Dual Diversity Space-Time Coding for Multimedia Broadcast/Multicast Service in MIMO Systems

Multimedia Broadcast/Multicast Service (MBMS) is a bandwidth efficient broadcast scheme for multimedia communications. To support prioritized transmissions, the unequal error protection (UEP) for multi-resolution multimedia sources can be realized through MBMS. Nevertheless, the enhancement on the transmission fidelity in base layer typically sacrifices the fidelity of enhancement layers. Herein, a novel dual diversity space-time coding (DDSTC) is proposed to exploit the intrinsic UEP capability of space-time codes by utilizing a constellation mapping duo for two consecutive transmission periods in multiple-input multiple-output (MIMO) systems. As compared with Alamouti coding, the DDSTC achieves coding gains on the transmission error rates of base layer without significant degradations on the enhancement layers. At the transmission rates of base and enhancement layers equal to 2 bits per transmission, the DDSTC obtains 1.3 dB and 3.0 dB coding gains for base layer in 2 × 2 and 2 × 3 MIMO systems respectively. Besides, analytical analysis on symbol error probabilities verifies that 6 dB asymptotic coding gain is reachable in rich transmit diversity scenarios. While attaining the considerable improvements on error rates, the DDSTC avoids the high decoding complexity by adopting our proposed decoding schemes. Simulation results show that DDSTC outperforms conventional UEP schemes based on hierarchical modulations or power allocations.