JP5091844B2 - Wireless base station, wireless terminal station, wireless communication system, and wireless communication method - Google Patents

Description

  The present invention relates to a radio terminal station, a radio base station, a radio communication system, and a radio communication method that perform spatial multiplexing transmission to a radio base station.

Conventionally, a transmission request transmission method from a terminal station to a base station in uplink spatial multiplexing transmission is known. In this method, the terminal station transmits a transmission request packet to the base station by random backoff based on CSMA / CA, and the base station transmits the data of the transmission request packet received from the transmission request packet within a certain period of time. The terminal station that permits transmission is selected and notified, and the transmission mode is selected and notified.
H. Jin, BC Jung, HY Hwang, and DK Sung “An uplink medium access protocol with SDMA support for multiple-antenna WLANs,” WCNC2008.

  In the above conventional technique, due to random backoff based on CSMA / CA, the base station needs to wait for a long time to receive transmission requests from a plurality of terminal stations, and performs uplink spatial multiplexing transmission Therefore, there is a problem that the overhead for the network is large and the throughput characteristics of the network deteriorate.

  The present invention has been made in view of the above-described problems, and a radio base station, a radio terminal station, a radio, and the like that can reduce overhead for performing uplink spatial multiplexing transmission to a radio base station A communication system and a wireless communication method are provided.

A radio base station as one aspect of the present invention is:
A wireless base station that simultaneously receives data from a wireless terminal station at the same time and at the same frequency,
First transmission means for transmitting an uplink period start packet indicating the start of an uplink period to the wireless terminal station;
A first receiving means for receiving a transmission request packet for performing a transmission request from the wireless terminal station via a dedicated resource individually assigned in advance;
Based on the received transmission request packet, specifying means for specifying a wireless terminal station that has transmitted the transmission request packet;
Second transmitting means for transmitting a pilot transmission instruction packet instructing transmission of a pilot signal to the specified wireless terminal station by designating different time slots;
Second receiving means for receiving a pilot signal from the identified wireless terminal station;
Selection means for selecting an allowed terminal to grant uplink transmission permission based on the received pilot signal;
A third transmitting means for transmitting a permitted terminal notification packet indicating permission for transmission of the uplink to the permitted terminal;
Is provided.

A wireless terminal station as one aspect of the present invention is:
A fourth receiving means for receiving an uplink period start packet indicating the start of an uplink period from the radio base station;
A fourth transmission means for transmitting a transmission request packet for performing a transmission request via a dedicated resource allocated in advance at a predetermined timing after receiving the uplink period start packet;
Fifth transmission means for receiving a pilot transmission instruction packet instructing transmission of a pilot signal from the radio base station by designating a time slot after transmitting the transmission request packet;
Fifth transmission means for transmitting a pilot signal in a time slot specified in the pilot transmission instruction packet;
Sixth receiving means for receiving a permitted terminal notification packet notifying that the transmission request is permitted;
Sixth transmission means for transmitting data at a predetermined timing after the permitted terminal notification packet is received;
Is provided.

A wireless communication method as one aspect of the present invention includes:
A wireless communication method executed in a wireless base station in which a wireless terminal station performs data transmission simultaneously at the same time and at the same frequency,
A first transmission step of transmitting an uplink period start packet indicating the start of an uplink period to the wireless terminal station;
A first reception step of receiving a transmission request packet for performing a transmission request from the wireless terminal station via a dedicated resource allocated individually in advance;
A identifying step for identifying a wireless terminal station that has transmitted the transmission request packet based on the received transmission request packet;
A second transmission step of transmitting a pilot transmission instruction packet instructing transmission of a pilot signal to the identified wireless terminal station by designating a different time slot;
A second receiving step of receiving a pilot signal from the identified wireless terminal station;
A selection step of selecting an allowed terminal to grant uplink transmission permission based on the received pilot signal;
A third transmission step of transmitting a permitted terminal notification packet indicating permission of transmission of the uplink to the permitted terminal;
Is provided.

A wireless communication method as one aspect of the present invention includes:
A wireless communication method executed in a wireless terminal station that performs data transmission to a wireless base station at the same time and at the same frequency as other wireless terminal stations,
A third receiving step of receiving an uplink period start packet indicating the start of an uplink period from the radio base station;
A fourth transmission step of transmitting a transmission request packet for performing a transmission request via a dedicated resource allocated in advance at a predetermined timing after receiving the uplink period start packet;
A fourth reception step of receiving a pilot transmission instruction packet instructing transmission of a pilot signal from the radio base station by designating a time slot after transmitting the transmission request packet;
A fifth transmission step of transmitting a pilot signal in a time slot designated in the pilot transmission instruction packet;
A fifth reception step of receiving a permitted terminal notification packet notifying that the transmission request is permitted;
A sixth transmission step of transmitting data at a predetermined timing after the permitted terminal notification packet is received;
Is provided.

A wireless communication system as one aspect of the present invention includes:
A wireless communication system comprising a wireless base station and a wireless terminal station, wherein the wireless terminal station performs data transmission to the wireless base station at the same time and at the same frequency,
The radio base station transmits an uplink period start packet indicating the start of an uplink period to the radio terminal station,
A wireless terminal station having transmission data to the wireless base station transmits a transmission request packet for performing a transmission request via a dedicated resource allocated in advance at a predetermined timing after receiving the uplink period start packet. And
The wireless base station transmits a pilot transmission instruction packet instructing transmission of a pilot signal by designating a different time slot to the wireless terminal station that has transmitted the transmission request packet,
The wireless terminal station that has received the pilot transmission instruction packet transmits a pilot signal in a time slot specified in the pilot transmission instruction packet;
Based on the received pilot signal, the radio base station selects a permitted terminal that grants uplink transmission permission, and transmits a permitted terminal notification packet indicating the uplink transmission permission to the permitted terminal,
The permitted terminal transmits data simultaneously at a predetermined timing after receiving the permitted terminal notification packet.

  According to the present invention, it is possible to reduce overhead for performing uplink spatial multiplexing transmission to a radio base station.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing an example of a schematic configuration of a communication network in which the radio base station 1 and the radio terminal stations 2 to 8 according to the first embodiment of the present invention perform radio communication.

  FIG. 1 shows a state in which the wireless terminal station 2 and the wireless terminal station 6 transmit frames to the wireless base station 1 simultaneously by spatial multiplexing transmission. Thus, according to the instruction from the radio base station 1, the radio terminal station transmits data addressed to the radio base station 1 at the same frequency and at the same time.

  FIG. 2 is a block diagram showing an example of a schematic configuration of the radio base station 1 according to the first embodiment of the present invention. The radio base station 1 in FIG. 2 includes four antennas 21, four radio communication units 22 corresponding to the antennas 21, a switch 23, a transmission unit 24, a frame generation unit 25, a reception unit 26, a request terminal identification unit 27, a control A unit 28, a pilot signal receiving unit 29, a channel information calculating unit 30, a transmission mode determining unit 31, a MIMO demodulating unit 32, a demodulating unit 33, and an error checking unit 34 are provided. Hereinafter, the operation of each element will be described with reference to FIG.

  FIG. 3 is a flowchart showing an example of uplink spatial multiplexing transmission processing performed by the radio base station 1 of FIG.

  The control unit 28 controls the frame generation unit 25, and the frame generation unit 25 transmits an uplink start period packet indicating that the uplink period has started (a packet for notifying that an uplink transmission request from a wireless terminal station is accepted). Generated and transmitted to one or more wireless terminal stations via the transmission unit 24, the switch 23, the four wireless communication units 22, and the four antennas 21 (step S31).

  The control unit 28 determines whether or not a transmission request packet has been received from the wireless terminal station via the four antennas 21, four wireless communication units 22, the switch 23, and the receiving unit 26 within a predetermined time (step). S32). A dedicated resource for transmitting a transmission request packet is individually allocated to each wireless terminal station in advance, and a transmission request packet in which a request signal is allocated to the dedicated resource is transmitted from each wireless terminal station that makes a transmission request. . Dedicated resources include frequency resources (eg, specific subcarriers), time resources (eg, specific time slots), and spatial resources (eg, specific spreading codes). The radio base station allocates a dedicated resource to each radio terminal station, for example, via a beacon signal that is periodically transmitted. In the following description, an example of transmitting a transmission request packet in which a signal is assigned to a specific subcarrier (terminal specific subcarrier) will be described, but the present invention is not limited to this. Since each wireless terminal station makes a transmission request via a dedicated resource, overhead due to random backoff based on the CSMA / CA system can be eliminated, and the time required for performing spatial multiplexing transmission can be shortened.

  If the transmission request packet is not received, the process ends. If the transmission request packet is received, the requesting terminal specifying unit 27 specifies the wireless terminal station that has transmitted the transmission request packet (step S33).

  Information on the wireless terminal station specified by the requesting terminal specifying unit 27 is input to the control unit 28, and the control unit 28 selects candidate terminals that are candidates for granting transmission permission (step S34). For example, in selection of candidate terminals, all wireless terminal stations that have transmitted transmission request packets may be selected as candidate terminals, or up to a predetermined maximum number of wireless terminal stations may be randomly selected, You may select from the highest priority set to the maximum number.

  The control unit 28 controls the frame generation unit 25. The frame generation unit 25 generates a pilot signal request packet (pilot transmission instruction packet) for requesting the candidate terminal to transmit a pilot signal, and transmits the transmission unit 24, the switches 23, 4 Transmission is performed via the two wireless communication units 22 and the four antennas 21 (step S35). The pilot signal request packet indicates the order in which each candidate terminal transmits a pilot signal (that is, information for specifying a time slot in which each candidate terminal transmits a pilot signal). Thus, by designating the order (time slot) in which each candidate terminal transmits a pilot signal, it is possible to eliminate the overhead due to carrier sense in the CSMA / CA system and to shorten the time until spatial multiplexing transmission is performed. it can.

  Whether the control unit 28 has received a pilot signal from each candidate terminal via the four antennas 21, the four wireless communication units 22, the switch 23, and the receiving unit 26 in the specified order (specified time slot). Is determined (step S36).

  Here, FIG. 4 shows the transmission timing of the pilot signal transmitted by the candidate terminal.

  Candidate terminals are wireless terminal station A, wireless terminal station B, and wireless terminal station C. The radio base station 1 requests that the pilot signal is transmitted in the order of the radio terminal station A, the radio terminal station B, and the radio terminal station C. Here, it is assumed that the maximum number of transmission antennas of the system is predetermined as four. In the example illustrated in FIG. 4, the wireless terminal station A includes two transmission antennas, the wireless terminal station B includes four transmission antennas, and the wireless terminal station C includes three transmission antennas.

