JP7794437B2 - Wireless communication method, wireless communication system, coordinator device, wireless communication device, and program - Google Patents

Description

Article 30, Paragraph 2 of the Patent Act applies. Published on March 2, 2022, at the Wireless Communication Systems Study Group (RCS) of the Institute of Electronics, Information and Communication Engineers (IEICE) RCS2021-259.

Article 30, Paragraph 2 of the Patent Act applies. Published on February 23, 2022, at the Wireless Communication Systems Study Group (RCS) of the Institute of Electronics, Information and Communication Engineers (IEICE) RCS2021-259 (2022-03).

The present invention relates to wireless communication technology, and in particular to wireless communication technology that assigns multiple wireless LAN systems to the same channel and appropriately controls the timing of traffic transmission.

In recent years, the age of the Internet of Things (IoT) has arrived in earnest, with IoT technology being utilized in a variety of fields, including manufacturing and infrastructure. For example, in factories, IoT devices are installed in manufacturing systems such as robots and machinery, and the operating status of these devices and machinery is monitored, controlled, and quality controlled via a wireless local area network (LAN). However, in factories where many manufacturing systems are densely packed, multiple wireless devices attempt to communicate simultaneously, resulting in frequent packet collisions, packet loss, and delays.

Methods for avoiding packet collisions include allocating channels to be used, detecting interference, changing channels when interference is detected, and controlling transmission power. For example, one possible approach is to change the channel to be used using the technology described in Patent Document 1.

Assuming control using a centralized control device (e.g., a controller), a control device is prepared, and the access points (APs) of the wireless LAN system to be controlled are connected to the centralized control device via a network, for example. The control device can prevent packet collisions by performing the above-mentioned control on the APs connected to the centralized control device.

However, when using the above technology, if there are many wireless LAN systems, channels will overlap on the frequency axis, resulting in interference between the systems. In such a situation, when traffic is transmitted by a wireless LAN system, numerous collisions will occur, necessitating retransmission, making it difficult to transmit that traffic within its allowable delay time. In other words, in such a situation, using the above technology makes it difficult to appropriately control the timing of traffic transmission.

One possible solution is to use technology such as that disclosed in Patent Document 2. In other words, the technology disclosed in Patent Document 2 uses a time slot that is commonly defined based on information from all devices included in the wireless communication system (information indicating communication status, information indicating communication performance, etc.), allowing multiple wireless systems to use a single channel in a time-sharing manner, thereby making it possible to control the timing of traffic transmission.

JP 2013-93708 A Japanese Patent Application Laid-Open No. 2020-155857

However, with the technology of Patent Document 2, if there is a device whose required transmission time for communication is shorter than the time slot length (if there is a device whose allocated time slot is used at a low rate), the time that the time slot is unused will be longer (the time that resources are not used effectively will be longer), and communication efficiency will decrease.

One possible solution to this problem is to shorten the time slot length to prevent a decline in communication efficiency, but shortening the time slot length complicates the management of time slot information and increases the frequency of synchronization processes between devices, requiring highly accurate transmission control, which results in increased processing load. Furthermore, shortening the time slot length increases the impact on the next time slot when sudden processing delays or interference occur, making the corresponding processing more complex.

In view of the above problems, the present invention aims to provide a wireless communication system, wireless communication method, coordinator device, wireless communication device, and program that can perform high-speed, high-precision wireless communication without degrading wireless communication performance by appropriately controlling traffic transmission timing, even in a small space where many wireless communication terminals are present.

To solve the above problem, the first invention is a wireless communication method used in a wireless communication system including multiple wireless communication devices assigned to groups identified by group identifiers, and includes a time slot definition data generation step, a time slot time sequence pattern identification data generation step, a transmission timing determination step, and a data transmission step.

The time slot definition data generation step generates time slot definition data that includes the time slot length and time slot start time of a time slot to be commonly used for time division communication between multiple wireless communication devices, information for identifying the group to which each of the multiple wireless communication devices belongs, and information on the number of wireless communication devices belonging to the group.

The time slot time series pattern identification data generation step generates time slot time series pattern identification data that includes time slot control information, which is information for identifying a repetitive pattern in the time slot time series, and time slot allocation information, which is information for identifying the group to which transmission rights are granted in the time slot and the number of wireless communication devices belonging to that group.

The transmission timing determination step determines the transmission timing of each wireless communication device belonging to the group that has been granted the right to transmit in the time slot, based on the time slot time sequence pattern identification data, so that the transmission timing within the time slot varies.

In the data transmission step, each wireless communication device belonging to the group that has been granted the right to transmit in the time slot transmits data at the transmission timing determined in the transmission timing determination step.

In this wireless communication method, a time slot length is set so that management and synchronization control are not complicated, and multiple devices can acquire the right to transmit in time slots of the set time slot length. Furthermore, in this wireless communication method, multiple devices with the right to transmit transmit data within the same time slot (common time slot) at transmission timings that are determined to vary, thereby distributing the transmission timings of multiple devices with the right to transmit in the same time slot. As a result, this wireless communication method can appropriately prevent communication collisions and improve communication efficiency.

In other words, this wireless communication method allows for high-speed, high-precision wireless communication without degrading wireless communication performance by appropriately controlling the timing of traffic transmissions, even in a small space where many wireless communication terminals are present.

A second invention is the first invention, wherein the transmission timing determination step determines the transmission timing within a time slot based on the time slot time sequence pattern identification data and a delay time calculated using a random number or a hash function.

As a result, with this wireless communication method, multiple devices with transmission rights can transmit data within the same time slot (common time slot) at transmission timings that are determined to vary, using delay times calculated using random numbers or hash functions.

A third aspect of the present invention is the first or second aspect of the present invention, wherein the number of wireless communication devices belonging to a group granted a transmission right in a time slot is M, and a delay time from a start time of the time slot is T, the transmission timing determination step determines the transmission timing in the time slot from the start time of the time slot by
Δt: duration of one time slot (hours)
rand(M): A function that outputs an integer between 0 and M-1 with a uniformly distributed probability (a function that generates random numbers)
The time is determined to be delayed by the delay time T obtained by

As a result, with this wireless communication method, multiple devices with transmission rights can transmit data within the same time slot (common time slot) at transmission timings that are determined to vary, using delay times calculated using uniform random numbers.

A fourth invention is the first or second invention, further comprising a device identifier assignment step of assigning a device identifier that is a unique identifier to the wireless communication device.

Let M be the number of wireless communication devices belonging to a group that has been granted the right to transmit in a time slot, and let T be the delay time from the start time of the time slot within the time slot. In the transmission timing determination step, the transmission timing within the time slot is determined by
Δt: duration of one time slot (hours)
ID: Device identifier Hash(x): Function (hash function) to obtain the hash value (integer value) of x
%x: "%" determines the time delayed by the delay time T obtained by an operator that obtains the remainder modulo x.

As a result, with this wireless communication method, multiple devices with transmission rights can transmit data within the same time slot (common time slot) at transmission timings that are determined to vary, using a delay time calculated using a hash function of a device identifier unique to each wireless device. Furthermore, with this wireless communication method, the delay time is calculated using a hash function of a device identifier unique to each wireless device, so the delay time within the time slot for each wireless device (delay time from the start time of the time slot) can be made the same.

A fifth aspect of the present invention is the first or second aspect of the present invention, wherein, when the number of wireless communication devices belonging to a group granted a transmission right in a time slot is M and the maximum total throughput amount realized in the time slot is C, the transmission timing determination step comprises:
R: Transmission rate M: Number of allocated devices α: Bandwidth adjustment coefficient (0≦α≦1)
The data transmission timing is determined so that the transmission rate R obtained by

As a result, this wireless communication method allows multiple devices with transmission rights to transmit data within the same time slot (common time slot) using a divided bandwidth (a communication rate calculated by dividing the total bandwidth by the number of devices granted transmission rights in that time slot). By transmitting data using divided bandwidths, the transmission timing is also distributed, making it possible to appropriately prevent communication collisions and improve communication efficiency.

A sixth invention is a wireless communication system for executing the wireless communication method of any one of the first to fifth inventions, comprising a coordinator device and multiple wireless communication devices.

The coordinator device executes a time slot definition data generation step and a time slot time sequence pattern identification data generation step.

Each of the multiple wireless communication devices performs a transmission timing determination step and a data transmission step.

This makes it possible to realize a wireless communication system that achieves the same effects as the first invention.

The seventh invention is a coordinator device that constitutes the wireless communication system of the sixth invention.

This makes it possible to realize a coordinator device that constitutes a wireless communication system that achieves the same effects as the sixth invention.

The eighth invention is a wireless communication device that constitutes the wireless communication system of the sixth invention.

This makes it possible to realize a wireless communication device that constitutes a wireless communication system that achieves the same effects as the sixth invention.

A ninth invention is a program for causing a computer to execute the wireless communication method of any one of the first to fifth inventions.

This makes it possible to realize a program that causes a computer to execute a wireless communication method that achieves the same effects as any one of the first to fifth inventions.

The present invention makes it possible to realize a wireless communication system, wireless communication method, coordinator device, wireless communication device, and program that can perform high-speed, high-precision wireless communication without degrading wireless communication performance by appropriately controlling traffic transmission timing, even in a small space where many wireless communication terminals are present.

