The deployment of Relay Nodes (RNs) in 4G LTE-A networks,mainly originating from the wireless backhaul link,provides an excellent network planning tool to enhance system performance.Better coordination between the base station and relays to mitigate inter-cell interference becomes an important aspect of achieving the required system performance,not only in the single-cell scenario,but also in multi-cell scenarios.In this paper,we model and analyze two basic approaches for designing a 4G LTE-A tri-sectored cellular system.The approaches are based on Antenna Selection Sectored Relaying (ASSR) and Beam Selection Sectored Relaying (BSSR).The main purpose of the proposed schemes is to enhance system performance by improving the quality of the wireless relay backhaul link.In this technique,antenna selection takes into consideration Non-Line-Of-Sight (NLOS) communication,whereas BSSR considers the case of Line-Of-Sight (LOS) communication using heuristic beam forming approach.The resource allocation problem has also been investigated for relay based cooperative LTE-A trisectored cell in the downlink.The best possible location for relay node in the sector,power allocation and MIMO channel modeling is formulated as an optimization problem with the aim of maximizing the end to end link rate and the Signal to Interference plus Noise Ratio (SINR) of 4G LTE-A systems.Power allocation/optimization has been solved by means of the duality equation of the stationary Karush-Kuhn-Tucker (KKT) condition and is used to derive optimal values for the beam forming vector on both the relay as well as the access link.The performance of the proposed scheme is verified through simulations carried out using MATLAB software.The simulation results show a significant improvement in the SINR,throughput capacity,and coverage area of the 4G LTE-A cell,while guaranteeing better quality of service.
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