On a problem by Ahlswede regarding the capacity region of certain multi-way channels : (prepublication)
Edward C. van der Meulen · Centrum Wiskunde & Informatica (CWI), the national research institute for mathematics and computer science in the Netherlands · 1973
A new Fano-type estimate is proved for multi-way channels.It yields upper bounds on the numbers of codewords and the products of these numbers in a code for a channel withs senders and r receivers in the case all senders send messages simultaneously to all receivers.The result is based on a new approach, which makes an approximation argument previously used by Ahlswede ( 1971b) and Ulrey ( 1973) unnecessary.It also leads to better Fano-estimates than the ones obtained by these authors.Our approach is canonical for weak converses of coding theorems for multi-way channels and applies also in other communication situations.