transmitted using a channel.

  The allocation of the subcarriers for the sounding signal to the communication terminal 2 is performed by the UL-MAP message in the UL-MAP area 101d. The UL-MAP message describes which subchannel is used when each communication terminal 2 communicating with the base station 1 transmits a sounding signal in the uplink subframe 102 following the downlink subframe 101 to which the UL-MAP message belongs. . Each communication terminal 2 that communicates with the base station 1 in the uplink subframe 102 that follows the downlink subframe 101 to which the UL-MAP message is sent uses the subchannel that is designated for its own device in the UL-MAP message. Then, a sounding signal is transmitted to the base station 1. Specifically, the communication terminal 2 modulates a plurality of designated subcarriers with a sounding signal and transmits a signal obtained by superimposing the modulated subcarriers to the base station 1.

  In mobile WiMAX, various methods are defined as subchannel arrangement methods. Among them, in PUSC (Partial Usage of Subchannels), there are a downlink PUSC applied in downlink communication and an uplink PUSC applied in uplink communication. In the downlink PUSC, a plurality of major groups each including a plurality of subchannels are defined. FIG. 4 is a diagram illustrating a configuration of six major groups 0 to 5 defined by the downlink PUSC when the FFT size is 1024.

  As shown in FIG. 4, each of the major groups 0, 2, and 4 is composed of six subchannels, and each of the major groups 1, 3, and 5 is composed of four subchannels. When the base station 1 adopts downlink PUSC as a subchannel arrangement method in the downlink burst area 101e and transmits user data to the communication terminal 2 by performing beamforming as in the present embodiment, the downlink burst area 101e needs to be allocated in the downlink subframe 101 in units of major groups. That is, the base station 1 must assign the subchannel to the communication terminal 2 that is the target of transmitting user data in units of major groups. One downlink burst region 101e may be allocated so as to occupy one major group, or may be allocated so as to occupy a plurality of major groups. The downlink burst area 101e indicated by a thick line in FIG. 4 is assigned to occupy three major groups 0-2. Hereinafter, it is assumed that downlink PUSC is adopted as a subchannel arrangement method of downlink burst region 101e.

  In the mobile WiMAX, the downlink burst region 101e has an OFDM symbol on the horizontal axis and a subchannel on the vertical axis, as shown in FIGS. 3 and 4, on the OFDM symbol (time) -subchannel plane. , Its shape must be rectangular. When one downlink burst region 101e occupies a plurality of major groups, the downlink burst region 101e is assigned so as to occupy a plurality of consecutive major groups so that it is rectangular.

  Further, in mobile WiMAX, the allocation of each area such as the downlink burst area 101e in the downlink subframe 101 and the allocation of each area such as the uplink burst area 102e in the uplink subframe 102 are “slots”. Is done in units called "." When downlink PUSC is adopted as the subchannel arrangement method, one slot is composed of one subchannel and two OFDM symbols. In uplink PUSC, one slot is composed of one subchannel and three OFDM symbols, and in FUSC (Full Usage of Subchannels), one slot is composed of one subchannel and one OFDM symbol.

  In the base station 1 according to the present embodiment, based on the number of slots required for transmitting user data in one downlink burst region 102e (hereinafter referred to as “necessary number of slots”), the one downlink burst By appropriately assigning the area 102e in the downlink subframe 101, it is possible to reduce the number of slots not used for user data transmission in a plurality of slots constituting the one downlink burst area 102e. In other words, it is possible to reduce the difference between the number of slots necessary for transmitting user data in one downlink burst area 102e and the number of slots constituting the one downlink burst area 102e. Thereby, a radio | wireless resource can be used efficiently. This will be described in detail below.

FIG. 5 is a flowchart showing the operation of the burst region allocation unit 16 when the burst region allocation unit 16 allocates the downlink burst region 101e in the downlink subframe 101. In the radio communication system according to the present embodiment, a plurality of reference values to be used when burst region allocation unit 16 allocates downlink burst region 102e in downlink subframe 101 are defined. The plurality of reference values, respectively, match the number of the plurality of measure groups subchannel subchannel or number constituting one measure group are continuous, and is determined so as to be mutually different values. In the present embodiment, for example, three reference values “4”, “6”, and “10” are stored in the burst area allocation unit 16 in advance. The reference value “4” matches, for example, the number of subchannels constituting the major group 1, the reference value “6” matches, for example, the number of subchannels constituting the major group 0, and the reference value “10” is For example, it matches the number of subchannels constituting the major groups 0 and 1.

