JP5574855B2 - Wireless communication system, wireless base station, wireless terminal station, and wireless communication method - Google Patents

Description

  The present invention relates to a radio communication system in which a radio base station transmits data to a plurality of radio terminal stations.

  In a wireless system using IEEE802.11a / b / g / n (hereinafter referred to as a WLAN (Wireless Local Area Network) system), a WLAN system is configured in consideration of interoperability with other networks or other systems. CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance), which is a radio access scheme in which each radio terminal performs carrier sense on a radio channel prior to transmission of a radio packet, has been mainly introduced. In CSMA / CA, if the wireless terminal confirms that the channel is in use (channel busy) as a result of carrier sense, the wireless terminal refrains from transmitting a wireless packet, and the channel unused (channel idle) determined in advance for each frame type. Send radio packets in time or after backoff time.

  Also, in the WLAN system, a wireless terminal performs a virtual carrier sense that causes a neighboring terminal to set a NAV (Network Allocation Vector) by a control frame or the like before transmitting a wireless packet, and refrains from transmitting a wireless packet during NAV setting. By using this method, a method of reserving a band of a frame and a frame sequence period has been introduced.

  For example, as a method for reserving a communication band, the following Non-Patent Document 1 discloses a PCF (Point Coordination Function) technique in which a non-collision time called CFP (Contention Free Period) is set for each fixed Beacon interval. . In PCF, a base station reserves a band for a certain period after Beacon transmission using NAV, and polls the wireless terminal stations under the base station to give each wireless terminal a transmission opportunity. .

  In IEEE 802.11e / n, priority is given to a specific wireless packet or a wireless packet defined by a specific packet sequence by changing the carrier sense time or the back-off time based on the priority of the wireless packet to be transmitted. A mechanism to transmit automatically is provided. For example, Non-Patent Document 2 below discloses a PSMP (Power Save Multiple Poll) technique defined in IEEE 802.11n. In PSMP, a base station notifies a transmission start time, a transmission allocation time, and the like for each transmission terminal using a PSMP packet, thereby enabling highly efficient communication with no carrier sense time.

  On the other hand, with regard to the retransmission method, in the conventional WLAN system, when the wireless packet does not normally reach the transmission partner due to packet collision, insufficient reception power, or the like, the transmission terminal transmits an acknowledgment frame (ACK) from the reception terminal. Is not returned, the frame is retransmitted after a predetermined channel unused time or backoff time. In addition, using the BlockACK method defined in IEEE802.11e / n, the retransmission method and the buffer capacity of the transmitting and receiving terminals are exchanged between the transmitting side and the receiving side in advance, and ACK is returned in batches for multiple packets. By doing so, the receiving terminal notifies the transmitting terminal of a packet that could not be normally received in the past.

  In the conventional WLAN system, the packet arrival establishment is improved by using these access methods and retransmission methods.

IEEE 802.11-2007 IEEE802.11n / D11.0, June 2009

  However, in the above conventional access method and retransmission method, even if the time for packet transmission can be reserved in advance, scheduling considering packet retransmission cannot be performed, and the delay time and packet arrival rate at the time of packet retransmission can be guaranteed. I can't. For this reason, there has been a problem that the wireless communication quality cannot be guaranteed in a wireless environment where the delay time and the packet arrival rate must be guaranteed. On the other hand, when the bandwidth is allocated in advance in consideration of the retransmission time, there is a problem that when the retransmission does not occur, the bandwidth is secured excessively and communication of other wireless terminal stations is reduced.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a radio communication system capable of performing delay time guarantee type user selection retransmission control.

  In order to solve the above-described problems and achieve the object, the present invention is a wireless communication system including a wireless base station and a wireless terminal station, wherein the wireless base station transmits a beacon at a predetermined interval. A bandwidth reservation frame for notifying a period allocated for transmitting / receiving data to / from a wireless terminal station subject to data transmission / reception, and a data transmission prohibition period to a wireless terminal station not subject to data transmission / reception, In the data transmission allocation period of the own station, scheduler means for transmitting a base station data frame to the data transmission / reception target wireless terminal station, and whether or not the terminal station data frame has been received from all the data transmission / reception target wireless terminal stations Based on the confirmation result and the number of times retransmission control was performed to receive the terminal station data frame that could not be received. Frame analysis means for determining whether to perform retransmission, and retransmission control means for instructing the scheduler means to transmit a bandwidth reservation frame when the frame analysis means determines to perform retransmission control, and When the wireless terminal station is the target for data transmission / reception, it transmits the terminal station data frame to the wireless base station in the period allocated to the own station included in the received bandwidth reservation frame, while the data transmission / reception target In the case of outside, an access control means that does not transmit data during the transmission prohibition period is provided.

  According to the present invention, there is an effect that the delay time and the packet arrival rate at the time of packet retransmission can be guaranteed.

FIG. 1 is a diagram illustrating a configuration example of a wireless communication system. FIG. 2 is a time chart showing the communication status between the radio base station and the radio terminal stations under the PCF system. FIG. 3 is a time chart showing the communication status between the radio base station and the radio terminal stations under the PSMP system. FIG. 4 is a time chart showing the communication status between the radio base station and the radio terminal stations under the PSMP system. FIG. 5 is a diagram illustrating a configuration example of a PSMP frame. FIG. 6 is a diagram illustrating a configuration example of the PSMP STA Info field. FIG. 7 is a diagram illustrating a configuration example of the radio base station (AP10). FIG. 8 is a flowchart showing delay time guarantee type user selection retransmission control. FIG. 9 is a time chart showing delay time guarantee type user selection retransmission control. FIG. 10 is a time chart showing delay time guarantee type user selection retransmission control. FIG. 11 is a flowchart showing delay time guarantee type user selection retransmission control. FIG. 12 is a diagram illustrating a configuration example of a BP-Reservation frame. FIG. 13 is a diagram illustrating an example of aggregation of a BP-Reservation frame and a BroadcastPolling frame.

  Embodiments of a wireless communication system according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
First, the conventional PCF method and PSMP method will be briefly described with reference to the drawings.

  First, the PCF method will be described. FIG. 1 is a diagram illustrating a configuration example of a radio communication system including a radio base station (AP10) and subordinate radio terminal stations (here, STA1, STA2, STA3, STA4, STA5, and STA6). The surrounding circles indicate the communication area of the radio base station (AP10), and all the terminal stations (STA1 to STA6) exist in the communication area. Although not shown, it is assumed that all wireless terminal stations (STA1 to STA6) exist in an area where they can communicate with each other. Further, the wireless base station (AP 10) can be connected to the Internet, another network, a subnet, or the like by Ethernet (registered trademark) or the like.

