Abstract:

An Adaptive STBC-Beamforming cross-layer design scheme is proposed to improve wireless communication network’s spectral efficiencies. The scheme is scheduled through combining multi-level adaptive modulation and coding with hybrid automatic repeat request protocol. The transmitter updates the modulation mode, chooses the optimal transmission vector adaptively and retransmits data automatically by outdated feedback information. The close-form expressions of cross-layer system for spectral efficiencies and the probability of outage under outdated feedback are obtained. Effects of outdated feedback on system’s performance are analyzed. Simulations show that, compared to SISO cross-layer system and Alamouti’s cross-layer system, the performance of the adaptive STBC-Beamforming cross-layer system is observably enhanced.

Key words: Cross-layer design, adaptive modulation and coding (AMC), hybrid-automatic repeat request (H-ARQ), beamforming, outdated feedback channel