Cooperative Multi-Antenna Multicasting for Wireless Networks

Multicast service is a key function of the next generation broadband mobile system. The performance of wireless multicasting is severely degraded due to the wireless channel fading. Multiple antennas and cooperative communication are promising techniques that can be used to improve the multicast performance. Most cooperative schemes are based on the decode-and-forward (DF) strategy that requires the cooperating users being able to correctly decode the multicast data. In this paper, we study the cooperative multiple antenna multicast schemes based on amplify-and-forward (AF) strategy. A cooperative protocol for multicast systems with multiple transmit antennas is proposed. We analyze the performance of the protocol for two multiple antenna transmission schemes: the diversity transmission and multiplexing transmission. The close form expression and two bounds on the multicast outage probability are derived. Thorough numerical evaluation shows that our proposed protocol can take full advantage of the degree of freedom provided by the multiple transmit antennas. And a larger outage capacity is obtained at moderate and high signal-to-noise ratio.