Achievable rates and decoding error probability for parallel channels with dependent noise and restricted number of active users

We analyze data transmission over parallel binary symmetric channels with dependent noise. If a sender is active, then he transmits a codeword. If a sender is nonactive, then he transmits the all-zero vector. The dependence of noise in the channels gives a possibility of using the multiple access technique to encode and to decode transmitted messages. We show that under certain symmetric assumptions on the distribution of noise, one can asymptotically reach the same maximum transmission rate in the cases when the decoder knows the set of active users and when he does not have this information.