  When the FFT size is 128 or 512, there is no odd-numbered major group. Therefore, in this case, “a plurality of major groups having consecutive numbers” means two major groups of No. 0 and No. 2, two major groups of No. 2 and No. 4, 3 of No. 0, No. 2, and No. 4. One of the major groups.

  As shown in FIG. 5, first, in step s1, the burst area allocating unit 16 assigns a downlink burst area 101e to be allocated within one downlink subframe 101 (hereinafter referred to as “target downlink subframe 101”) several frames ahead. Determine the number of. Here, it is assumed that the number of downlink burst regions 101e determined in step s1 is M (≧ 1). The burst region allocation unit 16 allocates the target downlink subframe 101 based on the number of communication terminals 2 to which user data should be transmitted in the target downlink subframe 101 and the communication quality between the communication terminal 2 and the base station 1. The number of downlink burst areas 101e is determined. The data processing unit 14 can determine the communication quality between the communication terminal 2 and the base station 1 based on the transmission signal from the communication terminal 2.

  Next, in step s2, the burst area allocation unit 16 sets one of the M downlink burst areas 101e determined in step s1 as the target downlink burst area 101e, and transmits user data in the target downlink burst area 101e. The required number of slots Nslot is obtained. In step s2, the burst area allocation unit 16 first determines a target communication terminal 2 to which user data is transmitted in the target downlink burst area 101e. That is, the burst area allocation unit 16 determines the communication terminal 2 to be associated with the target downlink burst area 101e. Then, the burst region allocation unit 16 determines the data amount of user data to be included in the target downlink burst region 101e based on the determined QoS (Quality of Service) for the communication terminal 2 and the past transmission data amount, and the data The required number of slots Nslot is obtained based on the amount.

  Next, in step s3, the burst area allocating unit 16 obtains the remainder when the necessary number of slots Nslot obtained in step s2 is divided by the reference value for each of the plurality of reference values stored in advance. For example, when the required number of slots Nslot is “41”, when this is divided by reference values “4”, “6”, and “10”, the remainders are “1”, “5”, and “1”, respectively. Hereinafter, the remainder when the necessary number of slots Nslot is divided by the reference values “4”, “6”, and “10” is set to “r4”, “r6”, and “r10”, respectively.

  Next, in step s4, the burst area allocation unit 16 obtains a value obtained by subtracting the remainder obtained in step s3 from the reference value for each reference value. That is, in step s4, “4-r4”, “6-r6”, and “10-r10” are obtained.

  Next, in step s5, the burst area allocation unit 16 identifies which burst group the target downlink burst area 101e belongs to. Here, in the base station 1 according to the present embodiment, a plurality of burst groups are defined, and the downlink burst region 101e is assigned to any region in the downlink subframe 101 according to the burst group to which the downlink burst region 101e belongs. It is decided whether to allocate. In the present embodiment, the burst group G4 associated with the reference value “4”, the burst group G6 associated with the reference value “6”, and the burst group G10 associated with the reference value “10”. Three burst groups are defined. The burst group G4 includes a downstream burst area 101e where r4 = 0 and a downstream burst area where “4-r4” has the smallest value among “4-r4”, “6-r6”, and “10-r10”. 101e belongs to. The burst group G6 includes a downstream burst region 101e where r6 = 0, and a downstream burst region where “6-r6” is the smallest value among “4-r4”, “6-r6”, and “10-r10”. 101e belongs to. The burst group G10 includes a downlink burst area 101e where r10 = 0 and a downlink burst area where “10-r10” is the smallest value among “4-r4”, “6-r6”, and “10-r10”. 101e belongs to.

  The burst area allocation unit 16 determines the target downlink burst area based on r4, r6, and r10 obtained in step s3 and “4-r4”, “6-r6”, and “10-r10” obtained in step s4. The burst group to which 101e belongs is specified. The burst area allocating unit 16 determines that the target downlink burst area 101e belongs to the burst group G4 when r4 = 0, the burst group G6 when r6 = 0, and the burst group G10 when r10 = 0. judge. The burst area allocation unit 16 specifies the smallest one of “4-r4”, “6-r6”, and “10-r10” when all of r4, r6, and r10 are not zero. When “4-r4” is the smallest, burst group G4, when “6-r6” is the smallest, burst group G6, and when “10-r10” is the smallest, burst group G10. It is determined that the burst area 101e belongs.

