IIIT Hyderabad Publications
SIMULTANEOUS WIRELESS INFORMATION AND ENERGY TRANSFER IN MULTICARRIER AND COOPERATIVE COMMUNICATION SYSTEMS
Author: Sumit Gautam
Report no: IIIT/TH/2017/1
Increasing complexity and diminishing size of wireless devices often lead to quick depletion of en- ergy stored in batteries with limited capacity. In certain applications, sensors are often installed at loca- tions that are hazardous or inaccessible, which makes the battery replacement or recharging impossible. This could often lead to interruptions in the operation of the network. In such scenarios, transferring energy to these devices wirelessly plays a significant role in prolonging the life of the sensor networks. Since most of these devices perform wireless communication, it is of practical interest to consider the transfer of energy to the device using the same electromagnetic wave that is used for communication. This technique, termed ‘simultaneous wireless information and energy transmission (SWIET)’, holds great promise in many applications. SWIET enables joint transfer of data and energy to the receiver, which performs both information decoding and energy harvesting simultaneously from the same re- ceived electromagnetic wave. This technique will be central to various emerging technologies and has gathered considerable attention recently. Many current and future technologies like wearable devices, sensors used in hazardous areas, 5G and beyond, etc., are expected to use SWIET technique. In this work, we develop transceiver algorithms for the application of SWIET in two types of com- munication networks. In the first scenario, we consider SWIET in a wireless network employing multi- carrier transmission technique. The transmitter is designed to support both information and energy transfer simultaneously. The network employs orthogonal frequency division multiplexing (OFDM) for signal transmission. Receivers are capable of decoding the information as well as harvesting energy from the same received signal. In this context, we address the problem of the optimal transceiver design for maximizing the weighted sum-rate under a constraint on harvested energy and for maximizing the total harvested energy under constraint on minimum rate. In the second scenario, we consider SWIET in a cooperative network employing amplify-and-forward (AF) relays. The source node, relays, and the destination node, are all capable of handling both data and energy transmission simultaneously. In this context, apart from the optimal transmit and receive processing, we also consider the problem of optimal selection of a relay out of L given relays to maximize the rate and the harvested energy. We investigate the problems for both time switching (TS) and power splitting (PS) schemes. In TS, the receiver harvests all the energy from the received signal for a fraction of the block duration; while for the remaining duration, the received signal is utilized for information decoding. On the other hand, a fraction of the received signal power is used for harvesting energy and the remaining power is used for decoding information simultaneously, in case of PS. We have developed optimal and reduced complexity sub-optimal algorithms to solve the problems described above and have analyzed the performance in various scenarios. It is assumed that the channel state information (CSI) is perfectly known for all the scenarios. The benefits of proposed designs under different operating conditions and parameter values are illustrated via numerical simulations.
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