Part Three
Experimental Link-Level Evaluation
Introduction
Part Three reports in six chapters on the experimental and simulative evaluation of cellular systems. We show various results, mainly utilizing High-Speed Downlink Packet Access (HSDPA) and Long-Term Evolution (LTE) standards, but also to a certain extent a comparison with Worldwide Inter-operability for Microwave Access (WiMAX). Ideally, the performance of communication systems such as HSDPA should be evaluated for general wireless channels. This is typically accomplished by two approaches: simulation and measurement. Both approaches have their individual pros and cons that are briefly discussed below.
Simulations always rely on models of wireless channels and do not (at least not directly) require costly measurement campaigns. In order to obtain reasonable simulation results, realistic channel models have to be employed. In general, such models are highly complex and have many parameters which have to be carefully set to meaningful values. One very recent example is the Winner Phase II+ channel model. It includes almost all known physical wave propagation effects. However, two significant effects that are currently (July 2010) not well modeled are antenna polarization effects and multi-user correlation. The problem of these (and possibly also other, currently unknown) missing physical effects in channel models can be circumvented by performing measurements. By performing measurements, all physical effects no matter if ...
