Single-radio multi-subchannel random access for OFDMA wireless networks

Orthogonal frequency division multiple access (OFDMA) is a promising technology owing to its flexibility in subcarrier/subchannel allocation. Since most applications in OFDMA wireless networks generate bursty traffic, it is efficient and flexible to employ a random access mechanism in such networks. A single-radio multi-subchannel carrier sense multiple access with collision avoidance (CSMA/CA)-based random access protocol (called SRMC-CSMA/CA) is proposed for OFDMA wireless networks. By means of intermittent carrier sense and cumulative update of backoff counters, a terminal with a single radio can utilise multiple subchannels to transmit packets concurrently. Simulation results indicate that the SRMC-CSMA/CA protocol apparently improves the channel utilisation, especially when the traffic loads of the terminals are unbalanced.