On the Effect of Correlation on the Capacity of Backscatter Communication Systems

TL;DR

The results show that correlation is indeed detrimental for a fixed target SNR; contrarily to the common belief, it is seen that correlation can be actually beneficial in some instances when a fixed power budget is considered.

Abstract

We analyse the effect of correlation between the forward and backward links on the capacity of backscatter communication systems. To that aim, we obtain an analytical expression for the average capacity under a correlated Rayleigh product fading channel, as well as closed-form asymptotic expressions for the high and low signal-to-noise ratio (SNR) regimes. Our results show that correlation is indeed detrimental for a fixed target SNR; contrarily to the common belief, we also see that correlation can be actually beneficial in some instances when a fixed power budget is considered.

Figures (4)

• Figure 1: Backscatter communication system set-up
• Figure 2: Average capacity $\overline{C}$ as a function of the average SNR at the receiver $\overline\gamma$, for different values of the power correlation coefficient $\rho$. Dashed lines correspond to the asymptotic results using \ref{['aAC2']}. Markers correspond to MC simulations.
• Figure 3: Average capacity $\overline{C}$ as a function of the average SNR at the receiver in the absence of correlation $\overline\gamma^I$ (i.e., for fixed transmit power $P_T$), for different values of the power correlation coefficient $\rho$. Dashed lines correspond to the asymptotic results using \ref{['aAC3']}. Markers correspond to MC simulations.
• Figure 4: Average capacity $\overline{C}$ normalised to that of the AWGN case, as a function of the average SNR at the receiver in the absence of correlation $\overline\gamma^I$ (i.e., for fixed transmit power $P_T$), for different values of the power correlation coefficient $\rho$. Markers correspond to MC simulations. For very low SNR, capacity tends to the asymptotic value in \ref{['aAC4']}.