Path loss model comparison for LTE-Advanced relay backhaul link in urban environment

Relaying technology is a key technical enhancement in 3GPP LTE-Advanced developed in order to improve the throughput for cell-edge users. Power-balanced path loss models for the links Base Station-Relay Station (BS-RS), Base Station-Mobile Station (BS-MS) and Relay Station-Mobile Station (RS-MS) are required to evaluate relaying system performances. This paper presents a measurement-based study which aims to compare Path Loss (PL) models for links BS-RS or BS-MS at MS different antenna heights in an urban environment. The PL decrease with increase in relay antenna height is modeled with an additional parameter called Antenna Height Correction Factor (AHCF). AHCF may be added to usual PL models at street level such as the WINNER C2 or ITU UMa model. The proposed AHCF is the one defined by the COST231 Walfish-Ikegami model and is approximated by a linear increase of 0.9 dB/m according to the measurement data. The paper also analyzes the impact of relay antenna height on shadowing. The shadowing standard deviation does not vary when changing the relay antenna heights. Furthermore, the shadowing values at different antenna heights are highly correlated with correlation coefficients around 0.8.