1 is a schematic configuration diagram of a wireless communication system 1000 according to a first embodiment. FIG. 1 is a schematic configuration diagram of a coordinator device 100 according to a first embodiment. FIG. 2 is a schematic configuration diagram of a first access point AP1-1 according to the first embodiment. FIG. 1 is a schematic configuration diagram of a wireless terminal STA1-1 according to the first embodiment. 10 is a sequence diagram for explaining a time slot definition process and a time slot allocation process in the wireless communication system 1000. FIG. 1 is a diagram showing a schematic configuration of a wireless communication system 1000, and shows an example in which wireless communication devices included in the wireless communication system 1000 are divided into three groups. 10 is a diagram showing an example of the data structure of data D_slot that is composed of a first header H1 (time slot control information) and a payload P1 (time slot allocation information). FIG. 8 is a timing chart showing a case where a plurality of wireless communication devices (access points, wireless terminals) communicate in a time-division manner on one channel based on the data D_slot of FIG. 7; 8 is a timing chart showing a case where a plurality of wireless communication devices (access points, wireless terminals) communicate in a time-division manner on one channel based on the data D_slot of FIG. 7 in a wireless communication system according to a first modified example of the first embodiment. FIG. 20 is a schematic diagram illustrating the configuration of a wireless communication system 2000 according to a second embodiment. FIG. 10 is a schematic configuration diagram of a first access point AP1-1A according to a second embodiment. FIG. 11 is a schematic configuration diagram of a wireless terminal STA1-1A according to a second embodiment. 8 is a timing chart (in the case of band division) when a plurality of wireless communication devices (access points, wireless terminals) communicate in a time-division manner on one channel based on the data D_slot of FIG. 7; FIG. 2 is a diagram showing a CPU bus configuration.

[First embodiment]
The first embodiment will be described below with reference to the drawings.

<1.1: Configuration of wireless communication system>
FIG. 1 is a schematic configuration diagram of a wireless communication system 1000 according to the first embodiment.

Figure 2 is a schematic diagram of the coordinator device 100 according to the first embodiment.

Figure 3 is a schematic diagram of the first access point AP1-1 according to the first embodiment.

Figure 4 is a schematic diagram of the wireless terminal STA1-1 according to the first embodiment.

As shown in FIG. 1, the wireless communication system 1000 includes a coordinator device 100 and L (L: natural number) wireless systems: a first wireless system SYS1, a second wireless system SYS2, ..., an L-th wireless system SYSL. As shown in FIG. 1, the coordinator device 100 and the first wireless system SYS1, the second wireless system SYS2, ..., the L-th wireless system SYSL are each connected to a network NW1 (e.g., a wired network) and can communicate with each other.

Note that the wireless communication system 1000 includes multiple wireless systems. For ease of explanation, the following description will be given using an example in which the number of wireless systems included in the wireless communication system 1000 is "3." However, this is not limited to this, and the number of wireless systems included in the wireless communication system 1000 may be a number other than "3."

(1.1.1: Coordinator Device)
As shown in FIG. 2, the coordinator device 100 includes a time slot definition unit 11, a time slot allocation information generation unit 12, a wireless system information acquisition and storage unit 13, a first communication processing unit 14, and a first communication interface 15.

The time slot definition unit 11 executes a process (time slot definition process) to define time slots used in the wireless communication system 1000. The time slot definition unit 11 inputs the wireless system information Info_sys output from the wireless system information acquisition and retention unit 13, executes the time slot definition process based on the wireless system information Info_sys, and acquires the data necessary to define (define) the time slot as data D_slot_def. The time slot definition unit 11 then outputs the acquired data D_slot_def to the first communication processing unit 14. The time slot definition unit 11 also acquires the data D_slot_def necessary to define the time slot as an initial value, for example, based on the initial state of the wireless communication system 1000 or the steady state of the wireless environment, and outputs the acquired data D_slot_def to the first communication processing unit 14.

The time slot allocation information generation unit 12 inputs the wireless system information Info_sys output from the wireless system information acquisition and storage unit 13. The time slot allocation information generation unit 12 generates time slot allocation information to be used in the wireless communication system 1000, and outputs the generated time slot allocation information as data D_slot to the first communication processing unit 14.

The wireless system information acquisition and retention unit 13 inputs data D12 output from the first communication processing unit 14. The wireless system information acquisition and retention unit 13 acquires information about each wireless system, information about the access points included in each wireless system, and/or information about wireless terminals from data D12.

When transmitting data to network NW1, the first communication processing unit 14 outputs data D11 to the first communication interface 15. When receiving data from network NW1, the first communication processing unit 14 inputs data D11 from the first communication interface 15. The first communication processing unit 14 also acquires data D12 including information on each wireless system, information on access points included in each wireless system, and/or information on wireless terminals from the data D11 input from the first communication interface 15, and outputs the acquired data D21 to the wireless system information acquisition and retention unit 13. The first communication processing unit 14 also inputs data D_slot_def output from the time slot definition unit 11 and data D_slot output from the time slot allocation information generation unit 12, generates data including data D_slot_def and/or data D_slot, and outputs the generated data as data D11 (transmission data) to the first communication interface 15.

The first communication interface 15 is a communication interface for sending and receiving data to and from external devices via the network NW1. The first communication interface 15 converts data D11 output from the first communication processing unit 14 into data D1_out in a format that can be communicated via the network NW1, and transmits the data D1_out via the network NW1. The first communication interface 15 also receives data D1_in via the network NW1. The first communication interface 15 converts the received data D1_in into data D11 that can be processed by the first communication processing unit 14, and outputs the data D11 to the first communication processing unit 14.

(1.1.2: First Wireless System)
As shown in FIG. 1, the first wireless system SYS1 includes a first access point AP1-1 and N1 (N1: natural number) wireless terminals STA1-1 to STA1-N1.

(1.1.2.1: First Access Point)
As shown in Figure 3, the first access point AP1-1 includes a second communication interface 21, an RF control unit 22, a time slot information memory unit 23, a wireless system information acquisition and retention unit 24, an antenna Ant1, an RF processing unit 25, an application unit 26, and a transmission buffer FIFO1.

The second communication interface 21 is a communication interface for transmitting and receiving data to and from external devices via the network NW1. The second communication interface 21 converts data D21 output from the RF control unit 22 into data D2_out in a format that can be communicated via the network NW1, and transmits the data D2_out via the network NW1. The second communication interface 21 also receives data D2_in via the network NW1. The second communication interface 21 converts the received data D2_in into data D21 that can be processed by the RF control unit 22, and outputs the data D21 to the RF control unit 22.

When transmitting data to network NW1, the RF control unit 22 outputs data D21 to the second communication interface 21. When receiving data from network NW1, the RF control unit 22 inputs data D21 from the second communication interface 21. The RF control unit 22 also acquires data D_slot including time slot allocation information from the data D21 input from the second communication interface 21, and outputs the acquired data D_slot to the time slot information storage unit 23. The RF control unit 22 also acquires data D_slot_def including information for defining time slots (time slot definition information) from the data D21 input from the second communication interface 21, and outputs the acquired data D_slot_def to the time slot information storage unit 23. Furthermore, the RF control unit 22 acquires data D23 including information about the first wireless system SYS1, which is the wireless system that includes the first access point AP1-1, from the data D22_in output from the RF processing unit 25, and outputs the acquired data D23 to the wireless system information acquisition and retention unit 24. The RF control unit 22 also inputs information Info_sys (SYS1) about the first wireless system output from the wireless system information acquisition and retention unit 24.

The RF control unit 22 also generates a control signal CTL1_RF for controlling the RF processing unit 25 and outputs this control signal CTL1_RF to the RF processing unit 25. For example, the RF control unit 22 inputs information Info1_CSMA indicating the wireless communication status output from the RF processing unit 25 (for example, information such as the availability of channels used for wireless communication, obtained using the CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) method), and generates the control signal CTL1_RF based on this information Info1_CSMA.

The RF control unit 22 also generates or acquires data to be transmitted externally and outputs the data to the RF processing unit 25 as data D22B_out.

The RF control unit 22 also generates a control signal CTL1_fifo for controlling the transmission buffer FIFO1 and outputs the control signal CTL1_fifo to the transmission buffer FIFO1.

The RF control unit 22 also receives a request signal Req1_info output from the application unit 26. The RF control unit 22 acquires the data requested by the request signal Req1_info from the time slot information storage unit 23 and/or the radio system information acquisition and retention unit 24, and outputs the acquired data to the application unit 26 as data D1_info.

The time slot information storage unit 23 inputs the data D_slot and/or data D_slot_def output from the RF control unit 22 and stores the input data. Furthermore, the time slot information storage unit 23 outputs the stored data D_slot and/or data D_slot_def to the RF control unit 22 in accordance with instructions from the RF control unit 22.

The wireless system information acquisition and retention unit 24 inputs data D23 output from the RF control unit 22, acquires information Info_sys(SYS1) about the first wireless system SYS1 from the data D23, and stores (retains) the acquired information Info_sys(SYS1). Furthermore, the wireless system information acquisition and retention unit 24 outputs the stored (retained) information Info_sys(SYS1) to the RF control unit 22 in accordance with instructions from the RF control unit 22.

The RF processing unit 25 inputs the control signal CTL1_RF output from the RF control unit 22 and the data D22A_out output from the transmission buffer FIFO1 or the data D22B_out output from the RF control unit 22. In accordance with the control signal CTL1_RF, the RF processing unit 25 performs RF processing for transmission (BB (baseband) modulation processing, RF modulation processing, etc.) on the data D22A_out output from the transmission buffer FIFO1 or the data D22B_out output from the RF control unit 22, and obtains the RF signal RF2_out that can be transmitted externally via antenna Ant1. The RF processing unit 25 then transmits the RF signal RF2_out externally via antenna Ant1. The RF processing unit 25 also receives an RF signal RF2_in from the outside via the antenna Ant1, performs RF processing for reception (RF demodulation processing, BB demodulation processing, etc.) on the received RF signal RF2_in, acquires data D22_in that can be processed by the RF control unit 22 and the application unit 26, and outputs the acquired data D22_in to the RF control unit 22 and/or the application unit 26. The RF processing unit 25 also acquires information Info1_CSMA indicating the wireless communication status (for example, information such as the availability of channels used for wireless communication, acquired using the CSMA/CA method), and outputs the information Info1_CSMA to the RF control unit 22.

Transmission buffer FIFO1 is a memory for storing and holding transmission packets, and is realized, for example, using a FIFO (First In First Out) memory. Transmission buffer FIFO1 inputs transmission packet data D25 output from the application unit 26 and stores and holds that data. Transmission buffer FIFO1 also inputs a control signal CTL1_fifo output from the RF control unit 22, and outputs the stored data (transmission packet data) to the RF processing unit 25 as data D22_out in accordance with the control signal CTL1_fifo.

