Patent ID: 8014464

Claim:
A communication apparatus used in a spectrum sharing environment in which multiple communication systems coexist on a same spectrum band, the apparatus comprising: a transmission pulse shaper configured to perform bandwidth limitation of a transmit signal; a monitoring unit configured to monitor an in-band interference condition from co-existing multiple communication systems other than a target system to which the communication apparatus belongs, and a usage condition of adjacent channels of the target system by other communication systems; a controller configured to control, based on a result of the monitoring unit, at least one of a signal information bandwidth and an excess bandwidth by changing a pulse transmission period and a pulse transmission width respectively; and a transmission unit configured to transmit the band-limited signal of the configured controller, wherein the pulse transmission period is broadened, while bandwidth of the transmission pulse shaper is maintained, when in-band interference from the co-existing multiple communication systems has occurred, and no determined quantity of unused spectrum on adjacent channels is available.