  When the burst group to which the target downlink burst region 101e belongs is specified in step s5, in step s6, the burst region allocation unit 16 sets the target downlink burst region 101e as the target downlink according to the burst group to which the target downlink burst region 101e belongs. Allocates within subframe 101.

  When the target downlink burst region 101e belongs to the burst group G4, the burst region allocation unit 16 occupies only at least one major group including the same number of subchannels as the corresponding reference value “4”. The target downlink burst region 101e is allocated in the target downlink subframe 101. For example, as shown in FIG. 6, the burst region allocation unit 16 allocates the target downlink burst region 101 e so as to occupy only the first major group composed of four subchannels.

  In addition, when the target downlink burst region 101e belongs to the burst group G6, the burst region allocation unit 16 occupies at least one major group including the same number of subchannels as the corresponding reference value “6”. Thus, the target downlink burst region 101e is allocated in the target downlink subframe 101. For example, as shown in FIG. 7, the burst area allocating unit 16 allocates the target downlink burst area 101e so as to occupy only the 0th major group composed of six subchannels.

  Further, when the target downlink burst region 101e belongs to the burst group G10, the burst region allocation unit 16 occupies only at least one major group composed of the same number of subchannels as the corresponding reference value “10”. Thus, the target downlink burst region 101e is allocated in the target downlink subframe 101. For example, as shown in FIG. 8, the burst area allocating unit 16 allocates the target downlink burst area 101e so as to occupy only two major groups of No. 0 and No. 1 composed of 10 subchannels.

  In addition, when the target downlink burst region 101e exists in a plurality of burst groups, it is configured by the same number of subchannels as the reference value corresponding to the burst group having the largest reference value among the plurality of burst groups. The target downlink burst region 101e is allocated so as to occupy only at least one major group. For example, when r4 and r6 are both zero, the downlink burst region 101e belongs to both burst groups G4 and G6. In this case, the target downlink burst region 101e is allocated so as to occupy only one major group including the same number of subchannels as the reference value corresponding to the burst group G6 having a large corresponding reference value.

  In addition, since the shape of the downlink burst region 101e is always rectangular, when at least one major group composed of the same number of subchannels as the reference value is a plurality of major groups, the plurality of major groups are , It becomes a plurality of major groups with consecutive numbers.

  When the assignment of the target downlink burst region 101e is completed in step s6, in step s7, the burst region assignment unit 16 determines whether or not there is a downlink burst region 101e that has not been assigned yet in the target downlink subframe 101, If it exists, one unassigned downlink burst area 101e is set as a new target downlink burst area 101e, and the processes after step s2 are sequentially executed. On the other hand, if it is determined in step s7 that there is no downlink burst region 101e that has not yet been allocated in the target downlink subframe 101, that is, all M downlink burst regions 101e determined in step s1 are targets. When allocated in the downlink subframe 101, the burst area allocation unit 16 ends the allocation process of the downlink burst area 101e.

  As described above, when all M downlink burst regions 101e have been allocated in the target downlink subframe 101, radio resources are allocated to all communication terminals 2 to which user data is to be transmitted in the target downlink subframe 101. Is completed. The transmission unit including the data processing unit 14 and the wireless transmission unit 12 uses the radio resources allocated to the communication terminal 2 to be communicated in the target downlink subframe 101 to perform user forming on the communication terminal 2 while performing beam forming. Send.

  FIG. 9 shows r4, r6, r10, “4-r4”, “6-r6” and “10” which are obtained when nine downlink burst regions 101e # 1 to # 9 are allocated in the downlink subframe 101. FIG. 10 is a diagram illustrating an example of −r10 ″. FIG. 10 is a diagram showing an example of assignment of downlink burst areas 101e of # 1 to # 9 in the example of FIG. In the example of FIG. 9, the required number of slots Nslot for transmitting data in the downlink burst areas 101e of # 1 to # 9 is “41”, “42”, “26”, “32”, “53”, respectively. “36”, “27”, “32”, and “140”.

  In the downlink burst region 101e of # 1, all of r4, r6 and r10 are not zero and “6-r6” is the smallest, so the downlink burst region 101e of # 1 belongs to the burst group G6. Accordingly, the downlink burst area 101e of # 1 is allocated so as to occupy only a major group composed of six subchannels as shown in FIG.

