 wireless energy, and information signals are transmitted over the same waveform to various EH circuits and information decoders. SWIPT has gained research attention due to the high information-energy transmission efficiency [10]. Ideally, the receiver circuits should perform both EH and information processing (IP) simultaneously. However, in the architectural prospective, due to practical circuit limitations, it cannot be realized [13, 19-21]. Hence, the limitation can be relaxed by splitting the signal into two phases: In the first phase, energy is harvested, and in the other phase, communication link is established. In SWIPT, EH can be performed by using time switching (TS) protocol and power splitting (PS) protocol [11] and are represented in Figs. 6.1 and 6.2, respectively. In TS protocol, dedicated Energy Harvesting Phase Information Transmission Phase (1) Information Transmission Phase(II) (1-a)I (1-a)I (1-a)T Fig. 6.1 SWIPT: Time switching protocol Energy Harvesting (pP) Information Transmission Phase (II) Information Transmission Phase (I) ((1-p)P) Fig. 6.2 SWIPT: Power splitting protocol P. Shaik and V. Bhatia time is allocated for harvesting energy at the energy-constraint node, whereas the information transfer is performed for the rest of the time. In PS protocol, power is divided for both EH and information transmission [11]. 6.2 Energy Harvesting Models EH models are basically classified as linear and nonlinear based on the relation between the RF signal power and the power of the energy harvester. 6.2.1 Linear Energy Harvesting Linear EH is a de facto standard in various seminal works [8, 11]. In linear EH, the power of the energy harvester is directly proportional to the RF signal power which increases linearly with the input RF signal power. In practice, the devices are nonlinear devices which include active elements such as diodes and transistors, and hence, EH circuits exhibit saturation for a long duration of input power exposure. Since the RF signal is random, thus power harvested is dynamic.