Distributed Resource Allocation for SWIPT-based Cognitive Ad-Hoc Networks
ABSTARCT :
Energy supplies, spectrum resources, and transmission overheads of wireless nodes are the bottlenecks in decentralized networks (e.g., device-to-device communication networks). In this paper, we study the total power minimization problem of secondary users (SUs) for a multiuser simultaneous wireless information and power transfer-based cognitive ad-hoc network by jointly optimizing the transmit power and power-splitting (PS) coefficients of SUs in a distributed way, where SUs can harvest ambient radio-frequency signals to prolong the lifetime of nodes via a PS-based scheme. Firstly, a resource allocation (RA) problem with perfect channel state information (CSI) is formulated under the quality of service constraints and the minimum energy-harvesting (EH) constraints. The non-convex problem is decomposed into a subproblem with a high EH threshold and a subproblem with a low EH threshold. The distributed closed-form solutions are obtained via Lagrange dual theory. Secondly, to overcome the impact of channel estimation errors, a robust RA problem with imperfect CSI is studied under bounded uncertainties. Both the feasible region and robust sensitivity are analyzed to give an insight into system performance. Simulation results demonstrate that the effectiveness of the proposed algorithm.
EXISTING SYSTEM :
? In general, there exist so many results that establish conditions on the optimization problem, that yield strong duality.
? On the other hand, OFDMA technology is a promising solution for effectively dividing the available bandwidth into orthogonal sub-channels so they can be flexibly allocated among existing users.
? Many optimization tools and packages exist for solving any given optimization problem.
? The purpose of the thesis is not to develop such optimization solvers nor to improve them, but rather to use the existing ones to solve the problems at hand.
? However, there exists an important point that should be kept in mind: increasing the transmit power does not improve data-rate perpetually.
DISADVANTAGE :
? In, the RA problem of the total throughput maximization of SUs was studied in a multichannel SWIPT-based CRN.
? In, the joint optimization problem of robust beamforming and PS ratio with the bounded and Gaussian CSI errors was studied to minimize the total transmit power of secondary BS under a non-linear EH model.
? In, the authors studied the problem of the robust secure artificial noise (AN)-aided beamforming and PS ratio under both the bounded and probabilistic CSI error models in a MISO SWIPT-based CRN with malicious EH receivers.
? If we consider this kind of channel uncertainty ahead of time in our optimization problem, this phenomenon will not happen.
PROPOSED SYSTEM :
• In the proposed system model, a portion of the spectrum is used for information decoding (ID) while the remaining portion is exploited for energy harvesting (EH) in an orthogonal frequency division multiple access (OFDMA) network.
• A heuristic algorithm was proposed in a study of resource allocation policies for maximizing the harvested energy for a single user in an OFDM SWIPT system.
• In, a multi-user MISO full-duplex system with PS-based SWIPT was proposed for a resource allocation policy design that jointly optimizes the PS ratios, the beamforming matrix, and the transmit power – subject to satisfying maximal SINR and harvested power constraints.
ADVANTAGE :
? In CR networks (CRNs), the terminals (also termed as secondary users (SUs)) are encouraged to reuse the spectrum resource dynamically for improving spectrum utilization without causing harmful interference to primary users (PUs).
? Moreover, the feasible region analysis and robust sensitivity with imperfect CSI are significantly important to verify the range of optimal variables and the impact of uncertain parameters on system performance.
? Resource allocation (RA) is significantly important to ensure the quality of service (QoS) requirements of PUs while improving the total energy efficiency (EE) of SUs since SUs are not only allowed to access spectrum resources but also actively harvest ambient signals.
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