  In the downstream burst area 101e of # 2, r6 = 0, so that the downstream burst area 101e of # 2 belongs to the burst group G6. Therefore, as shown in FIG. 10, # 2 downlink burst area 101e is allocated so as to occupy only a major group composed of six subchannels.

  In the downstream burst area 101e of # 3, since all of r4, r6 and r10 are not zero and “4-r4” is the smallest, the downstream burst area 101e of # 3 belongs to the burst group G4. Accordingly, the downlink burst area 101e of # 3 is allocated so as to occupy only a major group composed of four subchannels, as shown in FIG.

  In the downlink burst area 101e of # 4, r4 = 0, so that the downlink burst area 101e of # 4 belongs to the burst group G4. Accordingly, the downlink burst area 101e of # 4 is allocated so as to occupy only a major group composed of four subchannels, as shown in FIG.

  In the downstream burst area 101e of # 5, all of r4, r6 and r10 are not zero and “6-r6” is the smallest, so the downstream burst area 101e of # 5 belongs to the burst group G6. Accordingly, the downlink burst area 101e of # 5 is allocated so as to occupy only the major group composed of six subchannels, as shown in FIG.

  In the downstream burst area 101e of # 6, both r4 and r6 are zero, so the downstream burst area 101e of # 6 belongs to burst groups G4 and G6. In burst groups G4 and G6, burst group G6 has a larger value of the corresponding reference value. Therefore, downlink burst region 101e of # 6 is a major block composed of six subchannels as shown in FIG. Assigned to occupy only a group.

  In the downstream burst region 101e of # 7, all of r4, r6 and r10 are not zero, and “4-r4” is the smallest, so the downstream burst region 101e of # 7 belongs to the burst group G4. Therefore, the downlink burst area 101e of # 7 is allocated so as to occupy only a major group composed of four subchannels, as shown in FIG.

  In the downlink burst area 101e of # 8, r4 = 0, so that the downlink burst area 101e of # 8 belongs to the burst group G4. Accordingly, as shown in FIG. 10, # 8 downlink burst region 101e is allocated so as to occupy only a major group composed of four subchannels.

  In the downstream burst area 101e of # 9, both r4 and r10 are zero, so the downstream burst area 101e of # 8 belongs to burst groups G4 and G10. In burst groups G4 and G10, burst group G10 has a larger value of the corresponding reference value. Therefore, downlink burst region 101e of # 9 is composed of 10 subchannels as shown in FIG. Assigned to occupy only two major groups.

  As described above, in the present embodiment, when there is a remainder having a value of zero among the remainders r4, r6, r10, that is, a plurality of reference values (“4”, “6” and “10”). )), And when there is a reference value between a plurality of reference values that has a remainder obtained by dividing the required number of slots Nslot by the certain reference value, a plurality of major values The downlink burst region 101e is allocated in the downlink subframe 101 so as to occupy only at least one major group composed of the same number of subchannels as the reference value for which the remainder becomes zero. Therefore, user data can be transmitted using all of the plurality of slots constituting the downlink burst region 101e.

  For example, when Nslot = 42, r6 = 0, so the downlink burst region 101e is assigned to occupy a major group composed of six subchannels. At this time, since the necessary number of slots Nslot and the number of slots constituting the downlink burst area 101e can be matched, as shown in FIG. 11, the plurality of slots 400 constituting the downlink burst area 101e are All will be used for transmission of user data. In FIG. 11, the slot 400 used for user data transmission is indicated by a hatched rectangle. The same applies to FIGS. 12 to 16 described later.

  On the other hand, when Nslot = 42, if the downlink burst region 101e is allocated so as to occupy a major group composed of four subchannels, as shown in FIG. In the slot 400, there are two slots 400 (rectangles without diagonal lines) that are not used for user data transmission. In addition, when Nslot = 42, when the downlink burst region 101e is allocated so as to occupy two major groups configured with 10 subchannels, as shown in FIG. In this slot 400, there are eight slots 400 that are not used for transmitting user data.

  In this way, the downlink burst so as to occupy only at least one major group composed of the same number of subchannels as the reference value such that the remainder when the required number of slots Nslot is divided by its own value becomes zero. By assigning the area 101e in the downlink subframe 101, user data can be transmitted using all of the plurality of slots constituting the downlink burst area 101e. As a result, radio resources can be used efficiently.