The application unit 26 inputs data D22_in output from the RF processing unit 25. The application unit 26 performs predetermined processing using this data D22_in. The application unit 26 is also a functional unit for executing a predetermined application executed in the first access point AP1-1. The application unit 26 also generates a request signal Req1_info and outputs this request signal Req1_info to the RF control unit 22. The application unit 26 also inputs data D1_info output from the RF control unit 22 (data requested by the request signal Req1_info).

Furthermore, when the application unit 26 transmits a packet to the outside, for example, to execute a specific application, it generates data for the transmission packet and outputs the generated data as data D25 to the transmission buffer FIFO2.

The "storage unit" is realized using the time slot information storage unit 23 and/or the radio system information acquisition and retention unit 24.

(1.1.2.2: Wireless Terminal)
As shown in FIG. 4, the wireless terminal STA1-1 includes an antenna Ant2, an RF processing unit 31, an RF control unit 32, a time slot information storage unit 33, a wireless terminal information acquisition and retention unit 34, an application unit 35, and a transmission buffer FIFO2.

The RF processing unit 31 receives an RF signal RF3_in from the outside via the antenna Ant2, performs RF processing for reception (RF demodulation processing, BB demodulation processing, etc.) on the received RF signal RF3_in, acquires data D31_in that can be processed by the RF control unit 32 and/or the application unit 35, and outputs the acquired data D31_in to the RF control unit 32 and/or the application unit 35. The RF processing unit 31 also inputs a control signal CTL2_RF output from the RF control unit 32, and data D31A_out output from the transmission buffer FIFO2 or data D31B_out output from the RF control unit 32. In accordance with the control signal CTL2_RF, the RF processing unit 31 performs RF processing for transmission (BB modulation processing, RF modulation processing, etc.) on the data D31A_out output from the transmission buffer FIFO2 or the data D31B_out output from the RF control unit 32, and obtains an RF signal RF3_out that can be transmitted externally via antenna Ant2. The RF processing unit 31 then transmits the RF signal RF3_out externally via antenna Ant2.

The RF processing unit 31 also acquires information Info2_CSMA indicating the wireless communication status (for example, information such as the availability of channels used for wireless communication, acquired using the CSMA/CA method), and outputs this information Info2_CSMA to the RF control unit 32.

When receiving data from the outside via antenna Ant2, the RF control unit 32 inputs data D31_in from the RF processing unit 31. The RF control unit 32 acquires data D_slot including time slot allocation information from the data D31_in input from the RF processing unit 31, and outputs the acquired data D_slot to the time slot information storage unit 33. The RF control unit 32 also acquires data D_slot_def including information for defining the time slot (time slot definition information) from the data D31_in input from the RF processing unit 31, and outputs the acquired data D_slot_def to the time slot information storage unit 33. The RF control unit 32 also acquires data D32 including information about the wireless terminal STA1-1 from the data D31_in output from the RF processing unit 31, and outputs the acquired data D32 to the wireless terminal information acquisition and retention unit 34. The RF control unit 32 also receives information Info_sys (STA1-1) about the wireless terminal STA1-1 output from the wireless terminal information acquisition and storage unit 34.

The RF control unit 32 also generates a control signal CTL2_RF for controlling the RF processing unit 31 and outputs this control signal CTL2_RF to the RF processing unit 31. For example, the RF control unit 32 inputs information Info2_CSMA indicating the wireless communication status output from the RF processing unit 31 (for example, information such as the availability of channels used for wireless communication, obtained using the CSMA/CA method), and generates the control signal CTL2_RF based on this information Info2_CSMA.

The RF control unit 32 also generates or acquires data to be transmitted externally and outputs the data to the RF processing unit 31 as data D31B_out.

The RF control unit 32 also generates a control signal CTL2_fifo for controlling the transmission buffer FIFO2 and outputs the control signal CTL2_fifo to the transmission buffer FIFO2.

The RF control unit 32 also receives a request signal Req2_info output from the application unit 35. The RF control unit 32 acquires the data requested by the request signal Req2_info from the time slot information storage unit 33 and/or the wireless terminal information acquisition and retention unit 34, and outputs the acquired data as data D2_info to the application unit 26.

The time slot information storage unit 33 inputs the data D_slot and/or data D_slot_def output from the RF control unit 32 and stores the input data. Furthermore, in accordance with instructions from the RF control unit 32, the time slot information storage unit 33 outputs the stored data D_slot and/or data D_slot_def to the RF control unit 32.

The wireless terminal information acquisition and retention unit 34 inputs data D32 output from the RF control unit 32, acquires information Info_sys (STA1-1) about the wireless terminal STA1-1 from the data D32, and stores (retains) the acquired information Info_sys (STA1-1). Furthermore, in accordance with instructions from the RF control unit 32, the wireless terminal information acquisition and retention unit 34 outputs the stored (retained) information Info_sys (STA1-1) to the RF control unit 22.

The application unit 35 inputs data D31_in output from the RF processing unit 31. The application unit 35 performs predetermined processing using this data D31_in. The application unit 35 is also a functional unit for executing a predetermined application executed in the wireless terminal STA1-1. The application unit 35 also generates a request signal Req2_info and outputs this request signal Req2_info to the RF control unit 32. The application unit 35 also inputs data D2_info (data requested by the request signal Req2_info) output from the RF control unit 32.

Furthermore, when the application unit 35 transmits a packet to the outside, for example, to execute a specific application, it generates data for the transmission packet and outputs the generated data as data D33 to the transmission buffer FIFO2.

Transmission buffer FIFO2 is a memory for storing and holding transmission packets, and is realized, for example, using a FIFO (First In First Out) memory. Transmission buffer FIFO2 inputs transmission packet data D33 output from the application unit 35 and stores and holds that data. Transmission buffer FIFO2 also inputs a control signal CTL2_fifo output from the RF control unit 32, and outputs the stored data (transmission packet data) to the RF processing unit 31 as data D31_out in accordance with that control signal CTL2_fifo.

Note that the second wireless system SYS2 to the Lth wireless system SYSL have the same configuration as the first wireless system SYS1.

The second wireless system SYS2 also includes a second access point AP2-1 and N2 (N2: natural number) wireless terminals STA2-1 to STA2-N2. The second access point AP2-1 has a configuration similar to that of the first access point AP1-1, and each of the wireless terminals STA2-1 to STA-N2 has a configuration similar to that of the wireless terminal STA1-1.

The kth wireless system SYSk (k: natural number, 3≦k≦L) includes the kth access point AP2-k and Nk (Nk: natural number) wireless terminals STAk-1 to STAk-Nk. The kth access point AP2-k has a configuration similar to that of the first access point AP1-1, and each of the wireless terminals STAk-1 to STAk-Nk has a configuration similar to that of the wireless terminal STA1-1.

The "storage unit" is realized using the time slot information storage unit 33 and/or the wireless terminal information acquisition and retention unit 34.

<1.2: Operation of wireless communication system>
The operation of the wireless communication system 1000 configured as above will be described below with reference to the drawings.

Figure 5 is a sequence diagram illustrating the time slot definition process and time slot allocation process in wireless communication system 1000. The operation of wireless communication system 1000 will be described below with reference to Figure 5.

Figure 6 shows the general configuration of the wireless communication system 1000, and is a diagram showing an example in which the wireless communication devices included in the wireless communication system 1000 are divided into three groups.

Figure 7 shows an example of the data structure of data D_slot, which consists of a first header H1 (time slot control information) and a payload P1 (time slot allocation information).

Figure 8 is a timing chart showing when multiple wireless communication devices (access points, wireless terminals) communicate in a time-division manner on a single channel based on the data D_slot in Figure 7.

The number of devices (the number of wireless communication devices (for example, access points, wireless terminals)) included in the k-th wireless system SYSk is represented as "M _k " (k: natural number, 1≦k≦L).

For ease of explanation, the following description will be given of an example in which the wireless communication devices included in the wireless communication system 1000 are divided into three groups (first to third groups) as shown in Fig. 6. The first to third groups are as follows:
(1) The first group (the group ID (referred to as "GID") is "1") includes the first access point AP1-1 and wireless terminals STA1-1 to STA1-3 (three wireless terminals) of the first wireless communication system SYS1. The number of devices in the first group is M ₁ =4.
(2) The second group (with a group ID (GID) of "2") includes a second access point AP2-1 and wireless terminals STA2-1 to STA2-2 (two wireless terminals) of the second wireless communication system SYS2. The number of devices in the second group is M ₂ =3.
(3) The third group (with a group ID (GID) of "3") includes a third access point AP3-1 and wireless terminals STA3-1 to STA2-4 (four wireless terminals) of a third wireless communication system SYS3. The number of devices in the third group is M ₃ =5.

For ease of explanation, we have set up a case where the wireless communication devices included in the kth wireless system SYSk are included in the kth group (GID = k), but this is not limited to this, and any wireless communication device in any wireless system may be included in any group.

(Step S1):
In step S1, the time slot definition unit 11 of the coordinator device 100 executes a process for defining a time slot to be used in the wireless communication system 1000 (time slot definition process).

The time slot definition unit 11 obtains the data D_slot_def necessary to define the time slot as an initial value, for example, based on the initial state of the wireless communication system 1000 or the steady state of the wireless environment.

For example, if the wireless communication system 1000 is installed in a narrow space such as a factory, the steady state of the wireless environment (e.g., the state of the wireless environment when there are no transport vehicles or people moving) of the first wireless system SYS1, the second wireless system SYS2, ..., the Lth wireless system SYSL (in this embodiment, L = 3) can be known in advance, and based on this steady state, the time slot definition unit 11 determines (1) the slot length of the time slot and (2) the slot start time to be used by multiple wireless systems.The time slot definition unit 11 then generates data D_slot_def that includes the determined (1) slot length and (2) slot start time. Furthermore, the time slot definition unit 11 generates information about the groups set in the wireless communication system 1000, i.e., information indicating to which groups the devices included in the wireless communication system 1000 have been assigned, and information on the number of devices in each group (for example, data associating each device with the group ID of the group to which the device has been assigned, and data on the number of devices in the group to which the device belongs), and includes the generated data (information) in the data D_slot_def. The time slot definition unit 11 then outputs the generated data D_slot_def to the first communication processing unit 14.

