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Tytuł:
Suitable Spreading Sequences for Asynchronous MC-CDMA Systems
Autorzy:
Addad, M.
Djebbari, A.
Powiązania:
https://bibliotekanauki.pl/articles/307793.pdf
Data publikacji:
2018
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
BER
crest factor
multiple access interference
MC-CDMA
peak-to-average power ratio
zero correlation zone
Opis:
In order to meet the demand of high data rate transmission with good quality maintained, the multi-carrier code division multiple access (MC-CDMA) technology is considered for the next generation wireless communication systems. However, their high crest factor (CF) is one of the major drawbacks of multi-carrier transmission systems. Thus, CF reduction is one of the most important research areas in MC-CDMA systems. In addition, asynchronous MC-CDMA suffers from the effect of multiple access interference (MAI), caused by all users active in the system. Degradation of the system’s bit error rate (BER) caused by MAI must be taken into consideration as well. The aim of this paper is to provide a comparative study on the enhancement of performance of an MC-CDMA system. The spreading sequences used in CDMA play an important role in CF and interference reduction. Hence, spreading sequences should be selected to simultaneously ensure low CF and low BER values. Therefore, the effect that correlation properties of sequences exert on CF values is investigated in this study. Furthermore, a numerical BER evaluation, as a function of the signal-to-noise ratio (SNR) and the number of users, is provided. The results obtained indicate that a trade-off between the two criteria is necessary to ensure good performance. It was concluded that zero correlation zone (ZCZ) sequences are the most suitable spreading sequences as far as the satisfaction of the above criteria is concerned.
Źródło:
Journal of Telecommunications and Information Technology; 2018, 3; 9-13
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Network Selection in Wireless Heterogeneous Networks: a Survey
Autorzy:
Bendaoud, F.
Abdennebi, M.
Didi, F.
Powiązania:
https://bibliotekanauki.pl/articles/309296.pdf
Data publikacji:
2018
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
always best connected
fuzzy logic
game theory
multiple attribute decision making
quality of service
radio access technologies
Opis:
Heterogeneous wireless networks is a term referring to networks combining different radio access technologies with the aim of establishing the best connection possible. In this case, users with multi-mode terminals can connect via different wireless technologies, such as 802.16, 802.11, UMTS, HSPA and LTE, all at the same time. The problem consists in the selection of the most suitable from all radio access technologies available. The decision process is called network selection, and depends on several parameters, such as quality of service, mobility, cost, energy, battery life, etc. Several methods and approaches have been proposed in this context, with their objective being to offer the best QoS to the users, and/or to maximize re-usability of the networks. This paper represents a survey of the network selection methods used. Multiple attribute-dependent decision-making methods are presented. Furthermore, the game theory concept is illustrated, the use of the fuzzy logic is presented, and the utility functions defining the network selection process are discussed.
Źródło:
Journal of Telecommunications and Information Technology; 2018, 4; 64-74
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:
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:
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:
An Approximate Evaluation of BER Performance for Downlink GSVD-NOMA with Joint Maximum-likelihood Detector
Autorzy:
Hai, Ngo Thanh
Khoa, Dang Le
Powiązania:
https://bibliotekanauki.pl/articles/2142315.pdf
Data publikacji:
2022
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
generalized singular value decomposition
GSVD
joint maximum-likelihood
joint modulation
MIMO
non-orthogonal multiple access
NOMA
Opis:
Generalized Singular Value Decomposition (GSVD) is the enabling linear precoding scheme for multiple-input multiple-output (MIMO) non-orthogonal multiple access (NOMA) systems. In this paper, we extend research concerning downlink MIMO-NOMA systems with GSVD to cover bit terror rate (BER) performance and to derive an approximate evaluation of the average BER performance. Specifically, we deploy, AT the base station, the well-known technique of joint-modulation to generate NOMAsymbols and joint maximum-likelihood (ML) to recover the transmitted data at end user locations. Consequently, the joint ML detector offers almost the same performance, In terms of average BER as ideal successive interference cancellation. Next, we also investigate BER performance of other precoding schemes, such as zero-forcing, block diagonalization, and simultaneous triangularization, comparing them with GSVD. Furthermore, BER performance is verified in different configurations in relation to the number of antennas. In cases where the number of transmit antennas is greater than twice the number of receive antennas, average BER performance is superior.
Źródło:
Journal of Telecommunications and Information Technology; 2022, 3; 25--37
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
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:
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:
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:
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:
Ranking of LTE cells based on key performance indicators using MCDM methods
Autorzy:
Lopes Neto, Pedro Nunes
Freire Junior, José Celso
Tuna, Celso Eduardo
Powiązania:
https://bibliotekanauki.pl/articles/2211970.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Ekonomiczny w Katowicach
Tematy:
long-term evolution
multiple criteria methods
radio access network performance management
self-organizing networks
Opis:
The growth in worldwide data traffic and user subscriptions in mobile telecommunication networks makes it increasingly difficult to manage network performance in an environment already containing multiple radio access technologies. Despite the rise of 5G, LTE remains the dominant technology, and new cells are installed daily to support traffic growth and new services such as voice over LTE. Detecting faulty cells in the network is one of the main concerns of operators. Self organizing networks have been introduced to deal with this problem, and their self healing functionality has improved cell fault management. Nonetheless, faulty cell detection remains challenging, and most of the tasks involved are still done manually. This paper introduces a new method of faulty cell detection in an LTE radio access network, applying multiple criteria methods to this problem. The cells are ranked based on selected key performance indicators, using the multi attribute utility theory to construct a utility function. The analytic hierarchy process is used to define weights for the criteria.
Źródło:
Multiple Criteria Decision Making; 2022, 17; 46-68
2084-1531
Pojawia się w:
Multiple Criteria Decision Making
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:
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:
Performance Analysis of Filtered OFDM Based Downlink and Uplink NOMA System over Nakagami-m Fading Channel
Autorzy:
Mukhtar, Shaika
Begh, Gh. Rasool
Powiązania:
https://bibliotekanauki.pl/articles/1839342.pdf
Data publikacji:
2021
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
bit error rate
orthogonal multiple access
out-of-band emission
successive interference cancellation
Opis:
Efficient consumption of available resources and fulfillment of increasing demands are the two main challenges which are addressed by exploring advanced multiple access schemes along with efficient modulation techniques. To this end, non-orthogonal multiple access (NOMA) is discussed as a promising scheme for future 5G traffic. NOMA enables the users to share same resource block, permitting certain level of interference. In this paper, we propose filtered OFDM (F-OFDM) as a transmission waveform for NOMA systems, as it offers all the advantages of OFDM with the additional provision of sub-band filtering to satisfy the diverse services of the users. We examine F-OFDM in both downlink and uplink NOMA systems. Error-related performances of both downlink and uplink F-OFDM NOMA systems are analyzed and compared with conventional OFDM NOMA system over Nakagami-m fading channel. The results show that the error performance of F-OFDM NOMA is better than that of OFDM NOMA. An improvement of about 2 dB and 1 dB in bit error rate is achieved in downlink and uplink F-OFDM NOMA, respectively. Monte Carlo simulations are conducted for different values of fading parameter m, supporting the obtained analytical results.
Źródło:
Journal of Telecommunications and Information Technology; 2021, 2; 11-23
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
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

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