  In the present embodiment, if none of the remainders r4, r6, and r10 is zero, the smallest value among “4-r4”, “6-r6”, and “10-r10” is specified. Then, the downlink burst region 101e is allocated in the downlink subframe 101 so as to occupy only at least one major group including the same number of subchannels as the reference value corresponding to the value. That is, in the present embodiment, a reference value that is a reference value among a plurality of reference values and that has a zero remainder when dividing the required number of slots Nslot by the certain reference value is between the reference values. If there is not, the remainder (r4, r6, r10) obtained by dividing the required number of slots Nslot by the certain reference value is the value of the certain reference value. The value obtained by subtracting from (“4-r4”, “6-r6”, “10-r10”) is at least one composed of the same number of subchannels as the reference value that is the smallest among a plurality of reference values. The downlink burst region 101e is allocated in the downlink subframe 101 so as to occupy only one major group. Thereby, it is possible to reduce the number of slots not used for user data transmission among a plurality of slots constituting the downlink burst region 101e.

  For example, when Nslot = 41, “6-r6” is the smallest among “4-r4”, “6-r6”, and “10-r10”, and therefore, the downlink burst region 101e includes six subchannels. Assigned to occupy a configured major group. At this time, as shown in FIG. 14, it is possible to make only one slot 400 that is not used for user data among the plurality of slots 400 constituting the downlink burst region 101e.

  On the other hand, when Nslot = 41, if the downlink burst region 101e is allocated so as to occupy a major group composed of four subchannels, as shown in FIG. In this slot 400, there are three slots 400 (rectangles without diagonal lines) that are not used for user data transmission. In addition, when Nslot = 41, when the downlink burst region 101e is allocated so as to occupy two major groups configured with 10 subchannels, as shown in FIG. In the slot 400, there are nine slots 400 that are not used for transmitting user data.

  In this way, the required number of slots Nslot is divided by its own value, and the number obtained by subtracting the remainder from its own value is the same as the reference value that minimizes the value among the plurality of reference values. By allocating the downlink burst region 101e so as to occupy only at least one major group composed of subchannels, the number of slots not used for user data transmission among a plurality of slots constituting the downlink burst region 101e is suppressed. Can do.

  Further, in this embodiment, when there are a plurality of zeros among the remainders r4, r6, r10, at least one composed of the same number of subchannels as the largest of the reference values corresponding thereto. Since the downlink burst region 101e is allocated so as to occupy only one major group, the length of the downlink burst region 101e in the time direction on the time-subchannel plane can be suppressed.

  In the present embodiment, if none of the remainders r4, r6, and r10 is zero, the smallest value among “4-r4”, “6-r6”, and “10-r10” is specified. When there are a plurality of the smallest values, the downlink burst region 101e is allocated so as to occupy only at least one major group composed of the same number of subchannels as the largest reference value corresponding to them. Therefore, the length in the time direction of the downlink burst region 101e on the time-subchannel plane can be suppressed.

  FIG. 17 shows that one downlink burst region 101e is allocated so as to occupy the third major group including the same number of subchannels as the reference value “4”, and the same number as the reference value “6”. It is a figure which shows a mode that it allocated so that the 0th major group comprised with a subchannel might be occupied. As shown in FIG. 17, when the downlink burst region 101e is allocated so as to occupy a major group composed of the same number of subchannels as the reference value “6”, the same number as the reference value “4” The length of the downlink burst region 101e in the time direction is shorter than that in the case where the downlink burst region 101e is allocated so as to occupy a major group including the subchannels. This is because the number of slots 400 arranged in the subchannel direction increases when the downlink burst region 101e is allocated so as to occupy a major group including the same number of subchannels as the reference value “6”. .

  In this way, by suppressing the length of the downlink burst region 101e in the time direction, it becomes easy to allocate another downlink burst region 101e adjacent to the downlink burst region 101e in the time direction. As a result, a plurality of downlink burst regions 101e can be efficiently allocated in one downlink subframe 101.

