We consider a coupling information transmission modulation format utilized for communication over a multiple-access channel. A multitude of packets is transmitted by a number of sources to a common receiver. Each packet is modulated via simple repetition, interleaving, and an application of a signature sequence. The packets are transmitted with time offsets that initiate coupling of the transmitted signals into a received signal that lends itself to an efficient window-based iterative estimation and interference cancellation decoding. We present the window decoding formulation, a theoretic analysis, and numerical results for the achievable sum-rate, gap to the channel capacity and the optimal window size.