Wireless communication system, communication device, and wireless communication program

Abstract

This disclosure relates to a wireless communication system, a communication device, and a wireless communication program. The system is provided with a centralized control device and a plurality of APs. The centralized control device is configured to execute: a process for collecting information about the presence / absence and degree of mutual interference between the APs; a process for allocating a radio resource to each AP on the basis of the collected information; and a process for transmitting an update instruction for a parameter specifying a radio resource to the relevant AP. The update instruction is transmitted such that the timings at which the APs update the parameters are dispersed.

Description

Wireless communication system, communication device, and wireless communication program

[0001] The present disclosure relates to a wireless communication system, a communication device, and a wireless communication program.

[0002] RATOP (Resource allocation based on Area Throughput Optimization Policy) is known as a method for maximizing the effective capacity of the entire system by centrally controlling the wireless resources used by wireless LAN base stations (APs) (see, for example, Non-Patent Document 1).

[0003] In RATOP, a centralized control device grasps the state of mutual interference among the APs and allocates wireless resources such as frequency channels and bandwidths to be used by each AP.

[0004] BAHirantha Sithira Abeysekera et al., "Network Controlled Frequency Channel and Bandwidth Allocation Scheme for IEEE 802.11a / n / ac Wireless LANs: RATOP", 2014 IEEE 25th International Symposium on Personal, Indoor and Mobile Radio Communications, pp.1041-1045

[0005] In a centralized wireless resource control method such as RATOP, parameter updates for APs within the system are assumed. However, if all APs update their parameters simultaneously, temporary communication interruptions associated with the parameter update process occur simultaneously in many wireless devices connected to each AP. This poses a problem of temporary significant degradation in communication quality throughout the system.

[0006] In order to solve the above-mentioned problems, a first object of the present disclosure is to provide a wireless communication system that can prevent a temporary large decrease in communication quality of the entire system.

[0007] A second object of the present disclosure is to provide a communication device that can prevent a temporary large decrease in communication quality of the entire system.

[0008] A third object of the present disclosure is to provide a wireless communication program that can prevent a temporary large decrease in communication quality of the entire system.

[0009] A first aspect of the present disclosure is preferably a wireless communication system comprising a centralized control device and a plurality of APs, wherein the centralized control device is configured to perform a process of collecting information regarding the presence and degree of mutual interference between each AP, a process of allocating wireless resources to each AP based on the collected information, and a process of sending an instruction to update parameters specifying the wireless resources to the corresponding AP, and wherein the update instruction is sent so as to distribute the timing at which each AP updates its parameters.

[0010] A second aspect of the present disclosure is a communication device that controls multiple APs, and is configured to perform the following processes: collecting information on the presence and degree of mutual interference between each AP; allocating wireless resources to each AP based on the collected information; and sending an instruction to update parameters that specify the wireless resources to the corresponding AP; and preferably, the update instruction is sent so as to distribute the timing at which each AP updates its parameters.

[0011] A third aspect of the present disclosure is a wireless communication program to be executed by a communication device having a processor and a memory, the program being stored in the memory and computer-readable, and preferably including a program that causes the processor to perform the following processes: collecting information regarding the presence and degree of mutual interference between APs; allocating wireless resources to each AP based on the collected information; and sending an instruction to update parameters specifying the wireless resources to the corresponding AP.

[0012] According to the first to third aspects of the present disclosure, it is possible to prevent a temporary large decrease in communication quality of the entire system.

[0013] FIG. 1 is a diagram illustrating a configuration of a wireless communication system according to a first embodiment of the present disclosure. FIG. 2 is a diagram illustrating centralized control by a centralized control device according to a first embodiment of the present disclosure. FIG. 3 is a diagram illustrating timing of an update instruction by a centralized control device according to a first embodiment of the present disclosure. FIG. 4 is a diagram illustrating a hardware configuration of a centralized control device according to a first embodiment of the present disclosure. FIG. 5 is a flowchart illustrating an operation example of a wireless communication system according to a first embodiment of the present disclosure. FIG. 6 is a diagram illustrating timing of an update instruction by a centralized control device according to a second embodiment of the present disclosure. FIG. 7 is a diagram illustrating a first configuration of a wireless communication system according to a third embodiment of the present disclosure. FIG. 8 is a diagram illustrating a second configuration of a wireless communication system according to a third embodiment of the present disclosure. FIG. 9 is a diagram illustrating a configuration of a wireless communication system according to a fourth embodiment of the present disclosure. FIG. 10 is a diagram illustrating a configuration of a wireless communication system according to a fifth embodiment of the present disclosure.

