US Patent 7440432 Wireless access system

A wireless access system is provided which prevents the occurrence of a hidden terminal problem and minimizes the reduction in throughput. In the wireless access system, an access point divides terminals into groups such that terminals in one group cannot recognize radio waves sent from terminals in another group, and performs communication with the terminals on a per-group basis. By this, the wireless access system avoids the occurrence of the hidden terminal problem. RTS/CTS packets used to avoid the occurrence of the hidden terminal problem are exchanged between the access point and the terminals on a per-group basis, whereby overhead is reduced and the reduction in throughput is minimized.