Paper Info
Title
Is High Quality Sensing Really Necessary for Opportunistic Spectrum Usage?
Abstract
The major requirement for Cognitive Radio (CR) based opportunistic spectrum re-usage is reliable protection of the primary communication. This calls for a reliable detection of the presence of the Primary Users (PUs) as well as for an immediate reconfiguration of the secondary communication: Each time the PU has been detected, the Secondary Users (SUs) have to vacate the respective part of the spectrum and continue their communication elsewhere. Unfortunately enough, also false positives in the sensing process trigger the same type of reconfiguration, leading to more reconfigurations than actually necessary. Therefore, the efficiency of this reconfiguration process is of high interest. For a frequently postulated OFDM based spectrum pooling SU system two basic questions are considered: (1) How should the parameters of the secondary communication link be selected in order to achieve a stable Quality of Service (QoS) in spite of reconfigurations, and (2) how strongly is the QoS of the SU influenced by reconfigurations caused by a non ideal sensing process, i. e. by an excessive number of false positives. I. INTRODUCTION The Cognitive Radio (CR) concept (1) is well known to overcome the frequency scarcity due to the limited amount of spectral resources usable for wireless communication. Today, the majority of frequencies are licensed to so-called Primary Users (PUs) by the responsible regulation authorities. How- ever, it has been shown (2) that many of these frequencies are at least temporarily not used in certain locations. The CR concept envisions to allow reuse of these temporarily unused frequencies by so-called Secondary Users (SUs). It is of eminent importance to assure that the PUs are not suffering from the reutilization. The reuse can be accomplished on an opportunistic basis, where a sensing process is used to identify temporarily unused frequencies out of which Secondary User Links (SULs) are created and used for secondary communication. The sensing process is also responsible for the detection of re-appearing PUs on frequencies currently used by an SUL. To assure a reliable protection of the PU, the false negatives of the sensing process have to be below a very strict threshold, which is a hard constraint. This can only be achieved by either allowing a high number of false positives or by a significant complexity and spectral overhead of the sensing process. In contrast to the usually made assumptions we believe that low false positives are not a hard constraint for the sensing process.
Year
DOI
Venue
2010
10.1109/GLOCOM.2010.5683599
GLOBECOM
Keywords
Field
DocType
OFDM modulation,cognitive radio,quality of service,OFDM based spectrum pooling,QoS,cognitive radio,high quality sensing,opportunistic spectrum usage,quality of service
Computer science,Quality of service,Computer network,Real-time computing,Bandwidth (signal processing),Telephony,Control reconfiguration,Spite,Orthogonal frequency-division multiplexing,False positive paradox,Cognitive radio
Conference
ISSN
Citations 
PageRank 
1930-529X
1
0.40
References 
Authors
7
3
Name
Order
Citations
PageRank
Christian Dombrowski161.89
Daniel Willkomm232721.59
Adam Wolisz32693407.71