  FIG. 2 shows the relationship between the radio base station (AP10) and the subordinate radio terminal stations (STA1 to STA6) and other radio base stations or radio terminal stations that do not belong to the radio base station (AP10) with the horizontal axis as time. It is a time chart which shows a communication condition. The radio base station (AP10) transmits a beacon that is a broadcast signal at a constant period, and broadcasts base station information to subordinate radio terminal stations (STA1 to STA6). A certain period of time from Beacon to the next Beacon is defined as Superframe. Superframe is divided into PCF, which is the non-collision time (CFP), and DCF (Distributed Coordination Function), which is the collision period (CP). The former reserves the band in advance using the virtual carrier sense information of the radio base station (AP10). The latter is a period in which each wireless terminal station accesses by the carrier sense method. Note that other radio base stations or radio terminal stations that do not belong to the radio base station (AP10) exist in the communication area of the radio base station (AP10), but are connected to the radio base station (AP10). It is assumed that the wireless base station or the wireless terminal station is not used.

  Here, a state in which the radio base station (AP10) is accessing the radio terminal stations (STA1 to STA4) using the PCF method in the CFP period is shown. At this time, the wireless terminal stations (STA5 to STA6) and other wireless terminal stations operating at the same frequency (corresponding to Others in FIG. 2) are suppressed from transmission by the virtual carrier sense information (NAV). The frames used in the PCF method are “CF-Poll” which is a polling frame transmitted by the radio base station (AP10), data packet “Data (to STA X)” (X is the number of the radio terminal station), and PCF. “CF-End” indicating the end of the period.

  First, at time t0, the radio base station (AP10) transmits Beacon and sets a non-collision period CFP. Thereafter, at time t1, the radio base station (AP10) transmits a polling signal and “Data (to STA 1) + CF-Poll”, which is data for the radio terminal station (STA1), to the radio terminal station (STA1). . At time t2, the wireless terminal station (STA1) transmits “ACK”, which is an acknowledgment frame for the received data packet, and a data packet for the wireless base station (AP10) in “Data (from STA 1) + ACK”. Send.

  Next, at time t3, the radio base station (AP10) similarly polls the radio terminal station (STA2), data for the radio terminal station (STA2), and further from the radio terminal station (STA1). “ACK”, which is an acknowledgment frame for the received data, is transmitted by “Data (to STA 2) + CF-Poll + ACK”. At time t4, the wireless terminal station (STA2) transmits “ACK”, which is an acknowledgment frame for the received data packet, and a data packet for the wireless base station (AP10) in “Data (from STA 2) + ACK”. Send.

  Here, at time t5, when the wireless base station (AP10) polls and transmits a data frame to the wireless terminal station (STA3), there is no response frame (the frame at time t6 is an error or not yet). Transmission), the wireless base station (AP10) transmits “Data (to STA 4) + CF-Poll” which is polling and data for the wireless terminal station (STA4) at time t7 which is the next polling opportunity, and the wireless terminal No retransmission is performed for the station (STA3).

  When the polling for the wireless terminal stations (STA1 to STA4) listed in advance is completed, the wireless base station (AP10) transmits “CF-End” at time t9 to complete the PCF access and complete the CFP period. Shift to the CF period. In the CF period, the wireless base station (AP10) and the wireless terminal stations (STA1 to STA6) access using the above-described CSMA / CA.

  In the PCF method, the radio base station (AP 10) reserves a radio band as described above, thereby creating a non-collision period and enabling communication with guaranteed bandwidth to subordinate radio terminal stations (STA1 to STA4). It has become. On the other hand, when a packet is lost, retransmission is not performed, but retransmission is performed during the CF period or the CFP period of the next superframe.

  Next, the PSMP method will be described with reference to FIGS. 3 and 4 show the radio base station (AP10) and subordinate radio terminal stations (STA1 to STA6), and other radio base stations or radio terminals not belonging to the radio base station (AP10), with the horizontal axis as time. It is a time chart which shows the communication condition with a station. Note that the configuration of the wireless communication system is the same as that shown in FIG. Here, the wireless base station (AP10) shows a state in which communication is performed with subordinate wireless terminal stations (STA1 to STA4) using a PSMP packet sequence. At this time, wireless terminal stations (STA5 to STA6) and other wireless terminal stations operating at the same frequency (corresponding to Others in FIGS. 3 and 4) are suppressed from transmission by virtual carrier sense information (NAV). .

  In the PSMP method, a “PSMP Parameter Set” including the number of scheduling wireless terminals, More PSMP, PSMP sequence period, and the like included in the PSMP frame (FIGS. 5 and 6) transmitted by the wireless base station (AP10), and the terminal ID ( Or group ID), transmission start time for downlink (PSMP-DTT Start Offset) / transmission period (PSMP-DTT Duration), transmission start time for uplink (PSMP-UTT Start Offset) / transmission period (PSMP-UTT) The wireless terminal stations (STA1 to STA4) that have received the PSMP frame perform transmission / reception based on the scheduling information based on the “PSMP STA Info” field including the “Duration”.

  FIG. 5 is a diagram illustrating a configuration example of a PSMP frame. In the table of Order and Information, each item in the Information indicates the structure of the PSMP frame. The PSMP frame includes a “Category” field indicating HT (High Throughput), an “Action” field indicating PSMP or PSBP (Power Save Broadcast Polling), and a “PSMP Parameter Set” indicating the content and length of the PSMP STA Info field. ”Field and a“ PSMP STA Info ”field including PSMP time scheduling information.

  FIG. 6 is a diagram illustrating a configuration example of the “PSMP STA Info” field of the PSMP frame. FIG. 6A illustrates a group address, and FIG. 6B illustrates an individual address.

  The “PSMP STA Info” field in FIG. 6A includes “STA_INFO Type” indicating the STA Info type, “PSMP-DTT Start Offset” indicating the transmission start time for the downlink, and a transmission period for the downlink. “PSMP-DTT Duration” indicating “PSMP Group Address ID” indicating the address of the group.

  The “PSMP STA Info” field in FIG. 6B includes “STA_INFO Type” indicating the STA Info type, “PSMP-DTT Start Offset” indicating the transmission start time for the downlink, and a transmission period for the downlink. “PSMP-DTT Duration” indicating “STA_ID” indicating an address of an individual wireless terminal station, “PSMP-UTT Start Offset” indicating transmission start time for uplink, and “PSMP-UTT Start Offset” indicating transmission period for uplink “PSMP-UTT Duration” and “Reserved” indicating a spare area or the like.

  In FIG. 3, first, at time t0, the radio base station (AP 10) transmits a PSMP frame and sets a PSMP period. Thereafter, based on the downlink scheduling information in the PSMP frame, a data packet for the wireless terminal station (STA1) is transmitted at time t1. Similarly, data packets are transmitted to wireless terminal stations (STA2 to STA4) scheduled in advance by PSMP at times t2, t3, and t4.

