Energy EFFICIENT BANDWIDTH ALLOCATION SCHEME FOR RELAY IN MILLIMETER-WAVE MOBILE SYSTems

Abstract

Due to global bandwidth shortage, there have been some interests in investigating underutilized RF spectrum within 3-300GHz referred as millimeter-wave band. The mm-wave system can achieve high data rate by utilizing vast bandwidth and high beamforming gain. However, because of high levels of attenuation for certain building materials, the mm-wave signal is easily blocked by building in urban area. Due to this property, out-of-service areas where the signal does not reach occur frequently in the cell coverage. These out-of-service areas have a bad influence on coverage probability of the system. According to an analysis for coverage probability of the mm-wave system \cite{covcapanal}, the mm-wave system needs to increase base station (BS) density compared to conventional 4G LTE system in order to ensure high coverage probability. However, the high density of BSs significantly increases capital expenditure (CAPEX) and operating expenditure (OPEX) of the system. One solution to mitigate those expenditures is to treat some mm-wave BSs as relay nodes (RNs). However, additional energy consumption caused by relay operation is burden for the mm-wave system. In recent, energy efficiency becomes a crucial issue in wireless communication network, so energy efficiency must be considered for relay in mm-wave system. Nevertheless, there is no study about energy efficient utilization of vast bandwidth for relay to cover out-of-service areas in mm-wave system. In this thesis, we propose energy efficient bandwidth allocation scheme for relay in mm-wave mobile system. In order to do that, we first propose a new energy efficiency metric, called energy efficiency of mm-wave relay (EEMR) based on the standard. The proposed scheme allocates available bandwidth for relay considering following parameters: the number of MSs subordinated in RN, distance between BS and RN, and distance between RN and MS. Numerical results show that proposed scheme increases energy efficiency of the mm-...