Refinement of the sphere-packing bound

摘要

We provide a refinement of the sphere-packing bound for constant composition codes over discrete memoryless channels that improves the pre-factor in front of the exponential term. The order of our pre-factor is O(N^{−1/2(1+ρ∗R)}), where ρ^∗R is related to the slope of the sphere-packing exponent and N is the blocklength.