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In this paper, we study a spectrum allocation mechanism of Cognitive Radio Networks based on multi-backpack problem, and then propose a discrete hybrid leapfrog algorithm and a spectrum allocation method based on this algorithm. This algorithm uses the integer coding method and designs the corresponding algorithm search strategy, using the crossover and mutation operator to improve the algorithm performance...
Adjacent channel interference (ACI) is often not considered when spectrum sharing schemes are designed for cognitive radio networks (CRNs). In practice, it is necessary to avoid interference by deploying guard bands between two distinct receptions. However, using guard bands typically reduces spectrum efficiency. In this work, we study the impact of guard bands on spectrum efficiency under different...
Increasing number of mobile and wireless applications is threatened by the scarcity of frequency bands. Cognitive radio is a promising technology which would be hoped to solve the problem. Common Control Channel (CCC) plays an important role in these kind of networks and it also has its own issues. This paper considers the CCC problem in cognitive radio networks. A method is presented which increases...
Emerging standards in Cognitive Radio seek to alleviate the problem of spectrum scarcity by leveraging spectrum under-utilization through dynamic spectrum access (DSA). Unlicensed users (“secondary”) may opportunistically make use of channels during times when the licensed (“primary”) user is absent. The “open access” paradigm proposed by FCC mandates the study of primary-secondary dynamics, as well...
In cognitive radio networks, the available spectrum holes are usually discontinuous. Hence, it is hard to exploit these spectrum holes because the bandwidth of an individual one may not be able to satisfy the wide bandwidth requirement imposed by secondary users (SUs). Spectrum aggregation (SA) enables SUs to integrate several spectrum holes into one channel with wide bandwidth which may support high...
In cognitive radio networks, the available vacant frequency bands, referred to as spectrum holes, are usually discontinuous. Hence, it is hard to exploit these vacant frequency bands since the bandwidth of single one may not be able to meet the wide bandwidth requirement of secondary users (SUs). Spectrum aggregation (SA) enables SUs to access several discontinuous spectrum holes simultaneously to...
This paper elaborates on the design, implementation and performance evaluation of a prototype Radio Resource Management (RRM) framework for TV white spaces (TVWS) exploitation, under an auction-based approach. The proposed RRM framework is applied in a centralised Cognitive Radio (CR) network architecture, where exploitation of the available TVWS by Secondary Systems is orchestrated via a Spectrum...
In this paper, we discuss the issues of the QoS routing for group communications in Cognitive Radio (CR) networks. The problem of our concern is: given a CR ad hoc network and a QoS group communication request, how to set up a communication connection so that the total bandwidth consumption of the communication is minimized while the QoS requirement is met. In this paper, we focus on the bandwidth...
Cognitive radio (CR) as one of the most promising technologies to solve the problem of exhausting of spectrum resource, draws a lot of attention recently. However, for the highly intelligent wireless devices in the future, the assumption "CR devices introduce no interference to the primary users (PUs)" in traditional CR systems may do not exist anymore, due to that the devices are always...
In this paper, we discuss the causal ordering group communication for cognitive radio (CR) networks. The issue of causal ordering has been studied extensively by previous works. However, these works considered the problem at the application layer and the methods in the works incurred high communication overhead and the long latency for message delivery. In this paper, we discuss the causal ordering...
As a kind of effective way to improve the utilization ratio of the spectrum, more and more attention have been paid to the cognitive radio. This paper proposes an improved cognitive radio spectrum sharing model. In this model, the primary users provide idle spectrum to the secondary users. Secondary users have to pay when they share available spectrum with primary users while using the spectrum. The...
Spectrum sharing and power allocation are interesting issues in cognitive radio networks. In our paper, we introduce a pricing scheme to demonstrate the spectrum sharing scenario between primary users and secondary users. We demonstrate the joint optimal allocation scheme of both spectrum and power for secondary users buying spectrum from multiple primary users. The joint optimal allocation scheme...
Cognitive radio network exploits spectrum hole generated by vacation of primary user on the frequency. However, network design paradigms of primary and secondary can be different except for frequency bandwidth in which they are operating. One of differences is network scale which is stemming from transmission power gap between primary and secondary. Especially, small scale primary user such as microphone...
In this paper, we address the problem of channel sensing, channel allocation and transmission of multimedia signals in a cognitive radio network, while maintaining the required quality of service (QoS) constraints. Depending on the type of signal and QoS requirements, different types of multimedia signals need different bandwidths for communication. In typical wireless systems, unless a contiguous...
The ability of adapting to the environment in the most efficient way is a crucial issue in Cognitive Radio (CR) networks. For this purpose, an accurate estimation of the characteristics and activity of the Primary Users (PUs) is required. A system that takes into account heterogeneous PUs with several features is developed. A new scheme is integrated in the system to exploit these motleys and to improve...
Information-theoretic limits on resource consumption are employed to obtain analytical methods for conducting tradeoffs between power, bandwidth, and time for cognitive radio transmissions in ad hoc dynamic spectrum access networks. A quantitative measure of resource consumption is applied to the design and evaluation of protocols for adaptive modulation and coding. The application of information...
In this paper, we discuss the issues of QoS multicast routing in multi-hop Cognitive Radio (CR) networks. The problem of our concern is: given a CR network and a QoS multicast request, how to set up a multicast connection so that the total bandwidth consumption of the multicast is minimized while the QoS requirements are met. We propose a distributed protocol which uses shortest path tree as the multicast...
In the recent years, researches focus on decay of TCP throughput over wireless links, and many wireless TCP solutions are proposed to deal with this issue. On the other hand, followed by the improvement of hardware technology, new network structures and mechanisms are proposed to enhance wireless communications, for example, the Cognitive Radio (CR) networks. However this new network architecture...
Cognitive radios (CR) provides a promising solution to the problem of spectrum scarcity by increasing spectrum efficiency. CR coexists with the licensed users in a network. The network is assumed to be ad-hoc in nature where the master/controller of this ad-hoc network coordinates for spectrum allocation with the surrounding CR. In this paper, a two level hierarchical fuzzy system for adaptive bandwidth...
Cognitive Radio (CR) enables an unlicensed user to change its transmission and reception parameters adaptively according to spectrum availability in a wide range of licensed channels. The concept of a Cognition Cycle (CC) is the key element of CR to provide context awareness and intelligence so that each unlicensed user is able to observe and carry out an optimal action on its operating environment...
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