Reduced complexity sphere decoding

  • Authors:
  • Boyu Li;Ender Ayanoglu

  • Affiliations:
  • Center for Pervasive Communications and Computing, Department of Electrical Engineering and Computer Science, The Henry Samueli School of Engineering, University of California, Irvine, Irvine, CA ...;Center for Pervasive Communications and Computing, Department of Electrical Engineering and Computer Science, The Henry Samueli School of Engineering, University of California, Irvine, Irvine, CA ...

  • Venue:
  • Wireless Communications & Mobile Computing
  • Year:
  • 2011

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Abstract

In multiple-input multiple-output (MIMO) systems, sphere decoding (SD) can achieve a performance equivalent to a full-search maximum likelihood decoding, with reduced complexity. Several researchers reported techniques that reduce the complexity of SD further. In this paper, a new technique that decreases the computational complexity of SD substantially, without sacrificing performance, is introduced. The reduction is accomplished by deconstructing the decoding metric to decrease the number of computations and by exploiting the structure of a lattice representation. Furthermore, an application of SD employing a proposed smart implementation with very low computational complexity is introduced. This application calculates the soft bit metrics of a bit-interleaved convolutional-coded MIMO system in an efficient manner. On the basis of the reduced complexity SD, the proposed smart implementation employs the initial radius acquired by zero-forcing decision feedback equalization, which ensures no empty spheres. Other than that, a technique of a particular data structure is also incorporated to efficiently reduce the number of executions carried out by SD. Simulation results show that these approaches achieve substantial gains in terms of the computational complexity for both uncoded and coded MIMO systems. Copyright © 2011 John Wiley & Sons, Ltd. (In this paper, the term “spatial multiplexing” is used to describe the number of spatial subchannels, as in **. Note that the term is different from “spatial multiplexing gain” defined in *.)