| | |
Summary: SUBMITTED TO IEEE TRANS. WIRELESS COMMNS., NOV. 2009 1
An Orthogonal Relay Protocol with Improved
Diversity-Multiplexing Tradeoff
K. V. Srinivas, Raviraj Adve
Abstract
Cooperative relaying helps improve the reliability of data transmission over wireless fading
channels. In orthogonal relay protocols the source and the relay terminals transmit over orthogonal
channels, allowing a simple receiver at the destination. These protocols achieve the maximum
diversity gain but suffer from reduced multiplexing gain. We propose a new orthogonal decode-and-
forward relay protocol that employs rotated n-dimensional QAM constellations for input signaling
and, with a single cooperating relay, achieves a multiplexing gain of n
n+1 where n + 1 is the
cooperation frame length in symbol intervals. We show that the proposed protocol achieves a linear
diversity-multiplexing tradeoff (DMT) connecting the points (0, dmax) and (rmax, 0) where dmax =
2 and rmax = n
n+1 . With NR relays, our proposed protocol achieves a linear DMT connecting
(0, NR + 1) and n
n+NR
, 0 .
Index Terms
|
