| 1. |
- De, Swades, et al.
(författare)
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Stochastic Solar Harvesting Characterization for Sustainable Sensor Node Operation
- 2019
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Ingår i: IET Wireless Sensor Systems. - : Institution of Engineering and Technology (IET). - 2043-6386 .- 2043-6394. ; 9:4, s. 208-217
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Tidskriftsartikel (refereegranskat)abstract
- Self-sustainability of low power wireless sensor nodes is the need of the hour to realize ubiquitous wireless networks. To address this requirement we investigate the practical feasibility of sustainable green sensor network with solar-powered nodes. We propose simple yet efficient (i) analytical circuit model for solar panel assisted supercapacitor charging and (ii) statistical model for characterizing the solar intensity distribution. Combining these circuit and statistical models, we derive a novel solar charging rate distribution for the solar-powered supercapacitor. To gain analytical insights, we also propose an ideal diode based tight approximation for the practical supercapacitor charging circuit model. The accuracy of these proposed analytical models have been validated by extensive numerical simulations based on the real-world data, i.e., solar intensity profile and solar panel characteristics. The derived solar charging rate distribution is used to investigate the supported sampling rate of the node with different varying number of on-board sensors for a given energy outage probability. Results suggest that for an energy outage probability of 0.1, at New Delhi, a 40 F supercapacitor and a 3 W solar panel can support the operation of Waspmote with 6 on-board toxic gas sensors with a sampling rate of 65 samples per day. Further, we use the proposed models to estimate the practical supercapacitor and solar panel sizes required to ensure sustainability of sensor node operation at different geographical locations with varying sensing rate.
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| 2. |
- Kaushik, K., et al.
(författare)
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Experimental demonstration of multi-hop RF energy transfer
- 2013
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Ingår i: 2013 IEEE 24th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781467362351 ; , s. 538-542
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Konferensbidrag (refereegranskat)abstract
- Batteries of field nodes in a wireless sensor network pose an upper limit on the network lifetime. Energy harvesting and harvesting aware medium access control protocols have the potential to provide uninterrupted network operation, as they aim to replenish the lost energy so that energy neutral operation of the energy harvesting nodes can be achieved. To further improve the energy harvesting process, there is a need for novel schemes so that maximum energy is harvested in a minimum possible time. Multi-hop radio frequency (RF) energy transfer is one such solution that addresses these needs. With the optimal placement of energy relay nodes, multi-hop RF energy transfer can save energy of the source as well as time for the harvesting process. In this work we experimentally demonstrate multi-hop RF energy transfer, wherein two-hop energy transfer is shown to achieve significant energy and time savings with respect to the single-hop case. It is also shown that the gain obtained can be translated to energy transfer range extension.
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| 3. |
- Kaushik, K., et al.
(författare)
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Low-cost wake-up receiver for RF energy harvesting wireless sensor networks
- 2016
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Ingår i: IEEE Sensors Journal. - : Institute of Electrical and Electronics Engineers (IEEE). - 1530-437X .- 1558-1748. ; 16:16, s. 6270-6278
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Tidskriftsartikel (refereegranskat)abstract
- The existing passive wake-up receivers (WuRxs) are radio frequency identification (RFID) tag based, which incur high cost and complexity. In this paper, we study cost-effective and long-range WuRx solutions for range-based wake-up (RW) as well as directed wake-up (DW). In particular, we consider the case of an RF energy harvesting wireless sensor node and investigate how a low-cost WuRx can be built using an RF energy harvester available at the node. Experimental results show that our developed prototype can achieve a wake-up range of 1.16 m with +13 dBm transmit power. Furthermore, our empirical study shows that at +30 dBm transmit power the wake-up distance of our developed RW module is >9 m. High accuracy of DW is demonstrated by sending a 5-bit ID from a transmitter at a bit rate up to 33.33 kbps. Finally, we present optimized WuRx designs for RW and DW using Agilent advanced design system, which offer up to 5.69 times higher wake-up range for RW and energy savings per bit of about 0.41 mJ and 21.40 nJ, respectively, at the transmitter and the sensor node in DW.
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| 4. |
- Kaushik, K., et al.
(författare)
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RF energy harvester-based wake-up receiver
- 2015
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Ingår i: Sensors Journal IEEE. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781479982035 - 9781479982028 ; , s. 6270-6278
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Konferensbidrag (refereegranskat)abstract
- Wake-up receivers (WuRxs) can improve the lifetime of a wireless sensor network by reducing energy consumption from undesirable idle listening. The amplitude level of the incoming RF signal is used by a WuRx to generate an interrupt and wake up the radio of a sleeping sensor node. Existing passive WuRx designs are generally based on RFID tags that incur high cost and complexity. Thus, there is a need for cost-effective and low-complexity WuRxs suited for both long-range and directed wake-ups. In this work, we present a WuRx design using an RF energy harvesting circuit (RFHC). Experimental results show that our RFHC-based WuRx can provide a wake-up range sensitivity around 4 cm/mW at low transmit RF powers (<; 20 mff), which scales to a long wake-up range at high powers. Our design also obtains accurate selective wake-ups. We finally present simulation-based studies for optimizing the design of RFHCs that enhance decoding efficiency with improved rise and fall times.