  A packet 51 shown in FIG. 4 indicates a pilot signal transmission request packet transmitted by the radio base station 1. Packets 52, 53, 54, 55, and 56 are pilot signal transmission request packets received by the wireless terminal station A, the wireless terminal station B, the wireless terminal station C, the wireless terminal station D, and the wireless terminal station E, respectively. A blank period 81 after the radio base station 1 transmits the pilot signal transmission request packet 51 is a period similar to a SIFS (Short Inter Frame Space) period employed in an IEEE 802.11 wireless LAN system or the like.

  Since the wireless terminal station A has two transmission antennas, the pilot signal is transmitted from the first antenna in the slot 57 and the pilot signal is transmitted from the second antenna in the slot 59. Correspondingly, in slot 58, the base station receives a pilot signal transmitted from the first antenna of wireless terminal station A, and in slot 60, the base station transmits a pilot signal transmitted from the second antenna of wireless terminal station A. Receive a signal. In the slots 61 and 63, no pilot signal is transmitted. Therefore, in the slots 62 and 64, the base station does not receive the pilot signal, and the pilot signal is not transmitted.

  Since the wireless terminal station B has four transmission antennas, the pilot signal is transmitted from the first antenna in the slot 65, the pilot signal is transmitted from the second antenna in the slot 67, and the third signal is transmitted in the slot 69. The pilot signal is transmitted from the second antenna, and the pilot signal is transmitted from the fourth antenna in the slot 71. Correspondingly, in slot 66, the base station receives a pilot signal transmitted from the first antenna of wireless terminal station B, and in slot 68, the base station transmits a pilot signal transmitted from the second antenna of wireless terminal station B. In the slot 70, the base station receives a pilot signal transmitted from the third antenna of the wireless terminal station B, and in the slot 72, the base station transmits a pilot signal transmitted from the fourth antenna of the wireless terminal station B. A signal is being received.

  Similarly, since the number of transmission antennas of the wireless terminal station C is 3, the pilot signal is transmitted from the first antenna in slot 73, the pilot signal is transmitted from the second antenna in slot 75, and the slot 77 is transmitted. The pilot signal is transmitted from the third antenna. Correspondingly, in slot 74, the base station receives a pilot signal transmitted from the first antenna of wireless terminal station C, and in slot 76, the base station transmits a pilot signal transmitted from the second antenna of wireless terminal station C. In slot 78, the base station receives a pilot signal transmitted from the third antenna of the wireless terminal station C. In slot 79, no pilot signal is transmitted. Therefore, in slot 80, the base station does not receive the pilot signal, and the pilot signal is not transmitted.

無線端末局iから受信したパイロット信号を

とすると、無線端末局iのチャネル情報をH_iは、

のように求められる。 After receiving the pilot signal, the channel information calculation unit 30 calculates channel information with each candidate terminal (step S37). Now, channel information of wireless terminal station i is set to _Hi , and a predetermined pilot signal is

Pilot signal received from wireless terminal station i

When, H _i is the channel information of the wireless terminal station i,

It is required as follows.

  When the channel information calculation unit 30 finishes calculating the channel information, the control unit 28 selects a permitted terminal based on the channel information with each candidate terminal (step S38).

  The transmission mode determination unit 31 determines a transmission mode (MCS: modulation and coding scheme, for example, 40 Mbps, 20 Mbps, etc.) based on the channel information of the permitted terminal determined by the control unit 28 (step S39).

  The permitted terminal information selected by the control unit 28 and the transmission mode determined by the transmission mode determination unit 31 are input to the frame generation unit 25. The frame generation unit 25 transmits the identification information of the permitted terminal and the transmission order of pilot signals by the permitted terminal. (Information for specifying a time slot in which a permitted terminal transmits a pilot signal), a transmission mode of the permitted terminal, and a transmission timing of a permitted terminal that notifies the transmission timing at which the permitted terminal transmits data at the same time are generated and transmitted. The transmission is performed via the unit 24, the switch 23, the four wireless communication units 22, and the four antennas 21 (step S40). In this example, the transmission timing at which the permitted terminal simultaneously transmits data is implicitly included immediately after the transmission of the pilot signal of each permitted terminal, but the transmission timing is explicitly specified. Also good.

  After transmitting the permitted terminal notification packet, after a predetermined time elapses, pilot signals are received in order from each permitted terminal, and after receiving pilot signals from all permitted terminals, data is simultaneously received from all permitted terminals. The MIMO demodulator 31 performs a MIMO demodulation process (step S41).

  Here, FIG. 5 shows the transmission timing of the pilot signal and data transmitted by the permitted terminal.

  In the example illustrated in FIG. 5, the permitted terminals are the wireless terminal station A and the wireless terminal station B, and the wireless base station 1 requests that the pilot signal be transmitted in the order of the wireless terminal station A and the wireless terminal station B. . Also here, it is assumed that the maximum number of transmission antennas of the system is predetermined as four. In the example shown in FIG. 5, the wireless terminal station A is provided with two transmission antennas, and the wireless terminal station B is provided with four transmission antennas. A packet 91 in FIG. 5 indicates a permitted terminal notification packet transmitted by the wireless base station 1, and packets 92, 93, 94, 95, and 96 are a wireless terminal station A, a wireless terminal station B, a wireless terminal station C, and a wireless terminal. The permitted terminal notification packets received by the station D and the wireless terminal station E are shown. The blank period 116 after the wireless base station 1 transmits the permitted terminal notification packet is a period similar to the SIFS period employed in the IEEE 802.11 wireless LAN system or the like.

  Since the wireless terminal station A has two transmission antennas, the pilot signal is transmitted from the first antenna in the slot 97, and the pilot signal is transmitted from the second antenna in the slot 99. Correspondingly, in slot 98, the base station receives a pilot signal transmitted from the first antenna of the wireless terminal station A, and in slot 100, the base station transmits a pilot signal transmitted from the second antenna of the wireless terminal station A. Receive a signal. In the slots 101 and 103, no pilot signal is transmitted. Therefore, in the slots 102 and 104, the base station does not receive the pilot signal, and the pilot signal is not transmitted.

  Since the wireless terminal station B has four transmission antennas, the pilot signal is transmitted from the first antenna in the slot 105, the pilot signal is transmitted from the second antenna in the slot 107, and the third signal is transmitted in the slot 109. The pilot signal is transmitted from the second antenna, and the pilot signal is transmitted from the fourth antenna in the slot 111. Correspondingly, in slot 106, the base station receives a pilot signal transmitted from the first antenna of wireless terminal station B, and in slot 108, the base station transmits a pilot signal transmitted from the second antenna of wireless terminal station B. In slot 110, the base station receives a pilot signal transmitted from the third antenna of the wireless terminal station B, and in slot 112, the base station transmits a pilot signal transmitted from the fourth antenna of the wireless terminal station B. A signal is being received.

  After the pilot signal is transmitted from the fourth antenna of the wireless terminal station B, the wireless terminal station A transmits data 114, the wireless terminal station B transmits data 113, and the wireless base station 1 transmits the data 114 transmitted simultaneously. Data 113 is received as received data 115.

  The MIMO demodulator 31 performs the MIMO demodulation process, then the demodulator 32 performs the decoding process (step S42), and the error checker 33 performs error check such as CRC check on the data decoded by the demodulator 32 ( Step S43).

  The error check result of the error check unit 33 is input to the frame generation unit 25, and the frame generation unit 25 generates an Ack frame based on the error check result input from the error check unit 33, and transmits the transmission unit 24, the switches 23, 4 Transmission is performed via the two wireless communication units 22 and the four antennas 21 (step S44).

  FIG. 6 is a block diagram showing an example of a schematic configuration of the wireless terminal station 2 according to the first embodiment of the present invention. 2 includes four antennas 131, four wireless communication units 132, a switch 133, a transmission unit 134, a frame generation unit 135, a pilot signal holding unit 136, a data holding unit 137, a receiving unit 138, and a demodulation unit. 139, an error check unit 140, a frame type determination unit 141, and a control unit 144. Hereinafter, the operation of each element will be described with reference to FIG.

  FIG. 7 is a flowchart showing an example of uplink spatial multiplexing transmission processing performed by the wireless terminal station 2 shown in FIG.

  Signals received via the four antennas 131, the four wireless communication units 132, the switch 133, and the reception unit 138 are decoded by the demodulation unit 139, and an error check such as CRC is performed by the error check unit 140. If it is determined by the error check that there is no error, the type of the frame received and input to the frame type determination unit 141 is determined. If the error check determines that an error has occurred, the process ends. If it is determined in the error check that there is no error, the frame type determination unit 141 determines whether the received frame is an uplink period start packet (step S161).

  When it is determined that the packet is not an uplink period start packet, the process is terminated. When it is determined that the packet is an uplink period start packet, the control unit 144 inquires the data holding unit 137 and the data to be transmitted to the radio base station is It is determined whether or not there is (step S162).

  If there is no transmission data, the process is terminated, and if there is transmission data, the control unit 144 transmits a control signal to the frame generation unit 135, and the frame generation unit 135 preliminarily assigns a subcarrier (dedicated The transmission request packet is generated by mapping the signal to (resource) (step S163).

  The control unit 144 determines whether or not it is the transmission timing of the transmission request packet (step S164). If it is not the transmission timing, the control unit 144 waits until the transmission timing. A transmission request packet is transmitted through the four antennas 131 (step S165). Here, the transmission request is notified via the terminal-specific subcarrier, but as described above, the radio base station transmits other dedicated resources such as a time resource (such as a time slot) and a space resource (such as a spreading code). May be assigned to the wireless terminal station, and the wireless terminal station may make a transmission request via this resource.

  After transmitting the transmission request packet, the signals received via the four antennas 131, the four wireless communication units 132, the switch 133, and the receiving unit 138 are decoded by the demodulating unit 139, and the error checking unit 140 detects errors such as CRC. A check is made. If it is determined by the error check that there is no error, the type of the received frame input to the frame type determination unit 141 is determined (step S166).

  If the error check determines that the error has occurred, or if the frame type determination unit 141 determines that the packet is not a pilot signal transmission request packet, the process ends. It is determined whether there is a pilot signal transmission request addressed to the station (step S167).

  If there is no pilot signal transmission request addressed to the own station, the process ends. If there is a pilot signal transmission request addressed to the own station, the control unit 144 waits until the transmission timing (time slot) of the pilot signal described in the pilot signal transmission request packet. (Step S168) At the pilot signal transmission timing, the control signal is transmitted to the frame generation unit 135. The frame generation unit 135 transmits the pilot signal stored in the pilot signal holding unit 136 to the transmission unit 134, the switches 132, 4 and 4. Transmission is performed via the two wireless communication units 132 and the four antennas 131 (step S169).

