 
Summary: 1
A Novel Maximum Likelihood Detection
Algorithm for Orthogonal SpaceTime Block
Codes
Luay Azzam, Student Member, IEEE, and Ender Ayanoglu, Fellow, IEEE
Center for Pervasive Communications and Computing
Department of Electrical Engineering and Computer Science
University of California, Irvine
Abstract
In this letter, we propose a low complexity Maximum Likelihood (ML) decoding algorithm for
orthogonal spacetime block codes (OSTBCs) based on the realvalued lattice representation and QR
decomposition. We show that for a system with rate r = K/T, where K is the number of transmitted
symbols per T time slots, the proposed algorithm decomposes the original complexvalued system into a
parallel system represented by 2K realvalued components, thus allowing for a simple and independent
detection of the real and imaginary parts of each complex transmitted symbol. We further show that for
square LQAM constellations, the proposed algorithm reduces the decoding computational complexity
from O(L) for conventional ML to O(
L) without sacrificing the performance.
I. INTRODUCTION
