Downlink throughput enhancement of an OFDMA cellular system with closed-access indoor relays

We propose user-deployable closed-access indoor relays for throughput improvements in the downlink of LTE (long-term evolution) cellular system. The relays are assumed to be placed proximate to the destination user equipments (UEs). We propose a two-hop non-regenerative relaying scheme where the relay, equipped with multiple antennas, performs optimum combining to maximize the SINR (signal-to-interference-plus-noise ratio) before forwarding to a UE. The relaying is performed in a concurrent manner, where the base station (BS) transmits to some other receiver simultaneously when the relay is transmitting, and is therefore spectrally efficient. In order that the users served by a BS do not experience additional co-channel interference (CCI) because of the transmissions of the closed-access relays, we present an interference management scheme that can be implemented with minimal changes in the scheduling algorithm of a BS. Computer simulations, performed with large-scale deployment of indoor relays in the LTE framework, show that the UEs served by the relays see an improvement of over 100% in their respective throughputs, while the average cellular throughput improves by 24% when compared with a baseline system without relays. Also, the UEs served by the BSs do not experience any loss in their throughputs.