Buffering-aided resource allocation for Type I relay in LTE-Advanced cellular networks

3GPP LTE-Advanced (LTE-A) cellular networks support relay transmissions to improve the cell-edge users throughput as well as the system capacity, so that mobile communications services including multimedia transmissions, data download, real-time online gaming, etc., can be served with better quality-of-services (QoS). In LTE-A networks, Type I relay is widely used, where the relay station (RS) and evolved Node B (eNB) independently schedule and allocate resource for their served user equipments (UE). Existing research often assumes that the backhaul link (connecting eNB and relay) and the access link (connecting relay and UE) employ the same transmission rate, in order to avoid traffic congestions at the RS without queuing buffer. However, this makes the total relay throughput subject to the worse channel quality between the backhaul link and access link, thus severely degrading the system capacity as the wireless channels vary with time. To overcome this problem, this paper enables buffering function at RSs and proposes a buffering-aided three-step resource allocation scheme, which can efficiently make use of the time-varying channel qualities for data delivery. Furthermore, optimizations for the long-term fairness and overall network throughput are jointly designed. Also conducted is a set of system-level simulations to evaluate the performances of the proposed scheme. Simulation results show that the proposed scheme can not only improve the average network throughput compared with existing baseline schemes, but also achieve better long-term fairness over RS-served UEs and eNB-served UEs.