  Next, at time t5, based on the uplink scheduling information in the PSMP frame, the wireless terminal station (STA1) transmits a data packet. Similarly, at time t6, t9, t10, wireless terminal stations (STA2 to STA4) scheduled in advance by PSMP transmit data packets. Here, if the wireless terminal stations (STA2, STA3) miss the PSMP frame as shown in FIG. 3, the wireless base station (AP10) “PSMP-UTT2” at time t6 as shown in FIG. ”Is detected, a“ PSMP-Recovery ”frame is transmitted at a time t7 after a certain time, and the scheduling information is retransmitted again to the wireless terminal stations (STA2, STA3) that have missed the PSMP frame. .

  The wireless terminal station (STA2) that has received the “PSMP-Recovery” frame transmits a data packet from time t8 at the allocated time. Similarly, the wireless terminal station (STA3) also resets the uplink scheduling and transmits a data packet from time t9. The PSMP frame sequence is completed at time t11 reserved in advance with the PSMP frame.

  As described above, in the PSMP frame sequence, the radio base station (AP 10) notifies the subordinate radio terminal stations (STA1 to STA4) of downlink and uplink scheduling in advance, thereby enabling non-collision access. In addition to providing a system, a high-efficiency access system that does not require carrier sense time and back-off time unlike conventional CSMA / CA is provided. Further, when the “PSMP-UTT” frame is not notified from the wireless terminal station side, the wireless base station (AP 10) provides a mechanism for notifying the wireless terminal station side of scheduling information again using the “PSMP-Recovery” frame. ing.

  Next, the radio communication system according to the present embodiment will be described. The configuration of the wireless communication system is the same as in FIG. The wireless system includes a wireless base station (AP10) and wireless terminal stations (STA1 to STA6). The wireless base station (AP10) is, for example, a wireless base station connected to a LAN (Local Area Network) that is a wired network. The wireless terminal stations (STA1 to STA6) are wireless terminal stations installed in the service area of the wireless base station (AP10).

  The wireless terminal stations (STA1 to STA6) are information terminals such as a personal computer, a television, a video, and a music player, for example. The wireless base station (AP10) is connected to a wired network (LAN) as an example, but may be an information terminal such as a personal computer, a television, a video, or a music player, similarly to the wireless terminal stations (STA1 to STA6). Good. The network interface may be for wireless connection instead of wired connection.

  In the present embodiment, the wireless base station and the wireless terminal station are distinguished from each other and described as the infrastructure mode. However, the present invention is not limited to this. For example, the present invention can be applied to a network configuration in which a wireless terminal station adaptively operates as a wireless base station, and also to an Ad-hoc (ad hoc) mode in which wireless terminal stations cooperate in an autonomous and distributed manner. Applicable. The present invention is also applicable to a WDS (Wireless Distribution System) that performs communication between wireless base stations and expands a communication area, and a mesh network.

  FIG. 7 is a diagram illustrating a configuration example of the radio base station (AP10). The radio base station (AP 10) relates to radio propagation information such as an interface unit 20 that performs input / output control for a wired network or a device, and an antenna / directional beam direction / space multiplexing number related to the radio base station and the radio terminal station. Performs access control for transmission and reception with information storage unit 30 that holds information, information related to access control / network control such as connection terminal / base station information, scheduler information, frame multiplexing information (aggregation), and retransmission control method An access control (MAC: Media Access Control) unit 40, a modulation / demodulation unit 50 that modulates and demodulates transmission / reception signals, and selection of a directional beam and control of multiple input multiple output (MIMO) by antenna selection or antenna adjustment. Configure the beam control unit 60 to perform and a plurality of antennas shared for transmission and reception The antenna unit 70 can be used to transmit / receive a plurality of directional beams / a plurality of spatially multiplexed signals.

  The access control unit (MAC unit) 40 includes a scheduler unit 41 that determines data transmission timing, a frame analysis unit 42 that analyzes the content of the received frame, and a retransmission that instructs retransmission of the frame when the frame needs to be retransmitted. And a control unit 43.

  The modulation / demodulation unit 50 includes a transmission unit 51 that performs error correction and modulation of transmission data, a reception unit 52 that analyzes received data, performs demodulation and error correction, received power from the reception unit 52, S / N, C / And a quality measuring unit 53 that measures the quality of a frame received from information such as N.

  The antenna unit 70 includes an antenna for transmitting and receiving data to and from other radio communication devices (other radio base stations and radio terminal stations), and is controlled by the beam control unit 60. Each antenna constituting the antenna unit 70 may be, for example, a phased array antenna having directivity and a variable directivity direction, or an omnidirectional omni antenna. Furthermore, it may be a directional antenna that includes a plurality of directional antennas and that can change the directional direction by adaptively switching the antennas.

  Next, a data transmission / reception operation in the radio base station (AP 10) having the above-described configuration will be described with reference to FIG.

  As an example, in the case where the interface unit 20 includes an interface to the wired LAN, the frame check is performed on the data input from the wired LAN, the header and the like are processed, and then the access control unit (MAC unit) Hand over to 40. The reception data (from the wireless terminal station) received from the access control unit (MAC unit) 40 is output to the wired LAN after adding a header and a frame check sequence to the wired LAN format. As another example, an interface for an information terminal such as PCMCIA, USB, IEEE1394, SDIO, and HDMI can be mounted.

  The access control unit (MAC unit) 40 performs sub-frame headers when performing aggregation (A-MPDU (Aggregation MAC Protocol Unit) method) on data received from the interface unit 20 during data transmission to the wireless terminal station. Alternatively, after adding a delimiter and the like, a plurality of data is multiplexed, a MAC header and a frame check sequence are added, and then the data is delivered to the transmission unit 51 of the modem unit 50 according to the timing determined by the scheduler unit 41. Note that aggregation may not be performed for a predetermined frame type, and aggregation may be performed after adding a MAC header and a frame check sequence. At this time, the access control unit (MAC unit) 40 receives from the information storage unit 30 a directional beam number of the transmission destination (or a weight value for beam control), a control value for spatial multiplexing (MIMO) (phase). , Amplitude, antenna, etc.) and the like, and the beam control unit 60 is notified of the directional beam number to be transmitted and the spatial multiplexing method.

  In addition, the access control unit (MAC unit) 40 notifies the beam control unit 60 of the beam direction to be received based on information that is notified in advance at the time of data reception or that is measured at the time of packet reception. The received data is delivered from the modem unit 50 to the access control unit (MAC unit) 40, and the access control unit (MAC unit) 40 confirms the frame check sequence and the destination address in the MAC header with the frame analysis unit 42. As a result, if the frame is wrong or the frame is not addressed to the own station, the frame is discarded.

