A Rate $$\text{ M }_{\mathrm{T}}$$ Full Diversity STF Block Coded $$4\times 4$$ MIMO-OFDM System with Reduced Complexity

Abstract

Multiple input multiple output (MIMO) communication systems with orthogonal frequency division multiplexing (OFDM) has a great role to play for 4G broadband wireless communications. In this paper, a space time frequency (STF) code is presented with reduced decoder complexity and to achieve code rate $$\text{ M }_\mathrm{T}$$ with full diversity of $$\text{ M }_{\mathrm{T}} \text{ M }_{\mathrm{R}} \text{ N }_{\mathrm{b}}$$ L i.e., product of number of transmit antennas ( $$\text{ M }_\mathrm{T}$$ ), receive antennas $$(\text{ M }_{\mathrm{R}})$$ , fading blocks $$(\text{ N }_{\mathrm{b}})$$ and channel taps (L). The maximum achievable diversity with high rate of STF block coded MIMO-OFDM is analyzed and verified by simulation results. The decoder complexity is resolved by employing several approaches like maximum likelihood (ML), sphere decoder (SD) and array processing. The performance of STF code is compared with existing layered algebraic STF code in terms of decoder complexity and bit error rate (BER). Further, the closed form expressions for BER performance of STFBC MIMO-OFDM systems are derived and evaluated for frequency selective block fading channels with MPSK constellations.