  We consider multiple access with re-transmission diversity (RTxD) based on a
hybrid automatic request (HARQ) protocol with incremental redundancy (IR) in
this paper. In order to mitigate multiple access interference (MAI), we employ
successive interference cancellation (SIC) at a receiver and derive conditions
that all the signals from active users can be successfully decoded within a
certain number of re-transmissions of IR blocks. We consider two special cases,
and based on them we derive two multichannel random access schemes that have
subchannels in the power and rate domains. Through the analysis and
simulations, we can show that the proposed RTxD random access schemes can
outperform other existing similar RTxD random access schemes.
