Patent ID: 6850489

Claim:
A communication system in which a transmitting station and a receiving station are communicably connected through a transmission path, and the receiving station reserves a bandwidth used in data communication for the transmitting station in advance, wherein said transmitting station transmits a reservation request packet for bandwidth reservation to said receiving station when data to be transmitted is generated, said receiving station reserves the bandwidth in response to the reservation request packet from said transmitting station, and transmits a communication reservation packet for informing said transmitting station of the reserved bandwidth, said transmitting station creates a data packet according to the generated data, and transmits the created data packet through the bandwidth informed by the communication reservation packet from said receiving station, said receiving station stores a valid period of the bandwidth reserved for said transmitting station, and voluntarily and repeatedly transmits the communication reservation packet to said transmitting station during the stored valid period, an initial value of the valid period stored for said transmitting station is predetermined, and said receiving station further shortens the stored valid period with given timing, lengthens the stored valid period on reception of the data packet from said transmitting station, deletes the valid period when the valid period is equal to a predetermined reference value, and voluntarily and repeatedly transmits the communication reservation packet to said transmitting station as long as the valid period is stored.