  When a NACK is returned using BlockACK or the like, when an acknowledgment (ACK) cannot be received within a predetermined acknowledgment (ACK) timeout time, or received data from a wireless terminal station at a scheduled time If the signal does not come, the frame analysis unit 42 determines whether or not to perform retransmission control. When performing retransmission control, the frame analysis unit 42 notifies the retransmission control unit 43 to that effect and instructs the data to be retransmitted. If the frame requires a response, the frame analysis unit 42 notifies the scheduler unit 41 and instructs to transmit the response frame at the notified timing. Alternatively, the scheduler unit 41 determines the transmission timing and instructs to transmit a response frame. In addition, the frame analysis unit 42 delivers a normally received data frame to the interface unit 20. Note that, in delay time guarantee type user selection retransmission control, which will be described later in this embodiment, it is also possible to secure a band for retransmission control based on this function.

  Furthermore, the access control unit (MAC unit) 40 receives information on the reception quality measured by the quality measurement unit 53 of the modem unit 50, and includes a terminal address (terminal identifier such as a MAC address and a device address) included in this information, Information such as a channel number (spatial channel, frequency channel), directional beam number, spatial multiplexing (MIMO) control value, received power value, interference power value, etc. is recorded in the information storage unit 30 as needed and updated. By performing such an operation, the access control unit (MAC unit) 40 performs directional beam control, spatial multiplexing control, and operating frequency control using information read from the information storage unit 30, and a desired wireless terminal Communicate with the station.

  The configuration of the wireless base station (AP 10) and the operation of each unit at the time of data transmission / reception have been described above. However, the configuration of the wireless terminal station (STA1 to STA6) and the operation of each unit are the same. The number of antennas and the number of directional beams may be different between the radio base station (AP10) and each radio terminal station (STA1 to STA6).

  Subsequently, delay time guarantee type user selection retransmission control in the present embodiment will be described based on a flowchart. FIG. 8 is a flowchart showing the delay time guarantee type user selection retransmission control according to the present embodiment. Specifically, the case of the time chart shown in FIG. 9 will be described. FIG. 9 is a time chart showing the delay time guarantee type user selection retransmission control according to the present embodiment. It is the figure which showed the communication condition with a radio base station (AP10) and subordinate radio terminal stations (STA1-STA6), other radio base stations which do not belong to a radio base station (AP10), or a radio terminal station on the horizontal axis. is there.

  First, at time t0, in the radio base station (AP10), the scheduler unit 41 transmits a beacon that is a notification signal at regular intervals, and notifies base station information to subordinate radio terminal stations (STA1 to STA6). (Step S1). The bandwidth reservation period indicates a period during which the CFP, CAP, radio base station, or radio terminal station acquires TXOP. The random access period indicates a period during which the radio base station and the radio terminal station perform random access by CSMA / CA.

  Next, at time t1, in the radio base station (AP10), the scheduler unit 41 transmits a BP-Reservation frame, performs scheduling in the downlink direction for subordinate radio terminal stations (STA1 to STA6), and uplink direction. The scheduling time is notified (step S2). Details of the frame format will be described later with reference to FIG. At this time, in order to realize priority reservation for bandwidth reservation for the user-selected retransmission control (1) for the data communication period (time t1 to t6), the NAV setting for the other wireless terminal station is the original data communication period. A reservation is made at time t9, which is longer than time t6. By reserving the band, a BP-Reservation frame for performing user-selected retransmission control (1) can be preferentially transmitted.

  In addition, since transmission is not possible at timings other than the downlink scheduling information and uplink scheduling information specified in the BP-Reservation frame, each wireless terminal station is in a low power consumption mode other than the transmission / reception timing notified by BP-Reservation. (For example, the power of the transceiver is turned off, the mode is changed to the sleep mode, etc.).

  In this embodiment, the bandwidth reservation time of the BP-Reservation frame is set to + xIFS time after completion of transmission of the next BP-Reservation frame (xIFS time indicates PIFS, DIFS, AIFS, RIFS, or dedicated carrier sense time). However, the value is not limited to this value as long as the BP-Reservation frame can be preferentially transmitted. Also, if the priority for transmitting the BP-Reservation frame can be set with priority over other frames (the carrier sense time for the BP-Reservation frame is shortened, the random backoff time is shortened, or a combination thereof). , It is not necessary to take a long NAV setting.

  Next, at time t2, in the radio base station (AP10), the scheduler unit 41 transmits a BroadcastPolling frame and distributes data in the downlink direction to the subordinate radio terminal stations (STA1 to STA6) (step S3). Here, the BroadcastPolling frame is used to collectively transmit or control the same data to the wireless terminal stations (here, STA1 to STA6) scheduled in the BP-Reservation frame. Or it is also possible to transmit with respect to a specific radio | wireless terminal station group (for example, STA1, STA2, STA5). At that time, it is possible to transmit by using a group address (also referred to as a multicast address) whose destination address is determined in advance.

  In addition, when individually performing data communication with the wireless terminal stations (STA1 to STA6), as shown in FIG. 13 to be described later, it is also possible to realize by multiplexing (aggregating) frames on one data. Moreover, it is also possible to transmit for each terminal like the conventional PSMP-DTT1 to PSMP-DTT4 shown in FIGS.

  Thereafter, in each wireless terminal station (STA1 to STA6), the scheduler unit 41 transmits data to the wireless base station (AP10) based on the uplink scheduling information (transmission start time, transmission period) notified in the BP-Reservation frame. A frame is transmitted (step S4).

  At time t3, based on the scheduled uplink scheduling information in the BP-Reservation frame, the wireless terminal station (STA1) transmits a data frame, and the wireless base station (AP10) receives normally. .

  At time t4, based on uplink scheduling information in BP-Reservation, the wireless terminal station (STA2) is allocated as an opportunity to transmit a data frame in advance, but the wireless terminal station (STA2) transmits a BP-Reservation frame. It shows a state where the wireless terminal station (STA2) did not receive normally, or the wireless terminal station (STA2) transmitted a data frame but did not reach the wireless base station (AP10) normally.

  Similarly, at time t5, based on the uplink scheduling information in the BP-Reservation frame, the wireless terminal station (STA6) transmits a data frame and the wireless base station (AP10) normally receives the data frame. .

  Next, in the radio base station (AP10), the frame analysis unit 42 confirms whether or not data frames have been received from all radio terminal stations (STA1 to STA6) subject to data transmission / reception (step S5). Here, since there is a wireless terminal station that has not received a data frame (step S5: No), next, in the wireless base station (AP10), the frame analysis unit 42 is “data communication (first time)”. Therefore, the user-selected retransmission control (1) is executed within the prescribed number of retransmissions (step S6: Yes). At this time, the frame analysis unit 42 notifies the retransmission control unit 43 that the wireless terminal stations (STA2, STA3, STA5) perform retransmission control for data transmission / reception. That is, the frame analysis unit 42 instructs the retransmission control unit 43 to transmit a BP-Reservation frame whose data transmission / reception targets are wireless terminal stations (STA2, STA3, STA5).

  Next, it is assumed that uplink data from the wireless terminal stations (STA2, STA3, STA5) has dropped in the data communication (first time), and the subsequent operation of user-selected retransmission control (1) will be described.