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| 5. |
- Kumar, Sidharth, et al.
(författare)
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An accurate channel model for optimizing effect of non-LOS component in RF energy transfer
- 2017
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Ingår i: 23rd National Conference on Communications, NCC 2017. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509053568 - 9781509053575 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- Self-sustainability of wireless sensor nodes can be realized with the help of controlled radio frequency energy transfer (RF-ET). However due to significant energy loss in wireless dissipation, there is a need for novel schemes to improve the end-To-end RF-ET efficiency. In this work we propose a new channel model for accurately characterizing the harvested DC power at the receiver. This model incorporates the effects of non-line of sight (NLOS) component along with the other factors, such as, polarization of transmitting field, radiation pattern of transmit and receive antennas, polarization loss factor, and efficiency of power harvester circuit. We have validated accuracy of the proposed model by carrying out experiments in an anechoic chamber. In addition to this characterization, we formulate an optimization problem by accounting for the effect of NLOS component to maximize the RF-ET efficiency. To solve this nonconvex problem, we present a computationally-efficient golden section based iterative algorithm. Finally, via numerical investigation we show that significant efficiency improvement can be achieved with
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| 6. |
- Kumar, Sidharth, et al.
(författare)
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RF Energy Transfer Channel Models for Sustainable IoT
- 2018
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Ingår i: IEEE Internet of Things Journal. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2327-4662. ; 5:4, s. 2817-2828
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Tidskriftsartikel (refereegranskat)abstract
- Self-sustainability of wireless nodes in Internet-of-Things applications can be realized with the help of controlled radio frequency energy transfer (RF-ET). However, due to significant energy loss in wireless dissipation, there is a need for novel schemes to improve the end-to-end RF-ET efficiency. In this paper, first we propose a new channel model for accurately characterizing the harvested dc power at the receiver. This model incorporates the effects of nonline of sight (NLOS) component along with the other factors, such as radiation pattern of transmit and receive antennas, losses associated with different polarization of transmitting field, and efficiency of power harvester circuit. Accuracy of the model is verified via experimental studies in an anechoic chamber (a controlled environment). Supported by experiments in controlled environment, we also formulate an optimization problem by accounting for the effect of NLOS component to maximize the RF-ET efficiency, which cannot be captured by the Friis formula. To solve this nonconvex problem, we present a computationally efficient golden section-based iterative algorithm. Finally, through extensive RF-ET measurements in different practical field environments we obtain the statistical parameters for Rician fading as well as path loss factor associated with shadow fading model, which also asserts the fact that Rayleigh fading is not well suited for RF-ET due to presence of a strong line of sight component.
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| 7. |
- Mishra, Deepak, 1990-, et al.
(författare)
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Achievable throughput in relay-powered RF harvesting cooperative sensor networks
- 2016
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Ingår i: Twenty Second National Conference on Communication (NCC). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509023615 - 9781509023622 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- Aiming at uninterrupted sensor network, we consider a radio frequency (RF) harvesting cooperative communication scenario, where the field nodes (information sources) are powered by RF energy transfer (RFET) from a relay. The relay node can be either connected to the power grid or positioned at some ambient energy harvesting favorable location for the desired energy supply. To further reduce the field nodes’ energy consumption, the relay node decodes-and-forwards the field data to the information sink in a two-hop half-duplex fashion. In the relay-powered cooperative network (RPCN), we derive closed form expressions of the ergodic capacity and achievable throughput for each source-destination pair. Achievable sum-throughput as a function of different system parameters, e.g., RFET time, RF-to-DC conversion efficiency, relay location, channel conditions, and relay transmit power is numerically evaluated. Significant throughput performance imp
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| 8. |
- Mishra, Deepak, 1990-, et al.
(författare)
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Charging time characterization for wireless RF energy transfer
- 2015
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Ingår i: IEEE Transactions on Circuits and Systems - II - Express Briefs. - : Institute of Electrical and Electronics Engineers (IEEE). - 1549-7747 .- 1558-3791. ; 62:4, s. 362-366
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Tidskriftsartikel (refereegranskat)abstract
- Wireless energy transfer to the onboard energy storage element using dedicated radio frequency (RF) energy source has the potential to provide sustained network operations by recharging the sensor nodes on demand. To determine the efficiency of RF energy transfer (RFET), characterization of recharging process is needed. Different from classical capacitor-charging operation, the incident RF waves provide constant power (instead of constant voltage or current) to the storage element, which requires a new theoretical framework for analyzing the charging behavior. This work develops the charging equation for replenishing an energy-depleted storage element by RFET. Since the remaining energy on a sensor node is a random parameter, the RF charging time distribution for a given residual voltage distribution is also derived. The analytical model is validated through hardware experiments and simulations.
