Achievable rate with receivers using iterative channel estimation in stationary fading channels

We study the achievable rate with receivers based on synchronized detection and iterative code-aided channel estimation for stationary Rayleigh flat-fading channels. The main idea behind this type of receivers is that — additionally to the pilot symbols which are used for the initial channel estimation and coherent detection/decoding — the channel estimation is enhanced by iteratively feeding back reliability information on the data symbols acquired by the channel decoder. For a specific type of such a receiver, we derive an upper bound on the achievable rate. Based on an approximation of the upper bound, which is not a closed-form expression, we are able to upper-bound the possible performance gain when using this specific receiver based on code-aided channel estimation in comparison to receivers using synchronized detection with a solely pilot based channel estimation. Furthermore, we compare this approximate upper bound with a lower bound on the achievable rate with joint processing of data and pilot symbols given in [1]. In addition, we show which part of the mutual information between the transmitter and the receiver cannot be exploited by the given receiver structure using synchronized detection in combination with iterative code-aided channel estimation.