In this paper, we investigate the joint queuing at the data link layer and orthogonal frequency division multiplexing (OFDM) adaptive modulation at the physical layer for multiple-input-multiple-output (MIMO) relay system. A finite state Markov chain (FSMC) for this scenario has been proposed. Moreover, we consider an amplify and forward (AF) cooperative system with finite-length queue at the data link layer which leads to lower delay quantities. Finally, the packet loss rate and average spectral efficiency (ASE) of this system are evaluated in which the numerical results confirm the benefits of using MIMO nodes in our proposed cross-layer design and demonstrates that by employing cross-layer scheme the ASE decreases with respect to the case without queuing. Also, there is a good match between simulation and theoretical results.
