We proposed a cooperative MAC protocol with a low complexity relay selection scheme based on the standard DCF protocol. The partner is selected with respect to the SNR of the received packets and its ID is conveyed through a RTS frame. In the non-cooperative protocol, a station has to go through channel contention with no guarantee of immediate retransmission after an error, whereas cooperation allows immediate on-demand error recovery. AP uses a Request To Cooperate (RTC) frame to ask the partner to retransmit the lost packet. For a backward compatibility with the standard, all created and/or modified frames are based on the standard frame format. We also evaluate the coverage area of a terminal and we show that with cooperation, the stations can maintain a certain data rate for a wider coverage area. Future work will consist in refining the partner selection scheme and designing a cooperative rate adaptation scheme.