  Note that “a reference value having a plurality of reference values and having a value obtained by dividing the number of required slots by the certain reference value becomes zero” means “a reference value among a plurality of reference values”. Thus, it is synonymous with “a reference value in which a multiple of a certain reference value matches the required number of slots”. For example, when Nslot = 42, “a reference value having a plurality of reference values and a value obtained by dividing the number of necessary slots by the certain reference value becomes zero” is “6”, and “a plurality of references “6” is also a reference value that is a reference value among the values, and in which a multiple of the reference value matches the required number of slots. Therefore, “a reference value having a plurality of reference values and a reference value in which a value obtained by dividing the number of necessary slots by the certain reference value is zero exists between the plurality of reference values” and “ It is synonymous with “a reference value with a reference value, where a reference value whose multiple of the reference value matches the required number of slots exists between multiple reference values”. When a reference value is a reference value that does not exist between multiple reference values when the required slot number is divided by the reference value, and there is no reference value between multiple reference values. Thus, it is synonymous with the case where there is no reference value in which a multiple of a certain reference value matches the required number of slots among a plurality of reference values. In addition, “a reference value having a plurality of reference values, where there are a plurality of reference values in which a value obtained by dividing the required number of slots by the certain reference value is zero” and “a reference value having a plurality of reference values” "There is a plurality of reference values in which a multiple of a certain reference value matches the required number of slots" is synonymous.

  In addition, “a reference value of a plurality of reference values, and a value obtained by subtracting the remainder when the necessary number of slots is divided by the certain reference value from the value of the certain reference value is The reference value that is the smallest among them is “a reference value of a plurality of reference values, which is a multiple of the reference value that is greater than and closest to the required number of slots, and the required slot number Nslot. This is synonymous with “a reference value in which the difference between the reference values is the smallest among a plurality of reference values”. For example, when Nslot = 41, “6-r6” is the smallest value among “4-r4”, “6-r6”, and “10-r10”. The reference value that is obtained by subtracting the remainder when the necessary number of slots is divided by the certain reference value from the value of the certain reference value is the smallest among a plurality of reference values is “6”. . On the other hand, when Nslot = 41, the multiple value of “4” that is larger than and closest to the required number of slots Nslot is “44”, and the multiple value of “6” that is larger than and closest to the required number of slots Nslot. Is "42", and a multiple of "10" that is larger than and closest to the required number of slots Nslot is "50". The value obtained by subtracting “44” from the required slot number Nslot for the reference value “4” is “3”, and the value obtained by subtracting “42” from the required slot number Nslot for the reference value “6” is “1”. The value obtained by subtracting “50” from the reference value “10” by the required number of slots Nslot is “9”. Therefore, when Nslot = 41, “the difference between a certain reference value of a plurality of reference values and a multiple of the reference value that is larger than and closest to the required number of slots and the required number of slots Nslot” “6” is the smallest reference value among the plurality of reference values. Therefore, “a reference value of a plurality of reference values, and a value obtained by subtracting the remainder when the necessary number of slots is divided by the certain reference value from the value of the certain reference value is When there are a plurality of reference values that are the smallest among them ”and“ a reference value of a plurality of reference values that is larger than the required number of slots and nearest to the certain reference value, This is synonymous with “when there are a plurality of reference values whose difference from the required number of slots Nslot is the smallest among a plurality of reference values”. In the present embodiment, the burst area allocation unit 16 calculates “4-r4”, “6-r6”, and “10-r10”, but instead, for each of a plurality of reference values, a necessary slot is obtained. A multiple value that is larger than and closest to the number Nslot may be obtained, and the difference between the obtained multiple value and the required number of slots Nslot may be obtained. In this case, the downlink burst region 101e is specified such that the reference value having the smallest difference among the plurality of reference values is specified, and occupies at least one major group including the same number of subchannels as the specified reference values. Assign.

Further, in the present embodiment, as a plurality of reference values, "4", "6" and has been adopted a combination of "10", respectively, subchannel or numbers are consecutive constituting one measure group more match the number of sub carriers constituting the measure group, and if the plurality of reference values determined so as to be mutually different values, the combination of a plurality of reference values may be any other. That is, when the FFT size is 1024, “4”, “6”, “10”, “14”, “16”, “20”, “24”, “26” are combined as a plurality of reference values. A combination of two or more arbitrary values of “30” can be adopted.

It is a figure which shows the structure of the radio | wireless communications system which concerns on embodiment of this invention. It is a figure which shows the structure of the base station which concerns on embodiment of this invention. It is a figure which shows the example of a frame structure in mobile WIMAX. It is a figure which shows the structural example of a major group. It is a flowchart which shows the operation | movement of the burst area allocation part which concerns on embodiment of this invention. It is a figure which shows the example of allocation of a downlink burst area | region. It is a figure which shows the example of allocation of a downlink burst area | region. It is a figure which shows the example of allocation of a downlink burst area | region. It is a figure which shows each calculated value at the time of allocating nine downlink burst area | regions. It is a figure which shows the example of allocation of nine downstream burst area | regions. It is a figure which illustrates the mode of the slot which comprises a downlink burst area | region. It is a figure which illustrates the mode of the slot which comprises a downlink burst area | region. It is a figure which illustrates the mode of the slot which comprises a downlink burst area | region. It is a figure which illustrates the mode of the slot which comprises a downlink burst area | region. It is a figure which illustrates the mode of the slot which comprises a downlink burst area | region. It is a figure which illustrates the mode of the slot which comprises a downlink burst area | region. It is a figure which shows the example of allocation of a downlink burst area | region.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base station 2 Communication terminal 12 Wireless transmission part 14 Data processing part 16 Burst area | region allocation part 101 Down stream subframe 101e Down stream burst area 400 Slot