  At time t7, an example of user-selected retransmission control for a wireless terminal station in which the wireless base station (AP10) has not received uplink data in data communication (first time) from the time t0 to t6 is shown. In the radio base station (AP10), the scheduler unit 41 that has received an instruction from the retransmission control unit 43 transmits a BP-Reservation frame for transmitting / receiving data to / from the radio terminal stations (STA2, STA3, STA5), and the subordinate radio terminal The scheduling time in the uplink direction is notified to the stations (STA2, STA3, STA5) (step S2). At this time, although not shown in the figure, if the downlink direction frame is retransmitted or individually transmitted, the scheduling time in the downlink direction can be notified and transmitted. If there is no frame in the downlink direction, step S3 may be omitted.

  In transmitting this BP-Reservation frame, as described above, the NAV for another wireless terminal station is set redundantly in the BP-Reservation frame at time t1, or the carrier sense time or back-off time of the BP-Reservation frame is set. Is preferentially set with respect to other frames, so that a BP-Reservation frame is transmitted without obtaining a band in the other frames, and control is performed so that user-selected retransmission control (1) can be performed.

  At time t8, NAV is transmitted to other wireless terminal stations (here, subordinate STA1, STA4, and STA6 that are not included in the user-selected retransmission control (1) are included) by the BP-Reservation frame transmitted at time t7. Update. At this time, the reservation is made at time t15, which is longer than time t12, which is the original communication period, as in the previous NAV setting degree. By reserving the band, a BP-Reservation frame for performing user-selected retransmission control (2) can be transmitted with priority.

  Thereafter, in each wireless terminal station (STA2, STA3, STA5), based on the uplink scheduling information (transmission start time, transmission period) notified in the BP-Reservation frame, the scheduler unit 41 operates the wireless base station (AP10). A data frame is transmitted to (step S4).

  At time t9, based on the uplink scheduling information in the BP-Reservation frame, the wireless terminal station (STA2) is assigned as an opportunity to transmit a data frame, but again, the wireless terminal station (STA2) is BP- It shows a state where the Reservation frame has not been normally received, or the wireless terminal station (STA2) has transmitted the data frame but has not normally reached the wireless base station (AP10).

  At time t10, based on the uplink scheduling information in the BP-Reservation frame, the wireless terminal station (STA3) transmits a data frame, and the wireless base station (AP10) receives normally.

  At time t11, based on the uplink scheduling information in the BP-Reservation frame, the wireless terminal station (STA5) is assigned as an opportunity to transmit a data frame, but again, the wireless terminal station (STA5) is BP-Reservation. It shows a state where the frame is not normally received, or the wireless terminal station (STA2) transmits the data frame but does not reach the wireless base station (AP10) normally.

  Next, in the radio base station (AP10), the frame analysis unit 42 confirms whether or not data frames have been received from all the radio terminal stations (STA2, STA3, STA5) that are data transmission / reception targets (step S5). Here, since there is a wireless terminal station that has not received the data frame (step S5: No), the frame analysis unit 42 performs user selection retransmission control (1) in the wireless base station (AP10). Then, within the prescribed number of retransmissions (step S6: Yes), user-selected retransmission control (2) is executed. At this time, the frame analysis unit 42 notifies the retransmission control unit 43 that retransmission control is performed on the wireless terminal stations (STA2 and STA5) as data transmission / reception targets. That is, the frame analysis unit 42 instructs the retransmission control unit 43 to transmit a BP-Reservation frame whose data is transmitted / received to the wireless terminal stations (STA2, STA5).

  Next, assuming that uplink data from the wireless terminal stations (STA2 and STA5) has dropped in the user selection retransmission control (1), the subsequent operation of the user selection retransmission control (2) will be described.

  At time t13, similarly to the previous user selection retransmission control (1), the radio base station (AP10) has not received uplink data in the user selection retransmission control (1) during the period from time t7 to t12. The user selection resending control example with respect to a terminal is shown. In the radio base station (AP10), the scheduler unit 41 that has received an instruction from the retransmission control unit 43 transmits a BP-Reservation frame for data transmission / reception to the radio terminal stations (STA2, STA5), and the subordinate radio terminal station ( The scheduling time in the uplink direction for STA2 and STA5) is notified (step S2). At this time, similarly to the above-described contents, although not shown in the figure, if the frame in the downlink direction is retransmitted or individually transmitted, the scheduling time in the downlink direction can be notified and transmitted. It is. If there is no frame in the downlink direction, step S3 may be omitted.

  When transmitting this BP-Reservation frame, the NAV for other wireless terminals is set redundantly in the BP-Reservation frame at time t7 as described above, or the carrier sense time or back-off time of the BP-Reservation frame Is preferentially set to other frames, so that a BP-Reservation frame is transmitted without acquiring a band in the other frames, and control is performed so that user-selective retransmission control (2) can be performed.

  At time t14, with respect to other wireless terminal stations (here, subordinate STA1, STA3, STA4, and STA6 not included in the user selection retransmission control (2) are included) by the BP-Reservation frame transmitted at time t13 Update the NAV. At this time, for example, when the user-selected retransmission control is terminated with the specified number of retransmissions twice (step S6: No), the previous data communication (first time) is redundant as in the user-selected retransmission control (1). It is not necessary to set the NAV, and it is possible to set the time t17. However, when it is not determined whether further retransmission is performed at the start of this user-selected retransmission control (2), as in the case of data communication (first time) and user-selected retransmission control (1), time t17 which is the original communication period It is also possible to make a reservation at a longer time t18. At this time, even if the user-selective retransmission control (3) is not performed as illustrated in the present embodiment, it is possible to shift to the random access period with the minimum redundant NAV setting.

  Thereafter, in each wireless terminal station (STA2, STA5), the scheduler unit 41 transmits data to the wireless base station (AP10) based on the uplink scheduling information (transmission start time, transmission period) notified in the BP-Reservation frame. A frame is transmitted (step S4).

  At time t15, based on the uplink scheduling information in the BP-Reservation frame, the wireless terminal station (STA2) transmits a data frame, and the wireless base station (AP10) receives normally.

  At time t16, based on the uplink scheduling information in the BP-Reservation frame, the wireless terminal station (STA5) transmits a data frame, and the wireless base station (AP10) receives normally.

  Here, with respect to a frame error that has occurred in data communication (1), all the sequences of downlink data and uplink data for all wireless terminal stations (STA1 to STA6) are normal until the user-selected retransmission control (2). (Step S5: Yes), the bandwidth reservation is released and the mode is switched to the random access time. That is, the frame analysis unit 42 determines to end the bandwidth reservation (do not update the NAV).

  Further, at time t19, the scheduler unit 41 of the radio base station (AP10) is transmitting a Beacon frame at the start timing of the next superframe.