  After transmitting the pilot signal, the signals received via the four antennas 131, the four wireless communication units 132, the switch 133, and the receiving unit 138 are decoded by the demodulating unit 139, and the error checking unit 140 checks for errors such as CRC. Is done. If it is determined by the error check that there is no error, the type of the frame received and input to the frame type determination unit 141 is determined (step S170).

  If the error check determines that the error has occurred, or if the frame type determination unit 141 determines that the packet is not a permitted terminal notification packet, the process ends, and the frame type determination unit 141 determines that the packet is a permitted terminal notification packet. In this case, it is determined whether or not transmission to the own station is permitted (step S171).

  If there is no transmission permission addressed to the own station, the processing ends. If there is permission to transmit addressed to the own station, the control unit 144 waits until the transmission timing (time slot) of the pilot signal described in the permitted terminal notification packet (step S172). ), When the pilot signal transmission timing is reached, the control signal is transmitted to the frame generation unit 135. The frame generation unit 135 transmits the pilot signal stored in the pilot signal holding unit 136 to the transmission unit 134, the switch 132, and the four wireless communication units. The unit 132 transmits through the four antennas 131 (step S173).

  After transmitting the pilot signal, the control unit 144 transmits the data transmission timing (timing immediately after the pilot signals of all the permitted terminals are finished. The transmission order of the pilot signals of each permitted terminal is described in the permitted terminal notification packet. Therefore, each authorized terminal can specify this timing.) (Step S174), and when the data transmission timing is reached, the data holding unit 137 is instructed to output the held data, and the frame generating unit 135 receives the data holding unit 137. A packet is generated based on the data input from, and transmitted via the transmission unit 134, the switch 132, the four wireless communication units 132, and the four antennas 131 (step S175).

  FIG. 8 is a timing diagram of frame exchange of uplink spatial multiplexing transmission performed by the radio base station 1 and the radio terminal stations A to E.

  The radio base station 1 transmits an uplink period start packet 191 and the radio terminal stations A, B, C, D, and E receive the uplink period start packets 192, 193, 194, 195, and 196, respectively.

  After a predetermined period 227 has elapsed, the wireless terminal stations A, B, and C that hold the transmission data transmit transmission request packets 197, 198, and 199, respectively.

  The wireless base station 1 receives the transmission request packet 201 transmitted from the wireless terminal stations A, B, and C, and identifies the wireless terminal station that transmitted the transmission request packet. The radio base station 1 identifies candidate terminals from the identified radio terminal stations. Here, all the wireless terminal stations A, B, and C that have transmitted the transmission request packet are selected. After elapse of a predetermined period 228, a pilot signal transmission request packet 202 that describes the identifiers of the selected wireless terminal stations A, B, and C and the transmission order of the pilot signals is transmitted, and the wireless terminal stations A, B, and C The pilot signal transmission request packets 203, 204, and 205 are received, respectively. Here, it is assumed that the order in which the pilot signals are transmitted is the order of the wireless terminal stations A, B, and C.

  The wireless terminal station A that transmits the pilot signal first transmits the pilot signal 207 from each antenna in a time-division manner after a predetermined period 229 has elapsed from the end of the pilot signal transmission request packet. A signal 210 is received. The procedure for transmitting pilot signals from the respective antennas is as shown in FIG.

  As soon as the pilot signal transmission period assigned to the wireless terminal station A ends, the wireless terminal station B that transmits the pilot signal secondly transmits the pilot signal 208 from each antenna in a time division manner. Receives the pilot signal 211.

  Similarly, as soon as the pilot signal transmission period assigned to the wireless terminal station B ends, the wireless terminal station C that transmits the pilot signal thirdly transmits the pilot signal 209 from each antenna in a time-sharing manner. Base station 1 receives pilot signal 212.

  The radio base station 1 calculates channel information between the radio terminals A, B, and C from the pilot signals received from the radio terminal stations A, B, and C and the pilot signals held therein in advance. Then, based on the calculated channel information, a wireless terminal station that grants transmission permission is determined, and a transmission mode is determined from channel information with the wireless terminal station that grants transmission permission. In the example shown in FIG. 8, it is assumed that transmission permission is given to the wireless terminal stations A and C, and the transmission mode is, for example, the 72 Mbps mode.

  The radio base station 1, after elapse of a predetermined period 230 from the end of the last pilot signal transmission period, the terminal identifiers of the radio terminal stations A and C, the transmission order of pilot signals for data demodulation, and the determined transmission mode The wireless terminal stations A, B, and C receive the permitted terminal notification packets 214, 215, and 216, respectively.

  Here, it is assumed that the order of transmitting the pilot signals is the order of the wireless terminal stations A and C.

  The wireless terminal station A that first transmits the pilot signal transmits the pilot signal 217 from each antenna in a time-division manner after a predetermined period 231 has elapsed since the end of the permitted terminal notification packet, and the wireless base station 1 transmits the pilot signal. 219 is received. The procedure for transmitting pilot signals from the respective antennas is as shown in FIG.

  As soon as the pilot signal transmission period assigned to the wireless terminal station A ends, the wireless terminal station C that transmits the pilot signal secondly transmits the pilot signal 218 from each antenna in a time division manner. Receives the pilot signal 220.

  The wireless terminal stations A and C transmit data 221 and 222, respectively, as soon as the pilot signal transmission period of the wireless terminal station C ends.

  The radio base station 1 receives the data 223 and demodulates the data using the pilot signals 219 and 220 received from the radio terminal stations A and C. After the data is demodulated, an error check of data from each wireless terminal station is performed, and the result of the error check is written in the Ack packet 224 and transmitted to the wireless terminal stations A and C. Wireless terminal stations A and C receive Ack packets 225 and 226, respectively.

  As described above, according to the present embodiment, a wireless terminal station makes a transmission request to a wireless base station by assigning a signal to an individual subcarrier assigned in advance, and wirelessly responds to a request from the wireless base station. By transmitting pilot signals in the order (time slot) specified by the base station, in the CSMA / CA radio system, the radio base station waits for receiving transmission requests from a plurality of radio terminal stations. It is possible to reduce time and pilot transmission time, thereby reducing overhead for performing uplink spatial multiplexing transmission and improving network throughput characteristics. Also, channel information with each uplink transmission requesting terminal is acquired, one or more wireless terminal stations that permit uplink data transmission are determined based on the acquired channel information, and between the determined wireless terminal stations By determining and broadcasting the transmission mode from the channel information, it is possible to select a radio terminal station with little mutual interference and improve the packet error rate characteristics, thereby improving the network throughput.

(Second Embodiment)
FIG. 9 is a block diagram showing an example of a schematic configuration of a wireless terminal station according to the second embodiment of the present invention. A bidirectional arrow is provided between the data holding unit 137 and the control unit 144 in the block diagram shown in FIG. It is a tie.

  FIG. 10 is a flowchart showing an example of uplink spatial multiplexing transmission processing performed by the wireless terminal station shown in FIG.

  When data is input to the data holding unit 137 from the outside, the data holding unit 137 outputs a signal indicating that the data has been input to the control unit 144. The control unit 144 receives one piece of data, or the input data exceeds a predetermined threshold number, or the input data of a specific traffic type is a predetermined threshold value. When exceeding the number, the frame generation unit 135 outputs an uplink period start request packet generation request signal for requesting the start of the uplink period, and the frame generation unit 135 generates an uplink period start request packet. (Step S251).

  The frame generation unit 135 determines whether or not the transmission timing is reached (step S252). If the transmission timing is not reached, the frame generation unit 135 waits for the transmission timing. If the transmission timing is reached, the transmission unit 134, the switch 132, the four wireless communication units 132, An uplink period start request packet is transmitted via the antenna 131 (step S253).

  After transmitting the uplink period start request packet, reception determination of the uplink period start packet is performed (step S161). Since the processing after step S161 has already been described with reference to FIG.

  FIG. 11 is a block diagram showing an example of a schematic configuration of the radio base station 1 according to the second embodiment of the present invention. A frame type determination unit 271 is added to the block diagram shown in FIG. And the control unit 28 are connected to each other, and the receiving unit 26 and the demodulation unit 33 are connected to each other.

  FIG. 12 is a flowchart showing an example of uplink spatial multiplexing transmission processing performed by the radio base station 1 shown in FIG.

  Signals received via the four antennas 21, the four wireless communication units 22, the switch 23, and the reception unit 26 are decoded by the demodulation unit 33, and an error check such as CRC is performed by the error check unit 34. If it is determined by the error check that there is no error, the received frame is input to the frame type determination unit 271 and the type of the received frame is determined (step S281).

  If the error check determines that the error occurs, or if the frame type determination unit 271 determines that the packet is not an uplink period start request packet, the process ends, and if it is determined that the packet is an uplink period start request packet The control unit 28 controls the frame generation unit 25, and the frame generation unit 25 generates an uplink start period packet and transmits the packet via the transmission unit 24, the switch 23, the four wireless communication units 22, and the four antennas 21. (Step S31).

  The processing from step S31 to S37 has been already described in FIG.

  In step S37, after the channel information calculation unit 30 calculates channel information with each candidate terminal, the control unit 28 selects a permitted terminal based on the channel information with each candidate terminal. At this time, at least the wireless terminal station that has transmitted the uplink period start request packet is selected as a permitted terminal (step S282).

  After the control unit 28 selects the wireless terminal station including the wireless terminal station that transmitted the uplink period start request packet as the permitted terminal, the transmission mode determination unit 31 is based on the channel information of the permitted terminal determined by the control unit 28. The transmission mode is determined (step S39). The processing after step S39 has already been described in FIG.

  FIG. 13 is a second timing diagram of frame exchange of uplink spatial multiplexing transmission performed by the radio base station 1 and the radio terminal stations A to E.

  The radio terminal station D transmits an uplink period start request packet 300, and the radio base station 1 receives an uplink period start request packet 301.

  After receiving the uplink period start request packet 301, the radio base station 1 transmits an uplink period start packet 191 after a predetermined period 302 has elapsed, and the radio terminal stations A, B, C, D, and E Receiving uplink period start packets 192, 193, 194, 195, 196, respectively.

  After a predetermined period 227 has elapsed, the wireless terminal stations A, B, C, and D that hold the transmission data transmit transmission request packets 197, 198, 199, and 200, respectively. Here, an example has been shown in which the wireless terminal station D that has transmitted the uplink period start request packet transmits the transmission request packet 200, but the wireless terminal station that has transmitted the uplink period start request packet does not transmit the transmission request packet. It may be. In this case, it is assumed that the wireless base station 1 stores the wireless terminal station that has transmitted the uplink period start request packet, and has received a transmission request from the wireless terminal station.