[0014] 1 is a diagram illustrating a configuration of a wireless communication system according to a first embodiment of the present disclosure. The wireless communication system 100 includes APs 2a to 2f. The dashed arrows indicate mutual interference between APs. For example, AP 2a interferes with APs 2b, 2c, and 2d. This mutual interference occurs, for example, when APs in close proximity share wireless communication resources.

[0015] The wireless communication system 100 also includes a centralized control device 4. The centralized control device 4 first collects information on the presence and extent of mutual interference between APs. Next, the centralized control device 4 allocates wireless resources to each AP based on the collected information. The wireless resources include, for example, the frequency channel and bandwidth to be used. This allocation is performed so as to maximize the throughput of the entire wireless communication system 100. Furthermore, the centralized control device 4 transmits an instruction to update the parameters specifying the allocated wireless resources to the corresponding AP.

[0016] For example, AP 2a interferes with APs 2b, 2c, and 2d. Therefore, the centralized control device 4 allocates wireless resources so that APs 2a, 2b, 2c, and 2d use different channels for wireless communication. As a result, mutual interference between APs 2a to 2d is less likely to occur, and the throughput of the entire wireless communication system 100 can be maximized.

[0017] In the method using RATOP disclosed in Non-Patent Document 1, when all APs simultaneously update their parameters, temporary communication interruptions due to the parameter update process occur simultaneously in many wireless devices connected to each AP. This causes a temporary significant degradation in communication quality throughout the system. The present disclosure solves this problem.

[0018] 2 is a diagram illustrating centralized control by a centralized control device according to the first embodiment of the present disclosure. The wireless communication system of this embodiment includes, for example, a plurality of APs connected to a network 8, a centralized control device 4, and a plurality of wireless terminals 6. Each AP is centrally controlled by the centralized control device 4 to accommodate a plurality of wireless terminals 6.

[0019] The centralized control device 4 controls RATOP for multiple APs. As part of this control, the centralized control device 4 transmits a parameter update instruction to each AP. The parameter indicates the wireless resource allocated to the AP, such as an available channel.

[0020] At this time, the centralized control device 4 distributes the timing at which each AP updates its parameters. That is, even if the AP that accommodates the wireless terminal 6 is cut off from communication due to a parameter update, the wireless terminal 6 can continue wireless communication by connecting to another AP. As a result, it is possible to prevent a temporary large degradation in communication quality of the entire system.

[0021] 3 is a diagram showing the timing of an update instruction issued by the centralized control device according to the first embodiment of the present disclosure. The centralized control device 4 first transmits an update instruction to APs 2a and 2c. In response, APs 2a and 2c perform update processing. Next, the centralized control device 4 transmits an update instruction to AP 2b. In response, AP 2b performs update processing.

[0022] The timing for the centralized control device 4 to transmit the next update instruction may be after it has confirmed that the update process associated with the previous update instruction has been completed, or after a pre-calculated time required for the update process has elapsed. Completion of the update process may be confirmed, for example, by having the corresponding AP transmit a signal indicating that the update process has been completed, and then receiving the signal.

[0023] Although the embodiment shows that each AP performs the update process immediately after receiving the update instruction, the update instruction may also be given in accordance with the timing of the update process. In this case, the timing of the instruction may be, for example, the time from when the update instruction is received until the update process is performed, or the time when the update process is performed.

[0024] 4 is a diagram illustrating a hardware configuration of the centralized control device according to the first embodiment of the present disclosure. Each function of the centralized control device 4 may be partially or entirely configured by hardware such as a programmable logic device (PLD) or a field programmable gate array (FPGA), or may be configured as a program executed by a processor such as a CPU.

[0025] For example, the central control device 4 can be realized using a computer and a program, and the program can be recorded on a storage medium or provided via a network.

[0026] 4, the centralized control device 4 has an input unit 40, an output unit 41, a communication unit 42, a CPU 43, a memory 44, and an HDD 45 connected via a bus 46, and functions as a computer. The centralized control device 4 is also capable of inputting and outputting data to and from a computer-readable storage medium 47.

[0027] The input unit 40 is, for example, a keyboard and a mouse, etc. The output unit 41 is, for example, a display device such as a display.

