Energy savings in 3G using dynamic spectrum access and base station sleep modes

The energy consumption and energy efficiency of mobile telecommunication networks are crucial factors for the sustainability of this industry. This paper targets the reduction of the energy consumption at a Base Station (BS) level through the adoption of sleep modes during the off-peak periods of the day and relying in the existence of co-located and overlaid frequency bands to provide the coverage and capacity backup for the switched-off cells. It relies on the Dynamic Spectrum Allocation (DSA) method to opportunely relocate users during the low-load periods while maintaining the service quality of service (QoS). For the input data, real traffic statistics were used. Using this strategy and the proposed algorithm it was possible to achieve savings of about 43% per-site. The results were furthered to the study of a Portuguese mobile operator case and it was concluded that savings of more than 1.25 million euros were easily achieved.