  The wireless base station 1 receives the transmission request packet 201 transmitted from the wireless terminal stations A, B, C, and D, and identifies the terminal that transmitted the transmission request packet.

  It is assumed that the wireless base station 1 selects three wireless terminal stations A, B, and D as candidate terminals among the wireless terminal stations A, B, C, and D specified by the wireless base station 1. The radio base station 1 always selects the radio terminal station D that has transmitted the uplink period start request packet as a candidate terminal. After a predetermined period 228, a pilot signal transmission request packet 202 describing the identifiers of the selected wireless terminal stations A, B, and D and the transmission order of the pilot signals is transmitted, and the wireless terminal stations A, B, C, D receives pilot signal transmission request packets 203, 204, 205, and 206, respectively.

  Here, it is assumed that the order in which the pilot signals are transmitted is the order of the wireless terminal stations A, B, and D.

  The wireless terminal station A that transmits the pilot signal first transmits the pilot signal 207 from each antenna in a time-division manner after a predetermined period 229 has elapsed from the end of the pilot signal transmission request packet. A signal 210 is received. The procedure for transmitting pilot signals from the respective antennas is as shown in FIG.

  As soon as the pilot signal transmission period assigned to the wireless terminal station A ends, the wireless terminal station B that transmits the pilot signal secondly transmits the pilot signal 208 from each antenna in a time division manner. Receives the pilot signal 211.

  Similarly, as soon as the pilot signal transmission period assigned to the wireless terminal station B ends, the wireless terminal station D that transmits the pilot signal thirdly transmits the pilot signal 303 from each antenna in a time division manner. Base station 1 receives pilot signal 304.

  The radio base station 1 calculates channel information between the radio terminal stations A, B, and D from the pilot signals received from the radio terminal stations A, B, and D and the pilot signals held therein in advance. A wireless terminal station to which transmission permission is granted is determined based on the channel information. At this time, the radio base station 1 gives at least a transmission permission to the radio terminal station D that has transmitted the uplink period start request packet. Then, the radio base station 1 determines the transmission mode from the channel information with the radio terminal station that grants transmission permission. In the example shown in FIG. 8, it is assumed that transmission permission is given to the wireless terminal stations A and D, and the transmission mode is, for example, the 72 Mbps mode.

  The radio base station 1, after elapse of a predetermined period 230 from the end of the last pilot signal transmission period, the terminal identifiers of the radio terminal stations A and D, the transmission order of pilot signals for data demodulation, and the determined transmission mode The wireless terminal stations A, B, and D receive the permitted terminal notification packets 214, 215, and 306, respectively.

  Here, it is assumed that the order of transmitting the pilot signals is the order of the wireless terminal stations A and D.

  The wireless terminal station A that first transmits the pilot signal transmits the pilot signal 217 from each antenna in a time-division manner after a predetermined period 231 has elapsed since the end of the permitted terminal notification packet, and the wireless base station 1 transmits the pilot signal. 219 is received. The procedure for transmitting pilot signals from the respective antennas is as shown in FIG.

  As soon as the pilot signal transmission period assigned to the wireless terminal station A ends, the wireless terminal station D that transmits the pilot signal secondly transmits the pilot signal 307 from each antenna in a time division manner. Receives a pilot signal 308.

  The wireless terminal stations A and D transmit data 221 and 309, respectively, as soon as the pilot signal transmission period of the wireless terminal station D ends. The radio base station 1 receives the data 310 and demodulates the data using the pilot signals 219 and 308 received from the radio terminal stations A and D.

  After the data is demodulated, the radio base station 1 performs an error check on the data from each radio terminal station, writes the result of the error check in the Ack packet 311 and transmits the result to the radio terminal stations A and D. The wireless terminal stations A and D receive Ack packets 225 and 312 respectively.

  In the above, an example is given in which transmission permission is given to the wireless terminal station that has transmitted the uplink period start request packet. However, transmission permission may not necessarily be granted to the wireless terminal station that has transmitted the uplink period start request packet. As shown in FIG. 49, the radio base station 1 may transmit an uplink period start packet triggered by reception of an uplink period start request packet. 49 is obtained by replacing step S282 in FIG. 12 with step S38 in FIG. 3. In the permitted terminal selection process in step S38, the channel information is changed regardless of whether or not an uplink period start request packet is transmitted. Based on the candidate terminal, the permitted terminal is selected.

  In this way, by making a request to start the uplink period from the radio terminal station to the radio base station, the base station recognizes that the radio terminal station holds uplink transmission data and starts the uplink. Therefore, the transmission delay of data transmitted by the wireless terminal station can be reduced.

(Third embodiment)
FIG. 15 shows an example of a terminal identifier bitmap to which the radio base station 1 assigns. In the terminal identifier bitmap 351 of FIG. 15, “1” is set in the fourth bit from lsb, and “8” is expressed in decimal. As shown in FIG. 15, the radio base station 1 assigns any bit of the terminal identifier bitmap to the radio terminal station as a terminal specific bit. Therefore, the wireless terminal station is identified by the position where “1” of the terminal identifier bitmap is set.

  FIG. 16 shows a table showing the correspondence between the MAC address of the wireless terminal station and the terminal identifier bitmap. In the example shown in FIG. 16, the terminal identifier “0000000000000001” is assigned to the wireless terminal station whose MAC address is “12-34-56-78-9A-BC”, and the MAC address is “1F-2E-3D-4C-5B”. In this example, the terminal identifier “0000000000001000” is assigned to the wireless terminal station of “−6A”. The radio base station 1 holds the table shown in FIG.

  FIG. 17 is a diagram showing a configuration of a transmission request packet 361 transmitted by the wireless terminal station. A transmission request packet 361 transmitted by the wireless terminal station includes a preamble 360 and a terminal identification field 362.

  FIG. 18 is a diagram showing the configuration of the terminal identification field 362 shown in FIG. The terminal specific field 362 is formed from one or more OFDM symbols. The terminal identification field 362 shown in FIG. 18A shows an example formed from one OFDM symbol 371, and the terminal identification field 362 shown in FIG. 18B is formed from four OFDM symbols 372-375. An example is shown.

  FIG. 19 is a table showing the correspondence between the bits of the terminal identifier bitmap and the terminal specific subcarriers.

  FIG. 19A shows an example in which one terminal identifier bitmap corresponds to one OFDM symbol. In this example, the first bit of the terminal identifier bitmap corresponds to the first subcarrier, the second bit of the terminal identifier bitmap corresponds to the second subcarrier, and the kth bit of the terminal identifier bitmap is k. Corresponds to the second subcarrier.

  Also, one terminal identifier bitmap can be made to correspond to a terminal specific field including a plurality of OFDM symbols. FIG. 19B shows an example in which one terminal identifier bitmap corresponds to a terminal identification field 362 formed from four OFDM symbols. In this example, the first bit of the terminal identifier bitmap corresponds to the first subcarrier of the first OFDM symbol, and the second bit of the terminal identifier bitmap corresponds to the second subcarrier of the first OFDM symbol. The third bit of the terminal identifier bitmap corresponds to the third subcarrier of the first OFDM symbol, the fourth bit of the terminal identifier bitmap corresponds to the fourth subcarrier of the first OFDM symbol, The fifth bit of the terminal identifier bitmap corresponds to the first subcarrier of the second OFDM symbol, the sixth bit of the terminal identifier bitmap corresponds to the second subcarrier of the second OFDM symbol, and the terminal identifier The k-th bit of the bitmap is the (k% 4) th subcarrier of the ((k / 4) +1) th OFDM symbol. Corresponding to the A. Here, the symbol “A% B” represents the remainder when A is divided by B. When the number of terminals of the wireless communication network exceeds the number of subcarriers of one OFDM symbol, the above allocation method can be used.

  Further, discrete subcarriers within one OFDM symbol can be allocated, and an example of this is shown in FIG. The first bit of the terminal identifier bitmap corresponds to the first subcarrier of the first OFDM symbol, the second bit of the terminal identifier bitmap corresponds to the fifth subcarrier of the first OFDM symbol, and the terminal identifier The third bit of the bitmap corresponds to the ninth subcarrier of the first OFDM symbol, the fourth bit of the terminal identifier bitmap corresponds to the thirteenth subcarrier of the first OFDM symbol, and the terminal identifier bitmap 5 corresponds to the first subcarrier of the second OFDM symbol, the sixth bit of the terminal identifier bitmap corresponds to the fifth subcarrier of the second OFDM symbol, and k of the terminal identifier bitmap The bit is the (4 ((k% 4) -1) +1) th of the ((k / 4) +1) th OFDM symbol. Corresponding to the subcarrier.

The radio base station 1 transmits the table shown in FIG. 19 indicating the correspondence relationship between the bits of the terminal identifier bitmap and the terminal specific subcarriers as beacons to be transmitted periodically.
FIG. 20 shows a format of a terminal identifier bitmap and a terminal specific subcarrier assigned to the wireless terminal station by the wireless base station 1. The terminal identifier bitmap 351, the corresponding OFDM symbol, and the subcarrier number 391 are assigned to the wireless terminal station as a set. The radio base station sets data in this format in a beacon and transmits it to the corresponding radio terminal station.

  FIG. 14 is a block diagram showing an example of a schematic configuration of the radio base station 1 according to the third embodiment of the present invention, in which the requesting terminal specifying unit 27 in the block diagram shown in FIG. 11 is replaced with a subcarrier determining unit 331. Further, a terminal identifier assigning unit (identifier assigning means) 332 and a subcarrier assigning unit 333 are newly added.

  FIG. 21 is a flowchart showing an example of processing in which the radio base station 1 assigns a terminal identifier and a subcarrier to a radio terminal station.

  Signals received via the four antennas 21, the four wireless communication units 22, the switch 23, and the reception unit 26 are decoded by the demodulation unit 33, and an error check such as CRC is performed by the error check unit 34. If it is determined by the error check that there is no error, the received frame is input to the frame type determination unit 271 and the type of the received frame is determined (step S401).

  If the error check determines that the error has occurred, or if the frame type determination unit 271 determines that the packet is not a registration request packet requesting registration on the network, the process ends, and the frame type determination unit 271 ends the registration request packet. If it is determined that the registration is, the control unit 28 determines whether or not to permit registration (step S402). For example, whether or not the registration permission is permitted by the control unit 28 is determined based on whether or not the number of registered terminals in the network exceeds a predetermined threshold number, or a resource in the network is determined in advance. Or not.

