A New Approach to Synthesing Radio Frequency Channel Characteristics Models for TestinG of WCDMA Cellular Communication System
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Channel modeling for mobile cellular communication systems is a rapidly changing area, and the models are becoming increasingly accurate and more comprehensive to allow radio channel simulators to be implemented either by software or hardware to simulate diversity systems with many users. However, the challenge is to develop models that exhaustively reproduce the propagation scenarios accounted in reality. The paper introduces a new method of synthesizing RF channels of cellular communication systems for computer simulation and for controlled laboratory testing that is based on extensive observations of real signals in the field. Channel parameters are utilized as time histories of deterministic estimates derived from the field measurements. The stored channel data then be used to reconstruct the field channel conditions for laboratory testing. An iterative gradient search is performed to refine the state estimate (measurements are compared to the modeled output). The processing is performed using a WCDMA acquire search (Primary Synchronization Code Acquisition) to estimate the CPICH power and PN position of detectable primary scrambling. Full description of this deterministic stored channel impulse response model is presented. Using this methodology, an accurate channel model is possible, because it provides actual information from the channel. This was done to show how some physical link aspects such as power control and data rate can be tested for quality performance of these systems under real field conditions due to the ability of constructing controlled laboratory testing, though this type of controlled testing is extremely difficult to accomplish in the field due to the practical constraints.