scispace - formally typeset
Search or ask a question
Topic

Frequency band

About: Frequency band is a research topic. Over the lifetime, 35526 publications have been published within this topic receiving 314551 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: A cooperative approach to the sensing task of wireless cognitive radio (CR) networks is introduced based on a basis expansion model of the power spectral density map in space and frequency that reduces spatial and frequency spectrum leakage by 15 dB relative to least-squares alternatives.
Abstract: A cooperative approach to the sensing task of wireless cognitive radio (CR) networks is introduced based on a basis expansion model of the power spectral density (PSD) map in space and frequency. Joint estimation of the model parameters enables identification of the (un)used frequency bands at arbitrary locations, and thus facilitates spatial frequency reuse. The novel scheme capitalizes on two forms of sparsity: the first one introduced by the narrow-band nature of transmit-PSDs relative to the broad swaths of usable spectrum; and the second one emerging from sparsely located active radios in the operational space. An estimator of the model coefficients is developed based on the Lasso algorithm to exploit these forms of sparsity and reveal the unknown positions of transmitting CRs. The resultant scheme can be implemented via distributed online iterations, which solve quadratic programs locally (one per radio), and are adaptive to changes in the system. Simulations corroborate that exploiting sparsity in CR sensing reduces spatial and frequency spectrum leakage by 15 dB relative to least-squares (LS) alternatives.

499 citations

Proceedings ArticleDOI
12 Dec 2013
TL;DR: A basic tutorial on the types of radio frequency communications and the benefits and liabilities of each are given and specific topics to be explored will be licensed verses unlicensed frequencies, distance between remote radios and base stations, and communications architectures.
Abstract: Radio Frequency (RF) communications are an important smart grid enabler for functions such as volt/VAR control, recloser control, and feeder restorations and isolation. This paper will give a basic tutorial on the types of radio frequency communications and the benefits and liabilities of each. Specific topics to be explored will be licensed verses unlicensed frequencies, distance between remote radios and base stations, and communications architectures. Radio technology is often referred in numerical ranges or frequencies. The decision on which frequency to employ in a network depends on a few key variables. Prior to deciding which frequency for a network, the application for the radio use will assist with dictation of which frequency range to utilize. Applications such as recloser control and volt/Var control may require a radio device that can provide a high bandwidth/fast speed solution. Other SCADA applications such as sensor monitoring may only require small bandwidth and for data delivery to be at a much slower speed. Another variable when deciding on a radio network is the distance from the main SCADA hosts to end remote devices such as RTUs or PLCs. Lower end frequencies (100 MHz-900 MHz) provide further coverage and greater distance from base stations/Access Points to remote end devices, whereas higher frequencies (2.4 GHz-5.8 GHz) provide shorter distance coverage, but higher bandwidth and relay data back to SCADA hosts much faster. Determining a network's architecture should focus on either the desire of a private, licensed network or the notion of an unlicensed, less expensive network. The lower licensed frequency ranges (100 MHz, 200 MHz, 400 MHz and upper 900 MHz bands) are often referred to as MAS (Multiple Address Systems) networks and require license acquisition from the FCC once geographical coverage is determined. These licenses are granted for the lower frequencies as mentioned previously but are considered the proprietary use of the owner. Anyone operating in these frequencies will be fined/cited by the FCC. The less expensive, unlicensed network is allowable for frequencies ranging from 902 MHz-928 MHz, which is defined as the ISM (Industrial, Scientific, and Medical) bands. Within the unlicensed frequency band, there exist registered bands (3.65 GHz) that employ WiMax (Wireless Microwave Access for Broadband) technology that provide shorter coverage for remote devices, however, the bandwidth and speed provided by these frequencies make them just as popular for networks. Further analysis and discussion of licensed versus unlicensed radio wireless communications is proposed in this paper.

492 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a method based on the kurtosis of the envelope spectrum amplitudes of the demodulated signal, rather than on the filter time signal, to detect transients with smaller signal-to-noise ratio comparing to the spectral kurtogram.

487 citations

Journal ArticleDOI
01 Feb 2007
TL;DR: This paper investigates the behavior of capacity when constraints are placed on the channel output signal (as well as generalizations thereof), finding that in certain network scenarios, including multiple-access and relay situations, both the structure of the problem and the conclusions change.
Abstract: Capacity is often studied under constraints on the channel input signals. This paper investigates the behavior of capacity when constraints are placed on the channel output signal (as well as generalizations thereof). While such a change in perspective leaves the point-to-point problem (essentially) unchanged, the main conclusion is that in certain network scenarios, including multiple-access and relay situations, both the structure of the problem and the conclusions change. For example, capacity results are found for the many-user Gaussian multiple-access channel (MAC) with arbitrarily dependent sources, cooperation, or feedback, and for the nondegraded Gaussian relay network. The investigations are motivated by recent questions arising in spectrum sharing and dynamic spectrum allocation: Multiple independent networks share the same frequency band, but are spatially mostly disjoint. One approach to grant coexistence is via spatial interference power restrictions, imposed at the network level, rather than at the device level. The corresponding capacity question is posed and partially answered in this paper

469 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that the vorticity of each twisted electromagnetic wave is preserved after the propagation, paving the way for entirely new paradigms in radio communication protocols.
Abstract: We have shown experimentally that it is possible to propagate and use the properties of twisted non-monochromatic incoherent radio waves to simultaneously transmit to infinity more radio channels on the same frequency band by encoding them in different orbital angular momentum states. This novel radio technique allows the implementation of, at least in principle, an infinite number of channels on one and the same frequency, even without using polarization or dense coding techniques. An optimal combination of all these physical properties and techniques represents a solution for the problem of radio band congestion. Our experimental findings show that the vorticity of each twisted electromagnetic wave is preserved after the propagation, paving the way for entirely new paradigms in radio communication protocols.

468 citations


Network Information
Related Topics (5)
Antenna (radio)
208K papers, 1.8M citations
85% related
Amplifier
163.9K papers, 1.3M citations
84% related
Transmission (telecommunications)
171.3K papers, 1.2M citations
83% related
Wireless
133.4K papers, 1.9M citations
83% related
Wave propagation
55K papers, 1.1M citations
81% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023172
2022391
20211,083
20201,881
20192,240
20182,091