  Although the frame analysis unit 42 performs confirmation of the number of retransmissions (step S6), the present invention is not limited to this. For example, when the frame analysis unit 42 has not received a data frame from the wireless terminal station, the retransmission control unit 43 receives a notification from the frame analysis unit 42 and confirms the number of retransmissions (step S6). Also good.

  In this way, the radio base station (AP10) transmits a BP-Reservation frame to the radio terminal stations (STA1 to STA6) to reserve a certain time band, and the radio terminal stations (STA1 to STA6) -Data is transmitted based on the band allocation information included in the Reservation frame. In the radio base station (AP10), only the radio terminal station that could not receive data is re-secured and the user selection retransmission control (1) and (2) is performed. Thereby, user-selective retransmission control can be performed efficiently in the current Superframe up to the next Beacon.

  In addition, as shown in FIG. 10, it is also possible to receive ACK with respect to BP-Reservation and to determine whether BP-Reservation was received normally. FIG. 10 is a time chart showing delay time guarantee type user selection retransmission control. If ACK is not returned within a certain time for the BP-Reservation frame transmitted at time t2, it is possible to increase the arrival probability of the bandwidth reservation frame by retransmitting the BP-Reservation frame. is there. The flowchart at this time is shown in FIG. FIG. 11 is a flowchart showing delay time guarantee type user selection retransmission control. The difference is that an ACK transmission / reception process (steps S11 and S12) is added between steps S2 and S3 of the flowchart shown in FIG.

  In the wireless terminal stations (STA1 to STA6) that have received the BP-Reservation frame from the wireless base station (AP10), the scheduler unit 41 transmits an ACK to the wireless base station (AP10) (step S11). Then, in the radio base station (AP10), the frame analysis unit 42 confirms whether or not the ACK has been received from all the radio terminal stations (STA1 to STA6) targeted for data transmission / reception (step S12). When the ACK has been received from all the wireless terminal stations (STA1 to STA6) as after time t1 in FIG. 10 (step S12: Yes), in the wireless base station (AP10), the scheduler unit 41 performs the BroadcastPolling frame. Is transmitted to the subordinate wireless terminal stations (STA1 to STA6) in the downlink direction (step S3). On the other hand, when ACK is not received from all the wireless terminal stations (STA2, STA3, STA5) as after time t3 in FIG. 10 (step S12: No), the wireless base station (AP10) -Resend the Reservation frame (step S2). That is, the frame analysis unit 42 instructs the retransmission control unit 43 to retransmit the BP-Reservation frame. The retransmission control unit 43 instructs the scheduler unit 41 to retransmit the BP-Reservation frame.

  Here, the BP-Reservation frame will be described. FIG. 12 is a diagram illustrating a configuration example of a BP-Reservation frame in the present embodiment. This BP-Reservation frame includes “MAC Header”, “Frame Body”, and “FCS”.

  The MAC header is based on the IEEE 802.11n frame format, and includes a “Frame Control” field including a frame type indicating a BP-Reservation frame type, a “Duration / ID” field, and an “address” such as a destination / source / SSID. ”Field,“ Sequence Control ”field,“ QoS Control ”field, and“ HT Control ”field.

  The Frame Body is a “Category” field indicating HT, an “Action” field indicating PSMP or PSBP (Power Save Broadcast Polling), and a PSBP STA Info (or PSMP STA Info) field content, length, and the like. A PSBP Parameter Set (or “PSMP Parameter Set”) field and a “PSBP STA Info” (or “PSMP STA Info”) field including scheduling information of PSBP (or PSMP) time are configured.

  In addition, a “PSBP Parameter Set” (or “PSMP Parameter Set”) field includes an “N_STA” field indicating the number of STA Info fields, and “More PSBP” indicating whether the PSBP sequence further continues after this PSBP sequence. Alternatively, a “More PSMP” field indicating whether or not a PSMP sequence continues after this PSMP sequence, a “PSBP Duration” field indicating a PSBP sequence time (or a “PSMP Duration” field indicating a PSMP sequence time), Consists of

  Further, the “PSBP STA Info” field includes scheduling information for the number of terminals, and the scheduling method is shown in FIGS. 12A to 12D according to Group Address, BiDirectional (bidirectional), Downlink, and Uplink. It is written. When scheduling a plurality of terminals, the fields shown in FIGS. 12A to 12D are continuously arranged.

  FIG. 12A is used for broadcast or multicast. Although there is a difference between PSMP and PSBP, the configuration is the same as in FIG. FIG. 12B is used when assigning downlink scheduling and uplink scheduling to each wireless terminal individually. Although there is a difference between PSMP and PSBP, the configuration is the same as in FIG. FIG. 12C is used when only the downlink is allocated to each wireless terminal. Compared to FIG. 12A, the STA_INFO Type is different. Also, STA_ID is used instead of Group Address. FIG. 12D is used when only the uplink is allocated to each wireless terminal. Compared to FIG. 12A, the STA_INFO Type is different. Also, STA_ID is used instead of Group Address.

  As described above, by changing the field format in accordance with the scheduling method, “PSBP STA Info” can be used for all cases in which only FIG. 12A or FIG. 12B can be used. (Or “PSMP STA Info”) The field length can be shortened, and high efficiency can be realized. It is also possible to allocate a band a plurality of times by including scheduling information addressed to the same wireless terminal a plurality of times in the “PSBP STA Info” (or “PSMP STA Info”) field.

  Next, aggregation of the BP-Reservation frame and the BroadcastPolling frame will be described. FIG. 13 is a diagram illustrating an example of aggregation (A-MPDU) of a BP-Reservation frame and a BroadcastPolling frame in the present embodiment. Each frame has a frame format included in A-MPDU subframes 1 and 2. The A-MPDU subframe includes a reserve, MPDU Length, CRC, and a “Delimiter Signature” field that detects the start position of the subframe, an “MPDU Delimiter” field including data, an “MPDU” field including data, and an A-MPDU subframe of 4 bytes. It consists of a “Pad” field.

  The “MPDU” field is composed of a MAC Header field, a payload field, and an FCS field, as in the normal wireless LAN frame format. In this embodiment, the payload of A-MPDU subframe 1 is BP- The contents of the Reservation field are included, and the PSBP DLL (also referred to as Broadcast Polling for STAs) field is included in the payload of A-MPDU subframe2. By multiplexing a plurality of downlink frames in this way, it becomes possible to multiplex downlink frames (frames transmitted at times t1 and t2 in FIG. 9) transmitted by the base station (AP10), and carrier Higher efficiency can be achieved by reducing the sense time and back-off time. In this embodiment, the A-MPDU method has been described. However, the method is not limited to the aggregation method as long as a plurality of subframes are multiplexed and transmitted as one physical burst.

