Refinement of the Sphere-Packing Bound: Asymmetric Channels
Yücel Altuğ, Aaron B. Wagner · IEEE Transactions on Information Theory · 2014
We provide a refinement of the sphere-packing bound for constant composition codes over asymmetric discrete memoryless channels that improves the subexponential factor in front of the exponent. The order of our subexponential factor is Ω(N-0.5(1+ε+ρR*)) for any ϵ > 0, where ρR* is the left derivative of the sphere-packing exponent at rate R and N is the blocklength.