Patent ID: 8811204

Claim:
An access control apparatus for controlling communications between terminal apparatuses, the access control apparatus comprising: a detecting unit that is adapted to a scheme where a frame, which contains a first period including a plurality of slots for transmission from terminal apparatuses located in a first area around the access control apparatus and a second period for CSMA/CS communication of terminal apparatuses located in a second area outside the first area, is repeated, the detecting unit being further configured to detect an empty slot having received power smaller than a threshold value, from among the plurality of slots in the first period; a broadcasting unit configured to broadcast information on the empty slot detected by said detecting unit; and a determining unit configured to determine a length of the first period in the frame, wherein the access control apparatus is configured to control the communications between the terminal apparatuses without directly designating for the terminal apparatuses a slot that is used for data communication even when the terminal apparatuses perform data communication, the determining unit determines the length of the first period such that the larger the number of slots, the longer the first period and the shorter the second period, and the broadcasting unit broadcasts information on the length determined by the determining unit as well as the information on the empty slot.