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We present a composite suite of technologies for spectral coexistence of existing communication and radar systems using the Xampling framework. For a stand-alone communication system, we consider a cognitive radio (CRo) that receives multiband signals with unknown carrier frequencies and directions of arrival, and demonstrate joint spectrum sensing via CompreSsed CArrier and Direction-ofarrival Estimation...
In this paper, we consider a cognitive radio system, consisting of a primary user (PU), a secondary user (SU) transmitter, and a SU receiver. The SUs are equipped with directional antennas. The SU transmitter first performs spectrum sensing (with errors) and then transmits data. We assume the SU and PU can coexist and the SU transmits at two power levels, according to the result of spectrum sensing...
Learning-based sensing policies for multi-band flexible spectrum use, in particular cognitive radios operating in non-stationary radio environments are proposed. The proposed policies stem from the stochastic non-stationary restless multi-armed bandit formulation of opportunistic spectrum access. The non-stationary radio environment assumed in this paper is an appropriate model for a realistic cognitive...
In this paper, we describe a spectrum access system (SAS) based Citizens Broadband Radio Service (CBRS) field trial using a live LTE network in the 3.5 GHz band. The latest WInnForum specification guided the implementation of the relevant protocols for SAS operation. Here, we evaluate the performance of a CBRS field trial by using one of the most important performance indicators in a spectrum sharing...
Spectrum sharing in the 3.5 GHz band between commercial and government users along U.S. coastal areas depends on an Environmental Sensing Capability (ESC), a network of radio frequency sensors and a decision system, to detect the presence of incumbent shipborne radar systems and trigger protective measures, as needed. It is well known that the sensitivity of these sensors depends on the aggregate...
Opportunity detection at secondary transmitters (TXs) is a key technique enabling cognitive radio (CR) networks. Such detection however cannot guarantee reliable communication at secondary receivers (RXs), especially when their association distance is long. To cope with the issue, this paper proposes a novel MAC called sense-and-predict (SaP), where each secondary TX decides whether to access or not...
With rapid development in wireless applications, there arises a demand for available spectrum. Cognitive radio technology is a promising solution to enhance the spectrum utilization by enabling unlicensed users to exploit the spectrum in an opportunistic manner. Since unlicensed users are temporary visitors to the licensed spectrum, they are required to vacate the spectrum when a licensed user reclaims...
The Cognitive Radio (CR) is an emerging technology for modern wireless communication system that offers a great solution to scarcity of radio spectrum. The Cognitive Radio Network (CRN) is an intelligent wireless communication organization that is aware of its environment. Here, heterogeneous nodes meet spectrum sensing challenges due to the variation of transmission power, spectrum allocation and...
Spectrum sensing is the method used in Cognitive Radio (CR) to find the unused spectrum. Based on spectrum sensing only other functions of CR can be implemented. So for Cognitive Radio, efficient spectrum sensing is compulsory. In this paper, spectrum sensing techniques, challenges are presented. An overview of cognitive radio architecture, on the basis of research is discussed. This paper explains...
In this paper, a hybrid approach has been proposed for maximizing ergodic capacity of the cognitive radio networks. This hybrid scheme is based upon the sensing information (sensing Metric) obtained by the secondary receiver about the absence or the presence of the primary user. By adopting hybrid scheme, one can increase the ergodic capacity of the network subject to peak transmit power constraint...
In this paper, an asymptotic analysis of the inversely proportional setting (IPS) of carrier sense threshold (CST) and transmission power in densely deployed wireless local area networks (WLANs) is presented. In densely deployed WLANs, CST adjustment is a crucial technology to enhance spatial channel reuse, but it can starve surrounding transmitters due to an asymmetric carrier sensing relationship...
The performance of wireless body area networks (WBANs) may be degraded due to co-channel interference, i.e., when sensors of different coexisting WBANs transmit at the same time-slots using the same channel. In this paper, we exploit the 16 channels available in the 2.4 GHz unlicensed international band of ZIGBEE, and propose a distributed scheme that opts to avoid interference through channel to...
Sensor network virtualization enables the possibility of sharing common physical resources to multiple stakeholder applications. This paper focuses on addressing the dynamic adaptation of already assigned virtual sensor network resources to respond to time varying application demands. We propose an optimization framework that dynamically allocate applications into sensor nodes while accounting for...
In this document is presented a study about TV White Spaces (TVWS) current state in Ecuador, how this can solve coverage problems in difficult to reach geographic zones in comparison with other kind of technologies, facilitating the access to basic services such as Internet and Smart Grids support. Later the adopted standards by FCC in order to design White Spaces Devices are mentioned and the TVWS...
The article discusses the problem of the transmission of reliable monitoring and control signals through communication channels of complex energy supply of industrial objects control systems. Mathematically justified mismatch concept “accuracy of information” with “protected information from the noise in the communication channel.” The principles of the combined code, providing a high level of reliability...
The ultrathin graphene metasurface is proposed and analyzed as a cloaking shell for cylindrical objects with the aim of wideband tunable scattering cancellation in terahertz (THz) spectrum. This mantle cloak is structured by periodic array of graphene nanopatches. In this paper, it is analytically shown that the metasurface reactance can be tuned from inductive to capacitive, as a function of the...
In this paper, competitive interactions between a secondary transmitter-receiver pair and a jammer are investigated in a distributed manner over N orthogonal frequency bands, each of which is licensed to a primary user (PU). There is an interference restriction at the secondary receiver (SR) and power budget constraints at the secondary transmitter (ST) and the jammer. In addition, the ST (jammer)...
Satellite communications (SATCOM) are prone to both intentional and unintentional interference, which can significantly degrade the reliability of packet transmissions. Here, we investigate different approaches for interference mitigation in SATCOM based on dynamic frequency hopping (DFH). We consider a star topology, where multiple LEO satellites transmit packets to a common GEO satellite. The FH...
Sharing the spectrum among multiple operators seems promising in millimeter wave (mmWave) systems. One explanation is the highly directional transmission in mmWave, which reduces the interference caused by one network on the other networks sharing the same resources. In this paper, we model a mmWave cellular system where an operator that primarily owns an exclusive-use license of a certain band can...
Deployment of Multiple Cognitive Radio Networks (CRNs) is a very common scenario in today's world, like in the field of defence or disaster management. In this paper, we deal with the case of multiple numbers of co-located CRNs acting as secondary network along with one primary user (PU). We study the node based throughput performance of a CRN in presence of several coexisting CRNs. We generalize...
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