Claims (6)

A base station in WiMAX (Worldwide Interoperability for Microwave Access) that performs multiple access communication with a plurality of communication terminals using a plurality of subcarriers in an OFDM (Orthogonal Frequency Division Multiplexing) scheme,
A burst region allocation unit that allocates at least one downlink burst region in a downlink subframe defined on the time-subchannel plane;
A transmission unit for transmitting data using a downlink burst region allocated in a downlink subframe by the burst region allocation unit,
The plurality of subcarriers are divided into a plurality of subchannels,
The plurality of subchannels are divided into a plurality of major groups,
A slot is composed of one subchannel and at least one OFDM symbol,
The burst region allocation unit allocates the downlink burst region in a downlink subframe in slot units and major group units so that the downlink burst region is rectangular on the time-subchannel plane,
A plurality of reference values to be used when the burst area allocation unit allocates a downlink burst area in a downlink subframe is defined,
Said plurality of reference values, respectively, match the number of sub carriers constituting the plurality of measure group subchannel or numbers are consecutive forming one major group, defined to be the more mutually different values And
The burst area allocation unit
A reference value among the plurality of reference values, the reference value having a remainder of zero when dividing the number of slots necessary for transmitting data in one downlink burst region by the certain reference value is When there are multiple reference values, the corresponding major group only occupies at least one major group composed of the same number of subchannels as the reference value whose remainder is zero. One downlink burst area is allocated in the downlink subframe,
If there is no reference value with the remainder of zero among the plurality of reference values, the reference value is one of the plurality of reference values, and the required number of slots is divided by the certain reference value. So that the value obtained by subtracting the remainder from the reference value occupies at least one major group composed of the same number of subchannels as the smallest reference value among the plurality of reference values. A base station that allocates the one downlink burst region to a downlink subframe. The base station according to claim 1, wherein
The burst area allocation unit
A reference value among the plurality of reference values, the reference value having a remainder of zero when dividing the number of slots necessary for transmitting data in one downlink burst region by the certain reference value is When there are a plurality of reference values among the plurality of reference values, the one downlink burst region is assigned to the downlink sub-region so as to occupy only at least one major group composed of the same number of sub-channels as the largest reference value among them. Assigned in the frame,
In the case where there is no reference value between the plurality of reference values where the remainder is zero, the reference value is one of the plurality of reference values, and the necessary number of slots is divided by the certain reference value. When there are a plurality of reference values between the plurality of reference values that are obtained by subtracting the remainder of the time from the reference value, the largest reference among them A base station that allocates the one downlink burst region in a downlink subframe so as to occupy only at least one major group composed of the same number of subchannels as the value. A base station in WiMAX (Worldwide Interoperability for Microwave Access) that performs multiple access communication with a plurality of communication terminals using a plurality of subcarriers in an OFDM (Orthogonal Frequency Division Multiplexing) scheme,
A burst region allocation unit that allocates at least one downlink burst region in a downlink subframe defined on the time-subchannel plane;
A transmission unit for transmitting data using a downlink burst region allocated in a downlink subframe by the burst region allocation unit,
The plurality of subcarriers are divided into a plurality of subchannels,
The plurality of subchannels are divided into a plurality of major groups,
A slot is composed of one subchannel and at least one OFDM symbol,
The burst region allocation unit allocates the downlink burst region in a downlink subframe in slot units and major group units so that the downlink burst region is rectangular on the time-subchannel plane,
A plurality of reference values to be used when the burst area allocation unit allocates a downlink burst area in a downlink subframe is defined,
Said plurality of reference values, respectively, match the number of sub carriers constituting the plurality of measure group subchannel or numbers are consecutive forming one major group and is defined so as to be mutually different values And
The burst area allocation unit
A reference value which is a reference value of the plurality of reference values and whose multiple value is the same as the number of slots required when data is transmitted in one downlink burst region is the plurality of reference values. Among the plurality of major groups, the downlink burst region is downlinked so as to occupy only at least one major group composed of the same number of subchannels as the matching reference value. Assigned within a subframe,
