A Computationally Efficient Schnorr-Euchner Enumeration for Solving Integer Least-Squares Problem in Wireless Communications

Junil AHN  Jaewon CHANG  Chiho LEE  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E100-A   No.1   pp.327-331
Publication Date: 2017/01/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E100.A.327
Type of Manuscript: LETTER
Category: Communication Theory and Signals
Schnorr-Euchner enumeration,  integer least-squares problem,  sphere decoding,  finite lattice,  

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The integer least-squares (ILS) problem frequently arises in wireless communication systems. Sphere decoding (SD) is a systematic search scheme for solving ILS problem. The enumeration of candidates is a key part of SD for selecting a lattice point, which will be searched by the algorithm. Herein, the authors present a computationally efficient Schnorr-Euchner enumeration (SEE) algorithm to solve the constrained ILS problems, where the solution is limited into the finite integer lattice. To trace only valid lattice points within the underlying finite lattice, the authors devise an adaptive computation of the enumeration step and counting the valid points enumerated. In contrast to previous SEE methods based on a zig-zag manner, the proposed method completely avoids enumerating invalid points outside the finite lattice, and it further reduces real arithmetic and logical operations.