Opportunistic scheduling and spectrum reuse in relay-based cellular networks

In order to understand the key merits of multiuser diversity, opportunistic scheduling and spectrum reuse techniques in downlink relay-based cellular networks, this paper analyzes the spectral efficiency performance over a fading multihop broadcast channel (MBC) composed of a base station (BS), a relay station (RS), U far users and V near users in the asymptotic regime of large number of users. Using tools from extreme-value theory, we characterize the average spectral efficiency of the MBC as a function of the number of users and physical channel parameters. Our analysis yields very accurate formulas even for moderately low values of U and V , specified in detail and verified (via Monte Carlo simulations) for the case of Rayleigh fading. Next, we consider a relay-based broadband multi-cellular network in the downlink mode; with special focus on orthogonal frequency-division multiple-access (OFDMA) resource allocation and investigate the spectral efficiency performance of opportunistic multiuser scheduling and spectrum reuse techniques based on capacity analysis and system-level simulations. This empirical study validates our analytical insights and helps to further identify design tradeoffs associated with spectrum reuse, interference management and multiuser diversity techniques in relay-based cellular networks.