Temat: channels - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Error statistics for concatenated systems on non-renewal time-varying channels
Autorzy:: Pimentel, C.
Powiązania:: https://bibliotekanauki.pl/articles/309548.pdf
Data publikacji:: 2001
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: finite state channels
multigap distribution
constrained codes
concatenated systems
Gilbert-Elliott channels
combinatorial methods
Opis:: The statistics of the error process generated by a discrete super channel formed by the concatenation of a constrained encoder, a non-renewal finite state channel (FSC), and a constrained decoder is studied in this paper. First, recursions are developed for the error weight distribution. This statistics is relevant to the design of coding schemes and interleaving in concatenated. systems. We also study the renewal nature of the residual error process as modified by the constrained decoder. Ferreira et al. conjectured that if the channel model is a renewal FSC, the super channel can be modeled as a similar renewal model. We use a statistics called the multigap distribution to analytically disprove this hypothesis. Furthermore, the effect of interleaving is investigated from a new perspective using the variance of the multigap distribution.
Źródło:: Journal of Telecommunications and Information Technology; 2001, 3; 55-60
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 2.

Tytuł:: Characterization of the indoor radio propagation channel at 2.4 GHz
Autorzy:: Wysocki, T. A.
Zepernick, H.-J.
Powiązania:: https://bibliotekanauki.pl/articles/309221.pdf
Data publikacji:: 2000
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: indoor radiocommunication
microwave propagation
fading channels
jamming
Opis:: The unlicensed industrial, scientific, and medical (ISM) band at 2.4 GHz has gained increased attention recently due to the high data rate communication systems developed to operate in this band. The paper presents measurement results of fading characteristics, multipath parameters and background interference for these frequencies. Some statistical analysis of the measured data is presented. The paper provides information that may be useful in design and deployment of communication systems operating in the 2.4 GHz ISM band, like those compilant with IEEE 802.11 standard and Bluetooth open wireless standard.
Źródło:: Journal of Telecommunications and Information Technology; 2000, 3-4; 84-90
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 3.

Tytuł:: Modeling spatial aspects of mobile channel for low antenna height environments
Autorzy:: Simsim, M. T.
Khan, N. M.
Rapajic, P. B.
Powiązania:: https://bibliotekanauki.pl/articles/309429.pdf
Data publikacji:: 2006
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: Gaussian distributions
geometric modeling
multi-path channels
scattering
Opis:: It is essential to have deep understanding of the mobile radio channel in particular for radio communication modeling and advanced technology system design. Models for the mobile radio channel are vital for the study of smart antenna systems, both for the design of algorithms, system-testing purposes, and for network planning. This paper provides an intensive study of the spatial characteristics of the mobile channel for low antenna height cellular environments, i.e., picocells and microcells, assuming Gaussian distributed scatterers. We investigate previous work on the angle of arrival (AoA) statistics for Gaussian distributed scatterers and make appropriate comments. Further, we employ the recently proposed eccentro-scattering physical channel model, as a generalized model, to derive the probability density function (pdf) of AoA of the multipaths at base station (BS) assuming Gaussian distributed scatterers around both BS and mobile station (MS). We found that the pdf of AoA at BS is directly affected by the standard deviation of the scatterers' density and the size of the scattering disc. The derived formulas, in closed form, can be used further for performance assessment of smart antennas and beamwidth design purposes.
Źródło:: Journal of Telecommunications and Information Technology; 2006, 2; 97-105
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 4.

Tytuł:: An Efficient Chaotic Interleaver for Image Transmission over IEEE 802.15.4 Zigbee Network
Autorzy:: El-Bendary, M. A. M. M.
El-Azm, A. A.
Powiązania:: https://bibliotekanauki.pl/articles/309078.pdf
Data publikacji:: 2011
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: block interleaving
chaotic interleaving
convolutional interleaving
fading channels
ZigBee
Opis:: This paper studies a vital issue in wireless communications, which is the transmission of images over wireless networks. IEEE ZigBee 802.15.4 is a short-range communication standard that could be used for small distance multimedia transmissions. In fact, the ZigBee network is a wireless personal area network (WPAN), which needs a strong interleaving mechanism for protection against error bursts. Thispaper presents a novel chaotic interleaving scheme for this purpose. This scheme depends on the chaotic Baker map. A comparison study between the proposed chaotic interleaving scheme and the traditional block and convolutional interleaving schemes for image transmission over a correlated fading channel is presented. The simulation results show the superiority of the proposed chaotic interleaving scheme over the traditional schemes.
Źródło:: Journal of Telecommunications and Information Technology; 2011, 2; 67-73
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 5.

