Design of MAC access schemes for analog joint source channel coding

We address the transmission of discrete-time analog samples over a block fading Multiple Access Channel (MAC). At each transmitter, the source information is first encoded using analog Joint Source Channel Coding (JSCC) and then input to a MAC access scheme. We consider three different access schemes: Code Division Multiple Access (CDMA), linear MMSE access codes and opportunistic communication. CDMA allows the orthogonal transmission of the user information requiring only Channel State Information (CSI) at reception. Linear MMSE access strategy exploits the CSI knowledge at transmission to obtain the optimal linear access codes that minimize the MSE at the output of a linear receiver. Finally, opportunistic access allocates all the transmit power to the user with the strongest channel. Although opportunistic is the optimal access strategy when the CSI is available at transmission, it can lead to an unfair allocation of the power and transmission rates of the users.