Multi-user relaying with full frequency reuse for enhanced LTE-GBR coverage

LTE-OFDM systems will be deployed on the next generation of cellular networks. The peak data rate capability has undergone a tremendous improvement. Yet, novel outdoor to indoor coverage solutions are needed, mainly because more users are expected to be indoors where the fading loss is high. Relaying has been considered as a promising solution. Here we provide a novel scheme for delivering guaranteed instantaneous bit rate to users via decode and forward (DF) relays, which exploit full frequency reuse indoors. We employ hierarchical OFDMA to support multiple relays and to allow multiple users to access each relay. We then suggest optimisation of channel access to base station considering that the relays are half duplex. A pertinent question then arises whether relaying is performance-effective. We find that significant coverage gain can be obtained from our solution, mainly from taking advantage of the frequency diversity and spatial diversity available at the DF relay. To obtain realistic numerical results, we use measured channels and a motivational case of 2 Mbps user bit rates.