CCA THRESHOLD DETERMINATION SYSTEM, CCA THRESHOLD DETERMINATION DEVICE, CCA THRESHOLD DETERMINATION METHOD, AND CCA THRESHOLD DETERMINATION PROGRAM

1 . A CCA threshold determination system that determines a CCA threshold used in a wireless communication system including a plurality of wireless communicators configured by base stations or terminals,

at least two of the wireless communicators being configured to perform:

carrier sensing to determine presence or absence of a frame having a reception power value equal to or greater than a transmission CCA threshold when a transmission request occurs;

transmission of a frame in a case where the absence of the frame having the reception power value equal to or greater than the transmission CCA threshold is confirmed as a result of the carrier sensing; and

ignoring of a frame having a reception power value less than the reception CCA threshold and decoding the frame having a reception power value equal to or greater than the reception CCA threshold, and

the CCA threshold determination system comprising a controller that notifies the at least two of the wireless communicators of the reception CCA threshold,

wherein the controller is configured to perform:

receiving statistical information regarding an environment for receiving the frame from each of the at least two of the wireless communicators;

setting of the reception CCA threshold suitable for each of the at least two of the wireless communicators on a basis of the statistical information; and

notifying to the at least two of the wireless communicators of the reception CCA thresholds being set, and

the setting of the reception CCA threshold includes setting of a value at which each of the at least two of the wireless communicators easily decodes a frame addressed to its own BSS and easily ignores a frame addressed to another BSS, the value providing a desired balance to frame detection areas of the at least two of the wireless communicators.

2 . The CCA threshold determination system according to claim 1 ,

wherein the setting of the reception CCA threshold includes:

provisionally determining a threshold for generating an optimum frame detection area for each of the at least two of the wireless communicators as the reception CCA threshold;

specifying one reference communicator among the at least two of the wireless communicators;

finalizing the provisionally determined threshold as the reception CCA threshold for the reference communicator; and

finalizing a threshold that achieves the desired balance in combination with the finalized reception CCA threshold of the reference communicator as the reception CCA threshold for a wireless communicator obtained by excluding the reference communicator from the at least two of the wireless communicators.

3 . The CCA threshold determination system according to claim 2 ,

wherein the specifying one reference communicator includes:

counting the number of subordinate QoS communicators for each of the at least two of the wireless communicators on a basis of the statistical information, the QoS communicator being a wireless communicator that transmits a high-priority frame; and

setting, as the reference communicator, a wireless communicator that has the most QoS communicators as subordinate communicators.

4 . The CCA threshold determination system according to claim 2 ,

wherein the setting of the reception CCA threshold further includes counting the number of subordinate wireless communicators for each of the at least two of the wireless communicators on a basis of the statistical information,

the specifying one reference communicator includes:

setting a priority time allocated by a ratio of the numbers of subordinate wireless communicators for each of the at least two of the wireless communicators; and

maintaining each of the at least two of the wireless communicators as the reference communicator only for the priority time and sequentially changing the reference communicator every time the priority time elapses.

5 . The CCA threshold determination system according to claim 1 ,

wherein the setting of the reception CCA threshold includes:

counting the number of subordinate wireless communicators for each of the at least two of the wireless communicators on a basis of the statistical information; and

setting, for each of the at least two of the wireless communicators, the reception CCA threshold such that a ratio of radii of detection areas matches a ratio of the numbers of subordinate wireless communicators.

6 . A CCA threshold determination device that determines a CCA threshold used by a wireless communicator in a wireless communication system including a plurality of the wireless communicators configured by base stations or terminals, the CCA threshold determination device being configured to perform:

receiving statistical information regarding an environment for receiving a frame from at least two of the wireless communicators;

setting of a reception CCA threshold suitable for each of the at least two of the wireless communicators on a basis of the statistical information; and

notifying to each of the at least two of the wireless communicators of the reception CCA threshold being set,

wherein the setting of the reception CCA threshold includes setting of a value at which each of the at least two of the wireless communicators easily decodes a frame addressed to its own BSS and easily ignores a frame addressed to another BSS, the value providing a desired balance to frame detection areas of the at least two of the wireless communicators.

7 . A CCA threshold determination method for determining a CCA threshold used in a wireless communication system including a plurality of wireless communicators configured by base stations or terminals, the method including, causing at least two of the wireless communicators to perform:

carrier sensing to determine presence or absence of a frame having a reception power value equal to or greater than a transmission CCA threshold when a transmission request occurs;

transmission of a frame in a case where the absence of the frame having the reception power value equal to or greater than the transmission CCA threshold is confirmed as a result of the carrier sensing; and

ignoring of a frame having a reception power value less than the reception CCA threshold and decoding the frame having a reception power value equal to or greater than the reception CCA threshold, and

causing a controller that notifies the at least two of the wireless communicators of the reception CCA threshold to perform:

receiving statistical information regarding an environment for receiving the frame from the at least two of the wireless communicators;

setting of the reception CCA threshold suitable for each of the at least two of the wireless communicators on a basis of the statistical information; and

notifying to the at least two of the wireless communicators of the reception CCA thresholds being set,

wherein the reception CCA threshold is a value at which each of the at least two of the wireless communicators easily decodes a frame addressed to its own BSS and easily ignores a frame addressed to another BSS, the value providing a desired balance to frame detection areas of the at least two of the wireless communicators.

8 . A computer readable storage medium storing a CCA threshold determination program for determining a CCA threshold used by a wireless communicator in a wireless communication system including a plurality of the wireless communicators configured by base stations or terminals, the CCA threshold determination program being computer-readable, and causing a controller having a function of exchanging information with at least two of the wireless communicators to execute the CCA threshold determination method according to claim 7 .