A Strengthened Cutset Upper Bound on the Capacity of the Relay Channel and Applications

We develop a new upper bound on the capacity of relay channel that is tighter than previously known bounds. This proved using traditional weak converse techniques involving mutual information inequalities and Gallager-type explicit identification auxiliary random variables. show strictly all previous bounds for Gaussian with non-zero gains. When specialized to orthogonal receiver components, resolves conjecture by Kim class deterministic channels. further product-form channels generalized version Cover’s problem, recovers recent case Wu et al. , improves upon binary symmetric Barnes which were obtained non-traditional geometric proof techniques. For special we another utilizes an it Tandon Ulukus. Finally, through i.i.d. output sequence can be our main bound.