  We analyze the impact of arbitrary dependence between the forward and
backward links in backscatter communication systems. Specifically, we quantify
the effect of positive and negative dependence between these fading links on
channel capacity, using Copula theory. The benefits of this approach are
highlighted over the classical framework of linear dependence based on
Pearson's correlation coefficient, which is also analyzed. Results show that
for a fixed transmit power budget, capacity grows with positive dependence as
well as with fading severity in the low signal-to-noise ratio (SNR) regime.
Conversely, fading dependence becomes immaterial in the high SNR regime.