Tytuł:: Secrecy Rate Region Enhancement in Multiple Access Wiretap Channel
Autorzy:: Shah, Shahid Mehraj
Powiązania:: https://bibliotekanauki.pl/articles/2142307.pdf
Data publikacji:: 2022
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: multiple access channels
physical layer security
strong secrecy
wiretap channel
Opis:: It is commonly known that physical layer security is achieved with a trade-off in terms of the achievable rate. Hence, security constraints generate rate losses in wiretap channels. To mitigate such rate losses in multi-user channels, we propose a coding/decoding scheme for multi-user multiple access wiretap channel (MAC-WT), where previously transmitted messages are used as a secret key to enhance the secrecy rates of the transmitting users, until the usual Shannon capacity region of a multiple access channel (MAC) is achieved without the secrecy constraint. With this coding scheme, all messages transmitted in the recent past are secure with respect to all the information of the eavesdropper till now. To achieve this goal, we introduce secret key buffers at both the users and the legitimate receiver. Finally, we consider a fading MAC-WT and show that with this coding/decoding scheme, we can achieve the capacity region of a fading MAC channel (in the ergodic sense).
Źródło:: Journal of Telecommunications and Information Technology; 2022, 2; 14--25
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 6.

Tytuł:: Blind Estimation of Linear and Nonlinear Sparse Channels
Autorzy:: Georgoulakis, K.
Powiązania:: https://bibliotekanauki.pl/articles/307846.pdf
Data publikacji:: 2013
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: blind estimation and equalization
clustering techniques
sparse zero pad channels
Opis:: This paper presents a Clustering Based Blind Channel Estimator for a special case of sparse channels - the zero pad channels. The proposed algorithm uses an unsupervised clustering technique for the estimation of data clusters. Clusters labelling is performed by a Hidden Markov Model of the observation sequence appropriately modified to exploit channel sparsity. The algorithm achieves a substantial complexity reduction compared to the fully evaluated technique. The proposed algorithm is used in conjunction with a Parallel Trellis Viterbi Algorithm for data detection and simulation results show that the overall scheme exhibits the reduced complexity benefits without performance reduction.
Źródło:: Journal of Telecommunications and Information Technology; 2013, 1; 65-71
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 7.

Tytuł:: Design of filterbank transceivers for dispersive channels with arbitrary-length impulse response
Autorzy:: Mertins, A.
Powiązania:: https://bibliotekanauki.pl/articles/307670.pdf
Data publikacji:: 2003
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: joint transmitter/receiver design
filter banks
information rate maximization
dispersive channels
Opis:: This paper addresses the joint design of transmitter and receiver for multichannel data transmission over dispersive channels. The transmitter is assumed to consist of FIR filters and the channel impulse response is allowed to have an arbitrary length. The design criterion is the maximization of the information rate between transmitter input and receiver output under the constraint of a fixed transmit power. A link to minimum mean squared error designs for a similar setting is established. The proposed algorithm allows a straightforward transmitter design and generally yields a near-optimum solution for the transmit filters. Under certain conditions. the exact solution for the globally optimal transmitter is obtained.
Źródło:: Journal of Telecommunications and Information Technology; 2003, 2; 11-16
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 8.

Tytuł:: Performance Evaluation of MC-CDMA Systems with Single User Detection Technique using Kernel and Linear Adaptive Method
Autorzy:: Fateh, Rachid
Darif, Anouar
Safi, Said
Powiązania:: https://bibliotekanauki.pl/articles/2058482.pdf
Data publikacji:: 2021
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: BRAN channels
equalization
kernel method
MC-CDMA
reproducing kernel Hilbert space
Opis:: Among all the techniques combining multi-carrier modulation and spread spectrum, the multi-carrier code division multiple access (MC-CDMA) system is by far the most widely studied. In this paper, we present the performance of the MC-CDMA system associated with key single-user detection techniques. We are interested in problems related to identification and equalization of mobile radio channels, using the kernel method in Hilbert space with a reproducing kernel, and a linear adaptive algorithm, for MC-CDMA systems. In this context, we tested the efficiency of these algorithms, considering practical frequency selective fading channels, called broadband radio access network (BRAN), standardized for MC-CDMA systems. As far as the equalization problem encountered after channel identification is concerned, we use the orthogonality restoration combination (ORC) and the minimum mean square error (MMSE) equalizer techniques to correct the distortion of the channel. Simulation results demonstrate that the kernel algorithm is efficient for practical channel.
Źródło:: Journal of Telecommunications and Information Technology; 2021, 4; 1--11
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 9.

