Evaluation of Potential Relay Locations in a Urban Macro-Cell Scenario with Applicability to LTE-A

Relay base stations are expected to play an important role in extending coverage for beyond 3G networks, such as LTE-A. However, the signal quality experienced on the backhaul link between the macro-cell and the relay node has a major impact on the performance of the multi-hop transmission. This paper presents a measurement-based study focusing on the performance evaluation of the relay backhaul link for different potential relay locations and antenna configurations in a real urban macro-cell scenario. Based on the assumption that a similar network deployment would apply for LTE-A, a fully operational 3G network has been used for measuring both received signal strength and Signal-to-Interference-Ratio (SIR). Furthermore, the results have been used to estimate the performance of the multi-hop transmission under simplifying assumptions. The experimental results show that by increasing the relay height from 2.4 m to 5 m, the received signal strength improves on average by 1.7 dB for omnidirectional antennas. When a directional antenna is mounted at 5 m and pointed towards the serving macro cell, significant SIR gains (around 5.9 dB) and throughput improvements are achieved at the locations where the relay node and the macro-cell are in Line-of-Sight (LOS).