Energy Efficiency Optimization Techniques For Relay And Antenna Selection Schemes

Wireless communication technology has integrated into every aspect of our lives, but its energy efficiency raised much more attention in recent years because of increas-ing power consumption in communication industy and limited battery capacity of mo-bile terminals. Multiple-antenna and relay technology can greatly improve the capacity and reliabilty of wireless communication, but the total power consumption will also increase with more antennas and relay nodes activated. In order to balance the perfor-mance and power consumption of wireless systems, many relay selection and antenna selection schemes have been proposed and well studied both in academia and industry.Generalized Selection Combining (GSC) is a typical divisity combining scheme that has been applied to relay and antenna selection, but its energy efficiency has not been fully studied. In this thesis, we consider a muliple-antenna amplify-and-forward relaying system and analyze its energy efficiency when GSC scheme is applied to se-lect relays and antennas. Apart from transmisson power consumption, the circuit power consumption induced by hardware and the non-linearity of power amplifier are also considered. We first derive the expressions of GSC scheme’s energy efficiency for dif-ferent active numbers by using order statistic and other mathematic tools. Then we utilize the discrete characteristic of GSC scheme to find the most energy-efficient ac-tive number when transmission power is limited. The average active number of these energy-efficient GSC schemes are also derived. Finally, we use simulation results to further illustrate the effect of other system elements to energy-efficient GSC scheme’s performance.It can be found that our scheme is more energy efficient compared with typical GSC schemes. We also point out that spectrum efficiency, transmission distance, total number of relays and antennas, transmission power limitation can all make a significant difference in the choice of GSC scheme’s energy-efficient active number. Moreover, the effect these system elements bring to GSC relay selection and antenna selection may differ from system models and power consumption models.