Widely regarded as one of the most promising emerging technologies for driving the future development of wireless communications, cognitive radio has the potential to mitigate the problem of increasing radio spectrum scarcity through dynamic spectrum allocation. Drawing on fundamental elements of information theory, network theory, propagation, optimization, and signal processing, a team of lea...

An ATM-type multiplexer, with nite buuer and multimedia traac input, is investigated for packet loss and delay. It can also be subject to input rate regulation, overload control, and dynamic allocation of transmission bandwidth. This system model is fundamental to the ATM design, but has not been analyzed satisfactorily. In 1], an eecient and versatile technique, the folding algorithm, is devel...

In the US, adjudication of wireless entry under the ‘‘public interest’’ standard protects incumbent service providers. Excess demand exists for access to radio spectrum, despite a common misperception that license auctions held by regulators are tantamount to selling spectrum. Would-be suppliers are slowed by the regulatory process. After discussing the financial tolls extracted, the author sug...

In this paper, an enhanced greedy bit and power allocation algorithms for orthogonal frequency division multiplexing (OFDM) communication systems are introduced. These algorithms combine low complexity greedy power allocation algorithms with a simplified maximum ratio combining (MRC) precoding technique at the transmitter for maximizing the average data throughput of OFDM communication systems....

This paper presents a summary of some of the results on dynamic spectrum allocation (DSA) that have been obtained as part of the DRiVE project. During this project two main aspects of DSA were investigated. Temporal DSA attempts to adapt the spectrum allocations of networks to time-varying loads, and spatial DSA adjusts spectrum allocations according to the load demands of different regions. Th...

In the recently-suggested dynamic spectrum allocation policy of cognitive radio networks [1]–[3], sensing/monitoring of spectrum availability is identified as a key requirement. To meet this requirement we address an important MAC-layer sensing issue: which of proactive and reactive sensing is more energy-efficient? An algorithm is proposed to dynamically determine which sensing mode to use. Fo...

In traditional wireless systems, spectrum or frequency is allocated to licensed users over a geographic area. Within these constraints, spectrum is considered a scarce resource due to static spectrum allocation. Recent empirical studies of radio spectrum usage have shown that licensed spectrum is typically highly underutilized (Broderson et al., 2004; McHenry, 2003). To recapture the so-called ...

In this study, the interaction of Beam Forming and frequency allocation schemes on an OFDM-based system such as LTE or WiMAX is investigated in order to support the maximum capacity and minimum outage probability. The results of simulation show that rank1 precode scheme based on MISO channel, according to what considered in LTE standard, along with the cell region division in order to allocate ...

Ever increasing wireless services and networks results in spectrum scarcity. But already allocated spectrum is in under utilization in the current static fixed spectrum allocation method .So dynamic spectrum access is only solution for this issue .Spectrum sensing is one of the key technique in cognitive radio for dynamic spectrum access. There are many algorithm proposed for the spectrum sensi...

In this paper we present some of our work in progress in tuning strategies applied to two distributed algorithms that address the problem of frequency allocation for mobile networks. The tuning strategies attempt to address important aspects of mobile user access, such as connection response time, as well as the eeciency of the frequency acquisition process. In applying the strategies and exami...