Cross-layer combining of adaptive modulation with truncated ARQ in SIMO systems with imperfect CSI at receiver

In this paper we provide an adaptive cross layer design in single input multiple output systems which combines adaptive modulation at the physical layer with truncated automatic repeat request at the data link layer to maximize the spectral efficiency. The maximization is performed in the presence of imperfect channel state information at the receiver under prescribed quality of service such as delay and error rate constraints. Linear minimum mean square error filter with the aid of adaptive pilot symbols is used to facilitate estimation process. We provide closed forms expression for average spectral efficiency and average packet error rate over Rayleigh fading channel. Numerical results demonstrate that our adaptive cross layer design improves the spectral efficiency while meet the prescribed quality of service, especially when the large number of receive antennas is used. Also we find out that, the increment of spectral efficiency decreases when the maximum number of retransmission is higher than two.