Tytuł:: Comparison of Wavelet Decomposition Coefficients Transmission Systems Using Splines and Classical Types of Modulation
Autorzy:: Kutin, A. I.
Powiązania:: https://bibliotekanauki.pl/articles/309261.pdf
Data publikacji:: 2015
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: multi-speed channels
spline-modulation
spline Savitzky-Golay filter
wavelet decomposition
Opis:: Wavelets are becoming increasingly used as a tool for the analysis of non-stationary data. To transmit the coefficients resulting from the signal decomposition traditionally their combination into a single data packet is used, without including unequal energy contribution of each factor and impact of the decomposition level. This paper analyzes (at different transmission speeds) the signals properties produced by classical modulation methods and spline modulation for wavelet coefficients transmission proposed by the author. For all signal types the additive Gaussian noise is used as a noise disturbance.
Źródło:: Journal of Telecommunications and Information Technology; 2015, 3; 25-31
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 10.

Tytuł:: Higher Order Cumulants for Identification and Equalization of Multicarrier Spreading Spectrum Systems
Autorzy:: Safi, S.
Frikel, M.
Zeroual, A.
M'Saad, M.
Powiązania:: https://bibliotekanauki.pl/articles/309082.pdf
Data publikacji:: 2011
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: blind identification and equalization
communication channels
higher order cumulants
MC-CDMA systems
Opis:: This paper describes two blind algorithms for multicarrier code division multiple access (MC-CDMA) system equalization. In order to identify, blindly, the impulse response of two practical selective frequency fading channels called broadband radio access network (BRAN A and BRAN E) normalized for MC-CDMA systems, we have used higher order cumulants (HOC) to build our algorithms. For that, we have focussed on the experimental channels to develop our blind algorithms able to simulate the measured data with high accuracy. The simulation results in noisy environment and for different signal to noise ratio (SNR) demonstrate that the proposed algorithms are able to estimate the impulse response of these channels blindly (i.e., without any information about the input), except that the input excitation is i.i.d. (identically and independent distributed) and non-Gaussian. In the part of MC-CDMA, we use the zero forcing and the minimum mean square error equalizers to perform our algorithms. The simulation results demonstrate the effectiveness of the proposed algorithms.
Źródło:: Journal of Telecommunications and Information Technology; 2011, 2; 74-84
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 11.

Tytuł:: On a method to authenticate and verify digital streams
Autorzy:: Wysocki, B.J.
Wang, Y.
Safavi-Naini, R.
Powiązania:: https://bibliotekanauki.pl/articles/309279.pdf
Data publikacji:: 2002
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: authentication algorithms
hash chains
signing digital streams
Markov modelling
Gilbert-Elliott channels
Opis:: Recently, digital streams have become widely used to make audio, video, and other media available in real-time over the Internet. As with other transmission methods, the recipient needs to have a possibilty to verify the source and authenticity of the received information. Several techniques have been proposed to deal with this issue. Most of them are vulnerable to packet losses or they introduce unacceptable computational and/or communication overheads. Some of the graph-based techniques provide immunity to burst losses of certain length. However, these techniques are not immune to the loss of packets containing signatures or occasional burst of lengths greater than the assumed one. In the paper, we propose a modification to one of the graph-based techniques that introduces immunity to the loss of packets containing signatures, without introducing any additional overheads.
Źródło:: Journal of Telecommunications and Information Technology; 2002, 2; 45-52
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 12.

Tytuł:: Error probability and error stream properties in channel with slow Rician fading
Autorzy:: Noga, K.M.
Powiązania:: https://bibliotekanauki.pl/articles/309378.pdf
Data publikacji:: 2003
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: Rician fading channels
multipath propagation
bit error probability
stream of errors
weighted spectrum of errors
block error probability
Opis:: In a radio communication channel wave parameters fluctuate randomly. The signal envelope undergoes deep fades. When binary information is transmitted through such a channel, fading causes random variation of probabilities of error associated with the detection of individual elementary signals, which produces a clustering of errors. The paper presents an analytical description of the probability of bit error in the channel with very slow Rician fading and Gaussian noise for noncoherent and coherent detection. Digital systems employing error detection or error correction coding are generally based on the transmission of blocks of N sequential bits. Expressions are given for the probability of n errors occurring in N bits (weighted spectrum of errors) and the probability of more than n errors in a block of N bits (block error probability) for noncoherent frequency shift keying (NCFSK). Also the calculations are presented graphically. Keywords- Rician fading channels, multipath propagation, biterror probability, stream of errors, weighted spectrum of errors,block error probability.
Źródło:: Journal of Telecommunications and Information Technology; 2003, 4; 3-8
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Informacja

Wyszukujesz frazę "channels" wg kryterium: Temat

Źródło danych

Dostawca treści

Kolekcja

Rok wydania

Wydawca

Temat

Autor

Typ dokumentu

Język