Localization error bounds for 5G mm-wave systems under hardware impairments

Abstract

Localization and location aware systems are expected to be counted as one of the main services of 5G millimeter wave (mmWave) communication systems. mmWave communication systems are offering a large bandwidth from 30-300 GHz frequency band along with low latency communications. Although, they use massive number of antennas at their transmitters and receivers, their transceivers occupy a very small area, in order of centimeters. These features make 5G mmWave communication systems an exceptional candidate for the localization services. However, mmWave suffers from some limitations such as high vulnerability to the environment and hardware deficiency. The hardware used in mmWave system’s transceivers including power amplifiers and analog/digital converters, cannot be manufactured perfectly as of high costs. Therefore, it is highly probabilistic to see a non-linear behavior coming out of the mmWave transceivers, known as hardware impairments (HWIs). HWIs is generally caused as a result of nonlinearity of transmitter power amplifier and receiver low noise amplifier (LNA) as well as analog to digital (ADC) and digital to analog converters (DAC). Moreover, HWIs is the general form of phase noise and In/Quadrature phase (I/Q) imbalance. Because of the mmWave’s nature, even a slight shortcoming can cause severe effects on its performance. This thesis investigates the possible effects of HWIs on the user localization error bounds. Towards that and focusing on line-of-sight (LOS) path, we derive the Cramer-Rao Lower Bound (CRLB) for the user equipment (UE)’s location and orientation by starting with a conventional two dimension (2D) scenario and then, we extend it to the realistic three dimensional (3D) scenario. [...]