A Survey of Cognitive Radio Systems
A Survey of Cognitive Radio Systems
Željko Tabaković
Croatian Post and Electronic Communications Agency, Jurišićeva 13, Zagreb, Croatia zeljko.tabakovic@hakom.hr Abstract - A fundamental problem facing the future wireless systems is where to find suitable spectrum bands to meet the demand of future services. While essentially all of the radio spectrum is allocated to different services, applications and users, observation provide evidence that usage of the spectrum is actually quite low. In order to overcome this problem and improve spectrum utilization, cognitive radio concept has been proposed. This paper provides an overview of cognitive radio for opportunistic spectrum access and related research topics. Cognitive radio objective is to use scarce and limited natural resources efficiently without causing excessive interference to the primary licensed users. Consequently, cognitive radio has to sense and understand its spectrum environment, identify temporarily vacant spectrum, transmit adaptively and learn from its behaviour. A number of promising concepts for cognitive radio were briefly presented and discussed in this paper in the area of passive and active spectrum awareness, spectrum management and transmit power control.
Keywords - Cognitive Radio, Opportunistic Spectrum Access,
Spectrum Awareness, Spectrum Management, Transmit Power
Control
I.
INTRODUCTION
Radio spectrum is a valuable commodity, and a unique natural resource shared by various types of wireless services.
Unlike other natural resources, it can be repeatedly re-used, provided certain technical conditions are met. In practice radio spectrum can accommodate a limited number of simultaneous users. Therefore, radio spectrum requires careful planning and management to maximise its value for all users. Currently, spectrum regulatory framework is based on static spectrum allocation and assignment policy. Radio spectrum is globally allocated to the radio
Željko Tabaković
Croatian Post and Electronic Communications Agency, Jurišićeva 13, Zagreb, Croatia zeljko.tabakovic@hakom.hr Abstract - A fundamental problem facing the future wireless systems is where to find suitable spectrum bands to meet the demand of future services. While essentially all of the radio spectrum is allocated to different services, applications and users, observation provide evidence that usage of the spectrum is actually quite low. In order to overcome this problem and improve spectrum utilization, cognitive radio concept has been proposed. This paper provides an overview of cognitive radio for opportunistic spectrum access and related research topics. Cognitive radio objective is to use scarce and limited natural resources efficiently without causing excessive interference to the primary licensed users. Consequently, cognitive radio has to sense and understand its spectrum environment, identify temporarily vacant spectrum, transmit adaptively and learn from its behaviour. A number of promising concepts for cognitive radio were briefly presented and discussed in this paper in the area of passive and active spectrum awareness, spectrum management and transmit power control.
Keywords - Cognitive Radio, Opportunistic Spectrum Access,
Spectrum Awareness, Spectrum Management, Transmit Power
Control
I.
INTRODUCTION
Radio spectrum is a valuable commodity, and a unique natural resource shared by various types of wireless services.
Unlike other natural resources, it can be repeatedly re-used, provided certain technical conditions are met. In practice radio spectrum can accommodate a limited number of simultaneous users. Therefore, radio spectrum requires careful planning and management to maximise its value for all users. Currently, spectrum regulatory framework is based on static spectrum allocation and assignment policy. Radio spectrum is globally allocated to the radio
References: Genève, 2008 Federal Communications Commission, "Facilitating Opportunities for Shared Spectrum Company, "Spectrum Occupancy Measurements", 2005, retrieved from www.sharedspectrum.com/measurements on Sharing Detectors", In Proc. of IEEE International Symposium on New Frontiers in Dynamic Spectrum Access Networks (DySPAN 2007), Generation / Dynamic Spectrum Access / Cognitive Radio Wireless Networks: A Survey", Computer Networks, 2006, pp Software Defined Radio", PhD thesis, KTH Royal Institute of Technology, Stockholm, Sweden, 2000