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| 9. |
- Mishra, Deepak, 1990-, et al.
(författare)
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Dilemma at RF Energy Harvesting Relay : Downlink Energy Relaying or Uplink Information Transfer?
- 2017
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Ingår i: IEEE Transactions on Wireless Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1276 .- 1558-2248. ; 16:8, s. 4939-4955
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Tidskriftsartikel (refereegranskat)abstract
- The performance of RF powered communication networks is bottlenecked by the short downlink energy transfer range and the doubly near-far problem faced in uplink information transfer to hybrid access point (HAP). These problems can be resolved by cooperation of an RF energy harvesting node R present between HAP and RF energy harvesting information source S. However, there lies a dilemma at R on whether to transfer its harvested energy to S or to act as an information relay for transferring its data to HAP in a two-hop fashion. This paper resolves this dilemma at R by providing insights into its optimal positions suited for either energy relaying (ER) or information relaying (IR). It also investigates the possibilities of integrated ER and IR along with the regions where neither ER nor IR will be useful. In this regard, while considering Rician fading channels and practical nonlinear RF energy harvesting model, the expression for mean harvested dc power at S via energy transfer from HAP and ER from R is first derived. The closed-form outage probability expression is also derived for decode-and-forward relaying with maximal-ratio-combining at HAP over Rician channels. Using these expressions, insights into optimal relaying mode is obtained along with global-optimal utilization of harvested energy at R for ER and IR to maximize the delay-limited RF-powered throughput. Numerical results validate the analysis and provide insights into the optimal relaying mode.
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| 10. |
- Mishra, Deepak, 1990-, et al.
(författare)
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Effects of Practical Rechargeability Constraints on Perpetual RF Harvesting Sensor Network Operation
- 2016
-
Ingår i: IEEE Access. - : Institute of Electrical and Electronics Engineers (IEEE). - 2169-3536. ; 4, s. 750-765
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Tidskriftsartikel (refereegranskat)abstract
- Green perpetual sensor network operation is the need of the hour for critical applications, such as surveillance, military, and environment monitoring. Mobile integrated data collection and recharging is a promising approach to meet this requirement by routinely visiting the field nodes for collecting the sensed data and supplying energy via radio frequency (RF) energy transfer. Practical constraints, such as self-discharge and aging effects of the energy storage element (supercapacitor), significantly impact the renewable energy cycle (REC) and, hence, strongly influence the performance of RF energy harvesting networks. To account for the nonidealities in practical supercapacitors, in this paper, a circuit model for REC is proposed, and corresponding RF charging time and node lifetime expressions are derived. Hardware experiments are performed to validate the proposed REC model. REC for complicated supercapacitor models is characterized using duality principle and a generic simulation model. Using the developed analytical models for practical supercapacitors, the size of network for perpetual operation is estimated, which is demonstrated to be significantly less than that predicted by considering ideal supercapacitor behavior. For example, with three-branch supercapacitor model, the estimated sustainable network size is shown to be nearly 52% less than that offered by the ideal supercapacitor model. © 2013 IEEE.
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| 11. |
- Mishra, Deepak, 1990-, et al.
(författare)
-
Energy-Aware mode selection for throughput maximization in RF-Powered D2D Communications
- 2018
-
Ingår i: GLOBECOM 2017 - 2017 IEEE Global Communications Conference. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509050192 - 9781509050208 ; , s. 1-6
-
Konferensbidrag (refereegranskat)abstract
- Doubly-near-far problem in RF-powered networks can be mitigated by choosing appropriate device-To-device (D2D) communication mode and implementing energy-efficient information transfer (IT). In this work, we present a novel RF energy harvesting architecture where each transmitting-receiving user pair is allocated a disjoint channel for its communication which is fully powered by downlink energy transfer (ET) from hybrid access point (HAP). Considering that each user pair can select either D2D or cellular mode of communication, we propose an optimized transmission protocol controlled by the HAP that involves harvested energy-Aware jointly optimal mode selection (MS) and time allocation (TA) for ET and IT to maximize the sum-Throughput. Jointly global optimal solutions are derived by efficiently resolving the combinatorial issue with the help of optimal MS strategy for a given TA for ET. Closed-form expressions for the optimal TA in D2D and cellular modes are also derived to gain further analytical insights. Numerical results show that the joint optimal MS and TA, which significantly outperforms the benchmark schemes in terms of achievable RF-powered sum-Throughput, is closely followed by the optimal TA scheme for D2D users. In fact, about 2/3 fraction of the total user pairs prefer to follow the D2D mode for efficient RF-powered IT.
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| 12. |
- Mishra, Deepak, 1990-, et al.