  As described above, according to the present embodiment, in a wireless communication system that transmits data that has a strict tolerance time and communication quality is required, a wireless base station can perform arbitrary timing with respect to a wireless terminal station. A BP-Reservation frame is transmitted during a period to reserve a certain time band, and control information is transmitted collectively to the wireless terminal stations in the downlink direction using the BroadcastPolling frame. The wireless terminal station transmits data based on the band allocation information included in the BP-Reservation frame. Then, in the radio base station, for the radio terminal station that has not been able to receive data in the data communication (first time) period, the bandwidth is dynamically re-allocated in the frame to perform user-selective retransmission control (1, 2, ...) and user-selective retransmission control is efficiently performed within the current Superframe up to the next Beacon. As a result, it is possible to prevent an increase in delay time due to the carryover of the packet retransmission to the next superframe and retransmission outside the allowable delay time, and it is possible to improve the packet arrival rate for QoS data, so that the delay time and the packet arrival rate are guaranteed. Wireless communication quality can be guaranteed in a necessary wireless environment.

  In the present embodiment, the BP-Reservation frame is used as a radio band reservation method, but the present invention is not limited to this. For example, it is also possible to use PSMP Parameter Set and PSMP STA Info included in an existing PSMP frame. The PSMP STA Info field can be used for either a group address (FIG. 6A) or a field set of individual addresses (FIG. 6B). Alternatively, a combination thereof may be used. For example, scheduling in the downlink direction may be a PSMP STA Info field with a group address, and scheduling in the uplink direction may be a PSMP STA Info field for an individual address. At this time, as shown in the present embodiment, user-selective retransmission control can be preferentially performed by setting the NAV setting redundantly or by increasing the transmission priority with respect to other frames. is there.

  In the present embodiment, the number of times of user-selected retransmission control has been described as two times. However, the present invention is not limited to this, and if it is within an allowable processing delay time, a repeated user-selected retransmission control period is set and given priority. By retransmitting, the frame arrival rate can be increased. Alternatively, if the communication quality is known in advance and the frame arrival rate can be ensured at a certain level or more at a specific number of retransmissions (for example, the arrival rate is 99.99%), the user-selected retransmission control number is determined in advance. It is possible to control with.

  As described above, the radio communication system according to the present invention is useful for radio communication in which a radio base station transmits data to a plurality of radio terminal stations, and it is particularly necessary to improve the packet arrival rate within an allowable delay time. Suitable for certain highly reliable wireless communications.

1, 2, 3, 4, 5, 6 Wireless terminal station (STA)
10 Radio base station (AP)
20 interface unit 30 information storage unit 40 access control unit (MAC unit)
41 scheduler unit 42 frame analysis unit 43 retransmission control unit 50 modulation / demodulation unit 51 transmission unit 52 reception unit 53 quality measurement unit 60 beam control unit 70 antenna unit

Claims (17)

