Patent ID: 7804842

Claim:
A carrier sense multiple access method implemented in a wireless network comprising a plurality of wireless terminal apparatuses and a wireless base station apparatus, said wireless base station apparatus being capable of space division multiple access and comprising an antenna section that forms a directional beam according to locations of the plurality of wireless terminal apparatuses and a plurality of transmission and reception sections that are connected with said antenna section and are capable of parallel operation, the method comprising: an allocation step of allocating, in the wireless base station apparatus, the plurality of wireless terminal apparatuses to groups defined by coverage areas of the directional beam; an assigning step of assigning, in the wireless base station apparatus, signature signals to the plurality of wireless terminal apparatuses allocated in the allocation step, each of the signature signals being unique to each of the groups; a detection step of detecting, in at least one of the plurality of wireless terminal apparatuses, whether or not a signature signal assigned in the assigning step is present in a medium to be accessed; a determination step of determining, in the at least one wireless terminal apparatus, whether or not the medium is being used for data packet transmission; a decrement step of: decrementing, in the at least one wireless terminal apparatus, a backoff value at every slot time when the medium is determined to be idle; decrementing, in the at least one wireless terminal apparatus, the backoff value at every detection time when the medium is determined to be being used for data packet transmission by another wireless terminal apparatus allocated to a different group from that of the at least one wireless terminal apparatus; and not decrementing, in the at least one wireless terminal apparatus, the backoff value until an end of data packet transmission using the medium by another wireless terminal apparatus allocated to the same group as that of the at least one wireless terminal apparatus, when the medium is determined to be being used for data packet transmission by the other wireless terminal apparatus allocated to the same group; and a transmission step of concurrently transmitting, from the at least one wireless terminal apparatus, the signature signal and a data packet addressed to the wireless base station apparatus when the signature signal allocated to the same group is not present in the medium as a result of the detection in the detection step and the backoff value is decremented to zero in the decrement step, wherein: every detection time is longer than the slot time.