Coordinated Scheduling and Network Architecture for LTE Macro and Small Cell deployments

The support for Co-ordinated Multi-Point (CoMP) transmission has been recognized as a primary method of further enhancing the downlink spectral efficiency of LTE Rel-10. A series of air interface enhancements have been made in LTE Rel-11 to support CoMP with Ideal Backhaul (IB), but the support of CoMP using Non-Ideal Backhaul (NIB) was not considered in Rel-11. Recently, 3GPP evaluated CoMP performance gains with non- ideal backhaul and considered the necessary signaling to support inter-eNB CoMP. In this study, two types of network architecture are considered, namely i) the current distributed architecture and ii) the centralized architecture with a new node/entity to enable a centralized scheduler. In this paper, a dynamic co-ordinated muting scheme is proposed using LTE Rel-11 framework for both Macro and HetNet scenarios. Next, the performance of CoMP using non-ideal backhaul is evaluated under various traffic models with distributed and centralized architectures separately. It is shown that dynamic co-ordinated muting scheme with NIB can achieve a cell edge gain of approximately 40% over a system without co-ordination for Macro only and ~10% over FeICIC based HetNet scenario. The simulation results also indicate that a centralized architecture is more sensitive to backhaul latency comparing with distributed approach. Finally, it is concluded that the current LTE distributed architecture is well suited to support co-ordinated scheduling with non-ideal backhaul. Keywords?Centralized Scheduler; LTE; CoMP; MIMO; Non-Ideal Backhaul (NIB)