Optimization of the overall success probability of the energy harvesting cognitive wireless sensor networks

Wireless energy harvesting can improve the performance of cognitive wireless sensor networks (WSNs). This paper considers radio frequency (RF) energy harvesting from transmissions in the primary spectrum for cognitive WSNs. The overall success probability of the energy harvesting cognitive WSN depends on the transmission success probability and energy success probability. Using the tools from stochastic geometry, we show that the overall success probability can be optimized with respect to: 1) transmit power of the sensors; 2) transmit power of the primary transmitters; and 3) spatial density of the primary transmitters. In this context, an optimization algorithm is proposed to maximize the overall success probability of the WSNs. Simulation results show that the overall success probability and the throughput of the WSN can be significantly improved by optimizing the aforementioned three parameters. As RF energy harvesting can also be performed indoors, hence, our solution can be directly applied to the cognitive WSNs that are installed in smart buildings

Full-Duplex Cooperative Cognitive Radio Networks with Wireless Energy Harvesting

This paper proposes and analyzes a new full-duplex (FD) cooperative cognitive radio network with wireless energy harvesting (EH). We consider that the secondary receiver is equipped with a FD radio and acts as a FD hybrid access point (HAP), which aims to collect information from its associated EH secondary transmitter (ST) and relay the signals. The ST is assumed to be equipped with an EH unit and a rechargeable battery such that it can harvest and accumulate energy from radio frequency (RF) signals transmitted by the primary transmitter (PT) and the HAP. We develop a novel cooperative spectrum sharing (CSS) protocol for the considered system. In the proposed protocol, thanks to its FD capability, the HAP can receive the PT's signals and transmit energy-bearing signals to charge the ST simultaneously, or forward the PT's signals and receive the ST's signals at the same time. We derive analytical expressions for the achievable throughput of both primary and secondary links by characterizing the dynamic charging/discharging behaviors of the ST battery as a finite-state Markov chain. We present numerical results to validate our theoretical analysis and demonstrate the merits of the proposed protocol over its non-cooperative counterpart.Comment: 6 pages, 3 figures, conferenc

Optimal time sharing in underlay cognitive radio systems with RF energy harvesting

Due to the fundamental tradeoffs, achieving spectrum efficiency and energy efficiency are two contending design challenges for the future wireless networks. However, applying radio-frequency (RF) energy harvesting (EH) in a cognitive radio system could potentially circumvent this tradeoff, resulting in a secondary system with limitless power supply and meaningful achievable information rates. This paper proposes an online solution for the optimal time allocation (time sharing) between the EH phase and the information transmission (IT) phase in an underlay cognitive radio system, which harvests the RF energy originating from the primary system. The proposed online solution maximizes the average achievable rate of the cognitive radio system, subject to the $\varepsilon$-percentile protection criteria for the primary system. The optimal time sharing achieves significant gains compared to equal time allocation between the EH and IT phases.Comment: Proceedings of the 2015 IEEE International Conference on Communications (IEEE ICC 2015), 8-12 June 2015, London, U

Cognitive and Energy Harvesting-Based D2D Communication in Cellular Networks: Stochastic Geometry Modeling and Analysis

While cognitive radio enables spectrum-efficient wireless communication, radio frequency (RF) energy harvesting from ambient interference is an enabler for energy-efficient wireless communication. In this paper, we model and analyze cognitive and energy harvesting-based D2D communication in cellular networks. The cognitive D2D transmitters harvest energy from ambient interference and use one of the channels allocated to cellular users (in uplink or downlink), which is referred to as the D2D channel, to communicate with the corresponding receivers. We investigate two spectrum access policies for cellular communication in the uplink or downlink, namely, random spectrum access (RSA) policy and prioritized spectrum access (PSA) policy. In RSA, any of the available channels including the channel used by the D2D transmitters can be selected randomly for cellular communication, while in PSA the D2D channel is used only when all of the other channels are occupied. A D2D transmitter can communicate successfully with its receiver only when it harvests enough energy to perform channel inversion toward the receiver, the D2D channel is free, and the $\mathsf{SINR}$ at the receiver is above the required threshold; otherwise, an outage occurs for the D2D communication. We use tools from stochastic geometry to evaluate the performance of the proposed communication system model with general path-loss exponent in terms of outage probability for D2D and cellular users. We show that energy harvesting can be a reliable alternative to power cognitive D2D transmitters while achieving acceptable performance. Under the same $\mathsf{SINR}$ outage requirements as for the non-cognitive case, cognitive channel access improves the outage probability for D2D users for both the spectrum access policies.Comment: IEEE Transactions on Communications, to appea