[0028] The communication unit 42 is, for example, a communication interface that communicates with a wireless device to be controlled.

[0029] The CPU 43 controls each component of the central control device 4 and performs predetermined processing, etc. The memory 44 and the HDD 45 store data, etc.

[0030] The storage medium 47 is capable of storing programs and the like that cause the central control device 4 to execute the functions of the central control device 4. Note that the architecture that constitutes the central control device 4 is not limited to the example shown in FIG.

[0031] 5 is a flowchart showing an example of operation of the wireless communication system according to the first embodiment of the present disclosure. First, in step 100, the central control device 4 determines whether an opportunity to collect information from each AP and each wireless terminal has occurred. An opportunity to collect information may occur, for example, at a regular interval. If an opportunity to collect information has occurred, the process proceeds to step 102. If an opportunity has not occurred, the process of step 100 is repeated.

[0032] In step 102, the centralized control device 4 collects information from each AP and each wireless terminal. Next, in step 104, the centralized control device 4 determines whether the parameters of each AP should be updated based on the collected information. If they should be updated, the process proceeds to step 106. If they should not be updated, the process returns to step 100.

[0033] In step 106, the centralized control device 4 instructs each AP to update its parameters, and the process returns to step 100. More specifically, the centralized control device 4 first determines the contents of the wireless resources to be allocated to each AP based on the collected information. The centralized control device 4 then transmits the derived parameters for use of the allocated wireless resources to each AP as an update instruction. This embodiment solves the problem by dispersing the timing of the update process performed by each AP in accordance with this update instruction.

[0034] As described above, in the wireless communication system of this embodiment, all APs are prevented from simultaneously going into a communication cutoff state, and therefore it is possible to prevent a temporary large drop in communication quality of the entire system.

[0035] 6 is a diagram showing the timing of update instructions by a centralized control device according to a second embodiment of the present disclosure. This embodiment differs from the first embodiment in that the centralized control device 4 divides the APs into groups based on the time required for the update process and transmits an update instruction for each group.

[0036] In this embodiment, the centralized control device 4 first divides the APs into groups. Here, the time required for the update process may differ depending on the type of AP, the frequency of the migration destination, etc. Therefore, the centralized control device 4, for example, calculates in advance the time required for the update process of each AP, and divides the APs into groups so that APs with similar times are grouped together. "Similar times" means, for example, that the difference in time is equal to or less than a specific threshold.

[0037] 6, the update processing times for APs 2a and 2b are approximately the same, and the update processing times for APs 2c and 2d are approximately the same. Therefore, the centralized control device 4 groups APs 2a and 2b, and APs 2c and 2d, so that they are in the same group.

[0038] Next, the centralized control device 4 transmits an update instruction to each group. First, the centralized control device 4 transmits the update instruction to APs 2a and 2b. In response to this, APs 2a and 2b perform update processing. During this update processing, communication is cut off for APs 2a and 2b, but communication is not cut off for APs 2c and 2d.

[0039] Next, the central control device 4 transmits an update instruction to the APs 2c and 2d. In response to this, the APs 2c and 2d perform update processing. During this update processing, the APs 2c and 2d are in a communication disconnection state, but the APs 2a and 2b are not in a communication disconnection state.

[0040] In the example of Figure 6, for example, the time required to update AP 2a is shorter than the time required to update AP 2c. Now, consider the case where AP 2a and AP 2c are in the same group. Even after AP 2a completes its own update process, it must wait until AP 2c completes its update process. As a result, the time required to complete the update process for the entire wireless communication system 100 increases by the amount of waiting time. In this embodiment, by reducing this waiting time, the time required for the update process for the entire wireless communication system can be shortened.

[0041] As described above, in the wireless communication system of this embodiment, since all APs do not enter a communication interruption state at the same time, it is possible to prevent a temporary large deterioration in communication quality of the entire system. In addition, since the wireless communication system of this embodiment simultaneously updates APs that require approximately the same time for update processing, it is possible to shorten the time required for update processing of the entire wireless communication system.

[0042] 7 is a diagram illustrating a first configuration of a wireless communication system according to a third embodiment of the present disclosure. This embodiment differs from the first embodiment in that the centralized control device 4 divides the APs into groups based on the magnitude of mutual interference between the APs and transmits an update instruction to each group.

