Three dimensional channel aware scheduling in relay-assisted multi-cell LTE-A downlink

This paper presents a three dimensional (3D) radio resource allocation and interference coordination scheme in multicell LTE-A downlink. We formulate the resource allocation and interference coordination problem as proportional fairness based utility maximization problem. Interference has been minimized through time, frequency, and space domain resource allocation. The proposed 3D scheme utilizes two time slots for intercell interference management, geometrical position based frequency resource allocation for intracell interference mitigation, and frequency domain orthogonality across UEs and relays for inter-UE and UE-relays interference management. The relaxed convex optimization problem has been solved through Lagrange multipliers and Karush-Kuhn-Tucker (KKT) conditions. Simulations have been performed according to the 3GPP (Third Generation Partnership Project) standard parameters for relay-enhanced LTE networks. Simulation results show the efficacy of proposed 3D scheme as compared to the already presented 3 slots time domain interference coordination (TD-IC) with round robin (RR-TD-IC) and proportional fairness (PF-TD-IC) schemes. It has been observed that proposed 3D scheme provides 81% increase in average individual throughput at the cost of only 13.8% degradation in fairness as compared to the PF-TD-IC.