  When the control unit 28 rejects the registration, the frame generation unit 25 generates a registration response packet (rejection), and transmits the packet via the transmission unit 24, the switch 23, the four wireless communication units 22, and the four antennas 21 ( Step S406).

  On the other hand, when the radio base station 1 permits registration in step S402, the terminal identifier assigning unit 332 assigns a terminal identifier using a bitmap (step S403), and the subcarrier assigning unit 333 assigns the terminal specific subcarrier. This is performed (step S404).

  When the assignment of the terminal identifier and the subcarrier is completed, the control unit 28 outputs an instruction to the frame generation unit 25, and the frame generation unit 25 performs registration including the terminal identifier bit map and the terminal specific subcarrier format shown in FIG. A response packet (permission) is generated and transmitted via the transmission unit 24, the switch 23, the four wireless communication units 22, and the four antennas 21 (step S405).

  FIG. 22 is a block diagram showing an example of a schematic configuration of a radio terminal station according to the third embodiment of the present invention. A terminal identifier holding unit 142 and a terminal specific subcarrier holding unit 143 are newly added to the block diagram shown in FIG. It is added to.

  FIG. 23 is a flowchart illustrating an example of processing in which a wireless terminal station transmits a registration request packet.

  The control unit 144 outputs a registration request packet generation request signal to the frame generation unit 135, and the frame generation unit 135 generates a registration request packet (step S421).

  The frame generation unit 135 determines whether or not the transmission timing is reached (step S422). If the transmission timing is not reached, the frame generation unit 135 waits for the transmission timing. If the transmission timing is reached, the transmission unit 134, the switch 132, the four wireless communication units 132, A registration request packet is transmitted via the antenna 131 (step S423).

  After transmitting the registration request packet, signals received via the four antennas 131, the four wireless communication units 132, the switch 133, and the receiving unit 138 are decoded by the demodulating unit 139, and the error checking unit 140 detects errors such as CRC. A check is made. If it is determined by the error check that there is no error, the received frame is input to the frame type determination unit 141, and the type of the received frame is determined (step S424).

  If the error check determines that the error has occurred, or if the frame type determination unit 141 determines that the packet is not a registration response packet, the process ends. If the frame type determination unit 141 determines that the packet is a registration response packet, Then, it is determined whether or not registration is permitted (step S425). If the registration is not permitted, the process is terminated. If the registration is permitted, the assigned terminal identifier is stored in the terminal identifier holding unit 142 (step S426). The allocated subcarriers are stored in terminal specific subcarrier holding section 143 as terminal specific subcarriers (step S427).

  FIG. 24 is a flowchart illustrating the details of the process of generating a transmission request packet (step S163 in FIG. 10) performed by the wireless terminal station shown in FIG.

  The frame generation unit 135 sets a pilot signal (preamble) for synchronization (step S441), and maps the signal (transmission request) to the terminal specific subcarrier assigned to the own station input from the control unit 144 (step S441). S442), a transmission request packet is generated.

  FIG. 25 is a flowchart for explaining the details of the transmission request terminal identification process (step S33 in FIG. 12) performed by the radio base station 1 shown in FIG.

  The subcarrier determining unit 331 of the radio base station 1 illustrated in FIG. 14 performs subcarrier power measurement for each terminal-specific subcarrier (step S461) and determines whether or not a predetermined threshold value is exceeded. (Step S462).

  If the power of the subcarrier calculated in step S461 exceeds the threshold value, it is determined that there is a transmission request from the wireless terminal station assigned to the subcarrier (step S463), and the subcarrier power calculated in step S461 is determined. If the power is less than or equal to the threshold value, it is determined that there is no transmission request from the wireless terminal station assigned to the subcarrier (step S464).

  FIG. 26 is a diagram showing a configuration of a pilot signal transmission request packet 481 transmitted by the radio base station 1. A pilot signal transmission request packet 481 transmitted by the radio base station 1 includes a preamble 480 and a pilot signal request bitmap 482.

  FIG. 27 is a diagram showing a configuration example (491) of the pilot signal request bitmap 482 shown in FIG.

  In the pilot signal request bitmap 491 shown in FIG. 27, “1” is set in the first bit, the fourth bit, and the sixth bit, and the first bit is assigned as a terminal specific bit. This indicates that the terminal station requests transmission of a pilot signal to the wireless terminal station in which the fourth bit is assigned as the terminal specific bit, and the sixth bit is assigned to the wireless terminal station as the terminal specific bit.

  The three wireless terminal stations requested to transmit the pilot signal by the pilot signal transmission request packet 491 in which the pilot signal request bitmap shown in FIG. 27 is set are wireless signals in which the first bit is assigned as the terminal specific bit. The pilot signal is transmitted in the order of the terminal station, the wireless terminal station in which the fourth bit is assigned as the terminal specific bit, and the wireless terminal station in which the sixth bit is assigned as the terminal specific bit. That is, the pilot signal is transmitted in order from the radio terminal station assigned to the bit set to “1” in order from the lsb side of the pilot signal request bitmap.

  FIG. 28 is a diagram illustrating a configuration of the permitted terminal notification packet 501 transmitted by the radio base station 1.

  The permitted terminal notification packet 501 transmitted by the wireless terminal station includes a preamble 500, a permitted terminal designation bitmap 502, and a transmission mode field 503.

  The permitted terminal designation bitmap 502 has the same configuration as the pilot signal request bitmap shown in FIG. 27, and is assigned to the bits set to “1” in order from the lsb side of the permitted terminal designation bitmap. A pilot signal for data demodulation is transmitted in order from the terminal station.

  In this way, by making a transmission request by mapping signals to subcarriers individually assigned by a plurality of wireless terminal stations, the terminal can make an uplink transmission request in a short period of time, thereby improving the MAC efficiency. The network throughput can be improved.

(Fourth embodiment)
FIG. 29 is a block diagram showing an example of a schematic configuration of the radio base station 1 according to the fourth embodiment of the present invention, in which a channel information holding unit 521 and a timer 522 are newly added to the block diagram shown in FIG. It is.

  FIG. 30 is a flowchart illustrating details of pilot signal request packet transmission (step S35 in FIG. 12) performed by the wireless terminal station 1 shown in FIG.

  After determining the candidate terminal in the process of step S34 shown in FIG. 12, the control unit 28 makes an inquiry to the channel information holding unit 521 and sets a predetermined threshold time after the channel information acquisition of the candidate terminal. It is determined whether or not it exceeds (step S541). The channel information holding unit 521 holds the latest channel information of the wireless terminal station, and manages an elapsed time after acquiring the latest channel information of the wireless terminal station using the timer 522.

  If the elapsed time after acquiring channel information of a candidate terminal exceeds a predetermined threshold time, a pilot signal transmission request is made to the candidate terminal (in the pilot signal transmission request bitmap shown in FIG. 27). The bit assigned to the candidate terminal is set to “1”: step S542), and if the elapsed time after acquiring the channel information of the candidate terminal does not exceed a predetermined threshold time, transmission of a pilot signal No request is made (the bit assigned to the candidate terminal in the pilot signal transmission request bitmap shown in FIG. 27 is set to “0”: step S542).

  As described above, when channel information has already been acquired, transmission of a pilot signal for acquiring the channel information can be omitted, so that MAC efficiency can be increased and network throughput can be improved.

(Fifth embodiment)
FIG. 31 is a block diagram showing an example of a schematic configuration of the radio base station 1 according to the fifth embodiment of the present invention, in which an SNR estimation unit 551 and a channel capacity calculation unit 552 are added to the block diagram shown in FIG. It is.

  FIG. 32 is a flowchart illustrating details of the permitted terminal selection (step S38 in FIG. 3) performed by the radio base station 1 shown in FIG.

  The SNR estimation unit 551 calculates the SNR from the pilot signal received from the wireless terminal station (step S571). The channel capacity calculation unit 552 calculates the channel capacity for all combinations of candidate terminals using the channel information calculated by the channel information calculation unit 30 and the SNR calculated by the SNR estimation unit 551 (step S572).

と計算される。ここで、Ｎ_Ｒは無線基地局の受信アンテナ数である。 Now, assuming that the channel matrix between the wireless terminal station k and the wireless base station 1 is h _k , the spatial multiplexing matrix H _g when the combination of wireless terminal stations from k = 1 to k = K is _g is
_{H g = [h 1, ...} , h k, ..., h K] formula (1)
It becomes. The channel capacity C _g at this time is

Is calculated. Here, N _R is the number of receiving antennas of the radio base station.

  It is determined whether or not the calculated channel capacity is the maximum value (step S573), and if it is the maximum value, the combination of terminal candidates and the channel capacity are held (step S574).

  If the channel capacity calculated in step S573 is not the maximum value, the process of step S571 is performed for the next combination.

  The determination of the transmission mode (step S39) in the flowchart shown in FIG. 3 is performed as follows.

ここでｎ_Ｔは無線端末局の送信アンテナ数、ｐ_ｋは無線端末局ｋの送信電力、

は無線端末局ｋの雑音電力である。いま、システムの帯域幅をｂ［Ｈｚ］とすると、以下を満たすＭＣＳ_ｉ（変調符号化方式）を選択する。

ここで、αは伝送レートのマージンである。 The channel capacity C _{G, k} is calculated as follows for each wireless terminal station k of the combination G of wireless terminal stations that maximizes the expression (2).

Where n _T is the number of transmission antennas of the wireless terminal station, p _k is the transmission power of the wireless terminal station k,

Is the noise power of the wireless terminal station k. Now, assuming that the system bandwidth is b [Hz], an MCS _i (modulation coding scheme) that satisfies the following is selected.

Here, α is a transmission rate margin.

  Thus, by giving transmission permission to a terminal having the largest channel capacity, more data can be transmitted in a short time, and the network throughput can be improved.

(Sixth embodiment)
FIG. 33 is a diagram illustrating an example of a field configuration of a pilot signal transmitted by a wireless terminal station. The pilot signal shown in FIG. 33 shows the internal configuration of pilot signal 207 shown in FIG. Since the other pilot signals 208 and 209 shown in FIG. 8 have the same configuration, the description of the pilot signal 207 is replaced with the description of the pilot signals 208 and 209.

  The pilot signal 207 is obtained by adding a transmission delay request field (delay allowable time field) 600 to the pilot signals 57, 59, 61, and 63 transmitted from the respective antennas shown in FIG. For example, when the data transmitted by the wireless terminal station needs to be transmitted within 20 milliseconds from the time of transmission of the transmission request packet, the transmission delay request field (delay allowable time field) 600 is 20 milliseconds. Is indicated and transmitted.

  FIG. 34 is a block diagram showing an example of a schematic configuration of the radio base station 1 according to the sixth embodiment of the present invention, in which a transmission delay request receiving unit 610 is added to the block diagram shown in FIG.

