Date Added: Feb 2012
The problem of maximum rate achievable with analog network coding for a unicast communication over a layered relay network with directed links is considered. A relay node performing analog network coding scales and forwards the signals received at its input. Recently this problem has been considered with two conditions: each relay node scales its received signal to the maximum extent possible subject to its transmit power constraint, the relay nodes in specific subsets of the network operate in the high-SNR regime. The authors establish that the condition, in general, leads to suboptimal end-to-end rate.