Achievable Rate and Capacity Analysis for Ambient Backscatter Communications with Dynamic Sources

In this paper, we analyse the achievable rate and capacity for ambient backscatter communications with dynamic sources under the binary input and signal output (BISO) channel. Dynamic sources are the sources that transmit signals to the air intermittently, rather than continuously transmitting signals like static sources. Instead of assuming static ambient sources, we investigate the dynamic sources. Due to the complexity of the expression of mutual information, we resort to the numerical simulation results for the BISO channel capacity and the capacity-achieving distribution is obtained by one-dimensional searching. We utilize inequality to show the relationship between static sources and dynamic sources in terms of the achievable rate and capacity. The numerical studies show that the maximal of the mutual information of the BISO channel is not achieved by a uniform input distribution, and the mutual information and capacity of the BISO channel with dynamic sources are close to that of the BISO channel with static sources, scaled by the probability that the dynamic source is in the on-state.