Impact of Transceiver Impairments on Capacity and Optimum Number of Users for Massive MIMO Systems

Abstract

MIMO systems with more than tens of antennas in communication terminals, referred to as large-MIMO systems or Massive MIMO system. Growing the antennas at the base stations is a native methodology for increasing the capacity of wireless system. The usage of such large no. of antennas can improve the energy and/or spectral efficiency of the wireless communication systems because of the significant improvements in array gain and spatial resolution. But, the impact of hardware impairments at the transmitter and receiver on the massive MIMO systems has gained slight attention in these days, even though large number of antenna might just be attractive for the network organization if every antenna having the reasonable equipment. The employment of transmitter and receiver contains of numerous types of hardware modules and every one of them have diverse influence on the signal. This thesis studies a new model for the massive MIMO systems that includes overall hardware impairments at transmitter contains large no. of antennas and receiver side. At the receiver side, there is user equipment such as single antenna users. In comparison to the general case, in which transceiver have ideal hardware, we proved that the non-ideality of hardware makes an upper limit on the accuracy of channel estimation and also on the capacity of each user. In this thesis work, we also demonstrated that the massive MIMO system does not provide the full advantages to all the users i.e. we proved that how the capacity decreases as we increase the no. of users after a certain limit, because of more training time requirement as the number of user increases. We show that how many are the optimum users to which this system provides full advantages. We also proved that how the transceiver impairments affects the accuracy of channel estimation and impact of that on the capacity and optimum no. of users in massive MIMO system.