Hello, 

I read a paper titled "Cognitive Relay Networks With Energy Harvesting and Information Transfer: Design, Analysis, and Optimization" (link attached).

I have some difficulty in understanding equation 29 and Fig.3 and Fig. 4. 

More specifically, in eq, 29, since the relay in energy constrained and has no energy of its own then I am unable to understand that from the circuit power Pc is obtained? is it obtained from the harvested energy? or it is assumed that the relay has enough stored power for circuit activation? what is the considered value of Pc in the paper?

How they have obtained the results in Fig. 3? Lets assume the results from Fig. 9. where the optimal sum rate at  Ps=30 dBm=1W is 3.5 bps/Hz (when d1=0.5) and circuit power is 0.1W then the energy efficiency according to 29 will be EE=3.5/ (1+0.1) = 3.181. However, in Fig. 3 for Ps=30 dBm=1W  the EE is less than 0.01. How these values and graph is obtained?

Any kind of help in this regard will be very much appreciated.

Regards

http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7342976