  Simultaneous wireless information and power transfer (SWIPT) is a promising
solution for enabling long-life, and self-sustainable wireless networks. In
this thesis, we propose a practical non-linear energy harvesting (EH) model and
design a resource allocation algorithm for SWIPT systems. In particular, the
algorithm design is formulated as a non-convex optimization problem for the
maximization of the total harvested power at the EH receivers subject to
quality of service (QoS) constraints for the information decoding (ID)
receivers. To circumvent the non-convexity of the problem, we transform the
corresponding non-convex sum-of-ratios objective function into an equivalent
objective function in parametric subtractive form. Furthermore, we design a
computationally efficient iterative resource allocation algorithm to obtain the
globally optimal solution. Numerical results illustrate significant performance
gain in terms of average total harvested power for the proposed non-linear EH
receiver model, when compared to the traditional linear model.\
