JP6270148B2 - Wireless communication method, wireless communication system, and wireless communication program - Google Patents

Description

  The present invention relates to a radio communication network, and more particularly to a radio communication method, a radio communication system, and a radio communication method for performing radio communication between a base station and a terminal station in a range extending over a plurality of cells in a radio network configured in units of cells. The present invention relates to a wireless communication program.

  Currently, the wireless LAN system is operated in an unlicensed band that does not require a radio station license, and in order to share a frequency band with other wireless systems, the wireless LAN system is a CSMA / CA as a medium access control method. (Carrier Sense Multiple Access with Collision Avoidance) is adopted. The CSMA / CA system is an autonomous distributed medium access control system defined as a DCF (Distributed Coordination Function) system in the IEEE 802.11 standard (see, for example, Non-Patent Document 1). By using the CSMA / CA scheme, each terminal can acquire transmission rights in an autonomous and distributed manner while avoiding signal collision by carrier sense and random backoff.

  However, when the CSMA / CA method is used, the terminal tries to acquire the transmission right randomly, so even if there is a terminal requesting QoS (Quality of Service) in the same BSS (Basic Service Set), the system Communication with guaranteed QoS cannot be performed. In addition, when a terminal whose reception SNR (Signal-to-Noise power Ratio) has decreased due to the influence of fading of the radio propagation path acquires the transmission right, the use efficiency of the radio resource decreases and the reception SNR Compared with a case where a terminal having a higher acquisition right acquires a transmission right, the throughput decreases.

  In order to achieve high throughput by guaranteeing QoS with high probability and improving utilization efficiency of radio resources, information on traffic status and channel status of each terminal is collected, and radio resources are based on the collected information. Need to be assigned.

  As a technique for realizing such transmission, centralized control type resource management (for example, Non-Patent Document 2) in which an operator who centrally manages radio resources like a cellular system dynamically allocates radio resources according to the status of a terminal. See).

  However, since it is not easy for an operator to centrally manage all systems with different standards operated in the unlicensed band like a cellular system, centralized control type resource management in the cellular system is introduced directly into the wireless LAN system. That is not desirable.

  Therefore, a BSS centralized control OFDMA (Orthogonal Frequency Division Multiple Access) wireless LAN system has been proposed as a technique for improving QoS utilization and improving the utilization efficiency of radio resources while sharing frequencies with different types of radio systems. (For example, refer nonpatent literature 3).

  In an intra-BSS centralized control type OFDMA wireless LAN system, after a terminal (hereinafter referred to as an intra-BSS terminal) connected to an AP (base station; Access Point) in the BSS acquires a transmission right using the CSMA / CA scheme, An RTS (Request to Send) frame is transmitted, and after the AP receives this, a CTS (Clear to Send) frame is transmitted. Thereafter, each terminal in the BSS transmits a CTS frame in order. Reserving the wireless medium by notifying other terminals that have received these control frames and not participating in the BSS (hereinafter referred to as non-BSS terminals) of the time for occupying the radio resources, and making the reserved radio resources Can be shared within the BSS.

  Through the above procedure, the system configured with the terminals in the BSS performs centralized control type resource management centering on the AP while sharing the frequency with other wireless systems in the vicinity. Further, the AP estimates the channel status while collecting the traffic status of each terminal using the RTS frame and the CTS frame. Based on these collected information, QoS resources are guaranteed with high probability by preferentially allocating radio resources to terminals that request QoS, and the subchannel is allocated to the terminal having the highest received SNR with respect to a certain subchannel. In this way, the transmission rate of the data frame is improved to improve the throughput.

IEEE 802.11-2012, “IEEE Standard for Information Technology- Telecommunications and Information Exchange Between Systems- Local and Metropolitan Area Networks- Specific Requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications,” 2012. S. Xie, Y. Liu, Y. Zhang, and R. Yu, “A Parallel Cooperative Spectrum Sensing in Cognitive Radio Networks,” IEEE Trans. Vehic. Technol., Vol. 59, pp. 4079-4092, Oct. 2010 . S. Miyamoto, S. Sampei, and W. Jiang, “Novel DCF-Based Multi-User MAC Protocol for Centralized Radio Resource Management in OFDMA WLAN Systems,” IEICE Trans. Commun., Vol. E96-B, no. 9, pp. 2301-2312, Sept. 2013.

