AN IMPROVED SOFT FEEDBACK V-BLAST DETECTION TECHNIQUE FOR TURBO-MIMO SYSTEMS

**Seoul National University In this paper, an improved minimum mean square error (MMSE) soft feedback detector, called the soft input, soft output, and soft feedback (SIOF) symbol detector, is proposed for turbo multi-input multi-output (TURBO-MIMO) systems. The SIOF symbol detector is derived by minimizing the power of interference plus noise, given aprioriprobabilities of yet undetected layers and a posteriori probabilities of detected layers. As a result, soft feedback interference cancellation based on a posteriori information is derived, yielding symbol detection robust to error propagation effects. Furthermore, a low complexity implementation using approximate detection ordering and linear filtering is introduced. Simulations performed for block fading channels show that the SIOF symbol detector exhibits performance gains over the existing TURBO-BLAST algorithm [3]