802.11g CP: a solution for IEEE 802.11g and 802.11b inter-working

IEEE 802.11g is an emerging standard for a high data rate physical (PHY) layer supporting up to 54 Mbps at 2.4 GHz for wireless local area networks (WLANs). IEEE 802.11g is defined to be a superset of the 802.11b PHY. It includes the 802.11b modulation schemes and other higher rate modulation schemes, such as the orthogonal frequency division multiplexing (OFDM) schemes originally defined for 802.11a PHY at 5 GHz. One major problem with the 802.11g is that the OFDM signal is not detected by many legacy 802.11b devices operating at 2.4 GHz, and hence it introduces a severe problem since the 802.11 medium access control (MAC) is based on carrier-sensing. The 802.11g draft specification recommends the exchange of request-to-send (RTS)/clear-to-send (CTS) frames modulated with an 802.11b scheme before the transmission of the actual OFDM data frame. However, the RTS/CTS exchanges involve a large bandwidth waste. We propose an alternative solution, which improves the system throughput by avoiding the costly RTS/CTS usage. Our proposed solution utilizes the characteristics of the existing MAC with a minimal rule change, which requires virtually no change in the existing MAC implementation.