  In the above-mentioned centralized control type wireless LAN system in BSS, high-efficiency data transmission can be achieved while guaranteeing QoS with high probability if there is no overlap between wireless cells when deployed in a plane, but it will increase in the future. It cannot sufficiently cope with an inter-cell overlapping communication environment accompanying an increase in wireless LAN cells.

FIG. 11 is a diagram illustrating an application example of the related art in an overlapping cell environment. In FIG. 11, as an example of an overlapping cell environment, BSS # 1, BSS # 2, and BSS # 3 are arranged to overlap each other. When Non-Patent Document 1 and Non-Patent Document 2 are applied in the communication environment, there are the following problems (1) to (4).
(1) Since wireless medium acquisition competition is performed based on the CSMA / CA scheme, only one BSS can be transmitted at the same time, and it is difficult to guarantee QoS (delay) of other terminals in the BSS.
(2) Even if other intra-BSS terminals are spatially separated so that radio resources can be used repeatedly, simultaneous communication by NAV is impossible.
(3) The amount of resources used for transmission of management frames such as beacon frames and probe request / response frames becomes enormous.
(4) Since the terminal can transmit data only to the AP to which it is currently associated even when the channel status with other APs is better, resources are wasted.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a wireless communication method, a wireless communication system, and a wireless communication program capable of ensuring high communication quality and suppressing a decrease in throughput. To do.

The present invention is a wireless communication method in a communication configuration in which a base station and a plurality of terminal stations exist in the wireless cell in an arbitrary wireless cell belonging to a wireless communication network, and constructs a cooperative BSS group by a plurality of BSSs,該協tone BSS master base station base station for centrally controlling all the base stations belonging to the group, the rest of the base station when performing selection of a slave base station, selecting that you can communicate directly with all slave base stations conditions Selecting the master base station as follows, and after constructing the cooperative BSS group, through the pre-processing of CSMA / CA and RTS / CTS frame exchange, the wireless medium is reserved in units of the cooperative BSS group at the same time. The master base station collecting the traffic information and channel information of the terminals in the cooperative BSS group; Allocating radio resources based on the traffic information and channel information of each terminal so as to improve the communication quality index for each cooperative BSS group, and notifying the slave base station and the terminal station of the allocation result; the allocation result the is notified slave base station and the terminal station, in accordance with the assignment result perform information transmission, have a performing a success or failure response to the master base station or the slave base station, In the preprocessing, the master base station receives an RTS frame from any one of the terminal stations belonging to the cooperative BSS group, and requests the other terminal stations to transmit a CTS frame; The terminal station other than the transmission source transmits a CTS frame in response to the request; and the slave base station Transmitting to the master base station channel information between the terminal station estimated based on the CTS frame and the master base station communicating with the terminal station based on the RTS frame and the CTS frame, respectively. And further acquiring the traffic information of the terminal station from each of the RTS frame and the CTS frame, or the master base station transmitting the RTS frame, and the terminal A station transmitting a CTS frame in response to reception of the RTS frame, and a step of transmitting channel information between the slave base station and the terminal station estimated based on the CTS frame to the master base station And the master base station communicates with the terminal station based on the CTS frame. And estimating the channel information between the terminal stations and obtaining the traffic information of the terminal station from each of the CTS frames .

