Joint Adaptive Combining and Multiuser Down-Link Scheduling

In this paper, we propose two different types of multiuser access scheme based on assembling the schemes of (i) the switch and examine scheduling in the network layer and (ii) the joint adaptive modulation and output-threshold maximal ratio combining (OT-MRC) in the physical layer and thus attempt to find an efficient cross-layer access scheme to exploit the user diversity as well as the high spectral efficiency and the antenna diversity gain. We consider the multi-user environment where base station equipped with single antenna attempts to communicate with each user equipped with L receive antennas based on switch-and-examine transmission (SET) as a user selection scheduling scheme. We propose two different SETs: (i) spectral efficient SET and (ii) feedback load efficient SET. We analyze the performance of our proposed schemes and compare them with the optimal scheduling scheme in terms of the average spectral efficiency and the average number of estimated paths per user to quantify the complexity.