Pilot tones design using particle swarm optimization for OFDM-IDMA system

Abstract

Since the channel estimation performance is directly affected by the pilot positions, it has been a major task in multicarrier transmission schemes to adjust the pattern of pilot distribution for the purpose of minimizing the estimation errors. Therefore, in this paper, we utilize particle swarm optimization (PSO) algorithm for pilot design process in orthogonal frequency division multiplexing–interleave division multiple access (OFDM–IDMA) system. The main contributions of the paper are: (1) increasing the performance of least squares (LS) algorithm used for channel estimation in OFDM–IDMA system by optimizing the pilot positions using PSO algorithm, (2) instead of using MSE itself in which the matrix inversion process is required as the fitness function of PSO, using the upper bound of mean square error (MSE) in order to decrease the system complexity, (3) using two types of channel models known as COST 207 Rural Area and COST 207 Typical Urban in the simulations to be able to support the reliability and stability of the proposed method in different conditions. In the simulations, it is observed from the bit error rate (BER) and MSE graphs that optimizing the placement of pilot tones using our proposed method demonstrates a superior performance compared to the other considered pilot placement strategies by providing a significant increase in the performance of LS algorithm.