The global demand for higher wireless data rates is increasing. By continuing this trend, it seems that current generation of wireless communications systems can not satisfy their requirements regarding network data rates. Massive MIMO systems with high potential for increasing the spectral efficiency of the system can greatly help to meet some future network's requirements. On the other hand, cooperative relaying system is known as one of the important technologies for increasing capacity as well as coverage of the network and reducing system power consumption. By combining these two technologies together, even higher spectral efficiency is achievable, therefore Massive-MIMO relay systems can be considered as a suitable choice in the next generation of wireless telecommunication systems. In recent years with the development of telecommunication systems and rising global warming issues, it feels very necessary than before to optimize systems power consumption. In this thesis, the energy efficiency of cellular massive-MIMO relay system in both uplink and downlink cases is investigated, and some improving methods through the optimization of transmit power ( in downlink case or users transmit powers in uplink case ) and relay power under quality of services (QoS) constraints are provided. Since the QoS constraint is related to necessary minimum of these power variables, transmit and relay power could be optimized in a two dimensional way. Regarding the quasi-concave behavior of the energy efficiency function relative to the power variables, we propose using a Bisection Power search Algorithm (BPA) first in one dimension, along with the full search in other dimension (ODS), also as another algorithm, using BPA-alternative in two dimensions (AOP), for allocating the transmit power and relay power. Simulation results demonstrate the usefulness of the proposed power allocation algorithms. The results also show that the complexity of proposed algorithm is lower than full search one. Keywords: Energy Efficiency, Massive MIMO Relay System, Bisection Algorithm, Altemative Algorithm
