| | |
Summary: 3518 IEEE TRANSACTIONS ON INFORMATION THEORY, VOL. 51, NO. 10, OCTOBER 2005
SourceChannel Diversity for Parallel Channels
J. Nicholas Laneman, Member, IEEE, Emin Martinian, Member, IEEE, Gregory W. Wornell, Fellow, IEEE, and
John G. Apostolopoulos, Member, IEEE
Abstract--We consider transmitting a source across a pair
of independent, nonergodic channels with random states (e.g.,
slow-fading channels) so as to minimize the average distortion. The
general problem is unsolved. Hence, we focus on comparing two
commonly used source and channel encoding systems which cor-
respond to exploiting diversity either at the physical layer through
parallel channel coding or at the application layer through mul-
tiple description (MD) source coding. For onoff channel models,
source coding diversity offers better performance. For channels
with a continuous range of reception quality, we show the reverse
is true. Specifically, we introduce a new figure of merit called the
distortion exponent which measures how fast the average distor-
tion decays with signal-to-noise ratio. For continuous-state models
such as additive white Gaussian noise (AWGN) channels with
multiplicative Rayleigh fading, optimal channel coding diversity
at the physical layer is more efficient than source coding diversity
|
