On Multiple Users Scheduling Using Superposition Coding over Rayleigh Fading Channels

Abstract

Abstract-In this letter, numerical results are provided to analyze the gains of multiple users scheduling via superposition coding with successive interference cancellation in comparison with the conventional single user scheduling in Rayleigh blockfading broadcast channels. The information-theoretic optimal power, rate and decoding order allocation for the superposition coding scheme are considered and the corresponding histogram for the optimal number of scheduled users is evaluated. Results show that at optimality there is a high probability that only two or three users are scheduled per channel transmission block. Numerical results for the gains of multiple users scheduling in terms of the long term throughput under hard and proportional fairness as well as for fixed merit weights for the users are also provided. These results show that the performance gain of multiple users scheduling over single user scheduling increases when the total number of users in the network increases, and it can exceed 10% for high number of users.

A Suboptimal Scheme for Multi-User Scheduling in Gaussian Broadcast Channels

“…Hence, the pdf and the cdf of the fading process are given by respectively, whereγ is the average power gain. The channel power gain and all the the other simulation parameters are the same as in [6]. We compare the schemes for three specific schedulers, namely hard fairness, proportional fairness and fixed weights.…”

“…We compare the schemes for three specific schedulers, namely hard fairness, proportional fairness and fixed weights. These are the same as in [6]. However, the algorithms given in [6] for calculating the user weights for proportional fairness and hard fairness need to be slightly modified.…”

“…Reference [6] compared the performance of SU and SC with SIC for three operating points, namely hard fairness, proportional fairness and fixed weights. Reference [6] showed that SC with SIC can achieve a 10% or higher gain than SU, so it may be feasible in some scenarios.…”

“…Reference [6] showed that SC with SIC can achieve a 10% or higher gain than SU, so it may be feasible in some scenarios. Other works which considered the performance of SC with SIC include [7]- [10].…”

“…Motivated by the work in [6], this work proposes a suboptimal scheduling scheme for Gaussian broadcast channels which improves upon the classical SU and still has significantly less complexity than SC with SIC. In the proposed scheme, only the two 'best' users are first selected according to their respective weights and instantaneous capacity and then are combined using SC.…”