Spectrum Handoff Decision Schemes and Cognitive Radio Network

Copyright © 2019 by author(s) and International Journal of Trend in Scientific Research and Development Journal. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0) (http://creativecommons.org/licenses/ by/4.0) ABSTRACT Due to the growth and spread of wireless devices in the unlicensed spectrum bands, such as ISM, the bands become more and more crowded and therefore affect the performance of the wireless networks negatively. Thus, the cognitive spectrum access principles are required to utilize the existing spectrum bands more efficiently. There are many advantages of cognitive radio technology but there exists some obstacles like the CRT (Cognitive Radio Technology) is used over a heterogeneous radio spectrum of licensed and unlicensed spectrum bands and as for survey huge work in done in licensed spectrum bands and very small of work done in the amalgamation licensed and unlicensed bands for data transportation.


INTRODUCTION
With most of our activities involving some kind of access to network in one way or other, wireless communication has now become extremely important in modern society. This has caused the applications and services, standards, and the total of wireless users, to increase with every passing day, considering that the larger part of the limited available radio spectrum resources have been allocated well and can restrict this growth [1]. Also, finally, the amount of expansion is determined by the existing radio spectrum; the regulatory authorities and government bodies have taken up a stringent procedure/approach toward the distribution and licensing of radio frequency spectrum to disparate organizations (e.g., service providers, military applications, cellular telephony, service providers, and TV), all of these individual entities own absolute transmissions to their assigned frequency channels. By using this strict approach, the main method of accessing a radio spectrum resource is based on a fixed spectrum allocation method, known as Fixed Spectrum Access (FSA). An expansive report compiled by the (SPTF) Spectrum Policy Task Force [2] and issued by (FCC) The Federal Communication Commission, which conclusively proved the fact that a lot of the assigned (licensed) spectrum underwent quite low utilization efficiency, such as those dedicated to a military applications, analogue cellular telephony or TV, which are not completely utilized. The survey has uncovered temporal(time-related) as well as spatial(geographic) variations in the exploitation of radio spectrum, extending from 16-86% in the bands as low as 3GHz and below, while extending lower tan this at high frequencies [3].

II.
LITERATURE REVIEW Dhivya and Murugesh(2017) the research paper entitled "A STUDY ON QUANTITATIVE PARAMETERS OFSPECTRUM HANDOFF IN COGNITIVE RADIONETWORKS" describes the need of dynamic allocation of spectrum band in an efficient manner. The paper outlines the features of Cognitive Radio networks that makes possible for unlicensed users to use licensed spectrum absolutely free with switching from primary user to secondary due to interference engine and enables secondary users to use channel based on availability. The paper also describes the concept of spectrum mobility and its objectives. It is very important to select an effective spectrum handoff strategy for achieving better spectrum mobility.

Preetha and S. Kalaivani (2017) the research paper entitled "A Collaborative Scheme with Power Adaptation-Equalization and Spectrum Handoff for Mobile Cognitive
Radio Networks" is about power adaptation equalization and spectrum handoff scheme for cognitive radio networks of mobile based. The paper also describes how to offer better communication services to unlicensed users. The paper outlines the spectrum handoff concept and its objective to offer licensed users better accessibility to channel with minimum delay.
Hernández et al (2017) the research paper entitled "Multivariable Adaptive Handoff Spectral Model for Cognitive Radio Networks" defines multivariable adaptive spectrum handoff model for the cognitive radio networks. The paper describes MAPMFF with four algorithms for decision making with different approaches fuzzy, feedback statistics, predictive and multichannel. The paper also outlines the analysis made between the proposed algorithms.

IJTSRD24034
International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470 Page: 1004 Mardeni et al (2016) the research paper entitled "Spectrum Handoff Schemes in Cognitive Radio Network Using Particle Swarm Optimization" define spectrum mobility. The paper describes three spectrum handoff strategies that can be used to reduce the handoff delay which are proactive, reactive and hybrid. The paper also describes the implementation of PSO (particle swarm optimization) to minimize the service time of spectrum handoff to the optimal value.
Tiwari and Rastogi (2016) the research paper titled "Spectrum Handoff in Cognitive Radio Network" describes the modern wireless technology and the spectrum band. The paper focus on implementation of cognitive radio networks for resolving problem of spectrum scarcity through dynamic spectrum access. The paper also outlines the importance of cognitive radio technology and the best solution for spectrum inefficiency and spectrum shortage problems. At last the paper clearly demonstrates the spectrum handoff concept.
Hossain and Sarkar (2012) the research paper entitled "Spectrum Management in Cognitive Radio Networks: Modeling and performance Evaluation" describes the cognitive radio networks and its importance in today wireless computing. The paper outlines the challenge of sharing licensed spectrum with other licensed users without interfering. To address this the paper presents a proactive spectrum management schemes to use unoccupied spectrum with minimum latency. They must be able to adapt to the modulation scheme in order to improve spectrum access process. They must be able to operate on different systems with different protocols in a wideband frequency range supported by its hardware design. Using this capability, the best networks and channels can be selected and then CR users are able to reconfigure themselves to be compatible with the new environment. They must be able to frequency agility, which means the ability of the CR user can change its transmission frequency. They must be able to control the transmission power, for example, transmitting power control can be used to control the power level dynamically, which reduces the emitted power to allow greater sharing of the spectrum when a higher power level is not necessary.

V. CONCLUSION
The research paper presents the review of spectrum handoff decisions with literature survey. The paper reviews basic fundamentals of Spectrum Handoff Decision Schemes in Cognitive Radio Networks.