In addition, the coordinator device 100 may collect information such as device information and communication status from each access point (access points AP1-1, AP2-1, ..., APL-1) and wireless terminals included in each wireless system, and based on the collected information, determine (1) the slot length of the time slot and (2) the slot start time for use in multiple wireless systems.

(Step S2):
In step S2, coordinator device 100 executes a time slot allocation information generation process. Specifically, the process is executed as follows.

The coordinator device 100 uses the first communication processing unit 14 to generate data (request data) requesting information necessary for time slot allocation from each wireless system and the wireless terminals included in each wireless system, and transmits the generated request data via the first communication interface 15 and network NW1 to the first access point AP1-1, second access point AP2-1, ..., and Lth access point APL-1.

The first access point AP1-1 receives the request data via the network NW1 and the second communication interface 21, and based on the request data, generates data (request data) requesting information necessary for time slot allocation from the wireless terminals STA1-1, ..., STA1-N1 included in the first wireless system (for example, the request data is generated by the RF control unit 22). The first access point AP1-1 then transmits the generated request data to each of the wireless terminals STA1-1, ..., STA1-N1 via the RF processing unit 25 and antenna Ant1.

The wireless terminal STA1-1 receives an RF signal containing request data transmitted from the first access point AP1-1 and performs RF processing for reception (RF demodulation processing, BB demodulation processing, etc.) on the RF signal to acquire the request data. Then, based on the request data, the RF control unit 32 of the wireless terminal STA1-1 acquires the wireless terminal information Info_sys (STA1-1) stored in the wireless terminal information acquisition and storage unit 34 and outputs data D31B_out containing the acquired wireless terminal information Info_sys (STA1-1) to the RF processing unit 31. The RF processing unit 31 performs RF processing for transmission (BB modulation processing, RF modulation processing, etc.) on the data D31B_out containing the wireless terminal information Info_sys (STA1-1) to generate an RF signal containing the wireless terminal information Info_sys (STA1-1). The wireless terminal STA1-1 then transmits the generated RF signal to the first access point AP1-1 via antenna Ant2.

The first access point AP1-1 performs RF receiving processing on the RF signal received from the wireless terminal STA1-1 and acquires the data Info_sys(STA1-1) of the wireless terminal STA1-1. The RF control unit 22 of the first access point AP1-1 transmits the data Info_sys(STA1-1) of the wireless terminal STA1-1 to the coordinator device 100 via the second communication interface 21 and the network NW1.

The first communication processing unit 14 of the coordinator device 100 acquires data including data Info_sys (STA1-1) transmitted from the first access point AP1-1 via the network NW1 and the first communication interface 15 as data D12. The wireless system information acquisition and retention unit 13 acquires and retains data Info_sys (STA1-1) of the wireless terminal STA1-1 from data D12.

In this way, coordinator device 100 obtains data (information necessary for time slot allocation) Info_sys(STA1-1) for wireless terminal STA1-1. Furthermore, data (information necessary for time slot allocation) Info_sys(STA1-2) to Info_sys(STA1-N1) for wireless terminals STA1-2 to STA1-N1 (N1=3 in this embodiment) are also obtained by the same process as above.

Furthermore, the first access point AP1-1 acquires data Info_sys (SYS1), which is information necessary for time slot allocation for the first wireless system, based on request data from the coordinator device 100. Specifically, the RF control unit 22 of the first access point AP1-1 acquires data Info_sys (SYS1), which is information necessary for time slot allocation for the first wireless system, from the wireless system information acquisition and retention unit 24. Note that data Info_sys (SYS1), which is information necessary for time slot allocation for the first wireless system, includes data such as the packet generation period, packet generation timing, packet size, allowable delay, and ACK/NACK information used in the first wireless system. Furthermore, some or all of data Info_sys (SYS1), which is information necessary for time slot allocation for the first wireless system, may be acquired by the first access point AP1-1 executing a data collection process.

The first access point AP1-1 transmits data including the data Info_sys (SYS1), which is the information necessary for allocating time slots for the first wireless system obtained as described above, to the coordinator device 100 via the network NW1.

The first communication processing unit 14 of the coordinator device 100 acquires data including data Info_sys (SYS1) transmitted from the first access point AP1-1 as data D12 via the network NW1 and the first communication interface 15. The wireless system information acquisition and retention unit 13 acquires and retains data Info_sys (SYS1) of the wireless terminal STA1-1 from data D12.

In the same manner as above, the coordinator device 100 obtains information necessary for allocating time slots to the second wireless system SYS2 through the Lth wireless system SYSL and the wireless terminals contained therein.

In other words, the coordinator device 100 acquires and stores the information necessary for time slot allocation for all devices included in the wireless communication system 1000.

The information required for time slot allocation is, for example, as follows:
(1) Packet generation period, packet generation timing (2) Packet size (3) Allowable delay (4) ACK/NACK information (presence or absence of handshake communication)
(5) Traffic volume (6) Communication error information (communication error frequency, number of retransmissions, etc.)
Next, coordinator device 100 generates time slot allocation information based on the acquired information necessary for time slot allocation for all devices included in wireless communication system 1000. Coordinator device 100 generates time slot allocation information by determining which devices to allocate to each time slot, for example, based on the information (1) to (6) above. For example, coordinator device 100 generates time slot allocation information based on criteria such as allocating earlier time slots to devices with a small allowable delay, or allocating earlier time slots to devices belonging to a wireless system with a large amount of traffic.

The coordinator device 100 also divides all devices included in the wireless communication system 1000 into a predetermined number of groups and assigns group IDs (GIDs) to identify the divided groups. In this embodiment, as shown in Fig. 6, the coordinator device 100 divides (1) the devices included in the first wireless system SYS1 into a first group (GID = 1, number of devices _M1 = 4), (2) the devices included in the second wireless system SYS2 into a second group (GID = 2, number of devices _M2 = 3), and (3) the devices included in the third wireless system SYS3 into a third group (GID = 3, number of devices _M1 = 5).

For example, as shown in FIG. 7, the coordinator device 100 generates data D_slot in a data format consisting of a first header H1 and a payload P1. The first header H1 contains time slot control information, and the payload P1 contains time slot allocation information. Specifically, the first byte of the first header H1 (the first byte of data D_slot) is a field that contains information about the transmission interval of a series of time slot groups (200 ms in FIG. 7) (this transmission interval is referred to as the "time slot control beacon transmission interval"). The second byte of the first header H1 (the second byte of data D_slot) is a field that contains information about the number of time slots (three in FIG. 7) (the number of time slots for one cycle) to be included within the transmission interval of the time slot group.

Then, from the third byte onwards is payload P1 data, which contains two-byte sets of data for the number of time slots. Of the two-byte sets of data contained in payload P1, the first byte is a field containing group ID information, and the second byte is a field containing information on the number of devices (number of wireless communication devices (access points, wireless terminals)) assigned to the group having that group ID (the group identified by the group ID in the first byte).

The coordinator device 100 is aware of the devices included in the wireless communication system 1000, and stores and retains information such as group setting information, group IDs, and devices assigned to each group (for example, the coordinator device 100 acquires this information from data Info_sys received from devices included in the wireless communication system 1000) in the wireless system information acquisition and retention unit 13.

The coordinator device 100 generates data D_slot in the data format shown in Figure 7, for example.

(Step S3):
In step S3, the coordinator device 100 transmits (1) data D_slot_def containing time slot definition information and information about the group, and (2) data D_slot containing time slot allocation information, which were generated in step S2, to the first access point AP1-1, and the first access point AP1-1 receives the data transmitted from the coordinator device 100 (step S301).

The first access point AP1-1 stores the data D_slot_def and data D_slot received from the coordinator device 100 in the time slot information storage unit 23, and after performing RF processing on the wireless terminals STA1-1 to STA1-3, transmits them via antenna Ant1.

The wireless terminal STA1-1 receives the data transmitted from the first access point AP1-1 and stores it in the time slot information storage unit 33 (step S302). The wireless terminals STA1-2 and STA1-3 also perform the same process as the wireless terminal STA1-1 and store the data transmitted from the first access point AP1-1 (step S303).

The same processing as above is also performed on the wireless terminals STA2-1 to STA2-N2 (N2 = 2 in this embodiment) included in the second access point AP2-1 (steps S304 to S306).

The same processing as above is also performed by the wireless terminals STA3-1 to STA3-N3 (N3=4 in this embodiment) included in the third access point AP3-1.

In the wireless communication system 1000, data D_slot (time slot allocation information) is periodically transmitted from the coordinator device 100 to each access point, and is also periodically transmitted from each access point to wireless terminals in the wireless system to which the access point belongs, for example, by beacon.

As a result, all devices in the wireless communication system 1000 store and retain (1) data D_slot_def containing time slot definition information and information about groups, and (2) data D_slot containing time slot control information and time slot allocation information.

Each device in the wireless communication system 1000 communicates based on (1) data D_slot_def containing time slot definition information and information about the group, and (2) data D_slot containing time slot control information and time slot allocation information.

Below, we will explain the communications performed in the wireless communication system 1000 when the data D_slot in Figure 7 is set (as an example) while referring to the timing chart in Figure 8.

(Processing in the first time slot (time t0 to t1)):
Based on the data D_slot_def and the data D_slot in FIG. 7, in the first time slot (time t0 to t1), the first access point AP1-1 and wireless terminals STA1-1, STA1-2, and STA1-3 (a total of four devices (M ₁ =4)), which are devices belonging to the group with group ID=1, are permitted to transmit. Note that each of the first access point AP1-1 and the wireless terminals STA1-1, STA1-2, and STA1-3 understands from the received data D_slot_def that the group to which they belong is a group with GID=1 and that the number of devices included in the group (number of assigned devices) M ₁ =4.