The present invention is a wireless communication system in a communication configuration in which a base station and a plurality of terminal stations exist in the wireless cell in an arbitrary wireless cell belonging to a wireless communication network, and constructs a cooperative BSS group by a plurality of BSSs,該協tone BSS master base station base station for centrally controlling all the base stations belonging to the group, the rest of the base station when performing selection of a slave base station, selecting that you can communicate directly with all slave base stations conditions As the means for selecting the master base station and the cooperative BSS group, the wireless medium is reserved at the same time in units of the cooperative BSS group through preprocessing of CSMA / CA and RTS / CTS frame exchange, Means for collecting the traffic information and channel information of the terminals in the cooperative BSS group by the master base station; Based on the traffic information and channel information of each terminal, a radio resource is allocated so as to improve a communication quality index in units of the cooperative BSS group, and means for notifying the allocation result to the slave base station and the terminal station; the allocation result notified the slave base station and the terminal station, allocation result perform information transmission in accordance with the, have a means for performing the success or failure response to the master base station or the slave base station, wherein The pre-processing includes a process in which the master base station receives an RTS frame from any one of the terminal stations belonging to the cooperative BSS group, and requests other terminal stations to transmit a CTS frame; and transmission of the RTS frame The terminal station other than the original station transmits a CTS frame in response to the request, and the slave base station transmits the CTS frame. Processing to transmit channel information between the terminal station estimated based on the master base station to the master base station, and the master base station obtains channel information between the terminal station based on the RTS frame and the CTS frame, respectively. And the process of acquiring the traffic information of the terminal station from each of the RTS frame and the CTS frame, or the master base station transmits the RTS frame, and the terminal station A process of transmitting a CTS frame in response to reception of an RTS frame, a process of transmitting channel information between the slave base station and the terminal station estimated based on the CTS frame to the master base station, and the master The base station estimates channel information with the terminal station based on the CTS frame, and further, the C And a process of acquiring traffic information of the terminal station from each TS frame .

  The present invention is a wireless communication program for causing a computer to execute the wireless communication method.

  According to the present invention, it is possible to obtain an effect of ensuring high communication quality and suppressing a decrease in throughput in the cooperative BBS area.

It is a figure which shows the structure of the radio | wireless communications system by embodiment of this invention. It is a figure which shows an example of determination of the master AP and slave AP in a cooperation BSS group. It is a figure which shows the example which the terminal in a cooperation BSS group associates with a master AP or a slave AP. It is a figure which shows the BSS centralized control type wireless LAN technique by a prior art. 1 is a diagram illustrating a BSS centralized control type wireless LAN technology according to an embodiment of the present invention. FIG. It is a figure which shows the BSS centralized control type wireless LAN technique by a prior art. 1 is a diagram illustrating a BSS centralized control type wireless LAN technology according to an embodiment of the present invention. FIG. It is a figure which shows the example of a setting of the simulation of uplink communication. It is a figure which shows the relationship between the offered load of an NRT terminal, and a QoS satisfaction rate. It is a figure which shows the relationship between the offer load of NRT terminal, and a throughput. It is a figure which shows the example of application of the prior art in an overlapping cell environment.

  Hereinafter, a wireless communication system according to an embodiment of the present invention will be described. First, an outline of a wireless communication system according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of a wireless communication system according to an embodiment of the present invention.

  In the present embodiment, a cooperative BSS group including a plurality of BSSs is constructed, and an AP that performs central control of all APs belonging to the cooperative BSS group is a master AP, and the remaining APs are slave APs. Then, as a selection condition of the master AP of the cooperative BSS group, it is possible to directly communicate with all the slave APs or to directly communicate with a terminal associated with all the slave APs. After constructing the cooperative BSS group, the wireless medium is reserved at a time for each cooperative BSS group through preprocessing such as CSMA / CA and RTS / CTS frame exchange, and at the same time, traffic information and channel information of terminals in the cooperative BSS group Are collected to the master AP.

  Next, based on the collected traffic information and channel information of each terminal, the master AP of the cooperative BSS group allocates radio resources so that the communication quality index such as system throughput and QoS is improved for each cooperative BSS group, and The allocation result is communicated to each slave AP and each cooperative BSS group terminal. Then, each slave AP and each cooperative BSS in-group terminal whose allocation result is well-known perform information transmission with the base station AP according to the allocation result, and perform a success / failure response to the AP.

