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Tytuł:
Implementation of Multiple Access Techniques Applicable for Maritime Satellite Communications
Autorzy:
Ilcev, S. D.
Powiązania:
https://bibliotekanauki.pl/articles/116635.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
Global Maritime Distress and Safety System (GMDSS)
Maritime Mobile Satellite Communications (MMSC)
Multiple Access (MA)
Multiple Access Techniques
Code Division Multiple Access (CDMA)
Time Division Multiple Access (TDMA)
Frequency Division Multiple Access (FDMA)
Random (Packet) Division Multiple Access (RDMA)
Opis:
In this paper are introduced fundamentals, characteristics, advantages and disadvantages of Multiple Access (MA) employed as transmission techniques in the Maritime Mobile Satellite Communications (MMSC) between ships and Coast Earth Station (CES) via Geostationary Earth Orbit (GEO) or Not-GEO satellite constellations. In fixed satellite communication, as a rule, especially in MMSC many users are active at the same time. The problem of simultaneous communications between many single or multipoint mobile satellite users can be solved by using MA technique, such as Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA), Space Division Multiple Access (SDMA) and Random (Packet) Division Multiple Access (RDMA). Since the resources of the systems such as the transmitting power and the bandwidth are limited, it is advisable to use the channels with complete charge and to create a different MA to the channel. This generates a problem of summation and separation of signals in the transmission and reception parts, respectively. Deciding this problem consists in the development of orthogonal channels of transmission in order to divide signals from various users unambiguously on the reception part.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2013, 7, 4; 529-540
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of an LSTM-based NOMA Detector Over Time Selective Nakagami-m Fading Channel Conditions
Autorzy:
Shankar, Ravi
Bangare, Jyoti L.
Kumar, Ajay
Gupta, Sandeep
Mehraj, Haider
Kulkarni, Shriram S.
Powiązania:
https://bibliotekanauki.pl/articles/2142313.pdf
Data publikacji:
2022
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
deep learning
DL
multiple-input multiple-output
MIMO
non-orthogonal multiple access
NOMA
orthogonal multiple access
OMA
Opis:
This work examines the efficacy of deep learning (DL) based non-orthogonal multiple access (NOMA) receivers in vehicular communications (VC). Analytical formulations for the outage probability (OP), symbol error rate (SER), and ergodic sum rate for the researched vehicle networks are established Rusing i.i.d. Nakagami-m fading links. Standard receivers, such as least square (LS) and minimum mean square error (MMSE), are outperformed by the stacked long-short term memory (S-LSTM) based DL-NOMA receiver. Under real time propagation circumstances, including the cyclic prefix (CP) and clipping distortion, the simulation curves compare the performance of MMSE and LS receivers with that of the DL-NOMA receiver. According to numerical statistics, NOMA outperforms conventional orthogonal multiple access (OMA) by roughly 20% and has a high sum rate when considering i.i.d. fading links.
Źródło:
Journal of Telecommunications and Information Technology; 2022, 3; 17--24
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
CG-SCMA Codebook Design Based on Maximized Euclidian Distance
Autorzy:
Mohamed, Sura S.
Abdullah, Hikmat N.
Powiązania:
https://bibliotekanauki.pl/articles/2200958.pdf
Data publikacji:
2023
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
codebook
Euclidian distance
MPA
multiple access
sparse code
Opis:
Sparse code multiple access (SCMA) is a multi-dimensional codebook based on a class of non-orthogonal multiple access (NOMA) technologies enabling the delivery of non-orthogonal resource elements to numerous users in 5G wireless communications without increasing complexity. This paper proposes a computer-generated sparse code multiple access (CG-SCMA) technique, where the minimum Euclidian distance (MED) of a star 16-point quadrature amplitude modulation is maximized by CG-SCMA, thus creating a complex SCMA codebook based on optimizing the difference between the first and other radiuses over rotated constellations. To specify the most suitable values for this constellation, it is divided into four sub-constellations using trellis coded modulation (TCM) in an effort to optimize MED. The new codebook has four sub-constellations with MED values of 3.85, 2.26, 2.26, and 3.85, respectively. Application of the message passing algorithm (MPA) ensures low complexity of the decoding process
Źródło:
Journal of Telecommunications and Information Technology; 2023, 1; 18--24
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance improvement of a novel zero cross-correlation code using Pascal’s triangle matrix for SAC-OCDMA systems
Autorzy:
Driz, Samia
Fassi, Benattou
Kandouci, Chahinaz
Ghali, Fodil
Powiązania:
https://bibliotekanauki.pl/articles/2063900.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
multiple access interference
pascal’s triangle matrix
quality of service
spectral amplitude coding-optical code division multiple access
zero cross-correlation
Opis:
In order to minimize the receiver complexity and improve the performance of the spectral amplitude coding - optical code division multiple access system, a novel one-dimensional zero cross-correlation code using Pascal’s triangle matrix has been suggested. This research article shows that the position of chip “1” in the code sequences is one of the important factors affecting system performance. In fact, mathematical results show that, for the allwavelength direct detection, it is possible to reduce the number of filters without sacrificing system performance. In addition, compared to one-wavelength direct detection, the signalto-noise ratio value is increased with an increasing weight by using wide-bandwidth filters as decoders. Performance of the proposed system in terms of the minimum bit error rate is validated using the OptiSystem software. Compared with the previous systems at 622 Mbps, the suggested system gave the best values of bit error rate of around 10⁻⁴³, 10⁻³⁵, and 10⁻²⁶ for higher, medium, and lower service demand, respectively.
