ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Publication Date: 2020-06-06
    Description: A very important task in Mobile Cognitive Radio Networks (MCRN) is to ensure that the system releases a given frequency when a Primary User (PU) is present, by maintaining the principle to not interfere with its activity within a cognitive radio system. Afterwards, a cognitive protocol must be set in order to change to another frequency channel that is available or shut down the service if there are no free channels to be found. The system must sense the frequency spectrum constantly through the energy detection method which is the most commonly used. However, this analysis takes place in the time domain and signals cannot be easily identified due to changes in modulation, power and distance from mobile users. The proposed system works with Gaussian Minimum Shift Keying (GMSK) and Orthogonal Frequency Division Multiplexing (OFDM) for systems from Global System for Mobile Communication (GSM) to 5G systems, the signals are analyzed in the frequency domain and the Rényi-Entropy method is used as a tool to distinguish the noise and the PU signal without prior knowledge of its features. The main contribution of this research is that uses a Software Defined Radio (SDR) system to implement a MCRN in order to measure the behavior of Primary and Secondary signals in both time and frequency using GNURadio and OpenBTS as software tools to allow a phone call service between two Secondary Users (SU). This allows to extract experimental results that are compared with simulations and theory using Rényi-entropy to detect signals from SU in GMSK and OFDM systems. It is concluded that the Rényi-Entropy detector has a higher performance than the conventional energy detector in the Additive White Gaussian Noise (AWGN) and Rayleigh channels. The system increases the detection probability (PD) to over 96% with a Signal to Noise Ratio (SNR) of 10dB and starting 5 dB below energy sensing levels.
    Electronic ISSN: 1099-4300
    Topics: Chemistry and Pharmacology , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2020-10-02
    Description: Modular robots are flexible structures that offer versatility and configuration options for carrying out different types of movements; however, disconnection problems between the modules can lead to the loss of information, and, therefore, the proposed displacement objectives are not met. This work proposes the control of a chain-type modular robot using an artificial neural network (ANN) that enables the robot to go through different environments. The main contribution of this research is that it uses a software defined radio (SDR) system, where the Wi-Fi channel with the best signal-to-noise Ratio (SNR) is selected to send the information regarding the simulated movement parameters and obtained by the controller to the modular robot. This allows for faster communication with fewer errors. In case of a disconnection, these parameters are stored in the simulator, so they can be sent again, which increases the tolerance to communication failures. Additionally, the robot sends information about the average angular velocity, which is stored in the cloud. The errors in the ANN controller results, in terms of the traveled distance and time estimated by the simulator, are less than 6% of the real robot values.
    Electronic ISSN: 2079-9292
    Topics: Electrical Engineering, Measurement and Control Technology
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    facet.materialart.
    Unknown
    SciELO Books - Editorial Universidad del Rosario | SciELO Books - Editorial Universidad del Rosario
    Publication Date: 2022-03-22
    Description: El ejercicio de reunir estas historias, estos conocimientos disponibles, se propuso para encontrar las palabras y los signos que, como prenociones sobre la vida cotidiana de un grupo individuos, ilustraran (no solo) un mar de problemas (sociológicos): anomías, malestares —por ejemplo, los delirios de violencia, el abuso de alcohol y drogas, las rencillas familiares, etc.—, sino también solidaridades y, sobre todo, amores: múltiples y coloridas representaciones que los individuos-partes del grupo (mis familiares y yo mismo) hacemos de nuestro estado, de nuestras condiciones, del lugar que ocupamos con respecto a los demás. Bourdianamente, me corresponde como científico social “demandar al razonamiento, la revelación de las causas estructurales que las palabras y los signos aparentes no develan más que velándolas” (Bourdieu 2000, 558).
    Keywords: Social Science ; General ; bic Book Industry Communication::J Society & social sciences::JF Society & culture: general
    Language: Spanish
    Format: image/png
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...