<First Embodiment>
Next, a radio communication system according to the first embodiment of the present invention will be described. Here, uplink communication in an overlapping cell environment will be described. First, the construction of the cooperative BSS group according to the present embodiment will be described. FIG. 2 is a diagram illustrating an example of determining a master AP and a slave AP in the cooperative BSS group. FIG. 3 is a diagram illustrating an example in which terminals in a cooperative BSS group associate with a master AP or a slave AP.

  First, in order to construct a cooperative BSS group, it is necessary to determine a master AP and a slave AP. AP # X scans the channel for a certain period at the time of activation and checks for the presence of M-AP. Specifically, when one or a plurality of management frames are received from the master AP, the communication reliability with itself is highest (for example, communication quality such as maximum RSSI or minimum reception error rate). A cooperative participation frame is transmitted to the master AP (using an index to represent), and itself becomes a slave AP.

  Various policies can be applied to determine the master AP. For example, an AP of a BSS cell whose throughput is lower than a certain reference value is set as a master AP, or an AP of a BSS cell whose throughput is higher than a certain reference value is set as a master AP. In addition, not only the throughput value but also any index that seems to be effective for improving the communication quality of the wireless network, such as the frame error rate and the resource occupancy rate, can be used as a criterion for judgment. In addition, both absolute and relative standards can be applied for numerical index. That is, an absolute value may be provided as a reference for the numerical index, and values of a plurality of radio cells may be compared with each other so that the higher or lower value is used as the reference for the numerical index.

  Next, when the management frame cannot be received from the master AP, AP # X itself becomes the master AP. However, information indicating that it is the master AP is described in the management frame (beacon / probe response, etc.) transmitted by the master AP.

  Next, the master AP and the slave AP in the determined cooperative BSS group need to associate with the terminal. First, when the terminal associates with the master AP, the normal wireless LAN association process may be performed with the master AP (FIG. 3 (1)).

  Next, when the terminal associates with a plurality of APs including the slave AP, the terminal can transmit an association request frame to the plurality of APs including the slave AP to be associated and receive a response frame from the plurality of APs. Associate with the AP (Fig. 3 (2)). However, which master AP the slave AP is currently cooperating with is described in the management frame.

  Next, uplink communication in an overlapping cell environment after the cooperative BSS group has been constructed will be described. FIG. 4 is a diagram showing a BSS centralized control type wireless LAN technology according to the prior art. FIG. 5 is a diagram illustrating a BSS centralized control type wireless LAN technology according to an embodiment of the present invention.

  In the prior art (FIG. 4), a communication protocol (communication operation) when a certain BSS # 1 acquires a communication right will be described. First, a terminal in BSS # 1 transmits an RTS frame after random backoff. Upon receiving this, the AP of BSS # 1 transmits a CTS frame, and requests transmission of the CTS frame to all terminals in BSS # 1 other than the terminal that transmitted the RTS frame.

  Next, the terminals of the BSS # 1 other than the terminal that transmitted the RTS transmit CTS frames in order, and make a radio medium reservation for the terminals outside the BSS # 1 that can be an interference source. Since the traffic information of each terminal is described in the RTS / CTS frame transmitted by the terminal in BSS # 1, the AP receives the traffic information of each terminal in BSS # 1 by receiving these RTS / CTS frames. Can be collected.

  In addition, since the RTS / CTS frame transmitted by the terminal in BSS # 1 includes a preamble portion used for channel information estimation, the AP receives each RTS / CTS frame to receive each RSS / CTS frame. The channel information of all BSS # 1 internal terminals can be indirectly collected by estimating the channel information of the internal terminals.

  The AP allocates communication resources in BSS # 1 based on the information collected by these frames, and further notifies the allocation result of the resource allocation in an RBI (Resource Block Information) frame. Each terminal in BSS # 1 that has received the RBI frame transmits a data frame according to the allocation result, and releases the communication right after receiving a success / failure response from the AP.

