The Spherical Bound Stack Decoder

In this work, we are interested in the decoding of MIMO systems by using sequential decoders. These ones consist on tree search algorithms and were originally used to decode binary codes. They were rediscovered and adapted to MIMO systems by Murugan and al. We are interested here in the stack decoder. We propose a new sequential decoder that we call the spherical-bound stack decoder (SB-Stack) combining the stack decoder search strategy and the sphere decoder search region. We show that the SB-stack achieves the ML performance with a reduced complexity compared to the original stack and the sphere decoder. Furthermore by introducing the bias parameter the SB-stack offers a range of performances going from ML to ZF-DFE with proportional complexities.