Cost-Efficient Deployment of Relays for LTE-Advanced Cellular Networks

Relay is used in LTE-Advanced cellular networks to assist eNB(evolved Node Base-station) for coverage extension and throughput enhancement. Compared to eNB, relay is advantageous on both equipment cost and site cost. How to deploy relays to maximize the performance gain with a reasonable cost subject to a number of system constraints such as interference caused and backhaul subframe allocation is an important yet challenging issue. In this paper, we provide a solution for cost-efficient deployment of relays in LTE-A cellular networks. We establish a mathematical model to analyze the tradeoff between the deployment cost and the cell performance gain, and the tradeoff between overall cell performance and satisfaction level for individual users. Our interesting findings in this paper include: (1) the best cost-efficient number of relays in a cell is limited to a reasonable range between 7 and 11 for static relay deployment; (2) when progressive deployment is considered, the optimal number of relays decreases to 4 to achieve tradeoff gain between overall cell capacity and average user satisfaction level.