Energy efficiency analysis of linear receivers for large antenna system in fading channels

Abstract

ABSTRACTEnergy efficiency (EE) is a prominent research issue in massive Multiple Input Multiple Output (MIMO) wireless systems. In this paper, the energy efficiency of a large multiuser antenna system, using maximum ratio combining (MRC) and zero forcing receivers (ZF) has been analyzed in Rayleigh and Ricean fading channels. For Rayleigh fading both MRC and ZF receivers and for Ricean fading only MRC receiver is considered. The analysis is done assuming imperfect channel state information (CSI) and ignoring the effect of large scale fading. The effect of power consumption of all devices used in the channel, loss factors of antenna feeder, Direct current (DC)-DC and main power supplies and active coolant system are also considered. The results are derived for scaled down and un-scaled transmitted power. For Ricean fading channel when power is scaled down by the number of antennas at Base Station (BS), the energy efficiency increases with increase in spectral efficiency. For Rayleigh fading channel, with increase in transmitted power the spectral efficiency first increases, and after a certain level of transmitted power the energy efficiency decreases with increase in spectral efficiency. It has been observed here that MRC and ZF receivers give high spectral efficiency in Ricean and Rayleigh fading respectively.