[0043] In this embodiment, the centralized control device 4 first collects information on the presence and extent of mutual interference between APs.The centralized control device 4 then divides the APs into groups so that APs with greater mutual interference are grouped together.The centralized control device 4 then transmits an update command to each group.

[0044] 7, the central control device 4 groups APs so that APs that directly interfere with each other are in different groups. For example, wireless terminal 6 is a terminal that can connect to AP 2e and AP 2f, which directly interfere with each other. Therefore, even if communication with either AP 2e or AP 2f is interrupted, wireless terminal 6 can continue wireless communication by switching to the other AP.

[0045] In this embodiment, AP2e and AP2f, which directly interfere with each other, are grouped into different groups, so that wireless terminal 6 can continue wireless communication by using at least one of AP2e and AP2f.

[0046] 8 is a diagram illustrating a second configuration of a wireless communication system according to a third embodiment of the present disclosure. The centralized control device 4 illustrated in FIG. 8 groups APs so that APs that interfere with each other within a specific number of hops are grouped into different groups.

[0047] For example, when AP 2a is used as a reference, APs 2b and 2c interfere with each other at a hop count of 1, APs 2d and 2e at a hop count of 2, and AP 2f at a hop count of 3. Here, the centralized control device 4 performs grouping so that APs that interfere with each other at a hop count of 2 or less are grouped into different groups.

[0048] For example, even if communication with AP 2a is cut off, APs 2b, 2c, 2d, and 2f remain able to communicate, so it is possible to avoid a situation where many APs are unable to communicate over a wide area.

[0049] In this embodiment, AP2a and AP2f, which interfere with each other at 3 hops, are grouped together, and the other APs are grouped together with AP2a in a different group. That is, wireless terminal 6 can continue wireless communication by using any one of AP2a, 2c, or 2e.

[0050] As described above, in the wireless communication system of this embodiment, since all APs do not enter a communication cutoff state at the same time, it is possible to prevent a temporary large deterioration in communication quality of the entire system. In addition, since the wireless communication system of this embodiment does not simultaneously update APs that have large mutual interference, it is possible to reliably continue wireless communication of surrounding wireless terminals.

[0051] 9 is a diagram illustrating a configuration of a wireless communication system according to a fourth embodiment of the present disclosure. This embodiment differs from the first embodiment in that the centralized control device 4 divides APs into groups based on the frequency channels they use and transmits an update instruction for each group.

[0052] In this embodiment, the centralized control device 4 first collects information on the presence and extent of mutual interference between APs. Then, the centralized control device 4 allocates wireless resources to each AP so as to maximize the communication quality of the entire wireless communication system. In this case, the centralized control device 4 often allocates different channels to APs located close to each other.

[0053] Next, the central control device 4 divides the APs into groups so that APs using different channels are grouped together, and then transmits an update instruction to each group.

[0054] 9, for example, AP2a and AP2d are assigned channel 1, AP2b and AP2e are assigned channel 2, and AP2c and AP2f are assigned channel 3. In this case, the centralized control device 4 groups AP2a and AP2d, AP2b and AP2e, and AP2c and AP2f into the same group.

[0055] In this embodiment, APs that use different frequency channels are grouped into different groups. Here, APs that are assigned different frequency channels are often located close to each other.

[0056] For example, wireless terminal 6 is a terminal that can connect to AP 2e and AP 2f that are located in close proximity. Therefore, even if communication with either AP 2e or AP 2f is interrupted, wireless terminal 6 can continue wireless communication by switching to the other AP.

[0057] As described above, in the wireless communication system of this embodiment, all APs are prevented from being disconnected at the same time, so that a temporary significant drop in the communication quality of the entire system can be prevented. In addition, the wireless communication system of this embodiment does not simultaneously update APs located close to each other, so that wireless communication of surrounding wireless terminals can be reliably continued.

[0058] Although the present embodiment shows a mode in which APs are grouped by channel, multiple channels may be grouped together into one group, or one channel may be divided into multiple groups. In this way, by optimizing the number of APs included in one group, the time required for the update process of the entire wireless communication system can be shortened.

[0059] 10 is a diagram illustrating a configuration of a wireless communication system according to a fifth embodiment of the present disclosure. This embodiment differs from the first embodiment in that the centralized control device 4 divides APs into groups based on the communication volume of the corresponding APs and transmits an update instruction for each group.

