A Turbo Coding Scheme for the 2-User Gaussian Adder Channe

This paper discusses a coding scheme for the 2- user binary adder channel (2-BAC) employing a pair of distinct turbo convolutional codes, not necessarily forming a uniquely decodable code pair, in the presence of additive white Gaussian noise. The decoder is able to separate the binary data for each user by exploiting the code structure to combat noise and to resolve ambiguities, i.e., to distinguish between noisy versions of the two-user pairs (0;1) and (1;0). By means of computer simulation the performance of a particular pair of distinct turbo convolutional codes is determined and is presented as an example. The results are considerably better than those obtained by using a serial concatenation of 2-BAC uniquely decodable codes as outer codes and identical turbo convolutional codes as inner codes in the 2-BAC.