  Next, the communication operation of the wireless communication system according to the present embodiment will be described with reference to FIG. First, a certain terminal in the cooperative BSS group transmits an RTS frame after random backoff (FIG. 5 (1)).

  Next, the master AP of the cooperative BSS group that has received this transmits a CTS frame, and each terminal in the cooperative BSS group other than the terminal that transmitted the RTS frame requests transmission of the CTS frame (FIG. 5 (2)). ).

  Next, each terminal in the cooperative BSS group other than the terminal that transmitted the RTS transmits a CTS frame in order to reserve a wireless medium ((3) in FIG. 5).

  Next, each slave AP that has received the CTS frame from each terminal in the cooperative BSS group first estimates channel information based on the preamble portion included in the CTS frame. Subsequently, channel information CSI (Channel State Information) obtained by the estimation is described in the payload of the CSI frame and transmitted to the master AP (FIG. 5 (4)).

  At this time, since the traffic information of each node is described in the RTS / CTS frame transmitted by the terminals in the cooperative BSS group, the AP receives the RTS / CTS frame, thereby receiving the RTS / CTS frame. Can collect the traffic information of other terminals. In addition, since the RTS / CTS frame transmitted by the terminals in the cooperative BSS group includes a preamble portion used for channel information estimation, the master AP receives each RTS / CTS frame and receives each RTS / CTS frame. Channel information of terminals in the BSS group can be collected.

  Furthermore, the master AP can collect the channel information by receiving the CSI frame transmitted by the slave AP with the channel information between the terminal and the slave AP. The AP allocates communication resources in units of cooperative BSS groups based on the traffic information and channel information collected by these frames, and further notifies the allocation result in an RBI (Resource Block Information) frame. FIG. 5 (5)).

  Next, each terminal in the cooperative BSS group that has received the RBI frame transmits a data frame according to the allocation result (FIG. 5 (6)).

  Next, each terminal in the cooperative BSS group releases the communication right after receiving the success / failure response from the master AP and the slave AP (FIG. 5 (7)).

Second Embodiment
Next, a radio communication system according to the second embodiment of the present invention will be described. Here, downlink communication in an overlapping cell environment will be described. Since the method for constructing the cooperative BSS group is the same as the method described above, detailed description thereof is omitted here. FIG. 6 is a diagram showing a BSS centralized control type wireless LAN technology according to the prior art. FIG. 7 is a diagram illustrating a BSS centralized control type wireless LAN technology according to an embodiment of the present invention.

  In the prior art (FIG. 6), a communication protocol (communication operation) when a certain BSS # 1 acquires a communication right will be described. First, the AP in BSS # 1 transmits an RTS frame after random backoff, and requests all terminals in BSS # 1 to transmit CTS frames.

  Next, each terminal in the BSS # 1 that has received the RTS from the AP transmits a CTS frame in order to reserve the wireless medium. Since the traffic information of each terminal is described in the CTS frame transmitted by the terminal in BSS # 1, the AP can collect the traffic information of each terminal in BSS # 1 by receiving these RTS / CTS frames. .

  In addition, since the CTS frame transmitted by the terminal in BSS # 1 includes a preamble portion used for channel information estimation, the AP receives these CTS frames, and thereby the channel of each terminal in BSS # 1 The channel information of all the terminals in BSS # 1 can be collected indirectly by estimating the information.

  Next, the AP allocates communication resources in BSS # 1 based on the information collected by these frames, and further notifies the allocation result of the resource allocation in an RBI (Resource Block Information) frame. Each terminal in BSS # 1 that has received the RBI frame transmits a data frame according to the allocation result, and releases the communication right after receiving a success / failure response from the terminal.

  Next, the communication operation of the wireless communication system according to the present embodiment will be described with reference to FIG. First, the master AP in the cooperative BSS group transmits an RTS frame after random backoff, and requests the terminals in all the cooperative BSS groups to transmit the CTS frame (FIG. 7 (1)).

  Next, each terminal in the cooperative BSS group that has received the RTS from the master AP transmits a CTS frame in order to reserve the wireless medium (FIG. 7 (2)).