If the matching reference value does not exist between the plurality of reference values, the certain reference value of the plurality of reference values that is greater than and closest to the required number of slots The difference between the multiple of the value and the required number of slots occupies only one major group composed of the same number of subchannels as the smallest reference value among the plurality of reference values. A base station that allocates a downlink burst region in a downlink subframe. The base station according to claim 3, wherein
The burst area allocation unit
A reference value which is a reference value of the plurality of reference values and whose multiple value is the same as the number of slots required when data is transmitted in one downlink burst region is the plurality of reference values. If there is a plurality of sub-channels, the single downlink burst region is allocated in the downlink subframe so as to occupy only at least one major group composed of the same number of subchannels as the largest reference value. ,
The reference value that is a reference value of the plurality of reference values that is greater than and closest to the required number of slots when the matching reference value does not exist between the plurality of reference values. When there are a plurality of reference values between the plurality of reference values, the largest reference among them is the difference between the multiple of the reference number and the required number of slots among the plurality of reference values. A base station that allocates the one downlink burst region in a downlink subframe so as to occupy only at least one major group composed of the same number of subchannels as the value. A downlink burst area allocation method in a base station in WiMAX (Worldwide Interoperability for Microwave Access) that performs multiple access communication with a plurality of communication terminals using a plurality of subcarriers in an OFDM (Orthogonal Frequency Division Multiplexing) scheme,
The plurality of subcarriers are divided into a plurality of subchannels,
The plurality of subchannels are divided into a plurality of major groups,
A slot is composed of one subchannel and at least one OFDM symbol,
The downlink burst region is allocated in the downlink subframe in slot units and major group units so as to be rectangular on the time-subchannel plane.
A plurality of reference values used when a downlink burst region is allocated in a downlink subframe are defined,
Said plurality of reference values, respectively, match the number of sub carriers constituting the plurality of measure group subchannel or numbers are consecutive forming one major group and is defined so as to be mutually different values And
A reference value among the plurality of reference values, the reference value having a remainder of zero when dividing the number of slots necessary for transmitting data in one downlink burst region by the certain reference value is When there are multiple reference values, the corresponding major group only occupies at least one major group composed of the same number of subchannels as the reference value whose remainder is zero. One downlink burst area is allocated in the downlink subframe,
If there is no reference value with the remainder of zero among the plurality of reference values, the reference value is one of the plurality of reference values, and the required number of slots is divided by the certain reference value. So that the value obtained by subtracting the remainder from the reference value occupies at least one major group composed of the same number of subchannels as the smallest reference value among the plurality of reference values. A method for assigning a downlink burst region, wherein the one downlink burst region is assigned in a downlink subframe. A downlink burst area allocation method in a base station in WiMAX (Worldwide Interoperability for Microwave Access) that performs multiple access communication with a plurality of communication terminals using a plurality of subcarriers in an OFDM (Orthogonal Frequency Division Multiplexing) scheme,
The plurality of subcarriers are divided into a plurality of subchannels,
The plurality of subchannels are divided into a plurality of major groups,
A slot is composed of one subchannel and at least one OFDM symbol,
The downlink burst region is allocated in the downlink subframe in slot units and major group units so as to be rectangular on the time-subchannel plane.
A plurality of reference values used when a downlink burst region is allocated in a downlink subframe are defined,
Said plurality of reference values, respectively, match the number of sub carriers constituting the plurality of measure group subchannel or numbers are consecutive forming one major group and is defined so as to be mutually different values And
A reference value which is a reference value of the plurality of reference values and whose multiple value is the same as the number of slots required when data is transmitted in one downlink burst region is the plurality of reference values. Among the plurality of major groups, the downlink burst region is downlinked so as to occupy only at least one major group composed of the same number of subchannels as the matching reference value. Assigned within a subframe,
If the matching reference value does not exist between the plurality of reference values, the certain reference value of the plurality of reference values that is greater than and closest to the required number of slots The difference between the multiple of the value and the required number of slots occupies only one major group composed of the same number of subchannels as the smallest reference value among the plurality of reference values. A method for assigning a downlink burst region, wherein a downlink burst region is assigned in a downlink subframe.

Images