On the necessity of information transmission channel characteristics consideration in wireless systems planning

In wireless systems (networks) planning, the typical goal is to maximize two parameters: coverage and capacity. Metrics describing each of these parameters are system-level channel characteristics: BER or data rate spatial distributions, etc. However, in practice, metrics based on physical radio channel characteristics are commonly employed instead (spatial distributions of signal level, SINR, delay spread, etc.). Since determination of these parameters at a specific point of space is in general not possible with acceptable accuracy due to fast fading, their statistical estimates (local mean, outage probability, minimum, maximum values, variance, etc.), determined along small spatial areas typical of practical application, are used as metrics. Objective functions used in network planning further statistically generalize these local statistics. Since information transmission channel characteristics (BER, data rate, capacity, etc.) describing the obtained system performance are in general nonlinear functions of physical channel parameters, their statistical estimates cannot be correctly determined based on statistical estimates of physical parameters. Thus, network planning based on physical parameters will generally lead to errors. In the current contribution, this error is quantified analytically and experimentally. The obtained error values achieved 320% for local mean channel capacity and 3 orders for BER on significant part of analyzed spatial area. Thus, the high importance of considering and using system-level channel characteristics as a preferred metric in network planning is pointed out.