Master station in communications system and access control method

摘要

A communication band is divided into: a beacon period in which every master station transmits a beacon packet in competition with one another; a guaranteed-band period (e.g., a TDMA period or an FDMA period) in which only a specific permitted station is allowed access; and a CSMA period in which every station is allowed access in competition with one another. Plural master stations exchange information of a communication band used in the guaranteed-band period with each other, and based on the respective information, a communication band available to the master station's own communications system in the guaranteed-band period is calculated.

主权项

1. A control station in a first group controlling a communication of a slave station in the first group, the first group sharing a communication band with at least one second group including another slave station, and another control station controlling a communication of the other slave station in the second group, the control station comprising:
a bandwidth management section configured to specify a contention period and a non-contention period allocated periodically, the bandwidth management section dynamically setting the ratio between the contention period and the non-contention period in accordance with whether a total communication band required in the non-contention period by the first group, including a communication band for a communication to occur in response to a new request issued in the first group, is greater than a communication band available to the first group in the non-contention period where the communication band available to the first group in the non-contention period is calculated on the basis of a communication band used in the non-contention period by the second group, the contention period being a period, shared with the second group, during which any station in the first group or the second group is allowed to transmit a frame in contention with other stations, and the non-contention period being a period including a first non-contention period for the first group and a second non-contention period for the second group, wherein the bandwidth management section allocates a time slot in the first non-contention period to the slave station in the first group, when the total communication band is not greater than the communication band available to the first group in the non-contention period, the bandwidth management section grants the communication to occur in response to the new request, and when the total communication band is greater than the communication band available to the first group in the non-contention period,
(i) if a communication band which does not interfere with the communication to occur in response to the new request is present in a communication band which has already been allocated to the second group, the bandwidth management section grants the communication to occur in response to the new request in the communication band which does not interfere with the communication to occur in response to the new request, and(ii) if no communication band which does not interfere with the communication to occur in response to the new request is present in the communication band which has already been allocated to the second group, the bandwidth management section rejects the communication to occur in response to the new request.