  Next, each slave AP that has received the CTS frame from each terminal in the cooperative BSS group first estimates channel information based on the preamble portion included in the CTS frame. Subsequently, channel information CSI (Channel State Information) obtained by the estimation is described in the payload of the CSI frame and transmitted to the master AP (FIG. 7 (3)).

  At this time, since the traffic information of each terminal is described in the CTS frame transmitted by the terminal in the cooperative BSS group, the AP receives the CTS frame to thereby receive the traffic of the terminal in each cooperative BSS group. Information can be collected. In addition, since the CTS frame transmitted by the terminals in the cooperative BSS group includes a preamble portion used for channel information estimation, the master AP receives these CTS frames to receive the CTS frame. Collect terminal channel information. Further, the master AP can collect the channel information by receiving the CSI frame transmitted by the slave AP with the channel information between the terminal and the slave AP.

  The AP allocates communication resources in units of cooperative BSS groups based on the traffic information and channel information collected by these frames, and further notifies the allocation result in an RBI (Resource Block Information) frame. FIG. 7 (4)).

  Next, each terminal in the cooperative BSS group that has received the RBI frame transmits a data frame in accordance with the allocation result (FIG. 7 (5)).

  Next, after receiving a success / failure response from each terminal, the master AP and slave AP in the cooperative BSS group release the communication right (FIG. 7 (6)).

  Next, a numerical experiment of the above-described wireless communication system will be described. In order to evaluate the transmission characteristics of the wireless communication system described above, a computer simulation was performed for uplink communication. FIG. 8 is a diagram illustrating a setting example of simulation of uplink communication. The terminal arrangements assumed as simulation specifications are as shown here.

  There are two APs (AP # 1, AP # 2) in the transmission space. The distance between APs is 30 (m). Two terminals (STA # 1-1 and STA # 1-2) belong to AP # 1 and form BSS # 1. Two terminals (STA # 2-1, STA # 2-2) belong to AP # 2, and BSS # 2 is formed. It is assumed that each AP and each terminal exists at a point shown in FIG. Of all the terminals (four terminals), only the STA # 1-1 is an RT terminal, and the other three terminals are NRT terminals.

  As a comparison object, a system that performs uplink transmission using the DCF method defined by IEEE 802.11 in each BSS and a system that performs uplink transmission using a BSS centralized control type OFDMA method (Non-patent Document 3) are used.

  Prior Art (Part 1) In the DCF method (802.11 DCF), the AP (AP # 1, # 2) and each terminal (STA # 1-1 to # 2-2) are autonomously in accordance with the DCF. Access. BSS # 1 terminals (STA # 1-1, # 1-2) transmit to AP # 1, and BSS # 2 terminals (STA # 2-1, # 2-2) transmit to AP # 2.

  In the prior art (part 2) BSS centralized control type OFDMA method (Non-patent Document 3) (OFDMA w / o Inter-BSS Coop.), The AP is based on the traffic status and channel status of the terminal in the BSS to which the AP belongs. In addition, the medium access of each terminal is controlled. For example, AP # 1 determines resource allocation to these two terminals based on the traffic status and channel status of the terminals STA # 1-1 and STA # 1-2 belonging to the BSS # 1, so that these 2 Control the medium access of the terminal.

  In the inter-BSS centralized control OFDMA scheme (OFDMA w / Inter-BSS Coop.) According to the present embodiment, AP # 1 is a master AP, AP # 2 is a slave AP, and one AP is composed of two APs and four terminals. Form a collaborative BSS.

Area throughput is the throughput achieved in an area used by two BSSs. In this characteristic evaluation, since the position of the BSS does not change, the area throughput becomes the system throughput. That is, the throughput obtained in the entire network including two BSSs. Here, the QoS satisfaction rate refers to a ratio of packets transmitted within the requested delay time among all packets transmitted by the RT terminal.