  FIG. 35 is a flowchart for explaining details of the permitted terminal selection (step S38 in FIG. 3) performed by the radio base station 1 shown in FIG. 34, and is an improvement on the flowchart in FIG.

  34 outputs the transmission delay request 600 received from the wireless terminal station to the control unit 28. The control unit 28 has the smallest value among the transmission delay requests 600 received from the wireless terminal station. A wireless terminal station that has transmitted a transmission delay request (that is, a wireless terminal station that is most likely to perform data transmission earliest) or a wireless terminal station that has requested a transmission delay equal to or less than a threshold value is a terminal that allows uplink transmission (primary user). Select (step S621).

  The channel capacity calculation unit 552 uses the channel information calculated by the channel information calculation unit 30 and the SNR calculated by the SNR estimation unit 551 for all combinations of candidate terminals including the primary user. Calculation is performed (steps S571 and S572). It is determined whether or not the calculated channel capacity is the maximum value (step S573), and if it is the maximum value, the combination of terminal candidates and the channel capacity are held (step S574). If the channel capacity calculated in step S573 is not the maximum value, the process of step S571 is performed for the next combination.

(Seventh embodiment)
FIG. 36 is a diagram illustrating an example of a field configuration of a pilot signal transmitted by a wireless terminal station.

  The pilot signal shown in FIG. 36 shows the internal configuration of pilot signal 207 shown in FIG. Since the other pilot signals 208 and 209 shown in FIG. 8 have the same configuration, the description of the pilot signal 207 is replaced with the description of the pilot signals 208 and 209. The pilot signal 207 is obtained by adding a data size field 630 to the pilot signals 57, 59, 61, and 63 transmitted from the respective antennas shown in FIG. For example, when the data size transmitted by the wireless terminal station is 1000 bytes, a code indicating 1000 bytes is written in the data size field 630 and transmitted.

  FIG. 37 is a block diagram showing an example of a schematic configuration of the radio base station 1 according to the seventh embodiment of the present invention. The block diagram of FIG. 37 is obtained by adding a data size receiving unit 640 and a permitted data size determining unit 641 to the block diagram shown in FIG.

  FIG. 38 is a flowchart for explaining the details of permission data size determination performed by the radio base station 1 shown in FIG. 37, and is an improvement on the flowchart of FIG. In the flowchart shown in FIG. 38, the processing up to step S574 is the same as the processing in the flowchart in FIG.

  The permitted data size determination unit 641 includes the requested data size from each wireless terminal station input from the data size reception unit 640, the permitted terminal information input from the transmission mode determination unit 31, and the transmission mode of the permitted terminal. The packet time length of each permitted terminal is calculated (step S650).

  It is determined whether or not the difference between the maximum packet time length and the minimum packet time length is greater than or equal to a predetermined threshold value (step S651).

  In step S651, if the difference between the maximum and minimum packet time lengths is equal to or greater than a predetermined threshold, the data size of the wireless terminal station having the maximum packet time length is set to be equal to the second longest packet time length. Determination is made (step S652). In other words, if the difference in data size between wireless terminal stations is too large, efficient spatial multiplexing transmission cannot be performed and the network throughput characteristics deteriorate, so when the difference between the maximum and minimum packet time length is large The data size of the wireless terminal station having the maximum packet time length is adjusted to keep the data size of each wireless terminal station within a desired range. This improves network throughput.

  On the other hand, if the difference between the maximum and minimum packet time lengths is not greater than or equal to a predetermined threshold value in step S651, the data size is not adjusted.

For example, the permitted terminals are the wireless terminal station B, the wireless terminal station C, and the wireless terminal station E, the requested data size of the wireless terminal station B is 1000 bytes, the requested data size of the wireless terminal station C is 2000 bytes, the wireless terminal station Assume that the requested data size of E is 1800 bytes. Further, it is assumed that the transmission mode of the wireless terminal station B is determined to be 40 [Mbps], the transmission mode of the wireless terminal station C is determined to be 20 [Mbps], and the transmission mode of the wireless terminal station E is determined to be 24 [Mbps]. The packet time length D [microseconds] is determined from the data size L [bytes] and the transmission mode R [Mbps].
D = (8 × L) / R Formula (5)
Is calculated, the packet time length of the wireless terminal station B is (8 × 1000) / 40 = 200 [microseconds].
The packet time length of the wireless terminal station C is (8 × 2000) / 20 = 800 [microseconds].
The packet time length of the wireless terminal station E is (8 × 1800) / 24 = 600 [microseconds].
Is calculated.

If the threshold for the difference between the maximum and minimum packet time length is 500 microseconds, the difference between the maximum packet time length of 800 microseconds and the minimum packet time length of 200 microseconds is 600 microseconds, The threshold value of 500 microseconds is exceeded. In this case, the packet time length of the wireless terminal station C which is the maximum packet time length is 600 microseconds which is the packet time length of the wireless terminal station E which is the second longest packet time length. Determine the data size. The requested data size from the wireless terminal station C is 2000 bytes. If the data size of the wireless terminal station C is 1500 bytes, the packet time length is
(8 × 1500) / 20 = 600 [microseconds]
And becomes equal to the second longest packet time length. Therefore, the data size for granting transmission permission to the wireless terminal station C is determined to be 1500 bytes.

  In the above example, the data size of the wireless terminal station with the maximum packet time length is adjusted so that the maximum packet time length matches the second packet time length. However, with the predetermined data size adjustment unit width, The data size of the wireless terminal station with the maximum packet time length may be adjusted so as to be closest to the second packet time length. As described above, in this embodiment, the permitted data size of each wireless terminal station is determined so that the packet time length is within a desired range.

  FIG. 39 is a diagram showing a configuration of the permitted terminal notification packet 501 transmitted by the radio base station 1, in which a permitted data size field 661 is added to the configuration shown in FIG. The radio base station 1 determines the permitted data size according to the flowchart shown in FIG. 38, and transmits the determined permitted data size in the permitted data size field 661 of the permitted terminal notification packet shown in FIG.

  FIG. 40 is a diagram illustrating a specific example of the permitted terminal designation bitmap 502 and the permitted data size field 661 of the permitted terminal notification packet 501. In the example shown in FIG. 40, data transmission of 1000 bytes (see reference numeral 673) is permitted to the wireless terminal station corresponding to the second bit of the bitmap. Similarly, data transmission of 1500 bytes (see reference numeral 672) is permitted to the wireless terminal station corresponding to the third bit of the bitmap, and 1800 is transmitted to the wireless terminal station corresponding to the fifth bit of the bitmap. Data transmission of bytes (see reference numeral 671) is permitted.

(Eighth embodiment)
FIG. 41 is a block diagram showing an example of a schematic configuration of the radio base station 1 according to the eighth embodiment of the present invention. The block diagram of FIG. 41 is obtained by adding a pilot received power measuring unit 681 and a transmission power control unit 682 to the block diagram shown in FIG.

  FIG. 42 is a flowchart for explaining the details of the permitted terminal selection and transmission power control processing performed by the radio base station 1 shown in FIG. 41, and is an improvement on the flowchart of FIG.

  The pilot received power measuring unit 681 in FIG. 41 measures the received power of the pilot signal received from each wireless terminal station (step S691), and the transmission power control unit 682 includes one reference terminal selected from each wireless terminal station. A difference from the pilot reception power is calculated (step S692). The reference terminal may select any of the wireless terminal stations, or may be selected according to another reference (for example, the wireless terminal station that transmitted the uplink period start packet and the wireless terminal station with the shortest delay allowable time). May be.

  The SNR estimation unit 551 calculates the SNR when the difference input from the transmission power control unit 682 is added to the pilot signal received from the wireless terminal station (step S693). That is, the SNR is calculated when the radio terminal station has the same pilot reception power as that of the reference terminal. The channel capacity calculation unit 552 calculates the channel capacity for all combinations of candidate terminals using the channel information calculated by the channel information calculation unit 30 and the SNR calculated by the SNR estimation unit 551 (step S572). ).

  It is determined whether or not the calculated channel capacity is the maximum value (step S573), and if it is the maximum value, the combination of terminal candidates and the channel capacity are held (step S574).

  If the channel capacity calculated in step S573 is not the maximum value, the process of step S571 is performed for the next combination.

  When the permitted terminal is determined, the transmission power control unit 682 outputs the increase / decrease value of the transmission power of each permitted terminal (that is, the difference from the reception power of the reference terminal or a value corresponding thereto) to the control unit 28, and the frame generation unit 25. Is notified to the permitted terminal (step S694). The permitted terminal changes the transmission power by the notified value and transmits data.

  FIG. 43 is a diagram showing a configuration of the permitted terminal notification packet 501 transmitted by the radio base station 1, in which a transmission power control value field 701 is added to the configuration shown in FIG. The radio base station 1 performs selection of a permitted terminal and calculation of a transmission power control value according to the flowchart shown in FIG. 42, and the determined transmission power control value is transmitted in the transmission power control value field 701 of the permitted terminal notification packet shown in FIG. Send it as described in.

  FIG. 44 is a diagram showing a specific example of the permitted terminal designation bitmap 502 and the transmission power control value field 701 of the permitted terminal notification packet 501. In the example shown in FIG. 44, the wireless terminal station corresponding to the second bit of the bitmap is requested to transmit power control of +10 dB (see reference numeral 713) with respect to the transmission power of the pilot signal. Similarly, the wireless terminal station corresponding to the third bit of the bitmap is requested to transmit power control of −5 dB (see reference numeral 712) with respect to the transmission power of the pilot signal, and corresponds to the fifth bit of the bitmap. The wireless terminal station is requested to perform transmission power control of +3 dB (see reference numeral 711) with respect to the transmission power of the pilot signal. As a result, the received power of data from each permitted terminal is made approximately the same, and the reception characteristics in the radio base station are improved.

(Ninth embodiment)
FIG. 45 is a diagram showing a configuration example of the terminal identification field 362 of the transmission request packet 361 transmitted by the wireless terminal station shown in FIG. In FIG. 45, it is assumed that the terminal identifier bitmap is composed of 4 bits, and one OFDM symbol is composed of 4 subcarriers.

