C-OFDMA: Improved Throughput for Next Generation WLAN Systems Based on OFDMA and CSMA/CA

In Orthogonal Frequency Division Multiple Access (OFDMA), there are multiple sub-channels which enable multiple stations to transmit concurrently on different sub-channels. The stations can obtain the channel information of all the sub-channels at each time instant. Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) allows different stations to randomly contend for the available subchannels from the time domain to avoid collision with each other. This gives a resource in time and frequency domain. In this paper, we present a Concurrent OFDMA-based CSMA/CA (C-OFDMA) MAC protocol for Next Generation Wireless Local Area Network where all the stations that transmit successful Request-To-Send (RTS) packet in the contention phase send their traffic concurrently to the Access Point (AP). The proposed C-OFDMA protocol is compared with existing IEEE 802.11 DCF, IEEE 802.11 RTS/CTS, and Hybrid-OFDMA MAC protocols and simulation results show that it provides improved throughput for crowded WLAN systems.