Performance of space-frequency techniques over measured channels in MIMO-OFDM systems

In this paper we examine the performance of some space-time coding and signal processing techniques when applied to orthogonal frequency division multiplexing (OFDM) in multiple input multiple output (MIMO) configuration. Performance results using statistical multi-element channel models are compared with those using state-of-the-art MIMO channel measurements. We investigate space-frequency trellis coded modulations (SFTCM) along with a number of BLAST detection algorithms: ML, successive interference cancellation (original BLAST); linear ZF; ZF-ML hybrid. Since BLAST enhances mainly the data throughput and the SFTCM improves primarily the link quality, we also propose a scheme that efficiently distributes available degrees of freedom between spatial multiplexing and the diversity. The wideband MIMO measurements utilised here have been taken using a customised MIMO vector channel sounder operating in the 5.2 GHz band with 120 MHz of bandwidth. The primary focus of this work is to assess the robustness and performance loss of the different spacetime techniques when operating in real (measured) scenarios.