Źródło:
Opto-Electronics Review; 2022, 30, 1; 1--7
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Power Allocation for Energy-Harvesting-based Fading Cognitive Multiple Access Channels : with or without Successive Interference Cancellation
Autorzy:
Li, Q.
Xu, D.
Powiązania:
https://bibliotekanauki.pl/articles/963855.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cognitive radio
power allocation
multiple access channels
energy harvesting
Opis:
This paper considers a fading cognitive multiple access channel (CMAC), where multiple secondary users (SUs), who share the spectrum with a primary user (PU), transmit to a cognitive base station (CBS). A power station is assumed to harvest energy from the nature and then provide power to the SUs. We investigate the power allocation problems for such a CMAC to maximize the SU sum rate under the interference power constraint, the sum transmit power constraint and the peak transmit power constraint of each individual SU. In particular, two scenarios are considered: with successive interference cancellation (SIC) and without SIC. For the first scenario, the optimal power allocation algorithm is derived. For the second scenario, a heuristic algorithm is proposed. We show that the proposed algorithm with SIC outperforms the algorithm without SIC in terms of the SU sum rate, while the algorithm without SIC outperforms the algorithm with SIC in terms of the number of admitted SUs for a high sum transmit power limit and a low peak transmit power limit of each individual SU.
Źródło:
International Journal of Electronics and Telecommunications; 2017, 63, 1; 65-72
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of SHIFTZCC codes for Optical CDMA system
Autorzy:
Panda, Satyasen
Powiązania:
https://bibliotekanauki.pl/articles/1178705.pdf
Data publikacji:
2017
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
cross correlation (CC)
multiple access interference (MAI)
optical code division multiple access (OCDMA)
shift zero cross correlation code (SHIFTZCC) and signal to noise ratio (SNR)
spectral amplitude coding optical code division multiple access (SAC-OCDMA)
Opis:
In this paper, we propose a novel SAC-OCDMA code called Shift Zero Cross Correlation (SHIFTZCC) code with zero cross correlation property to minimize the Multiple Access Interface (MAI), to be more scalable and secure compared to the other existing SAC-OCDMA codes. This SHIFTZCC code is constructed using address segment and data segment. In this work, the proposed SHIFTZCC code is implemented in an optical network using the Opti-System software for the spectral amplitude coded optical code division multiple access (SAC-OCDMA) scheme. The chief advantage of the proposed SHIFTZCC code is the zero cross correlation property, which reduces both the MAI and other noises improving the system performance. The proposed SHIFTZCC code provides flexibility in selecting the code parameters, supports a large number of users with higher data rate and longer fiber length. Simulation results prove that the optical code division multiple access system based on the proposed SHIFTZCC code supports maximum number of simultaneous users with higher transmission rate, lower bit error rates (BER) and longer travelling distance without any signal quality degradation, as compared to the former existing SAC-OCDMA codes.
