Patent ID: 8135027

Claim:
A communication apparatus used for one communication system among a plurality of communication systems respectively coexisting with one another on a single power line communication medium, the communication apparatus comprising: a controller to divide a communication band so as to allow a first time period in which a coexistence signal for designating a communication slot exclusively used on the power line communication medium by the communication system belonging to the communication apparatus is transmitted, and a second time period in which a first communication slot and a second communication slot are allocated, to be alternately repeated at a predetermined coexistence signal cycle; and a transmitter to transmit the coexistence signal at the coexistence signal cycle, wherein the controller allocates, during the second time period at a first cycle, the first communication slot and the second communication slot; sets, for the first communication slot during the second time period, a communication right for a single communication system, repeatedly at the first cycle; sets, for the second communication slot during the second time period, a communication right for the single communication system, repeatedly at a second cycle which is longer than the first cycle; and allocates the communication slot exclusively used, as a combination of the first communication slot and the second communication slot, by the communication system belonging to the communication apparatus, wherein the second cycle is a subset of the coexistence signal cycle, and wherein the first cycle is a subset of the second cycle.