Almost 80 to 90 percent of the radio spectrum is left unutilized at any period of time, while at the same time some other regions of spectrum experience overcrowding. We consider a dynamic spectrum access system in which Secondary Users (SUs) choose to either acquire dedicated spectrum or to use spectrum-holes (white spaces) which belong to Primary Users (PUs). The tradeoff incorporated in this...

There has been considerable effort to let more wireless devices operate in “white space” spectrum, i.e. within frequency bands and geographic areas where no wireless devices are active. Making white space available is certainly useful, but there are other sharing opportunities as well, some of which have been obscured by dangerous misconceptions about the concept of “unused spectrum.” This pape...

Radio Spectrum is most precious and scarce resource and must be utilized efficiently and effectively. Cognitive radio is the promising solutions for the optimum utilization of the scared natural resource. The spectrum owned by the primary user should be shared among the secondary user, but primary user should not be interfered by the secondary user. In order to utilize the primary user spectrum...

Open Spectrum systems allow fast deployment of wireless technologies by reusing under-utilized pre-allocated spectrum channels, all with minimal impact on existing primary users. However, existing proposals take a reactive sense-andavoid approach to impulsively reconfigure spectrum usage based solely on the latest observations. This can result in frequent disruptions to operations of both prima...

Cognitive radio (CR) is a promising technique for future wireless communication systems. In CR networks, dynamic spectrum access (DSA) of frequency is implemented to mitigate spectrum scarcity. Specifically, a secondary (unlicensed) user may be allowed to access the temporarily unused frequency bands granted to a primary (licensed) user. DSA has to be implemented so that the quality of service ...

Spectrum sensing is the challenge for cognitive radio design and implementation, which allows the secondary user to access the primary bands without interference with primary users. Cognitive radios should decide on the best spectrum band to meet the Quality of service requirements over all available spectrum bands. This paper investigates the integrated centralized spectrum sensing techniques ...

Recently proposed dynamic spectrum leasing (DSL) for dynamic spectrum sharing (DSS) presumes that there is a reward for primary users for accepting secondary activity. The reward primary users received in previous DSL proposals, however, were considered to be proportional to the secondary interference level. In this paper, we propose a new way to encourage primary users to lease their spectrum:...

The last decade has witnessed a growing demand for wireless radio spectrum due to the rapid deployment of new wireless devices and applications. Spectrum is a precious resource and thus underutilization of a large part of allocated spectrum is not acceptable. Cognitive radio (CR) is proposed as a promising solution for increasing spectrum utilization and thereby helping to mitigate spectrum sca...

Cognitive radio (CR) can significantly improve spectrum efficiency by allowing the secondary users to temporarily access the primary user’s under-utilized licensed spectrum. Spectrum mobility issues arise when the primary user appears at the channels being occupied by the secondary users. The secondary users return to the occupied channel because the primary users have the preemptive priority t...

The rapid growth of wireless services and the breakneck proliferation of wireless devices continue to strain limited spectrum resource. While the need for efficient spectrum sharing mechanisms has been emphasised, opportunistic spectrum access has been considered as a promising mechanism for dynamic spectrum sharing. However, although the idle spectrum could exist, it is usually rather fragment...