Based on the received data D_slot_def and data D_slot, the first access point AP1-1 recognizes that it can transmit in the first time slot (has the right to transmit), and transmits the data. At this time, the first access point AP1-1 delays the timing of the data transmission by a time T from the start time of the first time slot (time t0 in FIG. 8). Specifically, the RF control unit 22 of the first access point AP1-1 calculates the delay time T (delay time from the time slot start time) for determining the timing of the data transmission using the following formula.
T: delay time Δt: duration of one time slot (hours)
M: Number of allocated devices rand(M): Function that outputs an integer between 0 and M-1 with a uniformly distributed probability (function that generates random numbers)
In the first time slot, GID = 1, M = _M1 = 4, and Δt = Tc/3 = 200/3 [ms] (Tc: transmission interval of the time slot control beacon, the time for one cycle (the total time of a series of time slots specified by data D_slot)).

Then, the RF control unit 22 of the first access point AP1-1 generates a control signal CTL1_RF to control the RF processing unit 25 so that data is transmitted at the transmission timing (time) determined by the delay time T (delay time from the start time of the timeslot) obtained above, and outputs this control signal CTL1_RF to the RF processing unit 25.

In accordance with the control signal CTL1_RF, the RF processing unit 25 of the first access point AP1-1 performs RF processing for transmission (BB (baseband) modulation processing, RF modulation processing, etc.) on the data D22A_out output from the transmission buffer FIFO1, obtaining an RF signal RF2_out that can be transmitted externally via antenna Ant1. The RF processing unit 25 then transmits the RF signal RF2_out via antenna Ant1 at the transmission timing (time) determined by the delay time T (the delay time from the start time of the timeslot). In the case of Figure 8, data is transmitted from the first access point AP1-1 during the period indicated by "AP1-1" in the first timeslot (times t0 to t1).

Based on the received data D_slot_def and data D_slot, the wireless terminal STA1-1 recognizes that it can transmit in the first time slot (has the right to transmit) and transmits the data. At this time, the wireless terminal STA1-1 delays the timing of the data transmission by a time T from the start time of the first time slot (time t0 in Figure 8). Specifically, the RF control unit 32 of the wireless terminal STA1-1 calculates the delay time T (delay from the start time of the time slot) used to determine the timing of the data transmission using the above (Equation 4).

Then, the RF control unit 32 of the wireless terminal STA1-1 generates a control signal CTL2_RF to control the RF processing unit 31 so that data is transmitted at the transmission timing (time) determined by the delay time T (delay time from the start time of the timeslot) obtained above, and outputs this control signal CTL2_RF to the RF processing unit 31.

In accordance with the control signal CTL2_RF, the RF processing unit 31 of the wireless terminal STA1-1 performs RF processing for transmission (BB (baseband) modulation processing, RF modulation processing, etc.) on the data D31A_out output from the transmission buffer FIFO2, obtaining an RF signal RF3_out that can be transmitted externally via antenna Ant2. The RF processing unit 31 then transmits the RF signal RF3_out via antenna Ant2 at the transmission timing (time) determined by the delay time T (the delay time from the start time of the timeslot). In the case of Figure 8, data is transmitted from the wireless terminal STA1-1 during the period indicated by "STA1-1" in the first timeslot (times t0 to t1).

Wireless terminals STA1-2 and STA1-3 also perform the same processing as that performed by wireless terminal STA1-1. As a result, in the case of Figure 8, data is transmitted from wireless terminal STA1-2 during the period indicated by "STA1-2" in the first time slot (time t0 to t1), and data is transmitted from wireless terminal STA1-3 during the period indicated by "STA1-3" in the first time slot (time t0 to t1).

As can be seen from the transmission status of each device in the first time slot in Figure 8, multiple devices (first access point AP1-1, wireless terminals STA1-1, STA1-2, and STA1-3) that have the right to transmit in the first time slot (times t0 to t1) each transmit data at a timing (time) delayed by a time (delayed by time T) calculated using uniform random numbers (random numbers following a uniform distribution) according to . Therefore, multiple devices (first access point AP1-1, wireless terminals STA1-1, STA1-2, and STA1-3) that have the right to transmit in the first time slot (times t0 to t1) transmit data approximately simultaneously at the start of the first time slot (times t0 to t1), thereby appropriately preventing communication collisions. In other words, by performing the above processing, the wireless communication system 1000 distributes the transmission timings of multiple devices that have the right to transmit in a common time slot (e.g., the first time slot (times t0 to t1)), thereby appropriately preventing communication collisions.

(Processing in the second time slot (time t1 to t2)):
Based on the data D_slot_def and the data D_slot in FIG. 7, in the second time slot (time t1 to t2), the second access point AP2-1 and wireless terminals STA2-1 and STA2-2 (a total of three devices (M ₂ = 3)), which are devices belonging to the group with group ID = 2, are permitted to transmit. Note that each of the second access point AP2-1 and the wireless terminals STA2-1 and STA2-2 understands from the received data D_slot_def that the group to which they belong is a group with GID = 2 and that the number of devices included in that group (number of assigned devices) M ₂ = 3.

The second access point AP2-1 performs the same process as the first access point in the first time slot to determine the timing for transmitting data from its own device. In other words, the second access point AP2-1 performs the process equivalent to (Equation 4) to obtain the delay time T (the delay time from the time slot start time (time t1)), and transmits data at the transmission timing (time) determined by the obtained delay time T. In the case of Figure 8, data is transmitted from the second access point AP2-1 during the period indicated by "AP2-1" in the second time slot (times t1 to t2).

In addition, wireless terminals STA2-1 and STA2-2 also perform the same processing as that performed by wireless terminal STA1-1 in the first time slot. As a result, in the case of Figure 8, data is transmitted from wireless terminal STA2-1 during the period indicated by "STA2-2" in the second time slot (time t1 to t2), and data is transmitted from wireless terminal STA2-2 during the period indicated by "STA2-2" in the second time slot (time t1 to t2).

As can be seen from the transmission status of each device in the second time slot in Figure 8, multiple devices (second access point AP2-1, wireless terminals STA1-1, STA1-2, and STA1-3) that have the right to transmit in the second time slot (times t1 to t2) each transmit data at a timing (time) delayed by a time (delayed by time T) calculated using uniform random numbers (random numbers following a uniform distribution) according to . Therefore, multiple devices (second access point AP2-1, wireless terminals STA1-1, STA1-2, and STA1-3) that have the right to transmit in the second time slot (times t1 to t2) transmit data approximately simultaneously at the start of the second time slot (times t1 to t2), thereby appropriately preventing communication collisions. In other words, by performing the above processing in wireless communication system 1000, the transmission timings of multiple devices that have the right to transmit in a common time slot (e.g., the second time slot (times t0 to t1)) are dispersed, thereby appropriately preventing communication collisions.

(Processing in the third time slot (time t2 to t3)):
Based on the data D_slot_def and the data D_slot in FIG. 7, in the third time slot (time t2 to t3), the third access point AP3-1 and wireless terminals STA3-1 to STA3-4 (a total of five devices (M ₃ =5)), which are devices belonging to the group with group ID=3, are permitted to transmit. Note that each of the third access point AP3-1 and the wireless terminals STA3-1 to STA3-4 determines from the received data D_slot_def that the group to which they belong has GID=3 and that the number of devices included in that group (number of assigned devices) M ₃ =5.

The third access point AP3-1 performs the same process as the first access point in the first time slot to determine the timing for transmitting data from its own device. In other words, the third access point AP3-1 performs the process equivalent to (Equation 4) to obtain the delay time T (the delay time from the time slot start time (time t1)), and transmits data at the transmission timing (time) determined by the obtained delay time T. In the case of Figure 8, data is transmitted from the second access point AP2-1 during the period indicated by "AP3-1" in the third time slot (times t2 to t3).

In addition, wireless terminals STA3-1 to STA3-4 also perform processing similar to that performed by wireless terminal STA1-1 in the first time slot. As a result, in the case of Figure 8, data is transmitted from wireless terminal STA3-1 during the period indicated by "STA3-1" in the third time slot (times t2 to t3), and data is transmitted from wireless terminal STA3-2 during the period indicated by "STA3-2" in the third time slot (times t2 to t3). Furthermore, data is transmitted from wireless terminal STA3-3 during the period indicated by "STA3-3" in the third time slot (times t2 to t3), and data is transmitted from wireless terminal STA3-4 during the period indicated by "STA3-4" in the third time slot (times t2 to t3).

As can be seen from the transmission status of each device in the third time slot in Figure 8, multiple devices (third access point AP3-1, wireless terminals STA3-1 to STA3-4) that have the right to transmit in the third time slot (times t2 to t3) each transmit data at a timing (time) delayed by a time (delayed by time T) calculated using uniform random numbers (random numbers following a uniform distribution) according to . Therefore, multiple devices (third access point AP3-1, wireless terminals STA3-1 to STA3-4) that have the right to transmit in the third time slot (times t2 to t3) transmit data approximately simultaneously at the start of the third time slot (times t2 to t3), thereby appropriately preventing communication collisions. In other words, by performing the above processing, wireless communication system 1000 distributes the transmission timing of multiple devices that have the right to transmit in a common time slot (e.g., the third time slot (times t0 to t1)), thereby appropriately preventing communication collisions.

(Processing in the fourth time slot (time t3 to t4), the fifth time slot (time t4 to t5), and the sixth time slot (time t5 to t6)):
In the fourth time slot (times t3 to t4), the fifth time slot (times t4 to t5), and the sixth time slot (times t5 to t6), the wireless communication system 1000 performs processing similar to that of the first to third time slots.

As can be seen from Figure 8, in each time slot, the transmission timing is determined by a delay time (delay time from the start time of the time slot) determined by a uniform random number, so there is a high probability that the transmission timing of each device (delay time from the start time of the time slot) will be different. In other words, there is a high probability that the transmission timing of each device in the i-th (i: natural number, 1≦i≦3) time slot will be different from the transmission timing of each device in the i+3 time slot.

