Abstract:

To improve wireless communication network’s spectral efficiencies， a MIMO-MRC cross-layer design scheme is proposed. The scheme is scheduled through combining multi-level adaptive modulation at physical layer with automatic repeat request protocol at data link layer. By utilizing channel state information and automatic repeat request which is fed back by the receiver， the transmitter updates the modulation mode adaptively， chooses the optimal transmitter beam-steering vector and retransmits data automatically. The effects of estimation errors on the system’s performance gains are analyzed and the close-form expressions of the system for spectral efficiencies and the probability of outage with imperfect channel estimation information are presented. The simulation results show that compared with the SISO cross-layer system and Alamouti’s cross-layer system， the performance of the MIMO-MRC cross-layer system is observably superior and achieves almost a diversity gain of 3 dB.