  FIG. 9 is a diagram showing the relationship between the offered load of the NRT terminal and the QoS satisfaction rate. As shown in FIG. 9, as the offered load of the NRT terminal increases, the QoS satisfaction rate of the conventional system (conventional DCF system and conventional BSS centralized control type OFDMA system) decreases.

  The ▲ shown on the horizontal axis of FIG. 9 indicates the maximum offered load that can achieve the required QoS satisfaction rate in the conventional DCF method and the conventional BSS centralized control type OFDMA method, respectively. If the load is overloaded, the QoS satisfaction rate ≧ 99% cannot be achieved.

  FIG. 10 is a diagram showing the relationship between the offered load and throughput of the NRT terminal. The ▲ shown on the horizontal axis in FIG. 10 indicates the maximum offered load that can achieve the required QoS (QoS satisfaction rate ≧ 99%) in the conventional DCF method and the conventional BSS centralized control type OFDMA method, respectively. Also, the ▲ shown on the vertical axis in FIG. 10 indicates the maximum area throughput that can maintain the required QoS satisfaction rate.

  In the conventional system (conventional DCF system and conventional BSS centralized control type OFDMA system), if traffic exceeding the horizontal axis ▲ occurs from the NRT terminal, higher area throughput can be obtained, but the RT terminal cannot maintain the required QoS. . When the first purpose is to secure the required QoS satisfaction rate, if traffic exceeding the horizontal axis ▲ occurs, the network will fail.

  On the other hand, in the case of the wireless communication system according to the present embodiment, only one cooperative BSS exists in the transmission space in this evaluation environment (all terminals belong to the cooperative BSS). It can be seen that the RT terminal can maintain the required QoS.

  As described above, in the BSS (Basic Service Set) centralized control type wireless LAN system capable of improving the QoS guarantee and the utilization efficiency of the radio resources while sharing the frequency with the different types of radio systems, When cells overlap, APs in each BBS perform resource management individually, so communication quality and system throughput decrease due to QoS unguaranteed, communication suspension by NAV, increase in control frames, and inability to allocate optimal resources There is a problem.

  In the present embodiment, a coordinated BSS group composed of a plurality of BSSs is constructed, and a centralized control type resource management is performed while sharing frequencies with other wireless systems in the vicinity by a master AP that centrally controls all APs belonging to the coordinated BSS group. I did it.

  With this configuration, a coordinated BSS including a plurality of BSSs can simultaneously transmit a plurality of overlapping BSSs included even based on the CSMA / CA scheme, so that QoS (delay) of a plurality of terminals in the BSS can be guaranteed. Further, if the terminals in the cooperative BSS are spatially separated, simultaneous communication by repeated use of radio resources becomes possible.

  Further, transmission of management frames such as beacon frames and probe request / response frames can be aggregated from a plurality of BSS APs to one cooperative BSS master AP, and the amount of radio resources used can be reduced. In addition, the terminal in the cooperative BSS can associate with a plurality of APs, and the degree of freedom of use of radio resources is improved.

  Due to the above effects, the wireless network that finally implemented the technology of the present invention has improved communication quality with higher area throughput, shorter transmission delay, etc. while ensuring the same QoS as compared with the wireless network to which the conventional technology is applied. Can be realized.

  You may make it implement | achieve AP and a terminal in embodiment mentioned above with a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory inside a computer system serving as a server or a client in that case may be included and a program held for a certain period of time. Further, the program may be for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in the computer system. It may be realized using hardware such as PLD (Programmable Logic Device) or FPGA (Field Programmable Gate Array).

  As mentioned above, although embodiment of this invention has been described with reference to drawings, the said embodiment is only the illustration of this invention, and it is clear that this invention is not limited to the said embodiment. is there. Therefore, additions, omissions, substitutions, and other modifications of the components may be made without departing from the technical idea and scope of the present invention.

  In the area of the cooperative BBS, high communication quality can be ensured and it can be applied to an application indispensable to suppress a decrease in throughput.