A wireless communication system including a wireless base station and a wireless terminal station,
The radio base station is
After beacon transmission at predetermined intervals, a period allocated to transmit and receive data to the data transmission and reception target wireless terminal station, a transmission prohibition period of the data to the data transmission and reception covered by the wireless terminal station, to notify And a scheduler means for transmitting a base station data frame to the data transmission / reception target wireless terminal station in the data transmission allocation period of the local station,
Based on the result of confirming whether or not the terminal station data frame has been received from all the wireless terminal stations subject to data transmission and reception, and the number of times of performing retransmission control for receiving the terminal station data frame that could not be received, Frame analysis means for determining whether to perform retransmission control;
A retransmission control unit that instructs the scheduler unit to transmit a bandwidth reservation frame when the frame analysis unit determines to perform the retransmission control;
With
The wireless terminal station
In the case of the data transmission / reception target, the terminal station data frame is transmitted to the radio base station in the period allocated to the own station included in the received bandwidth reservation frame, while the data transmission / reception target is not Is an access control means that does not transmit data during the transmission prohibition period,
Equipped with a,
The scheduler means of the radio base station is
Except when the number of retransmissions reaches the specified number of retransmissions, the next band reservation to be transmitted when the frame analysis means determines that the frame analysis means performs retransmission control from the end of transmission of the current band reservation frame, except when the transmission prohibition period ends. The period is longer than the period until the end of frame transmission.
A wireless communication system. The frame analysis means of the radio base station is
As a result of confirming whether or not the terminal station data frame has been received from all the wireless terminal stations subject to data transmission / reception, if not received, it is further confirmed whether or not the number of retransmission control is within a prescribed number. If it is within the number of times, it is determined to perform retransmission control with the source wireless terminal station of the terminal station data frame not received as the wireless terminal station subject to data transmission and reception,
On the other hand, as a result of the confirmation, if terminal station data frames are received from all radio terminal stations subject to data transmission / reception, or if the number of retransmission control exceeds the specified number, it is decided not to perform retransmission control. And
When the retransmission control means receives a notification from the frame analysis means that retransmission control is to be performed, the scheduler means sends the transmission source radio terminal station of the terminal station data frame not received to the data transmission / reception target Instructing the transmission of a bandwidth reservation frame as a wireless terminal station of
The wireless communication system according to claim 1. The access control means of the data transmission / reception target radio terminal station, when receiving a bandwidth reservation frame, transmits an ACK to the radio base station,
Frame analysis means of the radio base station, as a result of confirming whether or not ACK has been received from all of the radio terminal stations for data transmission / reception, determines to retransmit the bandwidth reservation frame if not received, On the other hand, if it was received, decide to transmit the base station data frame,
The retransmission control means that has received a notification from the frame analysis means that the decision to retransmit the bandwidth reservation frame has been made, instructs the scheduler means to retransmit the bandwidth reservation frame,
The scheduler means retransmits the bandwidth reservation frame to the data transmission / reception target radio terminal station when receiving a retransmission instruction of the bandwidth reservation frame from the retransmission control means, while the frame analysis means from the base station When receiving notification that the decision to transmit a data frame has been received, in the data transmission allocation period of its own station, to transmit the base station data frame to the wireless terminal station for data transmission and reception,
The wireless communication system according to claim 1 or 2, characterized in that. The scheduler unit of the radio base station multiplexes the band reservation frame and the base station data frame into one frame and transmits the frame reservation frame and the base station data frame.
The wireless communication system according to claim 1 or 2, characterized in that. The access control means of the wireless terminal station sets its own station in a low power consumption state except for a period allocated for the own station to transmit and receive data.
The wireless communication system according to any one of claims 1-4, characterized in that. A radio base station constituting a radio communication system with a radio terminal station,
After beacon transmission at predetermined intervals, a period allocated to transmit and receive data to the data transmission and reception target wireless terminal station, a transmission prohibition period of the data to the data transmission and reception covered by the wireless terminal station, to notify And a scheduler means for transmitting a base station data frame to the data transmission / reception target wireless terminal station in the data transmission allocation period of the local station,
Based on the result of confirming whether or not the terminal station data frame has been received from all the wireless terminal stations subject to data transmission and reception, and the number of times of performing retransmission control for receiving the terminal station data frame that could not be received, Frame analysis means for determining whether to perform retransmission control;
A retransmission control unit that instructs the scheduler unit to transmit a bandwidth reservation frame when the frame analysis unit determines to perform the retransmission control;
Equipped with a,
The scheduler means includes
Except when the number of retransmissions reaches the specified number of retransmissions, the next band reservation to be transmitted when the frame analysis means determines that the frame analysis means performs retransmission control from the end of transmission of the current band reservation frame, except when the transmission prohibition period ends. The period is longer than the period until the end of frame transmission.
A wireless base station characterized by that. The frame analysis means includes
As a result of confirming whether or not the terminal station data frame has been received from all the wireless terminal stations subject to data transmission / reception, if not received, it is further confirmed whether or not the number of retransmission control is within a prescribed number. If it is within the number of times, it is determined to perform retransmission control with the source wireless terminal station of the terminal station data frame that has not been received as the wireless terminal station subject to data transmission and reception,
On the other hand, as a result of the confirmation, if terminal station data frames are received from all radio terminal stations subject to data transmission / reception, or if the number of retransmission control exceeds the specified number, it is decided not to perform retransmission control. And
When the retransmission control means receives a notification from the frame analysis means that retransmission control is to be performed, the scheduler means sends the transmission source radio terminal station of the terminal station data frame not received to the data transmission / reception target Instructing the transmission of a bandwidth reservation frame as a wireless terminal station of
The radio base station according to claim 6 . The frame analysis means retransmits the bandwidth reservation frame if it is not received as a result of confirming whether or not the ACK has been received from all the wireless terminal stations subject to data transmission / reception that have received the bandwidth reservation frame. On the other hand, if it was received, decide to transmit the base station data frame,
The retransmission control means that has received a notification from the frame analysis means that the decision to retransmit the bandwidth reservation frame has been made, instructs the scheduler means to retransmit the bandwidth reservation frame,
The scheduler means retransmits the bandwidth reservation frame to the data transmission / reception target radio terminal station when receiving a retransmission instruction of the bandwidth reservation frame from the retransmission control means, while the frame analysis means from the base station When receiving notification that the decision to transmit a data frame has been received, in the data transmission allocation period of its own station, to transmit the base station data frame to the wireless terminal station for data transmission and reception,
The radio base station according to claim 6 or 7 , wherein The scheduler means multiplexes and transmits the bandwidth reservation frame and the base station data frame in one frame.
The radio base station according to claim 6 or 7 , wherein A wireless terminal station constituting a wireless communication system with a wireless base station,
From the radio base station, a period allocated to transmit and receive data to the data transmission and reception target wireless terminal station, the bandwidth for the transmission prohibition period of the data, notifies the data transmission and reception covered by the wireless terminal station The radio base station performs retransmission control during the transmission prohibition period from the end of transmission of the current bandwidth reservation frame, except for a reserved frame, when the number of retransmissions at the radio base station reaches a specified number of retransmissions. When a bandwidth reservation frame that is longer than the period until the end of transmission of the next bandwidth reservation frame to be transmitted is received,
In the case of the data transmission / reception target, the terminal station data frame is transmitted to the radio base station in the period allocated to the own station included in the received bandwidth reservation frame. , Access control means that does not transmit data during the transmission prohibition period,
A wireless terminal station comprising: The access control means transmits an ACK to the radio base station when the bandwidth reservation frame is received when data transmission / reception is performed,
Wireless terminal station according to claim 1 0, characterized in that. The access control means sets the local station in a low power consumption state except for a period allocated for the local station to transmit and receive data.
Wireless terminal station according to claim 1 0 or 1 1, characterized in that. A wireless communication method of a wireless communication system including a wireless base station and a wireless terminal station,
The wireless base station prohibits the transmission of data to wireless terminal stations not subject to data transmission / reception during the period allocated for transmitting / receiving data to / from wireless terminal stations subject to data transmission / reception after beacon transmission at predetermined intervals. A bandwidth reservation step for transmitting a bandwidth reservation frame for notifying the period;
The base station data transmission step in which the radio base station transmits a base station data frame to the data transmission / reception target radio terminal station in the data transmission allocation period of the local station;
A terminal station data transmission step of transmitting the terminal station data frame to the radio base station in a period allocated to the own station included in the received bandwidth reservation frame, the radio terminal station for data transmission and reception;
As a result of confirming whether or not the radio base station has received terminal station data frames from all the radio terminal stations subject to data transmission / reception, and retransmission control for receiving terminal station data frames that could not be received Frame analysis step for determining whether to perform retransmission control based on the number of times
A bandwidth reservation frame transmission step of transmitting a bandwidth reservation frame when the radio base station determines to perform retransmission control in the frame analysis step;
Only including,
The radio base station determines that the transmission prohibition period is determined by the frame analysis means to perform retransmission control from the end of transmission of the current bandwidth reservation frame, except when the number of retransmissions reaches a specified number of retransmissions. The period is longer than the period until the end of transmission of the next bandwidth reservation frame to be transmitted.
A wireless communication method. In the frame analysis step,
As a result of confirming whether or not the radio base station has received terminal station data frames from all the radio terminal stations subject to data transmission and reception, if not received, whether the number of retransmission control is within a specified number If it is within the specified number of times, it is determined to perform retransmission control with the wireless terminal station that is the data transmission / reception target as the transmission source wireless terminal station of the terminal station data frame that has not been received,
On the other hand, as a result of the confirmation, if terminal station data frames are received from all radio terminal stations subject to data transmission / reception, or if the number of retransmission control exceeds the specified number, it is decided not to perform retransmission control. And
In the bandwidth reservation frame transmission step,
Transmitting a bandwidth reservation frame in which a wireless terminal station that is a data transmission / reception target is a transmission source wireless terminal station of the terminal station data frame that has not been received;
The wireless communication method according to claim 1 3, characterized in that. further,
The ACK transmission step in which the wireless terminal station for data transmission / reception that has received the bandwidth reservation frame transmits ACK to the wireless base station;
As a result of confirming whether or not the radio base station has received ACK from all the radio terminal stations that are the target of data transmission / reception, it is determined to retransmit the bandwidth reservation frame if it has not been received. If so, a frame determining step for determining to transmit the base station data frame;
A bandwidth reservation frame retransmission step for retransmitting the bandwidth reservation frame when the radio base station determines retransmission of the bandwidth reservation frame in the frame determination step;
Including
When the radio base station determines to transmit the base station data frame, the base station data transmission step is performed.
The wireless communication method according to claim 1 3 or 1 4, characterized in that. The radio base station multiplexes and transmits the bandwidth reservation frame and the base station data frame in one frame.
The wireless communication method according to claim 1 3 or 1 4, characterized in that. The wireless terminal station is in a low power consumption state, except for a period allocated for data transmission by the local station.
The wireless communication method according to any one of claims 1 3 to 1 6, characterized in that.

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