(författare)
-
Energy harvesting and sustainable M2M communication in 5G mobile technologies
- 2016
-
Ingår i: Internet of Things (IoT) in 5G Mobile Technologies. - Cham : Springer. - 9783319309118 - 9783319309132 ; , s. 99-125
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Bokkapitel (refereegranskat)abstract
- With the fast growth of heterogeneous low-cost and high-end mobile devices, there is a need for green designs for ubiquitous development of Internet of things (IoT) due to both health and environment concerns. Unlike other energy harvesting techniques, radio frequency (RF) energy harvesting offers controlled and predictable energy replenishment, which can aid meeting the quality of service requirements of machine-to-machine (M2M) communications. This chapter evaluates the major challenges on the feasibility of RF-powered sustainable M2M communications in 5G mobile technologies and state-of-the-art research toward their practical implementation. Strategies for improving the RF energy transfer efficiency to realize the perpetual operation of IoT are also discussed.
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| 13. |
- Mishra, Deepak, et al.
(författare)
-
Energy Sustainable IoT With Individual QoS Constraints Through MISO SWIPT Multicasting
- 2018
-
Ingår i: IEEE Internet of Things Journal. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2327-4662. ; 5:4, s. 2856-2867
-
Tidskriftsartikel (refereegranskat)abstract
- Enabling technologies for energy sustainable Internet of Things (IoT) are of paramount importance since the proliferation of high data rate demands of low power network devices. In this paper, we consider a multiple input single output (MISO) multicasting system comprising of a multiantenna transmitter (TX) simultaneously transferring information and power to data hungry IoT nodes. Each IoT device is assumed to be equipped with power splitting (PS) hardware that enables energy harvesting (EH) and imposes an individual quality of service (QoS) constraint to the downlink communication. We study the joint design of TX precoding and IoT PS ratios for the considered MISO simultaneous wireless information and power transfer multicasting system with the objective of maximizing the minimum harvested energy among IoT, while satisfying their individual QoS requirements. In our novel EH fairness maximization formulation, we adopt a generic EH model capturing practical rectification operation, and resulting in a nonconvex optimization problem. For this problem, we first present an equivalent semi-definite relaxation formulation and then prove it possesses unique global optimality. We also derive tight upper and lower bounds on the globally optimal solution that are exploited in obtaining low complexity algorithmic implementations for the targeted joint design. Analytical expressions for the optimal TX beamforming directions, power allocation, and PS ratios are also presented. Representative numerical results including comparisons with benchmark designs corroborate the utility of proposed framework and provide useful insights on the interplay of key system parameters.
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| 14. |
- Mishra, Deepak, 1990-, et al.
(författare)
-
Harvested power fairness optimization in MISO SWIPT multicasting IoT with individual constraints
- 2018
-
Ingår i: 2018 IEEE International Conference on Communications (ICC). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538631805 - 9781538631812 ; , s. 1-6
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we consider a Multiple Input Single Output (MISO) multicasting Internet of Things (IoT) system comprising of a multiantenna Transmitter (TX) that simultaneously transfers information and power to low power and data hungry IoT devices. Each IoT device is assumed to be equipped with Power Splitting (PS) hardware that enables Energy Harvesting (EH) and imposes an individual Quality of Service (QoS) constraint to the downlink communication. We study the joint design of TX precoding and IoT PS ratios for the considered MISO Simultaneous Wireless Information and Power Transfer (SWIPT) multicasting IoT with the objective of maximizing the minimum harvested energy among IoT, while satisfying their individual QoS requirements. In our novel EH fairness maximization formulation, we adopt a generic Radio Frequency (RF) EH model capturing practical rectification operation, and resulting in a nonconvex optimization problem. For this problem, we first present an equivalent Semi- Definite Relaxation (SDR) for the considered design problem and prove that it possesses unique global optimality. Then, capitalizing on our derived tight upper and lower bounds on the optimal solution, we present an efficient algorithmic implementation for the jointly optimal TX precoding and IoT PS ratio parameters. Insights on the optimal TX precoding structure are also presented. Representative numerical results including comparisons with benchmark schemes corroborate the usefulness of the proposed design and provide useful insights on the interplay of critical system parameters on the optimized power vs achievable rate trade off.
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| 15. |
- Mishra, Deepak, 1990-, et al.
(författare)
-
I2ER : Integrated information and energy relaying protocol for RF powered communication network
- 2017
-
Ingår i: IEEE International Conference on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 1550-3607 .- 1938-1883. ; , s. 1-646
-
Tidskriftsartikel (refereegranskat)abstract
- Performance of RF powered communication network is bottlenecked by short downlink energy transfer range and doubly-near-far problem faced in uplink information transfer to Hybrid Access Point (HAP). Theses problems can be resolved by cooperation of an RF energy harvesting node R present between HAP and RF energy harvesting information source S. However, there lies a dilemma at R on whether to transfer its harvested energy to S or to act as an information relay for transferring its data to HAP in a two-hop fashion. This paper resolves this dilemma of R by proposing a novel integrated information and energy relaying (i2 ER) protocol. It also provides insights on the relay positions suited for either energy relaying (ER), or information relaying (IR), or where neither ER nor IR will be useful. In this regard, while considering Rician fading channels, we derive the expression for mean harvested dc power at S via energy transfer from HAP and ER from R. We also derive the closed-form outage probability expression for decode-and-forward relaying with maximal-ratio-combining at HAP over Rician channels. Finally numerical results validating the analytical results and providing insights on the relaying role (ER and/or IR) of RF harvesting helping node are presented.
