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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...
Nowadays, radio systems have to use the spectrum resource more intensely than in the past to meet the demanding expectations of the users. Several studies have demonstrated that portions of radio spectrum are not in use for significant periods of time, showing the necessity to design a more flexible way to manage the spectrum resource with respect to the traditional frequency allocation policy.
Cognitive Radio/Dynamic Spectrum Access, which intelligently and opportunistically uses underutilized portions of licensed wireless spectrum such as broadcast bands, has been proposed to effectively address spectrum scarcity problem. However, the dynamics of spectrum usage in licensed bands influences the performances of cognitive radio system because the licensed system takes priority over the cognitive...
In recent years, Wireless Sensor Networks (WSNs) have been largely deployed for various applications. Among them, monitoring in unlicensed frequency bands of the environment and historical sites assumes particular relevance. However, these bands are becoming more and more overcrowded due to the fast growth of wireless services relying on them. A possible solution to overcome this problem is offered...
Cognitive radio is an emerging technology for sensing and dynamic access of spectrum in mobile radio environments. It aims at dynamically allocating unused bandwidth among secondary users without causing harmful interference to the primary users. This approach, which has clear economical benefits, has recently attracted significant research effort. In this paper, we propose a new approach to dynamic...
A periodogram scheme, a multi-taper scheme, and a filter-bank scheme are proposed for spectrum sensing for dynamic spectrum access. The filter-bank scheme is advantageous in hardware implementation since the hardware required for communications can be reused for spectrum sensing. However, it is difficult for the conventional filter-bank scheme to change the detection bandwidth, filter type and frequency...
Opportunistic Spectrum Access (OSA) brings new research challenges in MAC protocol design. It allows unlicensed users to share licensed spectrum in space and time with no or little interference to Primary Users (PUs). When designing an OSA MAC protocol, one of the most difficult but important problem is how the unlicensed users decide when and which channel they should sense and access without conflicting...
In this paper, we consider the cognitive network (CR) that can provide a means for offering quality of service (QoS) required by real time services, streaming multimedia and other applications. We consider the approach where the licensed users (primary users, PUs) rent the surplus spectrum to unlicensed users (secondary users, SUs) to get some reward. However, when PU leases more spectrum to the SUs,...
Dynamic spectrum access is a technique to utilize the spectrum resources efficiently in a cognitive radio environment. To use spectrum efficiently various models were designed by researchers. Game theoretical models are few of the efficient techniques recently introduced in wireless communications. Game models are very useful for opportunistic selection of spectrum and help to utilize available spectrum...
Radios for public safety communication have some of the most stringent requirements for access, reliability and robustness. While wireless technology has seen tremendous strides in the past decade, large parts of the public safety infrastructure have unfortunately lagged behind. Today the majority of the Land Mobile Radios (LMR) used by police and fire departments, among others, utilize bandwidth...
The problem of sharing multiple channels owned by primary users with multiple cognitive users is considered. Each primary user transmits on its dedicated channel, and its occupancy is modeled by a continuous time Markov process. Each cognitive user is capable of sensing one channel at a time and it transmits according to a slotted structure. The transmissions of cognitive users on each channel are...
The fear of spectrum scarcity in licensed bands or the poor coexisting behavior in unlicensed bands demands the exploration of new resource sharing strategies. As a solution, dynamic spectrum access (DSA) is being addressed to allocate already assigned but sparsely used frequency bands to secondary users without causing any significant interference to primary users. It exploits opportunities in temporal...
Spectrum under-utilization is one of the bottlenecks of the development of wireless communication, and dynamic spectrum access (DSA) is envisioned as a novel mechanism to solve the problem of spectrum scarcity. Spectrum auction has been recognized as an effective way to achieve DSA, wherein the primary spectrum owner (PO) acts as an auctioneer who has free channels and is willing to sell them for...
Dynamic Spectrum Access (DSA) has the potential to vastly improve spectrum utilizations among heterogeneous networks. We present a continuous-time Markov chain (CT-MC) model to analyze the performance of three co-located cognitive systems with various priority classes and bandwidth requirements. The maximum spectrum utilization and minimum blocking probability are derived in a one-channel band scenario...
Cognitive Radio (CR) has been studied recently as an enabling technology for dynamic spectrum access. In this paper, the concept of Bandwidth Time Cube (BTC) is defined with a three dimensional space for maximizing spectrum usage to model radio spectrum management. In order to utilize unused frequencies, a DSHR (Dynamic Spectrum Heuristic Replacement) algorithm is proposed for a multi-hop CR networks...
Channel allocation is an important area of research in open spectrum networks which asserts a significant impact on the spectrum utilization and the fairness among users. This paper studies the optimization of channel allocation, considering multiple objectives. For each objective, a binary programming model is described. Then a new optimization objective called fairness constrained maximum throughput...
Spectrum sensing and spectrum management are the main challenging functions that cognitive radio (CR) networks have to perform. In this paper, we focus specifically on the spectrum decision problem. This problem is worsened in the presence of users with different demands and spectrum channels with different properties in a heterogeneous network. For accurate and proper spectrum management, we propose...
Optimal spectrum access is a fundamental issue for efficient wireless communications in multi-channel wireless networking systems. Opportunistic spectrum access, making fully use of channels with high quality, could pave a way for efficient transmission. Unfortunately, in heterogeneous wireless networks, these strategies suffer from the assumption of identical wireless channel quality, and the difficulties...
Cognitive radio is a highly promising technology to efficiently solve the spectrum scarcity challenge and harmonize the networks heterogeneity. Through component spectrum sharing, secondary users (SUs) are able to opportunistically access licensed spectrum shared with the primary system. In the literature, spectrum sharing is normally investigated on the basis of the assumption that the spectrum sensing...
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