Chirp-Z transform based pilot estimation for 2x2 MIMO-alamouti systems

Abstract

Wireless communication advancements brought simultaneous development in datarate along with high accuracy. 4G Technology demands high datarate and with Multiple Input-Multiple Output (MIMO) systems this can be achieved. MIMO system improves the datarate without additional transmission power and Bandwidth. Orthogonal Space Time Block Coding (OSTBC) achieves transmit diversity and receive diversity by a set of received signals with different antennas. MIMO-Alamouti systems require precise channel estimation and synchronization to reduce Bit Error Rate (BER). In this work, Transform Based Pilot Estimation (TBPE) techniques are used to compute CSI (Channel State Information). Various Pilot patterns have been designed using different signal transform techniques such as Hardamard, Hankel, Singular Value Decomposition (SVD) and compared with the random sequences for MIMO time varying channels. BER has been evaluated for various lengths of pilots like 4,8,16 symbols for2X2 MIMO systems with BPSK and QPSK Modulation. Least Square Error method has been used to compute Mean Square Error (MSE). In addition Trellis Coded Modulation (TCM) Channel Coding and Chirp-Z Transform (CZT) are used for MIMO Transmission. Although Hardamard Transform based pilot channel estimation gives least BER, CZT based pilot channel estimation outperforms all other transmission techniques with least BER.