Resource allocation for relay assisted transmission in millimetre wave wireless systems

Abstract

Conventional microwave bands below a frequency of 10 GHz are on the verge of saturation point. Thus, the global bandwidth shortage facing wireless carriers has motivated the exploration of the underutilized millimeter wave (mmWave) frequency spectrum for future broadband cellular communication networks. The mmWave frequency spectrum brings the possibility of developing the science for gigabit wireless networks. However, mmWave communication suffers from significant attenuation and shortage of multipath in NLOS transmissions and so mmWave wireless systems need to rely on LOS-propagation to achieve high data rates. In NLOS environments, relay techniques can compensate for severe path loss to improve the system throughput. This thesis investigates the use of directional antennas both at the transmitter and receiver and relays to compensate for severe path loss in NLOS environments. This thesis derives closed-form equations for the optimal allocation of antennas for beamforming to maximize capacity between a given source and destination in order to achieve high energy effciency.The use of Lagrange Multipliers is also introduced to study the optimal transmit power at the source along with the optimal number of transmit antennas to obtain maximum capacity between a source-destination pair.