Źródło:
World Scientific News; 2017, 67, 2; 365-389
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reduction of BER using RSC code for Optical Code Division Multiple Access Networks
Autorzy:
Panda, Satyasen
Powiązania:
https://bibliotekanauki.pl/articles/1178316.pdf
Data publikacji:
2017
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Cross Correlation (CC)
Multiple Access Interface (MAI)
Optical Code Division Multiple Access (OCDMA)
Random Sparse Code (RSC)
Wavelength hopping time spreading (WHTS)
Opis:
In this study, a two dimensional (2-D) wavelength hopping and time spreading (WHTS) optical code division multiple access (OCDMA) code is designed using Sparse ruler technique. The proposed 64 bit 2-D code is constructed by an algorithm based on random spacing of sparse codes referred in this work as Random Sparse Code (RSC). The performance of the proposed 2-D RSC is evaluated in terms of bit error rate (BER), received signal power and time domain analysis of received signals. The system performance of the OCDMA system utilizing 2-D RSC code improved significantly due to less BER, low cross correlation property and simple encoder/decoder design. The output BER is much lower at a data rate of 1.25 gbps and 2.5 gbps for a distance of 100 km with ITU-T standard single mode fiber with attenuation level of 0.2dB/km.
Źródło:
World Scientific News; 2017, 81, 2; 106-120
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
CDMA wireless system with blind multiuser detector
Autorzy:
Leong, W. Y.
Homer, J.
Powiązania:
https://bibliotekanauki.pl/articles/309140.pdf
Data publikacji:
2006
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
code division multiple access
independent component analysis
blind source separation
Opis:
In this paper we present an approach capable of countering the presence of multiple access interference (MAI) in code division multiple access (CDMA) channels. We develop and implement a blind multiuser detector, based on an independent component analysis (ICA) to mitigate both MAI and noise. This algorithm has been utilized in blind source separation (BSS) of unknown sources from their linear mixtures. It can also be used for estimation of the basis vectors of BSS. The aim is to include an ICA algorithm within a wireless receiver in order to reduce the level of interference in CDMA systems. This blind multiuser detector requires less precise knowledge of the channel than does the conventional single-user receiver. The proposed blind multiuser detector is made robust with respect to imprecise knowledge of the received signature waveforms of the user of interest. Several experiments are performed in order to verify the validity of the proposed learning algorithm.
Źródło:
Journal of Telecommunications and Information Technology; 2006, 1; 69-75
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimum double-matched detection and its application to SSMA systems
Autorzy:
Pawelec, J.J.
Powiązania:
https://bibliotekanauki.pl/articles/309576.pdf
Data publikacji:
2001
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
optimum detection
spread spectrum multiple access systems
NB interference
adaptation
Opis:
This paper is concerned with the issue of optimum detection of known signal in nonwhite noise and/or narrow-band interferences. The detection is carried out in three steps. First, some function related to the power spectrum of interfering process I(z) is estimated via adaptation. Second, the signal + interference is withened due to I(z). Third, the replica of signal is filtered via I(z) to match it to the deformed signal in the previous step. The simulation of SS reception in presence of NB interference shows a high gain in comparison to classical single-matched detection.
Źródło:
Journal of Telecommunications and Information Technology; 2001, 3; 80-85
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
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
Tytuł:
Uplink NOMA Scheme for Wi-Fi Applications
Autorzy:
Ghazi, H. S.
Wesołowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/226180.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
5G
Non-Orthogonal Multiple Access
NOMA
Successive Interference Cancellation
SIC
Opis:
Non-Orthogonal Multiple Access (NOMA) with Successive Interference Cancellation (SIC) is one of the promising techniques proposed for 5G systems. It allows multiple users with different channel coefficients to share the same (time/frequency) resources by allocating several levels of (power/code) to them. In this article, a design of a cooperative scheme for the uplink NOMA Wi-Fi transmission (according to IEEE 802.11 standards) is investigated. Various channel models are exploited to examine the system throughput. Convolutional coding in conformance to IEEE 802.11a/g is applied to evaluate the system performance. The simulation results have been addressed to give a clear picture of the performance of the investigated system.
Źródło:
International Journal of Electronics and Telecommunications; 2018, 64, 4; 481-485
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analyses of Code Division Multiple Access (CDMA) Schemes for Global Mobile Satellite Communications (GMSC)
Autorzy:
Ilcev, D. S.
