An Efficient Relay Selection and Clustering Technique for Spectrum Sharing Network

Abstract
When we consider a spectrum sharing networks it have primary user and secondary user. Spectrum share by the first user is called primary user. Primary user used the allocated spectrum without affected any interference. But in the case of secondary user used the primary user spectrum it has much interference occur, also need more emitted power. xG networks are envisioned to provide opportunistic access to the licensed spectrum using unlicensed users. This setting enables multiple systems being deployed in overlapping locations and spectrum.so primary user and secondary user speed also decreases. In our project above problem should be overcome by using proper relay selection and clustering technique. Here used distributed relay selection and clustering to improve the secondary rate and also reduced the secondary emitted power.
Keywords:spectrum sharing, relay, clustering
I.INTRODUCTION
Traditionally, use of radio spectrum has been highly regulated in order to prevent interference among users of adjacent frequencies or from neighboring geographic areas. In the past decade there have been significant innovations in the theory of spectrum management along with gradual changes in practice of spectrum management and regulation. This gradual change follows a growing consensus that past and current regulatory practices originally intended to promote the public interest have in fact delayed, [1] in some cases, the introduction and growth of a variety of beneficial technologies and services, or increased the cost of the same through an artificial scarcity[5]. In addition to these delays, the demand for spectrum has grown significantly Those reasons are making policy-makers and regulators worldwide focus on new methods of spectrum regulation with an increasing emphasis on striking the best possible balance between the certainty required to ensure stable roll-out of services and flexibility (or light-handed regulation) leading to improvements in cost, services and the use of innovative technologies[3]. In developing countries in particular, where mobile communications users now greatly outnumber those using fixed line telecommunication services, it is widely recognized that the spectrum is a highly valuable resource for future economic development. Access to the radio spectrum is based on the Table of Frequency Allocations of the International Telecommunications Union (ITU) Radio Regulations, where defined categories of radio service are allocated frequency bands in different parts of the spectrum[2][4]. The spectrum allocations can be on exclusive, shared, primary or secondary basis. Due to scarcity of the frequency spectrum, many bands are allocated for more than one radio service and are, therefore, shared. Spectrum sharing studies aim to identify technical or operational compatibilities that will enable radio services to operate in the same (or adjacent) frequency bands without causing unacceptable interference to each other[2][3]. Often, sharing becomes possible when limits are placed on certain system parameters — for example, antenna radiation patterns, transmission power etc. Decisions are made at the national levels on the purpose or purposes to which particular frequencies will be used. These decisions are reflected in the International and National Tables of Frequency Allocations.
CONCLUSION
Tour project investigated how increase the secondary rate and also decrease the interference level in primary user. Our project result shows the maximum secondary rate with minimum relay. Here there is no cross channel interference occur in primary and secondary user. The trade-off between the secondary rate and the interference on the primary was characterized. We have also developed a low-complexity Spectrum sharing and allocation suboptimal approach for relay selection.