Modeling and Analysis of Energy Efficiency and Interference for Cellular Relay Deployment

By relying on a wireless backhaul link, relay stations enhance the performance of cellular networks by achieving the required reliability at a savings of infrastructure cost and energy, but at the same time, they can aggravate the interference issue. In this paper, we analyze the maximum energy gain provided by relays for several coding schemes, including energy-optimized partial decode-forward relaying, accounting for the additional relay-generated interference to neighboring cells. First, we define new energy-efficient service areas for relaying in log-normal shadowing environments and propose easily computable and tractable models to predict: 1) the probability of energy-efficient relaying; 2) the spatial distribution of energy consumption within a cell; and 3) the average interference generated by relays. These models allow finding the optimal location and the number of relays with significantly lower complexity and execution time, as compared with system simulations. Finally, we analyze the gains provided by more advanced relaying coding schemes and propose a map showing how to use them across a cell, as a function of their respective circuitry consumption. The inclusion of more advanced relaying schemes not only alleviates the interference issue, but also leads to a reduction in the number of relays required for the same rate and outage performance.