Cost/revenue optimization of WiMAX networks with relay power saving modes: Measurement-Based scenario in a hilly region

This paper investigates cell zooming and relaying in conjunction with the use of opportunistic sleep modes to save energy at times of low load in WiMAX network deployments. It performs extensive propagation measurements in a hilly area of Covilhã, Portugal, in order to present a realistic and topographically challenging scenario in which to perform dynamic optimizations. It describes these measurements and their methodology in detail. Based on this scenario, it then investigates the performance achievable by networks that are deployed in various sectorization configurations with and without relays, and matches this to varying traffic loads at different times of the day to maximise the use of sleep modes, where possible, by relays, also in consideration of coverage constraints. Results demonstrate that savings typically of 47.6% in relays' average power consumption can be achieved. These savings are shown to map to a financial saving for the operator of 10% in operation and maintenance cost combined. It is also demonstrated that such solutions have to be used cautiously in such hilly regions due to challenges in maintaining coverage.