Μελέτη επίδρασης σφαλμάτων κατά την εκτίμηση παραμέτρων του καναλιού στην απόδοση τηλεπικοινωνιακών συστημάτων

Abstract

This work investigates how channel parameter estimation errors affect the performance of telecommunication systems. The telecommunication channel is (usually) modeled as a linear filter which is comprised of a fixed number of coefficients. In this sense, the term “channel parameters” is used to denote either the total number of these coefficients or the exact value of each one of them. Numerous algorithms/procedures in the telecommunication literature assume exact knowledge of these parameters and subsequently build upon this knowledge to carry out a specific telecommunication task. In real world conditions, however, nothing is known a priori and all such quantities must be estimated by means of a suitable procedure. Nevertheless, any estimation procedure is subject to errors, which can cause severe degradation of the overall system performance. The present study unfolds along two main axes: The performance analysis (in terms of equalization quality) of a blind second order statistics (SOS) equalization algorithm when channel order (i.e. number of channel coefficients) is unknown and the performance analysis (in terms of sum-rate degradation) of the uplink of a multiuser multiantenna system, when the exact values of channel coefficients for each user are unknown. Using rigorous mathematical analysis based on perturbation theory results together with simulation evidence, conditions and conclusions are derived as to the instances where estimation errors lead (or do not lead) to a significant system performance deterioration.