Design and evaluation of space-time coded multiple input multiple output-orthogonal frequency division multiplexing physical layer

Two fundamental aspects of wireless communication, which make it challenging and interesting, are fading and interference. Multiple input multiple output (MIMO) and orthogonal frequency division multiplexing (OFDM) techniques when utilized together effectively combat fading and interference thereby achieving the requirement of high data rate and high performance. In this paper, a 2 x 1 MIMO-OFDM baseband model of the physical layer according to IEEE 802.16.1 standard employing 256 subcarriers capable of transmitting 192 Mbps in a 21-MHz bandwidth frequency selective fading channel is designed. All essential blocks of the communication system like channel coding, modulation, time synchronization, frequency synchronization, channel estimation, residual carrier frequency offset (CFO) estimation, and channel decoding are covered at the algorithm level. A two-step time synchronization method is used in this work to avoid any ambiguity in frame detection. A long preamble, consisting of three short preambles, is designed to aid in time synchronization, frequency synchronization, and channel estimation. To evaluate the performance of the proposed design, simulations were carried out in MATLAB-SIMULINK. A 2 x 1 MIMO-OFDM baseband system employing 256 subcarriers capable of transmitting 192 Mbps in a 21-GHz bandwidth frequency selective fading channel is designed. A two-step time synchronization method is used in this work to avoid any ambiguity in frame detection. A long preamble consisting of three short preambles is designed to aid in time synchronization, frequency synchronization, and channel estimation. image