Antenna selection algorithm based on mutual coupling and spatial correlation between integrated antennas for maximum energy efficiency

Abstract

An energy efficient transmission becomes hot issue in multiple input multiple output (MIMO) system to achieve economic and environmental benefits. Because the energy consumption is directly related to money, it cannot be ignored anymore in modern society. Also, many antennas are used to increase data rate in MIMO system to satisfy user's requirement but a space to integrate the antennas is fixed. Generally, only one antenna like dipole antenna is integrated in a half-wavelength space to reduce correlation between antennas. Therefore, new antennas like dual polarization dipole antenna and pattern polarization antenna reducing the correlation between adjacent antennas have been developed to integrate more than one antenna in the half-wavelength space. However, there is an correlation between antennas in case of using not only dipole antenna but also dual polarization antenna and pattern polarization antenna. To transmit data energy efficiently, an energy efficiency metric which is channel capacity divided by total power consumption which consists of transmit power and circuit power consumption in radio frequency (RF) chains have to be maximized. Therefore, the energy efficiency can be maximized by not using all antennas but some of all antennas to reduce circuit power consumption. For these reasons, antenna selection algorithms to maximize energy efficiency have been researched very actively. In conventional antenna selection algorithm, antennas are selected based on only channel gain. However, existing researches about antenna selection algorithm maximizing the energy efficiency have not considered the correlation between antennas, which is not much practical. In recent trend of integrating more than one antenna in half-wavelength space to increase the channel capacity, the correlation between antennas have to be considered in view of practical approach. In this thesis, the antenna selection algorithm maximizing the energy efficiency considering mutual coupling and spatial correlation between antennas is proposed in downlink channel of cellular communication system. In the proposed algorithm, both transmit power and antenna subset maximizing the energy efficiency which are suboptimal solution can be achieved. Here, the proposed algorithm has lower complexity than an exhaustive search which can achieve optimal solution. In addition, three antenna configurations which are vertical polarization dipole antenna configuration (VP-DAC), dual polarization dipole antenna configuration (DP-DAC) and pattern polarization antenna configuration (PP-AC) are used to consider wireless communication environment more practically. To demonstrate the performance of the proposed algorithm, the simulation was proceeded in single-cell single-user MIMO system. The simulation results were investigated in according to channel conditions. It is confirmed that a performance of the proposed algorithm is better than that of conventional algorithm and approaches very close to that of the exhaustive search for three different antenna configurations.