<Summary>
As described above, in wireless communication system 1000, a time slot length is set so that management and synchronization control are not complicated, and multiple devices can acquire the transmission right in a time slot of the set time slot length. Furthermore, in wireless communication system 1000, multiple devices having the transmission right in the same time slot (common time slot) transmit data at transmission timing determined by uniform random numbers, so that the transmission timings of multiple devices having the transmission right in the same time slot can be dispersed. As a result, in wireless communication system 1000, communication collisions can be appropriately prevented, and communication efficiency can be improved.

In other words, wireless communication system 1000 can perform high-speed, high-precision wireless communication without degrading wireless communication performance by appropriately controlling the timing of traffic transmission, even in a small space where many wireless communication terminals are present.

First Modified Example
Next, a first modification of the first embodiment will be described. Note that the same parts as those in the above embodiment are given the same reference numerals, and detailed description thereof will be omitted.

Figure 9 is a timing chart showing a wireless communication system according to the first modification of the first embodiment, in which multiple wireless communication devices (access points, wireless terminals) communicate in a time-division manner on one channel based on the data D_slot in Figure 7.

In the wireless communication system of the first modification, the method of calculating the delay time T acquired by the devices included in the wireless communication system is different from that of the first embodiment. Specifically, while in the first embodiment each device calculates the delay time T using (Equation 4), in this modification each device calculates it using the following equation:
T: delay time Δt: duration of one time slot (hours)
M: Number of allocated devices ID: Device identifier Hash(x): Function (hash function) to obtain the hash value (integer value) of x
%x: "%" is an operator that obtains the remainder modulo x. Note that in the wireless communication system of this modified example, each device (access point, wireless terminal) included in the wireless communication system is set with a device identifier ID, which is a unique identifier.

The following describes the communications performed in the wireless communication system of this modified example when the data D_slot in Figure 7 is set (as an example), with reference to the timing chart in Figure 9. Note that the group allocation and group IDs (GIDs) of the devices included in the wireless communication system are assumed to be the same as in the first embodiment.

(Processing in the first time slot (time t0 to t1)):
Based on the data D_slot_def and the data D_slot in Figure 7, in the first time slot (time t0 to t1), the first access point AP1-1 and wireless terminals STA1-1, STA1-2, and STA1-3 (a total of four devices (M ₁ = 4)), which are devices belonging to the group with group ID = 1, are allowed to transmit.

Based on the received data D_slot_def and data D_slot, the first access point AP1-1 recognizes that it can transmit in the first time slot (has the right to transmit) and transmits the data. At this time, the first access point AP1-1 delays the timing of the data transmission by a time T from the start time of the first time slot (time t0 in Figure 9). Specifically, the RF control unit 22 of the first access point AP1-1 calculates the delay time T (delay from the start time of the time slot) used to determine the timing of data transmission using the above (Equation 5).

Then, the RF control unit 22 of the first access point AP1-1 generates a control signal CTL1_RF to control the RF processing unit 25 so that data is transmitted at the transmission timing (time) determined by the delay time T (delay time from the start time of the timeslot) obtained above, and outputs this control signal CTL1_RF to the RF processing unit 25.

In accordance with the control signal CTL1_RF, the RF processing unit 25 of the first access point AP1-1 performs RF processing for transmission (BB (baseband) modulation processing, RF modulation processing, etc.) on the data D22A_out output from the transmission buffer FIFO1, obtaining an RF signal RF2_out that can be transmitted externally via antenna Ant1. The RF processing unit 25 then transmits the RF signal RF2_out via antenna Ant1 at the transmission timing (time) determined by the delay time T (the delay time from the start time of the timeslot). In the case of Figure 9, data is transmitted from the first access point AP1-1 during the period indicated by "AP1-1" in the first timeslot (times t0 to t1).

Based on the received data D_slot_def and data D_slot, the wireless terminal STA1-1 recognizes that it can transmit in the first time slot (has the right to transmit) and transmits the data. At this time, the wireless terminal STA1-1 delays the timing of the data transmission by a time T from the start time of the first time slot (time t0 in Figure 9). Specifically, the RF control unit 32 of the wireless terminal STA1-1 calculates the delay time T (delay from the start time of the time slot) used to determine the timing of the data transmission using the above (Equation 5).

Then, the RF control unit 32 of the wireless terminal STA1-1 generates a control signal CTL2_RF to control the RF processing unit 31 so that data is transmitted at the transmission timing (time) determined by the delay time T (delay time from the start time of the timeslot) obtained above, and outputs this control signal CTL2_RF to the RF processing unit 31.

In accordance with the control signal CTL2_RF, the RF processing unit 31 of the wireless terminal STA1-1 performs RF processing for transmission (BB (baseband) modulation processing, RF modulation processing, etc.) on the data D31A_out output from the transmission buffer FIFO2, obtaining an RF signal RF3_out that can be transmitted externally via antenna Ant2. The RF processing unit 31 then transmits the RF signal RF3_out via antenna Ant2 at the transmission timing (time) determined by the delay time T (the delay time from the start time of the timeslot). In the case of Figure 9, data is transmitted from the wireless terminal STA1-1 during the period indicated by "STA1-1" in the first timeslot (times t0 to t1).

Wireless terminals STA1-2 and STA1-3 also perform the same processing as that performed by wireless terminal STA1-1. As a result, in the case of Figure 9, data is transmitted from wireless terminal STA1-2 during the period indicated by "STA1-2" in the first time slot (time t0 to t1), and data is transmitted from wireless terminal STA1-3 during the period indicated by "STA1-3" in the first time slot (time t0 to t1).

(Processing in the second time slot (time t1 to t2)):
In the second time slot, the wireless communication system of this modification executes the same processing as in the second time slot of the first embodiment. Note that in each device, the delay time T is calculated using (Equation 5) instead of (Equation 4). Then, each device transmits data at the transmission timing specified by the calculated delay time T. In the case of FIG. 9, data is transmitted from the second access point AP2-1 during the period indicated by "AP2-1" in the second time slot (time t1 to t2). Furthermore, data is transmitted from the wireless terminals STA2-1 and STA2-2 during the periods indicated by "STA2-1" and "STA2-2" in the second time slot (time t1 to t2), respectively.

(Processing in the third time slot (time t2 to t3)):
In the third time slot, the wireless communication system of this modification executes the same processing as in the third time slot of the first embodiment. Note that, in each device, the delay time T is calculated using (Equation 5) instead of (Equation 4). Each device then transmits data at a transmission timing specified by the calculated delay time T. In the case of FIG. 9 , data is transmitted from the third access point AP3-1 during the period indicated by "AP3-1" in the third time slot (time t2 to t3). Furthermore, data is transmitted from the wireless terminals STA3-1, STA3-2, STA3-3, and STA3-4 during the periods indicated by "STA3-1,""STA3-2,""STA3-3," and "STA3-4" in the third time slot (time t2 to t3), respectively.

(Processing in the fourth time slot (time t3 to t4), the fifth time slot (time t4 to t5), and the sixth time slot (time t5 to t6)):
In the fourth time slot (times t3 to t4), the fifth time slot (times t4 to t5), and the sixth time slot (times t5 to t6), in the wireless communication system of this modified example, processing similar to that of the first to third time slots is performed.

As can be seen from Figure 9, in the wireless communication system of this modified example, the transmission timing for each time slot is determined by the delay time (delay time from the start time of the time slot) determined by the remainder modulo M of the hash value obtained from the device's own ID (device identifier ID) using a hash function, so the transmission timing within the time slot of each device (delay time from the start time of the time slot) will be the same.

As described above, in the wireless communication system of this modified example, similar to the wireless communication system 1000 of the first embodiment, a time slot length is set so that management and synchronization control are not complicated, and multiple devices can acquire the right to transmit in time slots of the set time slot length. Furthermore, in the wireless communication system of this modified example, multiple devices with the right to transmit in the same time slot (common time slot) transmit data at a transmission timing specified by a delay time (delay time from the start time of the time slot) determined by the remainder modulo M of the hash value obtained from the ID (device identifier ID) of the device itself using a hash function. This allows the transmission timing of multiple devices with the right to transmit in the same time slot to be distributed, and further allows the transmission timing within the same time slot to be synchronized. As a result, the wireless communication system 1000 can appropriately prevent communication collisions and improve communication efficiency.

In other words, wireless communication system 1000 can perform high-speed, high-precision wireless communication without degrading wireless communication performance by appropriately controlling the timing of traffic transmission, even in a small space where many wireless communication terminals are present.

Second Embodiment
Next, a second embodiment will be described. Note that the same parts as those in the above embodiment are given the same reference numerals and detailed description thereof will be omitted.

<2.1: Configuration of wireless communication system>
FIG. 10 is a schematic diagram of a wireless communication system 2000 according to the second embodiment.

Figure 11 is a schematic diagram of the first access point AP1-1A according to the second embodiment.

Figure 12 is a schematic diagram of the wireless terminal STA1-1A according to the second embodiment.

As shown in FIG. 10, the wireless communication system 2000 has a configuration in which the first access point AP1-1, the second access point AP2-1, ..., the Lth access point APL-1 in the wireless communication system 1000 of the first embodiment are replaced with the first access point AP1-1A, the second access point AP2-1A, ..., the Lth access point APL-1A, respectively, and further the wireless terminals STA1-1 to STA1-N1, the wireless terminals STA2-1 to STA2-N2, ..., the wireless terminals STAL-1 to STAL-NL are replaced with the wireless terminals STA1-1A to STA1-N1A, the wireless terminals STA2-1A to STA2-N2A, ..., the wireless terminals STAL-1A to STAL-NLA, respectively.

As shown in FIG. 11, the first access point AP1-1A has a configuration similar to that of the first access point AP1-1 in the first embodiment, except that the RF control unit 22 is replaced with an RF control unit 22A and a band dividing unit 27 is further added.

The RF control unit 22A has the same functions as the RF control unit 22, and further has the function of outputting a control signal CTL1_div to the band splitting unit 27. The RF control unit 22A generates a control signal CTL1_div for causing the band splitting unit 27 to perform band splitting processing based on the maximum bandwidth C that can be used within a timeslot (the total throughput obtained at the maximum bandwidth that can be used within a timeslot (for example, if the upper limit communication rate that can be achieved at the maximum bandwidth that can be used within a timeslot is Dmax [bps], the total throughput that can be achieved at that communication rate Dmax [bps])), the number M of devices that have been granted transmission rights in the timeslot, and a bandwidth adjustment coefficient α (0≦α≦1), and outputs the control signal CTL1_div to the band splitting unit 27.

