Beamforming Strategies for Energy Efficient Transmission in LTE

The actual internet traffic growth is challenging the sustainability of mobile networks, therefore, the energy efficiency of the mobile communication infrastructure becomes a topic of particular relevance. Decreasing CO₂ emissions and energy demands while expanding the mobile infrastructure to satisfy traffic demands is essential. In this paper the energy efficient use of beamforming techniques and active antennas, in which an advanced antenna is utilized to direct the transmitted signal in a narrow direction, is evaluated. Slow beamforming based on reconfigurable antennas, exploits medium/long term variations of traffic in order to save energy. Fast beamforming, on the contrary, is immediately following the traffic distribution and can even allow saving more energy. From simulations it is observed that, when compared to existing state-of-art bases base stations, in a dense urban environment reconfigurable beamforming allows a maximum gain of about 8%. Adaptive beamforming, allows an additional consumed power reduction of up to 40%. Hence, the overall power consumption reduction that can be achieved by combining these techniques can be as high as 50%.