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| 16. |
- Mishra, Deepak, 1990-, et al.
(författare)
-
i2RES : Integrated information relay and energy supply assisted RF harvesting communication
- 2017
-
Ingår i: IEEE Transactions on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0090-6778 .- 1558-0857. ; 65:3, s. 1274-1288
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Tidskriftsartikel (refereegranskat)abstract
- To overcome finite lifetime bottleneck in the ubiquitous deployment of low-power wireless devices in Internet-of-Things, we propose a novel integrated information relay and energy supply (i2RES)-assisted RF harvesting co-operative communication model. i2RES aids the communication between two distant energy-constrained wireless nodes by: 1) RF energy transfer to the source and 2) relaying source data along with supplying energy to the destination. To enable efficient i2RES-powered information transfer to the destination, we first derive and then maximize the delay-limited achievable throughput over Rician channels by jointly optimizing time allocation for information and energy transfer along with relative position of i2RES between source and destination. Although the throughput maximization problem is nonconvex and highly nonlinear, we prove its generalized-convexity and obtain the global-optimal numerical solutions. To gain analytical insights, we also derive tight closed-form approximation for the optimized solutions. Numerical results validate the analysis and demonstrate significant gain in throughput performance via our proposed optimization schemes under practical hardware constraints. Finally, we discuss how the analysis and optimization results can be extended to general RF-EH system settings with relaxed constraints.
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| 17. |
- Mishra, Deepak, 1990-, et al.
(författare)
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Implementation of multi-path energy routing
- 2014
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Ingår i: 2014 IEEE 25th Annual International Symposium on Personal, Indoor, and Mobile Radio Communication (PIMRC). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781479949120 ; , s. 1834-1839
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Konferensbidrag (refereegranskat)abstract
- Harvesting energy from radio frequency (RF) waves brings us closer to achieving the goal for perpetual operation of a wireless sensor network (WSN) by replenishing the batteries of the sensor nodes. However, due to restrictions on the maximum transmitted power, path loss, and receiver sensitivity, only a small amount of energy can be harvested. While a dedicated RF source alleviates the problem to some extent, novel techniques are required to boost the energy transfer efficiency of the source. In this paper, we provide the first experimental demonstration of multi-path energy routing (MPER) for the case of a sparsely distributed WSNs and show its improved performance over direct energy transfer (DET). In addition, we extend this concept to the case of densely distributed WSNs and experimentally demonstrate and compare the gains obtained by 2- and 3-path energy routing over DET. Our experimental results show that significant energy gains can be achieved in a dense network deployment even when the node to be charged is partially blocked by the neighboring nodes.
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| 18. |
- Mishra, Deepak, 1990-, et al.
(författare)
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Joint Optimization Schemes for Cooperative Wireless Information and Power Transfer Over Rician Channels
- 2016
-
Ingår i: IEEE Transactions on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0090-6778 .- 1558-0857. ; 64:2, s. 554-571
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Tidskriftsartikel (refereegranskat)abstract
- Simultaneous wireless information and power transfer (SWIPT) can lead to uninterrupted network operation by integrating radio frequency (RF) energy harvesting with data communication. In this paper, we consider a two-hop source-relay-destination network and investigate the efficient usage of a decode-and-forward (DF) relay for SWIPT toward the energy-constrained destination. In particular, by assuming a Rician fading environment, we jointly optimize power allocation (PA), relay placement (RP), and power splitting (PS) so as to minimize outage probability under the harvested power constraint at the destination node. We consider the two possible cases of source-to-destination distance: (1) small distance with direct information transfer link; and (2) relatively large distance with no direct reachability. Analytical expressions for individual and joint optimal PA, RP, and PS are obtained by exploiting convexity of outage minimization problem for the no direct link case. In case of direct source-to-destination link, multipseudoconvexity of joint-optimal PA, RP, and PS problem is proved, and alternating optimization is used to find the global optimal solution. Numerical results show that the joint optimal solutions, although strongly influenced by the harvested power requirement at the destination, can provide respectively 64% and 100% outage improvement over the fixed allocation scheme for without and with direct link.
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| 19. |
- Mishra, Deepak, 1990-, et al.
