Throughout the entire simulations, the slot time, DIFS,PIFS, and SIFS are set to 9 ;34; 25, and 16 ms, respectively,and the transmission power is fixed to 17 dBm. We assume that the inter-transmission-attempt-time is 100 ms and the packet length is 1,500 bytes. The transmission time depends on the selected modulation and coding (MCS) level and number of control messages (RTS, CTS and ACK) with physical layer convergence protocol (PLCP) overhead of 20ms . Packet error events are emulated with PER values calculated from SINRs as in Section 4