Note that the maximum bandwidth C that can be used within a time slot and the bandwidth adjustment coefficient α are stored and held in the coordinator device 100, and are transmitted from the coordinator device 100 to the first access point AP1-1A, where they are stored and held in the first access point AP1-1A.

The band division unit 27 receives the control signal CTL1_div output from the RF control unit 22A, performs band division processing based on the control signal CTL1_div, generates a control signal CTL1_RFd for controlling the RF processing unit 25 to transmit data at the rate obtained by the band division processing, and outputs the control signal CTL1_RFd to the RF processing unit 25.

The RF processing unit 25 performs data transmission processing based on the control signal CTL1_RFd output from the band division unit 27.

Note that the second access point AP2-1, ..., and the Lth access point APL-1 have the same configuration as the first access point AP1-1A.

As shown in FIG. 12, the wireless terminal STA1-1A has a configuration similar to that of the wireless terminal STA1-1 of the first embodiment, except that the RF control unit 32 is replaced with an RF control unit 32A and a band dividing unit 36 is further added.

The RF control unit 32A has the same functions as the RF control unit 32, and further has the function of outputting a control signal CTL2_div to the band splitting unit 36. The RF control unit 32A generates a control signal CTL2_div for causing the band splitting unit 27 to perform band splitting processing based on the maximum bandwidth C that can be used within a timeslot (the total throughput obtained at the maximum bandwidth that can be used within a timeslot (for example, if the upper limit communication rate that can be achieved at the maximum bandwidth that can be used within a timeslot is Dmax [bps], then the total throughput that can be achieved at that communication rate Dmax [bps])), the number M of devices that have been granted transmission rights in the timeslot, and a bandwidth adjustment coefficient α (0≦α≦1), and outputs the control signal CTL2_div to the band splitting unit 36.

The maximum bandwidth C that can be used within a time slot and the bandwidth adjustment coefficient α are stored and held in the coordinator device 100, and are transmitted from the coordinator device 100 to the wireless terminal STA1-1A via the first access point AP1-1A, where they are stored and held in the wireless terminal STA1-1A.

The band division unit 36 receives the control signal CTL2_div output from the RF control unit 32A, performs band division processing based on the control signal CTL2_div, generates a control signal CTL2_RFd for controlling the RF processing unit 31 to transmit data at the rate obtained by the band division processing, and outputs the control signal CTL2_RFd to the RF processing unit 25.

The RF processing unit 31 performs data transmission processing based on the control signal CTL1_RFd output from the band splitting unit 27.

Note that the wireless terminals STA1-2A to STA1-N1A, the wireless terminals STA2-1A to STA2-N2A, ..., and the wireless terminals STAL-1A to STAL-NLA have the same configuration as the first access point AP1-1A.

<2.2: Operation of wireless communication system>
The operation of wireless communication system 2000 configured as above will now be described.

For ease of explanation, the following will be described as an example in which the wireless communication devices included in the wireless communication system 2000 are divided into three groups (first to third groups) as shown in Fig. 6, similarly to the first embodiment. The first to third groups are as follows:
(1) The first group (the group ID (referred to as "GID") is "1") includes the first access point AP1-1A and wireless terminals STA1-1A to STA1-3A (three wireless terminals) of the first wireless communication system SYS1. The number of devices in the first group is M ₁ =4.
(2) The second group (with a group ID (GID) of "2") includes a second access point AP2-1A and wireless terminals STA2-1A to STA2-2A (two wireless terminals) of the second wireless communication system SYS2. The number of devices in the second group is M ₂ =3.
(3) The third group (with a group ID (GID) of "3") includes a third access point AP3-1A and wireless terminals STA3-1A to STA2-4A (four wireless terminals) of the third wireless communication system SYS3. The number of devices in the third group is M ₃ =5.

For ease of explanation, we have set the case where the wireless communication devices included in the kth wireless system SYSk are included in the kth group (GID = k), but this is not limited to this, and any wireless communication device in any wireless system may be included in any group.

Below, we will explain the communications performed in the wireless communication system 2000 when the data D_slot in Figure 7 is set (as an example) while referring to the timing chart in Figure 13.

(Processing in the first time slot (time t0 to t1)):
Based on the data D_slot_def and the data D_slot in FIG. 7, in the first time slot (time t0 to t1), the first access point AP1-1A and wireless terminals STA1-1A, STA1-2A, and STA1-3A (a total of four devices (M ₁ =4)), which are devices belonging to the group with group ID=1, are permitted to transmit. Note that each of the first access point AP1-1A and the wireless terminals STA1-1A, STA1-2A, and STA1-3A understands from the received data D_slot_def that the group to which it belongs is a group with GID=1 and that the number of devices included in the group (number of assigned devices) M ₁ =4.

Based on the received data D_slot_def and data D_slot, the first access point AP1-1 recognizes that it can transmit in the first time slot (has the right to transmit), and then transmits data. At this time, the first access point AP1-1A performs transmission control so that data is transmitted at rate R. Specifically, the RF control unit 22A of the first access point AP1-1A generates a control signal CTL1_div to cause the band dividing unit 27 to perform band dividing processing based on the maximum bandwidth C that can be used within the time slot (the total throughput obtained at the maximum bandwidth that can be used within the time slot (for example, if the upper limit communication rate that can be achieved at the maximum bandwidth that can be used within the time slot is Dmax [bps], the total throughput that can be achieved at that communication rate Dmax [bps])), the number of devices M that have been granted the right to transmit in the time slot (= M ₁ = 4), and a bandwidth adjustment coefficient α (0≦α≦1), and outputs the control signal CTL1_div to the band dividing unit 27.

The band dividing unit 27 performs band dividing processing based on the control signal CTL1_div output from the RF control unit 22 A. That is, the band dividing unit 27 generates a control signal CTL1_RFd for controlling the RF processing unit 25 to perform data transmission at a communication rate R obtained by the following formula, and outputs the control signal CTL1_RFd to the RF processing unit 25.
R: Transmission rate M: Number of allocated devices α: Bandwidth adjustment coefficient (0≦α≦1)
The RF processing unit 25 performs data transmission processing based on the control signal CTL1_RFd output from the band dividing unit 27. The control signal CTL1_RFd output from the band dividing unit 27 is a signal that controls data transmission to be performed at the communication rate R (a signal that calculates the data transmission timing and transmission data amount so that data transmission is performed at the communication rate R, and instructs data transmission at the determined data transmission timing and transmission data amount based on the calculation results). Therefore, the RF processing unit 25 can transmit data at the transmission rate R by transmitting the amount of data indicated by the control signal CTL1_RFd at the timing indicated by the control signal CTL1_RFd. In the case of FIG. 13, data is transmitted from the first access point AP1-1A during the period indicated by "AP1-1A" in the first time slot (time t0 to t1). Note that FIG. 13 shows the case where α = 0.5.

Based on the received data D_slot_def and data D_slot, the wireless terminal STA1-1A recognizes that it can transmit in the first time slot (has the transmission right), and transmits data. At this time, the wireless terminal STA1-1A performs transmission control so as to transmit data at a rate R. Specifically, the RF control unit 32A of the wireless terminal STA1-1A generates a control signal CTL2_div for causing the band division unit 36 to perform band division processing based on the maximum bandwidth C that can be used in the time slot, the number M (= M ₁ = 4) of devices granted the transmission right in the time slot, and a band adjustment coefficient α (0≦α≦1), and outputs the control signal CTL2_div to the band division unit 36.

The band dividing unit 36 performs band dividing processing based on the control signal CTL2_div output from the RF control unit 32 A. That is, the band dividing unit 36 generates a control signal CTL2_RFd for controlling the RF processing unit 31 to perform data transmission at a communication rate R obtained by the following formula, and outputs the control signal CTL2_RFd to the RF processing unit 31.
R: Transmission rate M: Number of allocated devices α: Bandwidth adjustment coefficient (0≦α≦1)
The RF processing unit 31 performs data transmission processing based on the control signal CTL2_RFd output from the band dividing unit 36. The control signal CTL2_RFd output from the band dividing unit 36 is a control signal that controls data transmission to be performed at the communication rate R (a signal that calculates the data transmission timing and transmission data amount so that data transmission is performed at the communication rate R, and instructs data transmission at the determined data transmission timing and transmission data amount based on the calculation results), so the RF processing unit 31 can transmit data at the transmission rate R by transmitting the amount of data indicated by the control signal CTL2_RFd at the timing indicated by the control signal CTL2_RFd. In the case of FIG. 13 , data is transmitted from the wireless terminal STA1-1A during the period indicated by "STA1-1A" in the first time slot (time t0 to t1).

Note that wireless terminals STA1-2A and STA1-3A also perform the same processing as wireless terminal STA1-1A. In the case of Figure 13, data is transmitted from wireless terminals STA1-2A and STA1-3A, respectively, during the periods indicated by "STA1-2A" and "STA1-3A" in the first time slot (time t0 to t1).

(Processing in the second time slot (time t1 to t2)):
In the second time slot (time t1 to t2), the same processing as in the first time slot (time t0 to t1) is executed. Note that in the second time slot (time t1 to t2), the devices granted the transmission right are the second access point AP2-1A, wireless terminal STA2-1A, and wireless terminal STA2-2A, and the number of devices M ₂ =3.

In the case of Figure 13, data is transmitted from the second access point AP2-1A during the period indicated by "AP2-1A" in the second time slot (time t1 to t2). Furthermore, data is transmitted from the wireless terminals STA2-1A and STA2-2A during the periods indicated by "STA2-1A" and "STA2-2A" in the second time slot (time t1 to t2), respectively.