[0060] In this embodiment, the centralized control device 4 groups APs so that APs with high communication traffic are placed in different groups. APs with high communication traffic are APs that accommodate many terminals, perform real-time communication, or have a wide bandwidth for the assigned channel. For example, in FIG. 10, AP2e and AP2f are connected to many wireless terminals 6. In this case, the centralized control device 4 groups AP2e and AP2f into different groups. Furthermore, the centralized control device 4 transmits an update instruction for each group.

[0061] As described above, in the wireless communication system of this embodiment, all APs are prevented from being disconnected at the same time, so that it is possible to prevent a temporary large drop in communication quality of the entire system. In addition, the wireless communication system of this embodiment does not simultaneously update multiple APs with high communication traffic, so it is possible to prevent a simultaneous communication disconnection from occurring in many wireless terminals, or to minimize the impact of a communication disconnection.

[0062] Sixth Embodiment This embodiment differs from the second to fifth embodiments in that the central control device 4 determines the grouping criteria in accordance with information collected about the presence or absence and degree of mutual interference between APs.

[0063] In this embodiment, the centralized control device 4 first collects information regarding the presence and degree of mutual interference between APs. The collected information includes, for example, the communication volume and characteristics of each AP or each wireless terminal, the bandwidth of the channel used by each AP, the number of terminals accommodated by each AP, or the time required for parameter update processing of each AP. The centralized control device 4 then groups the APs according to grouping criteria determined based on the collected information. The centralized control device 4 then transmits an update instruction for each group.

[0064] An example of a method for determining the grouping criteria will be described. If the time required for parameter update processing for each AP varies greatly, the grouping criteria may be the time required for the update processing. In this case, the central control device 4 performs the same processing as in the second embodiment.

[0065] Furthermore, if the deviation in the amount of communication among the APs is large, the criterion for grouping may be the amount of communication of the corresponding AP. In this case, the central control device 4 performs the same process as in the fifth embodiment.

[0066] Furthermore, if the time required for parameter update processing for each AP and the imbalance in communication volume among APs are not large, the grouping criteria may be the magnitude of mutual interference between APs or the frequency channel used. In this case, the centralized control device 4 performs processing similar to that of embodiment 3 or 4. In addition, at least two of the grouping criteria shown in embodiments 2 to 5 may be combined.

[0067] 2a AP 2b AP 2c AP 2d AP 2e AP 2f AP 4 Centralized control device 44 Memory 100 Wireless communication system

Claims

1. A wireless communication system comprising a centralized control device and a plurality of APs, wherein the centralized control device is configured to perform a process of collecting information on the presence and degree of mutual interference between the APs, a process of allocating radio resources to each AP based on the collected information, and a process of transmitting an update instruction for a parameter specifying the radio resources to the corresponding AP, and the update instruction is transmitted so as to disperse the timing at which each AP updates the parameter.

2. The wireless communication system according to claim 1, wherein the centralized control device is further configured to perform a process of grouping the plurality of APs so that APs having substantially the same time required for the update process belong to the same group, and the update instruction is transmitted for each group.

3. The wireless communication system according to claim 1, wherein the centralized control device is further configured to perform a process of grouping the plurality of APs so that APs having a large mutual interference belong to different groups, and the update instruction is transmitted for each group.

4. The wireless communication system according to claim 3, wherein the APs having a large mutual interference are APs that directly interfere with each other.

5. The wireless communication system according to claim 3, wherein the APs having a large mutual interference are APs that interfere with each other within a specific number of hops or less.

6. The wireless communication system according to claim 1, wherein the centralized control device is further configured to perform a process of grouping the plurality of APs so that APs using different channels belong to different groups, and the update instruction is transmitted for each group.

7. A communication device for controlling a plurality of APs, the communication device being configured to perform a process of collecting information on the presence and degree of mutual interference between the APs, a process of allocating radio resources to each AP based on the collected information, and a process of transmitting an update instruction for a parameter specifying the radio resources to the corresponding AP, and the update instruction is transmitted so as to disperse the timing at which each AP updates the parameter.

8. A wireless communication program to be executed on a communication device including a processor and a memory, the program being stored in the memory, being computer-readable, and causing the processor to perform processing for collecting information on the presence and degree of mutual interference between APs, processing for allocating wireless resources to each AP based on the collected information, and processing for transmitting an update instruction for a parameter specifying the wireless resources to the corresponding AP.

Images