Soft decision decoding technique for collaborative coding multiple-access channels

The collaborative coding multiple-access (CCMA) scheme permits potentially efficient simultaneous transmission by several users sharing a common channel, without subdivision in time or frequency. A new low complexity soft decision decoding technique is introduced. The soft decision CCMA (SD-CCMA) decoding algorithm and the probability of error calculation for the T-user baseband adder channel are presented. In addition, the theoretical analysis and the decoding algorithm for one particular 2-user adder channel scheme are shown. Simulation results for this scheme are presented graphically in terms of the probability of error employing SD-CCMA and hard decision (HD-CCMA) decoding techniques. The energy gain achieved by this technique for different signal to noise ratios is also shown