(Processing in the third time slot (time t2 to t3)):
In the third time slot (time t2 to t3), the same processing as in the first time slot (time t0 to t1) is executed. Note that in the third time slot (time t2 to t3), the devices granted the transmission right are the third access point AP3-1A and wireless terminals STA3-1A to STA3-4A, and the number of devices M ₃ =5.

In the case of Figure 13, data is transmitted from the third access point AP3-1A during the period indicated by "AP3-1A" in the third time slot (times t2 to t3). Furthermore, data is transmitted from wireless terminals STA3-1A to STA3-4A during the periods indicated by "STA3-1A" to "STA3-4A" in the third time slot (times t2 to t3), respectively.

(Processing in the fourth time slot (time t3 to t4), the fifth time slot (time t4 to t5), and the sixth time slot (time t5 to t6)):
In the fourth time slot (times t3 to t4), the fifth time slot (times t4 to t5), and the sixth time slot (times t5 to t6), the wireless communication system 2000 performs processing similar to that of the first to third time slots.

As can be seen from Figure 13, in wireless communication system 2000, data is transmitted at the same transmission rate R in each time slot, but the amount of data and transmission timing transmitted from each device do not necessarily match (and usually do not match).

As described above, in wireless communication system 2000, similar to wireless communication system 1000 of the first embodiment, a time slot length is set that does not complicate management and synchronization control, and multiple devices can acquire the right to transmit in time slots of the set time slot length. In wireless communication system 2000, multiple devices with the right to transmit transmit data within the same time slot (common time slot) at a communication rate R (divided bandwidth) determined based on the number M of devices belonging to the group. Therefore, in wireless communication system 2000, the transmission timing of multiple devices with the right to transmit in the same time slot can be distributed. As a result, in wireless communication system 1000, communication collisions can be appropriately prevented, improving communication efficiency.

In other words, wireless communication system 2000 can perform high-speed, high-precision wireless communication without degrading wireless communication performance by appropriately controlling the timing of traffic transmission, even in a small space where many wireless communication terminals are present.

In the above description, the process of dividing the band and transmitting data in the divided band (communication rate R) in wireless communication system 2000 has been described as being implemented by the RF control unit, band dividing unit, and RF processing unit of the access point and wireless terminal, but this is not limited to this. For example, the RF control unit, band dividing unit, and RF processing unit, which are functional units that divide the band and transmit data in the divided band (communication rate R), may be configured by installing an OS that is compatible with a device driver that corresponds to the hardware. For example, in wireless communication system 2000, Linux may be used as the OS, and band division may be performed using TC commands supported by Linux to transmit data in the divided band.

Other Embodiments
In the above embodiment (including modified examples), the case where the delay time is determined using (Equation 4) and (Equation 5) has been described. However, the present invention is not limited to this. For example, when calculating the delay time, the coefficient by which Δt is multiplied may be replaced with a coefficient that is a real value in the range of [0, 1]. That is, the delay time T may be calculated by replacing (rand(M)+1)/(M+2) in (Equation 4) with a coefficient (e.g., a random variable) that is a real value in the range of [0, 1]. Furthermore, the delay time T may be calculated by replacing (Hash(ID)%M+1)/(M+2) in (Equation 5) with a coefficient (e.g., a random variable) that is a real value in the range of [0, 1].

In the above embodiment (including the modified example), we have described a case where each wireless system has one access point, but this is not limited to this, and each wireless system may have multiple access points.

Furthermore, the communication methods used in the wireless communication systems described in the above embodiments (including their variations) are included in the present invention.

Furthermore, in the wireless communication system, access point, and wireless terminal described in the above embodiment (including modified examples), each block may be individually implemented as a single chip using a semiconductor device such as an LSI, or may be integrated into a single chip to include some or all of the blocks.

Note that although we refer to it as an LSI here, it may also be called an IC, system LSI, super LSI, or ultra LSI depending on the level of integration.

Furthermore, the method of integration is not limited to LSI, but may be realized using dedicated circuits or general-purpose processors. It is also possible to use FPGAs (Field Programmable Gate Arrays), which can be programmed after LSI manufacturing, or reconfigurable processors, which allow the connections and settings of circuit cells within the LSI to be reconfigured.

Furthermore, some or all of the processing of each functional block in each of the above embodiments (including variations) may be realized by a program. Then, some or all of the processing of each functional block in each of the above embodiments is performed by a central processing unit (CPU) in a computer. Furthermore, the programs for performing each process are stored in a storage device such as a hard disk or ROM, and are read out and executed in ROM or RAM.

Furthermore, each process in the above-described embodiment (including variations) may be implemented by hardware, or by software (including cases where it is implemented together with an OS (operating system), middleware, or a specified library). Furthermore, it may also be implemented by a combination of software and hardware processing.

Furthermore, for example, when each functional unit of the above embodiment (including modified examples) is realized by software, each functional unit may be realized by software processing using the hardware configuration shown in FIG. 14 (for example, a hardware configuration in which a CPU (which may be a GPU), ROM, RAM, input units, output units, etc. are connected via a bus).

Furthermore, when each functional unit of the above embodiment is realized by software, the software may be realized using a single computer having the hardware configuration shown in Figure 14, or may be realized by distributed processing using multiple computers.

Furthermore, the execution order of the processing methods in the above embodiments is not necessarily limited to that described in the above embodiments, and the execution order can be changed without departing from the spirit of the invention. Furthermore, in the processing methods in the above embodiments (including modified examples), some steps may be executed in parallel with other steps without departing from the spirit of the invention.

The scope of the present invention includes a computer program that causes a computer to execute the above-described method, and a computer-readable recording medium on which that program is recorded. Examples of computer-readable recording media include flexible disks, hard disks, CD-ROMs, MOs, DVDs, DVD-ROMs, DVD-RAMs, high-capacity DVDs, next-generation DVDs, and semiconductor memories.

The computer program is not limited to being recorded on the recording medium, but may also be transmitted via a telecommunications line, a wireless or wired communication line, or a network such as the Internet.

The specific configuration of the present invention is not limited to the above-described embodiment (including variations), and various changes and modifications are possible without departing from the spirit of the invention.

1000, 2000 Wireless communication system 100 Coordinator devices AP1-1 to APL-1, AP1-1A to APL-1A Access points STA1-1 to STA1-N1, STA2-1 to STA2-N2, ..., STAL-1 to STAL-NL Wireless terminals STA1-1A to STA1-N1A, STA2-1A to STA2-N2A, ..., STAL-1A to STAL-NLA Wireless terminal 11 Time slot definition unit 12 Time slot allocation information generation unit 22, 22A RF control unit 23 Time slot information storage unit 24 Wireless system information acquisition and retention unit 25 RF processing unit 27 Band division unit 31 RF processing units 32, 32A RF control unit 33 Time slot information storage unit 34 Wireless terminal information acquisition and retention unit 36 Band division unit

Claims (9)

A wireless communication method used in a wireless communication system including a plurality of wireless communication devices assigned to groups identified by group identifiers,
a time slot definition data generating step of generating time slot definition data including a time slot length and a time slot start time of a time slot to be used in common for time division communication among the plurality of wireless communication devices, information for identifying a group to which each of the plurality of wireless communication devices belongs, and information on the number of the wireless communication devices belonging to the group;
a time slot time series pattern specifying data generating step of generating data for specifying a time slot time series pattern, the data including time slot control information, which is information for specifying a repetition pattern in the time series of the time slot, and time slot allocation information, which is information for specifying a group to which a transmission right is granted in the time slot and the number of the wireless communication devices belonging to that group;
a transmission timing determination step in which each of the wireless communication devices belonging to the group granted the transmission right in the time slot determines a transmission timing based on the time slot time sequence pattern identification data so that the transmission timing within the time slot varies;
a data transmission step in which each of the wireless communication devices belonging to the group granted the transmission right in the time slot transmits data at the transmission timing determined in the transmission timing determination step;
A wireless communication method comprising: The transmission timing determination step includes:
Based on the time slot time series pattern identification data, the transmission timing within the time slot is determined by a delay time calculated using a random number or a hash function.
The wireless communication method according to claim 1 . Let M be the number of wireless communication devices belonging to a group granted the transmission right in the time slot, and let T be the delay time from the start time of the time slot within the time slot.
The transmission timing determination step includes:
The transmission timing within the time slot is determined from the start time of the time slot.
Δt: duration of one time slot (hours)
rand(M): A function that outputs an integer between 0 and M-1 with a uniformly distributed probability (a function that generates random numbers)
The time is determined to be delayed by the delay time T obtained by
3. The wireless communication method according to claim 1 or 2. a device identifier assigning step of assigning a device identifier that is a unique identifier to the wireless communication device;
Let M be the number of wireless communication devices belonging to a group granted the transmission right in the time slot, and let T be the delay time from the start time of the time slot within the time slot.
The transmission timing determination step includes:
The transmission timing within the time slot is determined from the start time of the time slot.
Δt: duration of one time slot (hours)
ID: Device identifier Hash(x): Function (hash function) to obtain the hash value (integer value) of x
%x: "%" determines the time delayed by the delay time T obtained by an operator that obtains a remainder modulo x.
3. The wireless communication method according to claim 1 or 2. Let M be the number of wireless communication devices belonging to the group granted the transmission right in the time slot, and let C be the maximum total throughput achieved in the time slot.
The transmission timing determination step includes:
R: Transmission rate M: Number of allocated devices α: Bandwidth adjustment coefficient (0≦α≦1)
and determining the data transmission timing so as to realize the transmission rate R obtained by
3. The wireless communication method according to claim 1 or 2. A wireless communication system for performing the wireless communication method according to any one of claims 1 to 5,
a coordinator device;
a plurality of wireless communication devices;
Equipped with
the coordinator device,
the time slot definition data generating step;
the time slot time series pattern specifying data generation step;
Run
Each of the plurality of wireless communication devices
the transmission timing determination step;
the data transmitting step;
To execute
Wireless communication system. The coordinator device constituting the wireless communication system described in claim 6. The wireless communication device constituting the wireless communication system described in claim 6. A program for causing a computer to execute the wireless communication method described in any one of claims 1 to 5.