  As shown in FIG. 45, the terminal identification field 362 is composed of two OFDM symbols. In the first OFDM symbol, the first bit of the terminal identifier bitmap is set to the first subcarrier, and 2 of the terminal identifier bitmap. The bit is assigned to the second subcarrier, the third bit of the terminal identifier bitmap is assigned to the third subcarrier, and the fourth bit of the terminal identifier bitmap is assigned to the fourth subcarrier. On the other hand, in the second OFDM symbol, the first bit of the terminal identifier bitmap is the third subcarrier, the second bit of the terminal identifier bitmap is the fourth subcarrier, and the third bit of the terminal identifier bitmap is 1. The 4th bit of the terminal identifier bitmap is allocated to the 2nd subcarrier in the 2nd subcarrier. This is an allocation obtained by adding an offset of 2 subcarriers to the allocation of subcarriers in the first OFDM symbol in the second OFDM symbol. The radio base station 1 broadcasts the subcarrier allocation information corresponding to the terminal identifier bitmap shown above by a beacon that is periodically transmitted.

  In this way, by using a plurality of OFDM symbols as the terminal identification field and changing the subcarriers allocated to the terminals in each OFDM symbol, even when distortion due to multipath occurs in a specific subcarrier, different OFDM symbols are different. Since the terminal can be specified from the subcarrier position, the detection characteristic of the terminal is improved.

  FIG. 46 is a diagram showing another configuration example of the terminal identification field 362 of the transmission request packet 361 transmitted by the wireless terminal station shown in FIG. In FIG. 46, it is assumed that the terminal identifier bitmap is composed of 4 bits, and one OFDM symbol is composed of 16 subcarriers. As shown in FIG. 46, the 4-bit terminal identifier bitmap is repeatedly assigned four times to 16 subcarriers (see reference numerals 721, 722, 723, and 724), but each is added with an offset. Assigned.

  In this way, by repeatedly assigning a terminal identifier bitmap in one OFDM symbol, even when distortion due to multipath occurs in a specific subcarrier, the terminal can be specified from different subcarrier positions. The detection characteristics are improved.

  FIG. 47 is a diagram showing still another configuration example of the terminal identification field 362 of the transmission request packet 361 transmitted by the wireless terminal station shown in FIG. In FIG. 47, it is assumed that the terminal identifier bitmap is composed of 16 bits, and one OFDM symbol is composed of 16 subcarriers.

  As shown in FIG. 47, the radio base station 1 first assigns the first bit and the first subcarrier of the terminal identifier bitmap to the radio terminal station that permits registration to the network (see reference numeral 731).

  The wireless base station 1 is the 16th bit and 16th bit of the terminal identifier bitmap located farthest from the subcarrier assigned to the first registered terminal with respect to the wireless terminal station that permits the second registration to the network. The subcarrier is assigned (see reference numeral 732).

  The radio base station 1 has the 8 bits of the terminal identifier bitmap located farthest from the subcarriers assigned to the first and second registered terminals with respect to the radio terminal station that permits the third registration to the network. The eighth and eighth subcarriers are assigned (see reference numeral 733).

  The radio base station 1 has a terminal identifier bitmap 12 in the position farthest from the subcarriers assigned to the second and third registered terminals with respect to the radio terminal station that permits the fourth registration to the network. The bit and the 12th subcarrier are allocated (see reference numeral 734).

  The wireless base station 1 has four bits of the terminal identifier bitmap located farthest from the subcarriers assigned to the first and third registered terminals with respect to the wireless terminal station that permits the fifth registration to the network. The fourth and fourth subcarriers are assigned (see reference numeral 735).

  In this way, by sequentially assigning subcarriers whose frequencies are separated from the already assigned terminal specific subcarriers as terminal specific subcarriers, it is possible to reduce the influence of side lobe components from the subcarriers of the terminals that request transmission. Therefore, the detection characteristics of the terminal are improved.

  FIG. 48A is a format diagram showing an example of the configuration of an uplink period start request packet transmitted by the radio terminal station, and FIG. 48B is an uplink period start packet transmitted by the radio base station 1. It is the format figure which showed an example of the structure of.

  As shown in FIG. 48 (a), an uplink period start request packet transmitted by a wireless terminal station includes an RTS (Request To Send) frame 741 and an uplink period start request specified by the existing IEEE 802.11 wireless LAN. A packet identifier field 742, and an uplink period start request packet identifier field 742 is added to the end of the RTS frame.

  As shown in FIG. 48 (b), the uplink period start packet transmitted by the radio base station 1 includes a CTS (Clear To Send) frame 751 and an uplink period defined in the existing IEEE 802.11 wireless LAN. A start packet identifier field 752, and an uplink period start packet identifier field 752 is added to the end of the CTS frame 751.

  As described above, by adding a unique field for uplink multi-user MIMO transmission to the end of the frame defined in the existing system, backward compatibility with the existing wireless system can be maintained. The same applies to other fields other than those described above. That is, transmission request data in the transmission request packet, packet type identifier field and terminal identifier bitmap of the pilot signal transmission request packet, packet type identifier field and terminal identifier bitmap of the permitted terminal broadcast packet, transmission request packet transmitted by the wireless terminal station Similarly to the above, the terminal identification field can be added to the end of the packet of the existing wireless communication system.

1 is a block diagram showing an example of a schematic configuration of a network in which a wireless base station 1 and wireless terminal stations 2 to 8 perform wireless communication. The block diagram which shows an example of schematic structure of the wireless base station 1 which concerns on the 1st Embodiment of this invention. 3 is a flowchart showing an example of uplink spatial multiplexing transmission processing performed by the radio base station 1 of FIG. The transmission timing diagram of the pilot signal which a candidate terminal transmits. The pilot signal and data transmission timing diagram which a permission terminal transmits. 1 is a block diagram showing an example of a schematic configuration of a wireless terminal station 2 according to a first embodiment of the present invention. 7 is a flowchart illustrating an example of uplink spatial multiplexing transmission processing performed by the wireless terminal station 2 illustrated in FIG. 6. The timing diagram of the frame exchange of the uplink spatial multiplexing transmission performed by the radio base station 1 and the radio terminal stations A to E. The block diagram which shows an example of schematic structure of the radio | wireless terminal station which concerns on the 2nd Embodiment of this invention. 10 is a flowchart showing an example of uplink spatial multiplexing transmission processing performed by the wireless terminal station shown in FIG. 9. The block diagram which shows an example of schematic structure of the wireless base station 1 which concerns on the 2nd Embodiment of this invention. 12 is a flowchart showing an example of uplink spatial multiplexing transmission processing performed by the radio base station 1 shown in FIG. 11. The 2nd timing diagram of the frame exchange of the uplink spatial multiplexing transmission which the radio base station 1 and the radio | wireless terminal stations A to E perform. The block diagram which shows an example of schematic structure of the wireless base station 1 which concerns on the 3rd Embodiment of this invention. An example of the terminal identifier bitmap which the wireless base station 1 allocates. A table showing a correspondence relationship between a MAC address of a wireless terminal station and a terminal identifier bitmap. The figure which showed the structure of the transmission request packet 361 which a wireless terminal station transmits. The figure which showed the structure of the terminal specific field 362 shown by FIG. The table which shows the correspondence of the bit of a terminal identifier bitmap, and a terminal specific subcarrier. A terminal identifier bitmap assigned to the wireless terminal station by the wireless base station 1 and a format of a terminal-specific subcarrier. The flowchart of the process in which the wireless base station 1 allocates a terminal identifier and a subcarrier to a wireless terminal station. The block diagram which shows an example of schematic structure of the radio | wireless terminal station which concerns on the 3rd Embodiment of this invention. The flowchart of the process which a wireless terminal station transmits a registration request packet. 23 is a flowchart for explaining details of a process (step S163) for generating a transmission request packet in the flowchart illustrating an example of the uplink spatial multiplexing transmission process illustrated in FIG. 10 performed by the wireless terminal station illustrated in FIG. The flowchart explaining the detail of the transmission request | requirement terminal specific process (step S33) of the uplink spatial multiplexing transmission process shown in FIG. 12 which the radio base station 1 shown in FIG. 14 performs. The figure which showed the structure of the pilot signal transmission request packet 481 which the wireless base station 1 transmits. The figure which showed an example of the pilot signal request | requirement bitmap 482 shown in FIG. The figure which showed the structure of the permission terminal alerting | reporting packet 501 which the wireless base station 1 transmits. The block diagram which shows an example of schematic structure of the wireless base station 1 which concerns on the 4th Embodiment of this invention. The flowchart explaining the detail of the pilot signal request packet transmission (step S35) of the uplink spatial multiplexing transmission process shown in FIG. 12, which is performed by the wireless terminal station 1 shown in FIG. The block diagram which shows an example of schematic structure of the wireless base station 1 which concerns on the 5th Embodiment of this invention. The flowchart explaining the detail of the permission terminal selection (step S38) of the uplink spatial multiplexing transmission process shown in FIG. 3 which the radio | wireless terminal station 1 shown in FIG. 31 performs. The figure which shows an example of the field structure of the pilot signal which a radio | wireless terminal station transmits. The block diagram which shows an example of schematic structure of the wireless base station 1 which concerns on the 6th Embodiment of this invention. The flowchart explaining the detail of the permission terminal selection (step S38) of the uplink spatial multiplexing transmission process shown in FIG. 3 which the radio base station 1 shown in FIG. 34 performs. The figure which shows an example of the field structure of the pilot signal which a radio | wireless terminal station transmits. The block diagram which shows an example of schematic structure of the wireless base station 1 which concerns on the 7th Embodiment of this invention. The flowchart explaining the detail of permission data size determination which the wireless base station 1 shown in FIG. 37 performs. The figure which showed the structure of the permission terminal alerting | reporting packet 501 which the wireless base station 1 transmits. The figure which showed the specific example of the permission terminal designation | designated bitmap 502 and the permission data size field 661 of the permission terminal alerting | reporting packet 501. FIG. The block diagram which shows an example of schematic structure of the wireless base station 1 which concerns on the 8th Embodiment of this invention. FIG. 42 is a flowchart for explaining details of processing for selecting a permitted terminal and processing for controlling transmission power in uplink spatial multiplexing transmission processing performed by the radio base station 1 shown in FIG. 41; The figure which showed the structure of the permission terminal alerting | reporting packet 501. FIG. The figure which showed the specific example of the permission terminal designation | designated bitmap 502 and the transmission power control value field 701 of the permission terminal alerting | reporting packet 501. FIG. The figure which showed the structural example of the terminal specific field 362 of the transmission request packet 361. The figure which showed the other structural example of the terminal specific field 362 of the transmission request packet 361. The figure which showed the further another structural example of the terminal specific field 362 of the transmission request packet 361. FIG. The format figure which showed an example of the structure of an uplink period start request packet and an uplink period start packet. The flowchart which shows the flow of the process which changed the step of the process of FIG. 12 partially.