(författare)
-
Optimal power allocation and relay placement for wireless information and RF power transfer
- 2016
-
Ingår i: IEEE International Conference on Communications (ICC) Date of Conference. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 1-6
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we develop an optimization framework to jointly optimize the efficiency of wireless information and RF power transfer to the destination of a two hop decode- and-forward source-relay-destination network. In particular, we investigate the performance of three optimization schemes: (i) optimal power allocation (PA) with fixed relay placement (RP), (ii) optimal RP with fixed PA, and (iii) joint optimization of PA and RP, for minimizing the outage probability under the harvested power constraint at the destination. In absence of direct source to destination reachability, closed-form global-optimal solutions are obtained for all three optimization schemes. Numerical results show that the optimized schemes significantly outperform fixed allocation and the joint optimal PA and RP provides an outage improvement of about 35%. Also, a tradeoff exists between minimized outage probability and minimum required average harvested power at destination for its uninterrupted operation.
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| 20. |
- Mishra, Deepak, 1990-, et al.
(författare)
-
Optimal relay placement in two-hop RF energy transfer
- 2015
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Ingår i: IEEE Transactions on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0090-6778 .- 1558-0857. ; 63:5, s. 1635-1647
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Tidskriftsartikel (refereegranskat)abstract
- Recently, wireless radio frequency energy transfer (RFET) has emerged as an effective technology for prolonging lifetime of the energy-limited wireless sensor networks. However, low RFET efficiency is still a fundamental bottleneck in its widespread usage. Multi-hop RF energy transfer (MHET) can improve the RFET efficiency by deploying relay nodes that scavenge the dispersed energy and transfer it to the nearby sensor node. The efficiency of MHET is strongly influenced by the relay node’s placement. To maximize the RFET efficiency for a two-hop scenario, in this paper a novel optimization model is proposed to determine the optimal relay placement (ORP) on an Euclidean x-y plane. Nontrivial tradeoff between the energy scavenged at the relay versus the effective energy delivered by the relay to the target node is investigated. Due to the nonconvex and highly nonlinear nature of the optimization problem, an α-based branch and bound algorithm has been used. The proposed optimization model is further extended by incorporating distributed beamforming to enhance the RFET efficiency. Numerical results illustrate that the proposed algorithm provides convergence to the ∈-global optimal solution in a few iterations, and ORP provides significant energy saving over arbitrary relay positions for commercial RF energy harvesting systems.
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| 21. |
- Mishra, Deepak, 1990-, et al.
(författare)
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Optimal time allocation for RF-powered DF relay-assisted cooperative communication
- 2016
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Ingår i: Electronics Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 0013-5194 .- 1350-911X. ; 52:14, s. 1274-1276
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Tidskriftsartikel (refereegranskat)abstract
- A decode-and-forward (DF) relay-assisted RF-powered cooperative communication between an RF energy harvesting source and an information sink is considered. DF relay aids the communication between these two distant wireless nodes by (i) RF energy transfer to the source, and (ii) relaying source data to the sink. To enable efficient RF-powered delay-constrained information transfer to the sink under Rayleigh fading, joint global-optimal time allocations for information and energy transfer are derived. Impact of relay position on throughput and optimality of the analytical solutions are numerically investigated.
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| 22. |
- Mishra, Deepak, 1990-, et al.
(författare)
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Relay-assisted RF harvesting sensor networks
- 2016
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Ingår i: 2016 13th IEEE Annual Consumer Communications & Networking Conference (CCNC). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 791-792
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Konferensbidrag (refereegranskat)abstract
- We propose a relay-assisted RF harvesting sensor network (R2FSN) model, where the field nodes having finite battery capacity are powered by RF energy transfer (RFET) from a single relay, thus leading to perpetual sensor network operation. The relay node also forwards the field data to the information sink in a two-hop, half-duplex decode-and-forward fashion. We derive closed-form expression of the average end-to-end signal-to-noise ratio (SNR) for each source-destination link in cooperative R2FSN. The performance improvement provided by R2FSN over conventional RF-powered networks is numerically investigated along with the impact of RFET time and relay location on the maximum and minimum average end-to-end SNR over all links.
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| 23. |
- Mishra, Deepak, 1990-, et al.
(författare)
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Smart RF energy harvesting communications : Challenges and opportunities
- 2015
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Ingår i: IEEE Communications Magazine. - : Institute of Electrical and Electronics Engineers (IEEE). - 0163-6804 .- 1558-1896. ; 53:4, s. 70-78
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Tidskriftsartikel (refereegranskat)abstract
- RF energy harvesting (RFH) is emerging as a potential method for the proactive energy replenishment of next generation wireless networks. Unlike other harvesting techniques that depend on the environment, RFH can be predictable or on demand, and as such it is better suited for supporting quality-of-service-based applications. However, RFH efficiency is scarce due to low RF-to-DC conversion efficiency and receiver sensitivity. In this article, we identify the novel communication techniques that enable and enhance the usefulness of RFH. Backed by some experimental observations on RFH and the current state of the art, we discuss the challenges in the actual feasibility of RFH communications, new research directions, and the obstacles to their practical implementation.
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| 24. |
- Mishra, Deepak, 1990-, et al.