  AP ... access point (base station), STA ... terminal, M-AP ... master AP, S-AP ... slave terminal

Claims (3)

In any radio cell belonging to a radio communication network, a radio communication method in a communication configuration in which a base station and a plurality of terminal stations exist in the radio cell,
When constructing a cooperative BSS group by a plurality of BSSs and selecting a base station that centrally controls all base stations belonging to the cooperative BSS group as a master base station and the remaining base stations as slave base stations, all slaves are selected. a step of selecting the master base station as a selection condition that you can communicate directly with the base station,
After constructing the cooperative BSS group, through pre-processing of CSMA / CA and RTS / CTS frame exchange, wireless medium reservation is performed at a time in units of the cooperative BSS group, and at the same time, traffic information of terminals in the cooperative BSS group Collecting channel information by the master base station;
Based on the traffic information and channel information of each terminal collected by the master base station, radio resources are allocated so as to improve the communication quality index in units of the cooperative BSS group, and allocated to the slave base station and the terminal station Notifying the result,
The allocation result notified the slave base station and the terminal station, in accordance with the assignment result perform information transmission, have a performing a success or failure response to the master base station or the slave base station,
The pretreatment includes
The master base station receiving an RTS frame from any of the terminal stations belonging to the cooperative BSS group and requesting the other terminal stations to transmit a CTS frame;
The terminal station other than the source of the RTS frame transmits a CTS frame in response to the request;
The slave base station transmitting channel information with the terminal station estimated based on the CTS frame to the master base station;
The master base station estimates channel information with the terminal station based on the RTS frame and the CTS frame, and further obtains traffic information of the terminal station from the RTS frame and the CTS frame, respectively. Including
Or
The master base station transmitting an RTS frame;
The terminal station transmitting a CTS frame in response to receiving the RTS frame;
The slave base station transmitting channel information with the terminal station estimated based on the CTS frame to the master base station;
The master base station estimating channel information with the terminal station based on the CTS frame, and further acquiring the traffic information of the terminal station from each of the CTS frames. Communication method. In any radio cell belonging to a radio communication network, a radio communication system in a communication configuration in which a base station and a plurality of terminal stations exist in the radio cell,
When constructing a cooperative BSS group by a plurality of BSSs and selecting a base station that centrally controls all base stations belonging to the cooperative BSS group as a master base station and the remaining base stations as slave base stations, all slaves are selected. means for selecting said master base station as a selection condition that you can communicate directly with the base station,
After constructing the cooperative BSS group, through pre-processing of CSMA / CA and RTS / CTS frame exchange, wireless medium reservation is performed at a time in units of the cooperative BSS group, and at the same time, traffic information of terminals in the cooperative BSS group Means for the master base station to collect channel information;
Based on the traffic information and channel information of each terminal collected by the master base station, radio resources are allocated so as to improve the communication quality index in units of the cooperative BSS group, and allocated to the slave base station and the terminal station A means of notifying the result;
The allocation result notified the slave base station and the terminal station performs information transmission in accordance with the assignment result, we have a means for performing the success or failure response to the master base station or the slave base station,
The pretreatment includes
Processing in which the master base station receives an RTS frame from any of the terminal stations belonging to the cooperative BSS group and requests the other terminal stations to transmit a CTS frame;
A process in which the terminal station other than the source of the RTS frame transmits a CTS frame in response to the request;
A process in which the slave base station transmits channel information with the terminal station estimated based on the CTS frame to the master base station;
The master base station estimates channel information with the terminal station based on the RTS frame and the CTS frame, and further acquires the traffic information of the terminal station from the RTS frame and the CTS frame, respectively. Including
Or
A process in which the master base station transmits an RTS frame;
A process in which the terminal station transmits a CTS frame in response to reception of the RTS frame;
A process in which the slave base station transmits channel information with the terminal station estimated based on the CTS frame to the master base station;
And a process in which the master base station estimates channel information with the terminal station based on the CTS frame, and further acquires traffic information of the terminal station from each of the CTS frames. Communications system.   A wireless communication program for causing a computer to execute the wireless communication method according to claim 1.

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