Random Access and Source-Channel Coding Error Exponents for Multiple Access Channels

A new universal coding/decoding scheme for random access with collision detection is given in case of two senders. The result is used to give achievable joint source-channel coding error exponents for multiple access channel and independent sources. In a modified model admitting zero rate communication between the senders, an improved exponent is derived, of form similar to Csiszar's joint source-channel exponent for the one-sender case.