Department of Electrical and Electronics Engineering

Permanent URI for this collectionhttp://localhost:4000/handle/123456789/1925

Browse

Author: search.filters.author.Bitragunta, SainathSubject: search.filters.subject.Cognitive radio

Search Results

Now showing 1 - 4 of 4
  • No Thumbnail Available
    Item
    Optimizing Fading-Averaged Bandwidth Efficiency of Underlay Cognitive Radio System by Transmit Power Adaptation
    (IEEE, 2019) Bitragunta, Sainath
    Power adaptation has been widely studied in the literature, given its significance in designing power efficient adaptive wireless systems. Specifically, transmit power adaptation is an important technique that is naturally appealing for underlay cognitive radio systems, which are intelligent and reconfigurable. In this paper, we consider a secondary underlay transmitter whose transmissions are constrained by an average interference threshold, also it adapts its transmit power as a function of its local channel state information (CSI). In this paper, we derive the optimal power adaptation factor (PAF) that maximizes the fading-averaged bandwidth efficiency (FABE) and also calculate the corresponding energy efficiency. We develop insightful analysis for average spectral efficiency, that is, FABE and energy efficiency for two scenarios: i). CSI-independent PAF and ii). CSI-dependent PAF. Our numerical results reveal that FABE for transmit power adaptation with CSI-dependent PAF delivers superior performance than the PAF that does not depend on instantaneous CSI at the expense of slight decrease in energy efficiency
  • No Thumbnail Available
    Item
    Doubly Constrained Underlay Cognitive Radio System: Optimization and Analysis
    (IEEE, 2019) Bitragunta, Sainath
    In this paper, we consider a doubly constrained underlay cognitive radio (CR) system. In it, a secondary user (SU) transmitter (Tx) is subject to average interference constraint, and spectral efficiency constraint. For the underlay system, we investigate both average energy efficiency and average spectral efficiency. Specifically, we develop an algorithm that determines the suboptimal operating point of transmit power with which the SU-Tx must operate for maximum energy efficiency. We derive an analytical expression for the fading-averaged spectral efficiency assuming Rayleigh fading with path loss and shadowing. To validate the analytical results, we simulate the model in MATLAB using Monte-Carlo simulations and investigate the system performance. The analysis that we present is useful for constrained cognitive radio systems and networks.
  • No Thumbnail Available
    Item
    Application of Game Theory to Cooperative Underlay Cognitive Radio IoT
    (IEEE, 2019) Bitragunta, Sainath
    Internet of things (IoT) is a new paradigm in wireless communication that offers a host of new opportunities to exploit the finite resources available. Cognitive radio networks (CRNs) employ these spectrum opportunities by using their inherent adaptive nature to automatically detect available channels in the spectrum and change transmission parameters to allow more communications to run concurrently, thus improving overall efficiency. The application of game theoretic principles to solving problems in this domain allows for the creation of fairly realistic models that clearly outline the relationship between the stakeholders involved, under the assumption of rationality. This paper presents a model for an IoT-based CRN in the underlay mode of operation. A triangular lattice with a set of relays is considered to model the secondary user network. The interference and power constraints accounted for in calculating the Nash equilibrium bring the model closer to direct applicability in the real world by including variations depending on channel strength and desirability.
  • No Thumbnail Available
    Item
    A Survey of Energy and Spectrum Harvesting Technologies and Protocols for Next Generation Wireless Networks
    (IEEE, 2021-04) Bitragunta, Sainath; Chamola, Vinay; Joshi, Sandeep
    Energy harvesting (EH) and spectrum harvesting (SH) are two promising and useful green communication and networking mechanisms for the next-generation wireless networks. While the former techniques exploit ambient energy sources to scavenge energy, the latter exploit the unused or moderately used electromagnetic spectrum. With the advent of cyber-physical systems and the Internet-of-Things (IoT), the presence of tens of billions of low power sensor devices would soon be a reality. These small sensing devices would be present in many systems around us, such as home appliances, telecommunication devices, medical electronics, transport systems, etc. These miniaturized, low-power consuming devices may exploit EH and SH techniques for energy storage and communication. These EH-SH-enabled sensors or low-power nodes need to consume very little energy for sensing and communicating opportunistically. However, several theoretical problems and practical challenges exist in EH-SH communications. In this comprehensive survey paper, we first present the historical background of EH, and SH techniques, and their development over several decades. Specifically, we focus on EH-SH communication technologies and protocols for a wide range of systems and networks. We present a detailed survey of the various harvesting techniques and protocols from recent literature. Finally, we describe exciting open, intra-disciplinary, and inter-disciplinary challenges for further research on EH-SH communication technologies.