A novel feedback reduction technique for cellular downlink with CDF-based scheduling

Cumulative distribution function (CDF)-based scheduling is known as an efficient scheduling method that can assign different time fractions for user access or, equivalently, satisfy different channel access ratio requirements of users in cellular downlink while exploiting multi-user diversity. In this paper, we propose CDF-FR, a feedback reduction technique for CDF-based scheduling that reduces feedback overhead from users in a cell. Although several threshold based feedback reduction schemes have been proposed for various scheduling algorithms, none of them considers users´ different channel access ratio requirements for which CDF-based scheduling is designed. In the proposed technique, a single threshold is used for all users who have different channel access ratio requirements. We show that this simple setting is sufficient for CDF-FR to satisfy users´ diverse channel access ratio requirements. It is proved that the average feedback overhead of CDF-FR is upper-bounded by - lnp for an arbitrary number of users in a cell, where p represents the probability that no user satisfies the threshold condition. Furthermore, the normalized throughput loss due to feedback reduction is upper-bounded by p in fading channels with arbitrary statistics.