(författare)
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Utility maximization models for two-hop energy relaying in practical RF harvesting networks
- 2017
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Ingår i: IEEE International Conference on Communications Workshops (ICC Workshops). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 41-46
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Konferensbidrag (refereegranskat)abstract
- Cooperative energy relaying helps in improving the radio frequency (RF) energy transfer (ET) efficiency by harvesting the otherwise dissipated energy and then transferring it to the nearby energy receiver. The achievable RF-ET gains are strongly influenced by the relative relay placement (RP), which may cause blocking of the direct energy transfer (DET) path between RF source and receiver, or energy signals from RF source and relay may add destructively. So, to maximize the utility of an RF energy harvesting (RF-EH) energy relay, we propose (a) a novel slotted harvest-then-transfer-energy protocol to avoid interference to DET, and (b) optimal no-impact on line-of-sight (Ni-LoS) RP model for avoiding obstruction to the existing LoS or DET path due to its physical presence. Further, an accurate piecewise linear approximation for harvested dc power as a function of received RF power is presented to incorporate the practical RF-EH hardware constraints. Since the optimal RP problem for maximizing harvested energy at receiver from EH relay is nonconvex, conditional generalized convexity principles are used to obtain the closed-form global-optimal solution. Numerical performance of the proposed utility maximization models for EH RP is investigated under practical RF-EH system settings.
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| 25. |
- Mukherjee, Priyadarshi, et al.
(författare)
-
Exploiting Temporal Correlation in Wireless Channel for Energy-Efficient Communication
- 2017
-
Ingår i: IEEE Transactions on Green Communications and Networking. - : Institute of Electrical and Electronics Engineers (IEEE). - 2473-2400. ; 1:4, s. 381-394
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Tidskriftsartikel (refereegranskat)abstract
- Widespread adoption of Internet-of-Things (IoT) technology depends on cost-affordability of the devices and convenience of their usage in terms of long life. Energy-efficiency of the miniaturized wireless IoT devices is a key to the cost and convenience factors. While there have been a few prior studies on wireless channel adaptive communication strategies, in this paper we relook at the problem aiming at effectively characterizing the wireless fading channel and devising energy-efficient link-layer retransmission strategy suitable for IoT devices. In particular, we propose a new channel-adaptive strategy that depends on the rate of variation of wireless channel irrespective of the underlying channel fading distribution. We further show that the concept of average fade duration dependent retransmission is a special case of the proposed strategy. Extensive simulations show that the proposed scheme most effectively characterizes the temporal variations of wireless channel in comparison with the other existing schemes. Performance of the proposed retransmission strategy is compared with the competitive protocols using the Markov model. Numerical results demonstrate that, the proposed scheme offers a gain of about 9% in terms data throughput and about 12% in terms of energy efficiency in comparison to its nearest existing benchmark scheme.
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| 26. |
- Panda, B. S., et al.
(författare)
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Boru̇vka-incremental power greedy heuristic for strong minimum energy topology in wireless sensor networks
- 2015
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Ingår i: Proceeding ICDCN '15 Proceedings of the 2015 International Conference on Distributed Computing and Networking. - New York, NY, USA : Association for Computing Machinery. - 9781450329286
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Konferensbidrag (refereegranskat)abstract
- Given a set of sensors, the strong minimum energy topology (SMET) problem is to assign transmission range to each sensor node so that the sum of the transmission range for all the sensor is minimum subject to the constraint that the network is strongly connected (there is a directed path between every pair of nodes in the Network). This problem is known to be NP-hard. As this problem has lots of practical applications, several approximation algorithms and heuristics have been proposed. In this paper, we propose a new heuristic called Boru̇vka-incremental power greedy heuristic based on the Boru̇vka algorithm for the minimum spanning tree (MST) problem for solving the SMET problem. We compare the performance of the Boru̇vka-incremental power greedy heuristic with Kruskal-incremental power greedy heuristic and Prim-incremental power greedy heuristic. Extensive simulation results illustrate that Boru̇vka heuristic outperforms the Kruskal-incremental power greedy heuristic and Prim-incremental power greedy heuristic. We have also proved that apart from providing significant improvement in terms of average power savings, Boru̇vka incremental power greedy heuristic takes O(n) time for planar graphs as compared to O(n log n) time taken by Kruskal-incremental power greedy heuristic and O(n2) time taken by Prim-incremental power greedy heuristic, where n is the number of nodes in the network.
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| 27. |
- Panda, B. S., et al.