Claims (25)

A wireless base station that simultaneously receives data from a wireless terminal station at the same time and at the same frequency,
First transmission means for transmitting an uplink period start packet indicating the start of an uplink period to the wireless terminal station;
A first receiving means for receiving a transmission request packet for performing a transmission request from the wireless terminal station via a dedicated resource individually assigned in advance;
Based on the received transmission request packet, specifying means for specifying a wireless terminal station that has transmitted the transmission request packet;
Second transmitting means for transmitting a pilot transmission instruction packet instructing transmission of a pilot signal to the specified wireless terminal station by designating different time slots;
Second receiving means for receiving a pilot signal from the identified wireless terminal station;
Selection means for selecting an allowed terminal to grant uplink transmission permission based on the received pilot signal;
A third transmitting means for transmitting a permitted terminal notification packet indicating permission for transmission of the uplink to the permitted terminal;
Wireless base station with A third receiving means for receiving a start request packet for requesting the start of the uplink period from the wireless terminal station;
The first transmission means transmits the uplink period start packet when receiving the start request packet,
The radio base station according to claim 1, wherein the selection unit selects at least a radio terminal station that has transmitted the start request packet as the permitted terminal. Subcarrier allocation means for allocating different terminal specific subcarriers to the radio terminal station; and notification means for notifying terminal specific subcarriers allocated to the radio terminal station as the subcarriers,
The said specifying means specifies the radio | wireless terminal station which transmitted the said transmission request packet by carrying out threshold value determination of each subcarrier which forms the terminal specific field of the said transmission request packet. Wireless base station. Further comprising identifier assigning means for assigning individual bits of a bitmap including a plurality of bits corresponding to different subcarriers to the wireless terminal station as terminal specific bits,
The notifying means notifies the radio terminal station of the allocated terminal specific bit and the terminal specific subcarrier corresponding to the terminal specific bit,
The second transmission means transmits the pilot transmission instruction packet including a bitmap in which terminal specific bits of the specified wireless terminal station are set, and the order of the terminal specific bits set in the bitmap is specified. The radio base station according to claim 3, wherein each radio terminal station indicates an order of transmitting a pilot signal, and thereby designates a different time slot for the identified radio terminal station. The radio base station according to claim 4, wherein the terminal identification field in the transmission request packet is formed from a plurality of OFDM symbols corresponding to one bitmap. The transmission request packet includes a plurality of the terminal identification fields,
The radio base station according to claim 4, wherein the subcarrier allocation unit allocates a different terminal specific subcarrier for each terminal specific field to the radio terminal station. The radio base station according to claim 4, wherein the subcarrier allocation means allocates a plurality of the terminal specific subcarriers in each subcarrier forming the terminal specific field to the radio terminal station. 5. The radio according to claim 4, wherein the subcarrier allocating unit sequentially allocates subcarriers having a frequency farthest from an already allocated subcarrier when allocating the terminal specific subcarrier to the radio base station. base station. The radio base station according to any one of claims 4 to 8, wherein the notification unit performs notification through a beacon signal that is periodically transmitted. Channel information calculating means for calculating channel information of the specified wireless terminal station based on a pilot signal received from the specified wireless terminal station;
Channel information holding means for holding the channel information;
A channel information elapsed timer for measuring an elapsed time since the channel information was acquired,
The selection means selects the permitted terminal based on the channel information,
The second transmission means omits the designation of a radio terminal station whose elapsed time since the acquisition of the channel information is equal to or less than a threshold time, and designates only the radio terminal station that is greater than the threshold time The radio base station according to any one of claims 1 to 9, wherein a transmission instruction packet is transmitted. Channel information calculating means for calculating channel information of each of the specified wireless terminal stations based on pilot signals received from a plurality of the specified wireless terminal stations;
SNR measuring means for measuring a signal-to-noise ratio (SNR) based on pilot signals received from the plurality of specified wireless terminal stations;
Channel capacity calculating means for generating a combination of the specified wireless terminal stations and calculating a channel capacity from the channel information and the SNR for each of the combinations;
The radio base station according to any one of claims 1 to 10, wherein the selection unit selects the combination having the maximum channel capacity as the permitted terminal. Power measuring means for measuring received power of a pilot signal received from at least the permitted terminal among the identified wireless terminal stations;
Transmission power control means for determining an increase / decrease value of the transmission power for the permitted terminal so that the received power from the permitted terminal falls within a predetermined range;
The radio base station according to any one of claims 1 to 11, wherein the third transmission unit includes an increase / decrease value determined for the permitted terminal in the permitted terminal notification packet. The second receiving means receives a signal of an allowable delay time of data to be transmitted on the uplink together with the pilot signal from the specified wireless terminal station,
The said selection means selects the said permission terminal so that the radio | wireless terminal station which notified at least the minimum allowable delay time or the allowable delay time below a threshold value may be included. The radio base station described in 1. Transmission mode determining means for determining a transmission mode of the permitted terminal based on a pilot signal received from the permitted terminal;
An authorized data size determining means for determining an authorized data size of the authorized terminal;
The second receiving means receives a signal indicating a data size of data to be transmitted on the uplink together with the pilot signal,
The permitted data size determining means calculates a packet time length from the transmission mode and the data size for the permitted terminal, and determines the permitted data size of the permitted terminal so that each packet time length falls within a predetermined range. And
The third transmission means includes the transmission mode determined for the permitted terminal and the permitted data size in the permitted terminal notification packet.
The radio base station according to claim 1, wherein the radio base station is a radio base station. A packet type identifier field of the uplink period start packet;
A packet type identifier field of the pilot transmission instruction packet, identification data of the specified wireless terminal station, time slot data of the specified wireless terminal,
The packet type identifier field of the permitted terminal notification packet and the identification data of the permitted terminal are:
The radio base station according to any one of claims 1 to 14, wherein the radio base station is added to the end of a packet of an existing radio communication system. A wireless terminal station that performs data transmission to a wireless base station at the same time and at the same frequency as other wireless terminal stations,
A fourth receiving means for receiving an uplink period start packet indicating the start of an uplink period from the radio base station;
A fourth transmission means for transmitting a transmission request packet for performing a transmission request via a dedicated resource allocated in advance at a predetermined timing after receiving the uplink period start packet;
Fifth transmission means for receiving a pilot transmission instruction packet instructing transmission of a pilot signal from the radio base station by designating a time slot after transmitting the transmission request packet;
Fifth transmission means for transmitting a pilot signal in a time slot specified in the pilot transmission instruction packet;
Sixth receiving means for receiving a permitted terminal notification packet notifying that the transmission request is permitted;
Sixth transmission means for transmitting data at a predetermined timing after the permitted terminal notification packet is received;
Wireless terminal station equipped with. The radio terminal station according to claim 16, further comprising: seventh transmission means for transmitting a start request packet for requesting the start of the uplink period to the radio base station. 17. The wireless terminal station according to claim 16, wherein the transmission request in the transmission request packet is added to the end of a packet of an existing wireless communication system. A seventh receiving means for receiving a terminal specific subcarrier allocation notification as the dedicated resource from the radio base station;
The said 4th transmission means allocates a request signal to the said terminal specific subcarrier among each subcarrier which forms the terminal specific field of the said transmission request packet. The one of Claim 16 thru | or 18 characterized by the above-mentioned. Wireless terminal stations. The seventh receiving means receives an allocation notification as a terminal specific bit for one of individual bits of a bitmap including a plurality of bits from the radio base station,
The fifth transmission means determines that the pilot transmission instruction packet transmitted from the radio base station includes the bitmap, and transmits the pilot signal when the terminal specific bit is set in the bitmap. The time slot for transmitting the pilot signal is determined based on a relative position of the terminal specific bit among all bits standing in the bitmap. The wireless terminal station according to one item. The radio terminal station according to any one of claims 16 to 20, wherein the fifth transmission means transmits a signal of an allowable delay time of data transmitted on the uplink together with the pilot signal. The radio terminal station according to any one of claims 16 to 21, wherein the fifth transmission means transmits a signal indicating a data size of data to be transmitted on the uplink together with the pilot signal. A wireless communication method executed in a wireless base station that simultaneously receives data from a wireless terminal station at the same time and at the same frequency,
A first transmission step of transmitting an uplink period start packet indicating the start of an uplink period to the wireless terminal station;
A first reception step of receiving a transmission request packet for performing a transmission request from the wireless terminal station via a dedicated resource allocated individually in advance;
A identifying step for identifying a wireless terminal station that has transmitted the transmission request packet based on the received transmission request packet;
A second transmission step of transmitting a pilot transmission instruction packet instructing transmission of a pilot signal to the identified wireless terminal station by designating a different time slot;
A second receiving step of receiving a pilot signal from the identified wireless terminal station;
A selection step of selecting an allowed terminal to grant uplink transmission permission based on the received pilot signal;
A third transmission step of transmitting a permitted terminal notification packet indicating permission of transmission of the uplink to the permitted terminal;
A wireless communication method comprising: A wireless communication method executed in a wireless terminal station that performs data transmission to a wireless base station at the same time and at the same frequency as other wireless terminal stations,
A third receiving step of receiving an uplink period start packet indicating the start of an uplink period from the radio base station;
A fourth transmission step of transmitting a transmission request packet for performing a transmission request via a dedicated resource allocated in advance at a predetermined timing after receiving the uplink period start packet;
A fourth reception step of receiving a pilot transmission instruction packet instructing transmission of a pilot signal from the radio base station by designating a time slot after transmitting the transmission request packet;
A fifth transmission step of transmitting a pilot signal in a time slot designated in the pilot transmission instruction packet;
A fifth reception step of receiving a permitted terminal notification packet notifying that the transmission request is permitted;
A sixth transmission step of transmitting data at a predetermined timing after the permitted terminal notification packet is received;
A wireless communication method comprising: A wireless communication system comprising a wireless base station and a wireless terminal station, wherein the wireless terminal station performs data transmission to the wireless base station at the same time and at the same frequency,
The radio base station transmits an uplink period start packet indicating the start of an uplink period to the radio terminal station,
A wireless terminal station having transmission data to the wireless base station transmits a transmission request packet for performing a transmission request via a dedicated resource allocated in advance at a predetermined timing after receiving the uplink period start packet. And
The wireless base station transmits a pilot transmission instruction packet instructing transmission of a pilot signal by designating a different time slot to the wireless terminal station that has transmitted the transmission request packet,
The wireless terminal station that has received the pilot transmission instruction packet transmits a pilot signal in a time slot specified in the pilot transmission instruction packet;
Based on the received pilot signal, the radio base station selects a permitted terminal that grants uplink transmission permission, and transmits a permitted terminal notification packet indicating the uplink transmission permission to the permitted terminal,
The wireless communication system, wherein the authorized terminal simultaneously transmits data at a predetermined timing after receiving the authorized terminal notification packet.

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