Abstract
In this paper, we study opportunistic round robin (ORR) uplink scheduling for vertical Bell Labs layered space-time architecture (V-BLAST) systems over multiuser multiple-input multiple-output (MIMO) channels. The proposed ORR scheduling method is compared to greedy scheduling. In greedy scheduling, the base station selects the best user based on a certain criterion without any consideration for fairness. On the other hand, ORR scheduling guarantees full fairness and each user will be served by excluding the previous selected users from the competition in the next round. The selected user spatially multiplexes his data over the transmit antennas. This spatial multiplexing (SM) scheme provides high data rates, while multiuser diversity obtained from scheduling improves the performance of the uplink system. The results show the performance and capacity gains obtained by scheduling. The greedy scheduler captures full multiuser diversity. In contrast, the ORR scheduler provides substantial signal-to-noise ratio (SNR) gains compared to round robin while guaranteeing full fairness to all users.
Highlights
In multiuser multiple-input multiple-output (MIMO) wireless systems, optimizing the physical layer for each user does not necessarily optimize system performance nor takes advantage of statistical independence of fading channels for different users
Outage capacity The capacity gains for opportunistic round robin (ORR) and greedy uplink MIMO scheduling at 10% outage versus the number of users are shown in Figures 7 and 8, respectively
The main results of this paper show the signal-to-noise ratio (SNR) and capacity gains obtained by ORR scheduling while providing full fairness to all users
Summary
In multiuser multiple-input multiple-output (MIMO) wireless systems, optimizing the physical layer for each user does not necessarily optimize system performance nor takes advantage of statistical independence of fading channels for different users. Greedy multiuser scheduling over MIMO systems was studied in [9], where we proposed and compared the performance of several user selection criteria for uplink vertical Bell Labs layered space-time architecture (V-BLAST) systems. It has been shown that in single-antenna systems, selecting the user that has the maximum SNR (MaxSNR) is optimal [1] and it maximizes the system information capacity.
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