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Software Defined Radio (SDR) and Cognitive Radio (CR) are promising technologies, which can be used to alleviate the spectrum shortage problem or the barriers to communication interoperability in various application domains. The successful deployment of SDR and CR technologies will depend on the design and implementation of essential security mechanisms to ensure the robustness of networks and terminals...
In this study, orthogonal frequency division multiple access (OFDMA) based primary and secondary usage in a cognitive radio system is considered and conventional power spectral density (PSD) based technique is used to detect the opportunities in the spectrum. Primary user employs block-based or scattered subcarrier allocation scheme and the overlay system aims to utilize the spectral gaps. Comparison...
Resource allocation is an important issue in cognitive radio systems. It can be done by carrying out negotiation among secondary users. However, significant overhead may be incurred by the negotiation since the negotiation needs to be done frequently due to the rapid change of primary users' activity. In this paper, a channel selection scheme without negotiation is considered for multi-user and multi-channel...
Conflict-free power allocation for secondary user (SU) in cognitive networks is a challenging problem since the accessible spectrum of the SU is shared with the primary user (PU); the problem becomes to be especially difficult when it is wanted to achieve the maximum network capacity considering the mutual interference between PU and SU. In this paper, specifying the single SU case with multiple PUs,...
A cognitive OFDM-based relay network is considered in this paper. Communication between any node pair occurs on a spectrum pool of OFDM subcarriers where the subcarriers are not used by primary users. Therefore, the available spectrum for different transmitter-receiver pairs is distinct due to their location difference and so on. To satisfy different traffic demand and improve system performance,...
In this paper, a binary power allocation scheme is proposed for dense cognitive networks with plentiful secondary nodes. During the power allocation, the capacity loss of the primary system is controlled to be lower than a predefined level; and the capacity of the secondary system is ensured to some extent. Most importantly, based on the theoretical derivations, the power allocation is proved to be...
In this paper, we propose an efficient power allocation scheme that aims at maximizing the system throughput in joint spectrum overlay and underlay cognitive radio network. We show that our proposed scheme enlarges the achievable throughput region comparing to the overlay strategy, and causes less interference than the underlay strategy. In addition, since the unlicensed users adopting the overlay...
To settle the contradiction between scarce radio spectrum resource and the exigent requirement, effective methods of dynamic spectrum allocation are proposed in cognitive radio system. In this paper, game theory model and graph-coloring model are analyzed, which can improve spectrum efficiency and solve the deficiency of spectrum resource.
Cognitive radio technology has arisen as a hot topic in wireless communication in recent years. Special spectrum allocation algorithms are essential to adapt to the time-space varying characteristics of wireless spectrum in cognitive networks. In this paper, we study and simulate the guard channel policy proposed by Huang Zhen, etc. We find that the blocking probability of secondary users is relatively...
An expanding model based on graph coloring is built for channel allocation, which is more suitable to the actual requirement of cognitive radios. Several representative channel allocation algorithms are analyzed contrastively, including list-coloring greedy algorithm and fair algorithm. A novel channel allocation algorithm using Maximal Independent Set (MIS) is proposed aiming at the characteristic...
Among the major challenges in the development of effective dynamic spectrum access techniques are the realization of the control channel, the detection of primary users, and the efficient use of the available spectrum. Most of the previous work in this field has addressed only a subset of these issues. In a previous paper we proposed a distributed multi-channel medium access strategy based on a network...
Cognitive radio networks are envisioned to solve the problem of spectral scarcity in wireless networks; through providing highly configurable radios and protocol stacks to support the application of a variety of efficient and possibly cross-layered solutions. However, the large numbers of hardware and software modules involved in realising these goals raises a fundamental design problem. Specifically,...
Opportunistic spectrum access system allows the secondary user to access spectrum holes not being utilized by the primary user. Traditional opportunistic spectrum access approaches only sense and utilize current spectrum holes. This can result in uncontrollable collision probability, which exceed the maximum collision probability allowed by the primary user network. In this paper, we consider a cognitive...
Cognitive radios (CRs) have a potential to improve spectrum utilization by enabling users to access the spectrum dynamically without disturbing licensed primary users (PUs). In this paper, we consider the spectrum allocation in wireless networks with multiple selfish secondary users (SUs) and a spectrum pool formed by underutilized spectrum of primary users. A novel spectrum allocation mechanism is...
Rapid growth in the consumer base for mobile services against the backdrop of limited spectrum demands intelligent networks for optimum utilization of the allocated spectrum with minimal changes in the existing infrastructure. This paper introduces a novel three stage predictive channel allocation scheme called Intelligent Channel Allocation (ICA) based on long term call statistics, instantaneous...
Cognitive radio is an emerging technique to improve the utilization of radio frequency spectrum in wireless communication networks. In this paper, we consider the problem of spectrum sharing among a few primary users and multiple secondary users through auction games. With the second-price auction and VCG auction, we adopt a utility function to obtain the optimal total payoffs the secondary users...
In this paper we propose a mechanism to enable flexible spectrum usage (FSU) in local area indoor deployment scenario with several operators in the given geographical area. The proposed scheme is referred to as policy assisted light cognitive radio (CR) enabled FSU, because it follows the CR cycle and considers policy as an important element to assist FSU. It facilitates allocation of spectral resources...
This paper addresses the subcarrier and power allocation problem in the uplink of an OFDMA system under the cognitive radio environment. The objective is to maximize the sum-rate of secondary users, without causing adverse interference to the primary users. We formulate the optimization problem subject to the individual power constraints and the interference constraints. Since the problem cannot be...
Opportunistic allocation of resources to the best link in large multiuser networks offers considerable improvement in spectral efficiency, which is often referred to as multiuser diversity gain and can be cast as double logarithmic growth of the network throughput with the number of users. In this paper we consider large decentralized cognitive networks granted concurrent spectrum access with license-holding...
In this paper, we study the distributed multichannel spectrum sharing problem for the cognitive radio networks (CRNs). We are interested in dynamic spectrum sharing schemes that maximize the spectrum utilization of the cognitive network while appropriately protecting primary users. Existence and optimality of the Nash Equilibrium (N.E.) are investigated. Distributed Multichannel Spectrum Sharing (MCSS)...
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