Powiązania:
https://bibliotekanauki.pl/articles/1841573.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
Global Mobile Satellite Communications
Code Division Multiple Access
Multiple Access Technique
Satellite Communication Systems
Mobile Earth Station
orthogonal channels of transmission
GMSC Networks
very small aperture terminals
Opis:
This paper describes in particular Code Division Multiple Access (CDMA) applicable in Global Mobile Satellite Communications (GMSC). In satellite communication systems, as a rule, especially in GMSC networks many users are active at the same time. The problem of simultaneous communications between many single or multipoint mobile satellite users, however, can be solved by using Multiple Access Technique (MAT) system. Since the resources of the systems such as the transmitting power and the bandwidth are limited, it is advisable to use the channels with complete charge and to create a different MAT to the channel. This generates a problem of summation and separation of signals in the transmission and reception parts, respectively. Deciding this problem consists in the development of orthogonal channels of transmission in order to divide signals from various users unambiguously on the reception part.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2020, 14, 4; 805-810
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative Analysis of NOMA and OMA Schemes: GSVD-based NOMA Systems and the Role of Mobile Edge Computing
Autorzy:
Dursun, Yunus
Powiązania:
https://bibliotekanauki.pl/articles/24200752.pdf
Data publikacji:
2023
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
generalized singular value decomposition
MIMO
mobile edge computing
non-orthogonal multiple-access
Opis:
This paper presents a comprehensive study that examines the fundamental concept of the non-orthogonal multiple access (NOMA) scheme and provides its detailed comparison with the orthogonal multiple access (OMA) technique. Furthermore, the paper explores the application of the generalized singular value decomposition (GSVD) method in conjunction with NOMA, accompanied by a detailed review of GSVD-based NOMA systems. This study also introduces the concept of mobile edge computing (MEC) and extensively discusses its key parameters. Furthermore, a comprehensive analysis of NOMA MEC is presented, shedding light on its potential advantages and challenges. The aims of this study are to provide a comprehensive understanding of the aforementioned topics and contribute to the advancement of MIMO-NOMA systems.
Źródło:
Journal of Telecommunications and Information Technology; 2023, 3; 11--20
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design Low Complexity SCMA Codebook Using Arnold’s Cat Map
Autorzy:
Mohamed, Sura S.
Abdullah, Hikmat N.
Powiązania:
https://bibliotekanauki.pl/articles/2174447.pdf
Data publikacji:
2022
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
chaotic interleaving
codebook design
dimension rotation
Euclidean distance
sparse code multiple access
Opis:
In 5G wireless communications, sparse code multiple access (SCMA) – a multi-dimensional codebook based on a specific category of the non-orthogonal multiple access (NOMA) technique - enables many users to share non-orthogonal resource components with a low level of detection complexity. The multi-dimensional SCMA (MD-SCMA) codebook design presented in this study is based on the constellation rotation and interleaving method. Initially, a subset of the lattice Z 2 is used to form the mother constellation’s initial dimension. The first dimension is then rotated to produce other dimensions. Additionally, interleaving is employed for even dimensions to enhance fading channel performance. Arnold’s chaotic cat map is proposed as the interleaving method to reduce computational complexity. Performance of the SCMA codebook based on interleaving is evaluated by comparing it with selected codebooks for SCMA multiplexing. The metrics used for performance evaluation purposes include bit error rate (BER), peak to average power ratio (PAPR), and minimum Euclidean distance (MED), as well as complexity. The results demonstrate that the suggested codebook with chaotic interleaving offers performance that is equivalent to that of the conventional codebook based on interleaving. It is characterized by lower MED and higher BER compared to computer-generated and 16-star QAM codebook design approaches, but its complexity is lower than that of the conventional codebook based on interleaving.
Źródło:
Journal of Telecommunications and Information Technology; 2022, 4; 13--20
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Three dimensional optical CDMA framework with direct detection technique
Autorzy:
Panda, Satyasen
Powiązania:
https://bibliotekanauki.pl/articles/1178377.pdf
Data publikacji:
2017
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Cross correlation (CC)
Multiple access interference (MAI)
Phase induced intensity noise (PIIN)
Spectral amplitude coding optical code division multiple access (SAC-OCDMA)
Three dimensional modified quadratic congruence/prime hop code (3-D MQC/PHC)
Three dimensional optical code division multiple access (3-D OCDMA)
Opis:
In this paper, a three-dimensional (3-D) wavelength/time/space code is developed for optical code division multiple access (OCDMA) networks with direct detection technique in the receiver side. The 3-D codes are developed by mixing two-dimensional modified quadratic congruence (MQC) code and one-dimensional prime hop code (PHC) code. The encoders and decoders are constructed using fiber Bragg gratings and delay lines to minimize the bit error rate (BER). The performance analysis of the 3-D OCDMA system is based on measurement of signal to noise ratio (SNR), BER, received power and eye diagram for different numbers of simultaneous users. Also, in the analysis, various types of noises and multiple access interference (MAI) effects are considered. The received optical power is also measured at various levels of BER to analyze the effect of attenuation.
Źródło:
World Scientific News; 2017, 77, 2; 337-353
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 22

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