Efficient procedure for avoiding redundant data retransmissions in IEEE 802.11 WLAN

In IEEE 802.11 MAC protocol, the four-way handshake mechanism (RTS/CTS/DATA/ACK) has been standardized. This mechanism can efficiently combat hidden terminal problem and have high throughput when the payload of data packet is large. However, this mechanism cannot efficiently cope with ACK losses; every time the ACK frame is lost, unnecessary retransmission of data packet occurs. These unnecessary data retransmissions due to ACK losses wastefully consume the bandwidth of the channel, and degrade the performance of WLAN. Therefore, in this paper, we propose an algorithm that can efficiently avoid such unnecessary retransmissions. The proposed algorithm assigns the role of ACK also to CTS, and avoids unnecessary retransmissions by using this implicit acknowledgement. In order to perform sequence control by using RTS frame without any overhead, we employ the one-bit sequence ARQ scheme. Our simulation results show that the RTS/CTS mechanism with proposed algorithm can improve the goodput performance as compared with the conventional mechanism.