Summary: 242 IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 57, NO. 1, JANUARY 2009
MAP Decoding for Multi-Antenna Systems with
Non-Uniform Sources: Exact Pairwise Error
Probability and Applications
Firouz Behnamfar, Fady Alajaji, Senior Member, IEEE, and Tam´as Linder, Senior Member, IEEE
Abstract--We study the maximum a posteriori (MAP) decod-
ing of memoryless non-uniform sources over multiple-antenna
channels. Our model is general enough to include space-time
coding, BLAST architectures, and single-transmit multi-receive
antenna systems which employ any type of channel coding.
We derive a closed-form expression for the codeword pairwise
error probability (PEP) of general multi-antenna codes using
moment generating function and Laplace transform arguments.
We then consider space-time orthogonal block (STOB) coding
and prove that, similar to the maximum likelihood (ML) decoding
case, detection of symbols is decoupled in MAP decoding. We
also derive the symbol PEP in closed-form for STOB codes.
We apply these results in several scenarios. First, we design a
binary antipodal signaling scheme which minimizes the system
bit error rate (BER) under STOB coding. At a BER of 10-6