The traditional medium access control (MAC) protocol was designed for a single-input single-output (SISO) antenna system to support the transmission of only one packet at a time. Although multiple-input multiple-output (MIMO) antenna systems, the next generation of antenna technology, can support multiple packet transmissions without collision, the standard MAC protocol does not allow multiple transmissions. Thus, the MAC protocol should be modified to support MIMO antennas and to improve the network performance. In this paper, we propose a new MAC protocol that allows multiple packet transmissions at a time. In the proposed protocol, multiple request-to-send (RTS) frames are sent before data transmissions. With this technique, the network performance can be improved. We have also developed a mathematical model called a Markov chain model to evaluate the network performance. Results obtained from the mathematical model show that the proposed MAC protocol provides a higher probability that wireless users in a network will successfully transmit packets than that for the conventional MAC protocol. Moreover, our protocol gives a lower probability that the wireless channel will be idle; thus, the proposed protocol allows the wireless channel to be utilized more than the conventional MAC protocol.
['Kittipong Warasup', 'Masanori Hamamura']
Multiple-request technique for wireless networks