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Joint Wireless Transfer of Information and Energy in Cooperative Relay NetworksAuthor: Prudhvi Deep Mutyala Date: 2018-12-14 Report no: IIIT/TH/2018/86 Advisor:Ubaidulla P AbstractWireless devices are typically powered by batteries to ensure their portability. The finite energy storage capacity of the batteries limits operational period of the network. Recharging and replacing batteries of devices is time consuming or expensive, particularly when the sensors are deployed in hostile or hard-to-access environments. Energy harvesting (EH), a technique to collect energy from the ambient energy sources including radio frequency (RF) signals, has received considerable attention as a viable solution to this problem. Simultaneous wireless information and energy transfer (SWIET) explores a dual use of RF signals to transfer information jointly with energy using the same waveform. This can guarantee a reliable supply of energy unlike the case of other ambient energy sources. In this work, we consider SWIET in a cooperative wireless network involving two transceiver nodes whose communication is assisted by energy-constrained two-way amplify-and-forward (AF) relay nodes. The transceiver nodes can simultaneously transmit information and energy, and the relay nodes harvest the energy from the received signal and use the harvested energy to amplify and retransmit the received signal to the transceiver nodes. We consider two practical receiver architectures, namely, time switching (TS) and power splitting (PS). In TS, the receiver harvests energy for a fraction of transmission block and then decodes information for the remaining fraction. In PS, a fraction of the received signal is used for energy harvesting and the rest for information decoding. Based on the TS and PS receiver architectures, we propose the TSR and PSR protocols to facilitate simultaneous energy harvesting and information processing at the relay. For both protocols, we address the problem of resource allocation along with energy harvesting and optimal relay selection. The performance of the proposed PSR and TSR protocols for different parameters is illustrated by numerical simulations. We extend the relaying protocols discussed above to a cognitive radio (CR) scenario. Cognitive radio networks (CRNs) achieve better spectral efficiency by allowing the licensed users to share their spectrum with unlicensed users. The interference produced by the unlicensed users is kept below an accepted threshold. We consider a CRN with a licensed primary user (PU), two secondary transceivers, and a set of secondary two-way amplify and forward (AF) relays. The secondary user (SU) nodes share the spectrum with the PU node, and each node is assumed to be equipped with a single antenna. SU transceivers communicate with each other only via the relay optimally selected form the set of available relays. The transmit signals from the SU transceivers are designed so as to carry both information and energy. The relay harvests energy from these signals and uses this energy to process the received signals for further transmission. Full thesis: pdf Centre for Communications |
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