MAC protocol of WLAN using smart adaptive array antennas

Based on the characteristics of IEEE 802.11 WLAN, a medium access control protocol SADCF is proposed to support smart adaptive array antennas. A smart antenna has omnidirectional and directional operation modes. In SADCF, before sending any data frame, the station stimulates the corresponding station to transmit a training sequence by means of omnidirectional RTS/CTS handshake mechanism. Based on the training sequence, the directional beam can be formed by the smart antenna. Then the station can transmit and receive data frames in directional mode. Other stations save the transmission time of the sender in omnidirectional mode by using the omnidirectional network allocation vector, and multiplex channel when it transmits in directional mode. SADCF is compatible with IEEE 802.11. Simulation results show that the SADCF protocol can support smart antennas effectively and provide high throughput by multiplexing the channel, and results of the analysis are close to the simulation results.