Wireless Downlink Schemes in a Class of Frequency Selective Channels with Uncertain Channel State Information
OFDM; DS-CDMA; TDMA; MC-CDMA; spectral efficiency
The fourth generation of cellular wireless technology will be called upon to perform at data rates far exceeding those of any existing system. The most fundamental decision in the design of the physical layer of 4G wireless systems is the choice of downlink channel allocation scheme. The four prospective technologies are OFDM, TDMA, MC-CDMA, and DS-CDMA. We contend that spectral efficiency is an essential metric with which to compare the performance of the different schemes. In this thesis, we contribute in three essential areas to the analysis of broadcast spectral efficiency by accounting for the cost of channel estimation, the uncertainty of channel estimates, and the effects of a variety of frequency-selective channels. We begin by analyzing two path channels. Then we extend our analytical results to create a more versatile and practical simulation technique that serves as a useful tool for making 4G design decisions.