Faster Projection in Sphere Decoding

TL;DR

This paper introduces a new method for sphere decoding that eliminates redundant calculations, significantly increasing computational efficiency especially at higher dimensions, with a 75% reduction in floating-point operations at dimension 60.

Contribution

A novel sphere decoding algorithm that reduces redundant calculations, leading to faster performance without sacrificing accuracy, applicable to lattices and finite constellations.

Findings

Speed gain increases linearly with lattice dimension

At dimension 60, about 75% of floating-point operations are avoided

Method is applicable to both lattices and finite constellations

Abstract

Most of the calculations in standard sphere decoders are redundant, in the sense that they either calculate quantities that are never used or calculate some quantities more than once. A new method, which is applicable to lattices as well as finite constellations, is proposed to avoid these redundant calculations while still returning the same result. Pseudocode is given to facilitate immediate implementation. Simulations show that the speed gain with the proposed method increases linearly with the lattice dimension. At dimension 60, the new algorithms avoid about 75% of all floating-point operations.