Full Duplex Spectrum Sensing and Energy Harvesting in Cognitive Radio Networks

النطاق المزدوج (FD) للطيف الترددي في شبكات الاتصالات اللاسلكية للراديو الادراكي مع حصاد الطاقة (Full-duplex Energy Harvesting Cognitive Radio Networks “FD EHCRNs”)، والتي هي عبارة عن مزيج من تقنية الإرسال المزدوج الكامل (FD) الراديو الادراكي (CRN) وتقنية حصاد الطاقة (EH)، هي تقنية اتصالات لاسلكية جديدة الغرض منها تحسين كفاءة الطيف وتحسين كفاءة الطاقة. باستخدام النطاق المزدوج (FD) للطيف يمكن لأجهزة الراديو الادراكي عمل تحسس واستشعار متزامن لطيف الشبكات الأخرى التي يرغب في استخدام النطاق الترددي الغير مستخدم فيها وعمل نقل البيانات عبر هذا النطاق وكذلك عمل حصاد للطاقة بشكل متزامن في نفس الوقت، لذلك يمكن لنظام النطاق المزدوج في EH CRNs حل مشاكل الطيف المتقطع المتواجدة في شبكات CRN التقليدية. في هذه البحث تم تقديم اقتراح نموذج جديد من FD EHCRN من خلال التركيز على تصميم حدود الكشف (detection thresholds) ونموذج تجميع الطاقة (energy harvesting) وذلك لغرض تحسين أداء النظام الراديو الادراكي مع تحصيل الطاقة باستخدام النطاق المزدوج. مع العلم أن هذا البحث لا يسعى إلى تصميم تقنية جديدة لاستشعار الطيف من أجل EH-CRN بل إعادة تصميم واقتراح نموذج جديد لتقنية استشعار الطيف من خلال استخدام النطاق المزدوج باستخدام هوائيين. حيث تم عرض كل من التحليل الرياضي والنتائج العددية في هذا البحث.Full-duplex Energy Harvesting Cognitive Radio Networks (FD EHCRNs), which is a combination of full-duplex (FD) technique, cognitive radio (CR), and radio frequency (RF) energy harvesting technique, is a new wireless communication model to improve spectrum efficiency (SE) and energy efficiency (EE). Using FD, the Energy Harvesting Cognitive Radio Networks (EH CRN) equipment of the cognitive users can perform spectrum sensing, data transmission, and energy harvesting simultaneously. Consequently, full duplex in EH CRNs can solve the spectrum waste and transmission discontinuation problems caused by traditional CRNs. In this paper, a new proposal model for FD EHCRN is presented focusing on detection threshold design and energy harvesting model to try improving the system performance. Therefore, the purpose of this paper is to redesign the existing EHCRN and proposes a new model for spectrum sensing technique using full-duplex with only two antennas. Both mathematical analysis and numerical results are presented in this paper

Simultaneous wireless information and power transfer in modern communication systems

Energy harvesting for wireless communication networks is a new paradigm that allows terminals to recharge their batteries from external energy sources in the surrounding environment. A promising energy harvesting technology is wireless power transfer where terminals harvest energy from electromagnetic radiation. Thereby, the energy may be harvested opportunistically from ambient electromagnetic sources or from sources that intentionally transmit electromagnetic energy for energy harvesting purposes. A particularly interesting and challenging scenario arises when sources perform simultaneous wireless information and power transfer (SWIPT), as strong signals not only increase power transfer but also interference. This article provides an overview of SWIPT systems with a particular focus on the hardware realization of rectenna circuits and practical techniques that achieve SWIPT in the domains of time, power, antennas, and space. The article also discusses the benefits of a potential integration of SWIPT technologies in modern communication networks in the context of resource allocation and cooperative cognitive radio networks