Patent ID: 9628997
Date: 2017-04-18
CPC Classifications: H04W

Claim:
1. A digital cordless telephone system for business use comprising a base station and a terminal employing PHS (Personal Handy-Phone System) technology, the base station comprising: a carrier sense unit that carrier-senses nearby radio waves at each predetermined sampling period, determining whether radio wave interference with a communication channel to be used for communication with the terminal is occurring by identifying whether the radio wave is a radio wave of another type of radio system different from PHS or a jamming wave, or by combining identifying whether the radio wave is a radio wave modulated by a modulation method different from a PHS modulation method with the identifying whether the radio wave is a radio wave of another type of radio system or a jamming wave, and outputting a result of monitoring whether radio wave interference with a communication channel to be used for communication with the terminal is occurring as a carrier sense result; a communication channel management unit that manages of communication channels by ranking usable communication channels to be allocated to communication with the terminal as an allocation priority order based on the carrier sense result output from the carrier sense unit; and a communication channel switching control unit, when a request for acquiring a communication channel to be used for communication with the terminal or a request for switching to another communication channel is made, preferentially selects and allocates a communication channel being high in the ranking among the communication channels whose ranking is managed by the communication channel management unit; wherein the carrier sense unit uses, as a monitor channel being a time for periodically carrier-sensing nearby radio waves, any one of a first channel being an unused time slot not in use due to PHS frame structural reasons or being, in addition to the unused time slot, a receiving time slot of a communication channel in an idle state unallocated to communication among communication channels for communication with the terminal, a second channel placed for, when a dedicated base station for carrier-sensing nearby radio waves is included, receiving the carrier sense result transmitted from the dedicated base station at each sampling period, and a third channel placed for, when a terminal in an idle state being not in communication among the terminals located nearby carrier-senses nearby radio waves at an arbitrary timing, receiving the carrier sense result transmitted from the terminal at each sampling period.