APPROXIMATING THE PAIRWISE ERROR-PROBABILITY FOR FADING CHANNELS

The computation of the pairwise error probability (PEP) for coded digi tal communications in the presence of fading is often performed by usi ng the Chernoff upper bound, which is simple to evaluate but rather lo ose. Exact evaluation of the PEP is possible in principle by computing the residues of a complex function, but this may be complicated in pr actice. In the Letter the authors derive two approximations to the PEP . The first one, based on saddle-point integration, is simple to compu te and generally tighter than the Chernoff bound. The second one, base d on Gauss-Chebyshev quadrature rules, is both easy to use and computa tionally stable, and approximates the true value of PEP within any deg ree of accuracy.