(författare)
-
New heuristics for strong minimum energy topology with reduced time complexity
- 2018
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Ingår i: 2017 IEEE International Conference on Advanced Networks and Telecommunications Systems (ANTS). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538623473 - 9781538623466 - 9781538623480 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- The strong minimum energy topology (SMET) problem is to assign transmission range to a set of sensors, such that the resulting topology is strongly connected and the sum of transmit powers of all the sensors is minimized. This problem, having wide range of applications, is known to be NP-hard and also APX-hard for 3-dimension space. Several heuristics and approximation algorithms have been proposed for this problem. In this paper, we first present an enhanced version of Prim-incremental power greedy heuristic which improves the running time of the existing algorithm by a factor of n, i.e., from O(n3) to O(n2), where n is the number of nodes in the network. Simulations results are also presented to support the theoretical result. Next we propose a new heuristics for SMET problem called Hybrid heuristic, which is based on BorÛvka and Prim MST algorithms and is shown to have lower complexity than both of them. Lastly, we show that this Hybrid heuristics which can provide energy efficiency gains over the existing ones is also the fastest power greedy heuristics for SMET problem when the nodes and links of the network form a planar graph.
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| 28. |
- Saini, Ravikant, et al.
(författare)
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Novel subcarrier pairing strategy for DF relayed secure OFDMA with untrusted users
- 2018
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Ingår i: 2017 IEEE Globecom Workshops (GC Wkshps). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538639207 - 9781538639214 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- This paper investigates joint resource allocation problem involving subcarrier allocation, subcarrier pairing (SCP), and power allocation for maximizing sum secure rate in a decode-and-forward (DF) relay assisted OFDMA system with untrusted users. Optimal SCP is highlighted as a novel notion of channel gain tailoring rather than conventional channel gain matching. It is proven that the optimal SCP intends to pair subcarriers such that the variance between the effective channel gains is minimized. It is also shown that depending on the individual power budget constraints at source and the relay, SCP can take either a subordinate role for improving the energy efficiency or the main role of improving the spectral efficiency of the system. SCP as a channel gain tailoring strategy and its role in improving the spectral as well as energy efficiency of cooperative secure communication are highlighted through the simulation results.
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| 29. |
- Saini, Ravikant, et al.
(författare)
-
OFDMA-Based DF Secure Cooperative Communication With Untrusted Users
- 2016
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Ingår i: IEEE Communications Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1089-7798 .- 1558-2558. ; 20:4, s. 716-719
-
Tidskriftsartikel (refereegranskat)abstract
- In this letter, we consider resource allocation for OFDMA-based secure cooperative communication by employing a trusted decode and forward (DF) relay among the untrusted users. We formulate two optimization problems, namely, 1) sum rate maximization subject to individual power constraints on source and relay, and 2) sum power minimization subject to a fairness constraint in terms of per-user minimum support secure rate requirement. The optimization problems are solved utilizing the optimality of KKT conditions for pseudolinear functions.
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| 30. |
- Saini, Ravikant, et al.
(författare)
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Subcarrier pairing as channel gain tailoring: Joint resource allocation for relay-assisted secure OFDMA with untrusted users
- 2019
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Ingår i: Physical Communication. - : ELSEVIER SCIENCE BV. - 1874-4907 .- 1876-3219. ; 32, s. 217-230
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Tidskriftsartikel (refereegranskat)abstract
- Joint resource allocation involving optimization of subcarrier allocation, subcarrier pairing (SCP), and power allocation in a cooperative secure orthogonal frequency division multiple access (OFDMA) communication system with untrusted users is considered. Both amplify and forward (AF), and decode and forward (DF) modes of operations are considered with individual power budget constraints for source and relay. After finding optimal subcarrier allocation for an AF relayed system, we prove the joint power allocation as a generalized convex problem, and solve it optimally. Compared to the conventional channel gain matching view, the optimal SCP is emphasized as a novel concept of channel gain tailoring. We prove that the optimal SCP pairs subcarriers such that the variance among the effective channel gains is minimized. For a DF relayed system, we show that depending on the power budgets of source and relay, SCP can either be in a subordinate role where it improves the energy efficiency, or in a main role where it improves the spectral efficiency of the system. In an AF relayed system we confirm that SCP plays a crucial role, and improves the spectral efficiency of the system. The channel gain tailoring property of SCP, various roles of SCP in improving the spectral and energy efficiency of a cooperative communication system are validated with the help of simulation results. (C) 2018 Elsevier B.V. All rights reserved.
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| 31. |
- Saini, Ravikant, et al.
(författare)
-
Utility Regions for DF Relay in OFDMA-Based Secure Communication with Untrusted Users
- 2017
-
Ingår i: IEEE Communications Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1089-7798 .- 1558-2558. ; 21:11, s. 2512-2515
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Tidskriftsartikel (refereegranskat)abstract
- This letter investigates the utility of a trusted decode-And-forward relay in OFDMA-based secure communication system with untrusted users. For deciding on the use of relay, we first present optimal subcarrier allocation policies for direct communication (DC) and relayed communication (RC). Next, we identify exclusive RC mode, exclusive DC mode, and mixed (RDC) mode subcarriers which can support both the modes. In RDC mode, we present optimal mode selection policy and a suboptimal strategy independent of power allocation which is asymptotically optimal at both low and high SNRs. Via numerical results we present insights on relay utility regions.
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| 32. |
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