Temat: Access - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Performance of CDMA systems with Walsh and PN coding
Autorzy:: Gajewski, P.
Dołowski, J.
Powiązania:: https://bibliotekanauki.pl/articles/308358.pdf
Data publikacji:: 2001
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: PN spreading
CDMA
multi-access interference
Opis:: Wideband CDMA method has been recently investigated for its using in the future communication systems. Such systems capacity depends on many factors, the main is multi-access interference (MAI). MAI is an inherent CDMA property connected to correlation characteristics of codes used to access and to spreading. The influence on CDMA performance of these codes families and parameters is presented in this paper. The standard Gaussian approximation has been used for interference analysis. Bit error rate (BER) on detector output is a measure of interference influence on transmission quality. It can be used for SNR(i) evaluation on receiver input for channel assignment and handover procedures. The results of interference analysis for the pseudo-noise sequences (M-sequences, Gold, de'Bruin and Jennings) as well as for the Walsh orthogonal mapping are presented in this paper.
Źródło:: Journal of Telecommunications and Information Technology; 2001, 2; 41-45
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: An Attribute-Based Encryption Method Using Outsourced Decryption and Hierarchical Access Structure
Autorzy:: Mujawar, Tabassum N.
Bhajantri, Lokesh B.
Powiązania:: https://bibliotekanauki.pl/articles/2142312.pdf
Data publikacji:: 2022
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: cloud computing
CPABE
hierarchical access structure
Opis:: Cloud computing is being rapidly adopted by many organizations from different domains and large amounts of data is stored in the cloud. In order to ensure data security, the attribute-based access control mechanism has been emerging recently as a fine-grained access control model that grants access based on the data user’s attributes. In this model, the data owner builds the access policy using the attributes of the data users and access to the data is granted only if the requirements of such an access policy are satisfied. Ciphertext policy-based attribute-based encryption (CPABE) is one of the most widely used methods for providing encrypted access control. Complex, time consuming and costly paring operations are the major issue with the CPABE method. Hence, another efficient method is needed to reduce the data user’s overhead while decrypting data. This paper presents an efficient method consisting in outsourcing decryption operations to a third-party server, so that complex operations may be performed by that machine with only some simple calculations left on the data user’s side. The concept of a hierarchical access structure is also integrated with the traditional CPABE technique. The hierarchical approach enables the data owner to encrypt multiple data using a single common hierarchical access structure. This allows the user to decrypt only the relevant part of ciphertext, depending on which fragment of the hierarchical access structure is satisfied. The paper evaluates also the performance of the proposed model in terms of time and storage cost.
Źródło:: Journal of Telecommunications and Information Technology; 2022, 2; 75--81
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

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

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Skocz do pozycji: 4.

Tytuł:: BSBI - a Simple Protocol for Remote Verification of Identity
Autorzy:: Kozakiewicz, A.
Pałka, P.
Powiązania:: https://bibliotekanauki.pl/articles/309333.pdf
Data publikacji:: 2012
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: access control
authentication
biometric verification
network protocols
Opis:: The paper presents the design and the rationale behind a simple verification protocol for autonomous verification modules, and the architecture enabling use of such modules. The architecture assumes strict separation of all personal metadata and the actual verification data. The paper also describes a prototype implementation of the protocol and its extension enabling the state of the module to be monitored from the main system. The proposed design solves the problem of using advanced verification methods, especially biometric ones, in systems where direct implementation is not possible due to hardware incompatibilities, insufficient resources or other limitations.
Źródło:: Journal of Telecommunications and Information Technology; 2012, 3; 50-57
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

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

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Skocz do pozycji: 6.

Tytuł:: Modulo N Backoff Scheme for Effective QoS Differentiation and Increased Bandwidth Utilization in IEEE 802.11 Networks
Autorzy:: Janczar, T.
Konorski, J.
Wodniak, J.
Pawlikowski, K.
Powiązania:: https://bibliotekanauki.pl/articles/308888.pdf
Data publikacji:: 2009
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: channel access
MAC
performance analysis
random backoff
WLAN
Opis:: The paper presents a new modulo N channel access scheme for wireless local area networks (WLANs). The novel solution derives from the distributed coordination function (DCF) of the IEEE 802.11 standard, further elaborated as enhanced distribution channel access (EDCA) by the 802.11e draft specification. The main innovation concerns improvement of the binary exponential backoff scheme used for collision avoidance in 802.11 networks. The most appealing feature of the new modulo N backoff scheme is that it outperforms the original 802.11 solution in terms of channel utilization ratio under any traffic conditions. Furthermore, the modulo N proposal can be naturally augmented with QoS differentiation mechanisms like 802.11e extensions. The prioritized modulo N scheme achieves better throughput-delay characteristics for multimedia traffic when compared with the original 802.11e proposal. At the same time, the new solution retains backward compatibility and includes all features which have made IEEE 802.11 networks extremely popular nowadays.
Źródło:: Journal of Telecommunications and Information Technology; 2009, 2; 41-47
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Two Extensions of Trust Management Languages
Autorzy:: Felkner, Anna
Powiązania:: https://bibliotekanauki.pl/articles/307850.pdf
Data publikacji:: 2020
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: access control
conditional credentials
inference system with time constraints
Opis:: This article is focused on the family of role-based trust management languages (RT). Trust management languages are a useful method of representing security credentials and policies in large distributed access control mechanisms. They provide sets of credentials that are assigned to individual roles performed by the speciﬁc entities. These credentials provide relevant information about security policies issued by trusted authorities and deﬁne user permissions. RT languages describe the individual entities and the roles that these entities play in a given environment. A set of credentials representing a given security policy deﬁnes which entity has the necessary rights to access a speciﬁc resource and which entity does not have such rights. This study presents the results of research focusing on the potential of the family of RT languages. Its purpose is to show how security policies may be applied more widely by applying an inference system, and then using the extensions of the credentials, by taking into account time-related information or the conditions imposed with regard to the validity of such credentials. Each of these extensions can be used jointly or separately, oﬀering even a wider range of opportunities.
Źródło:: Journal of Telecommunications and Information Technology; 2020, 1; 87-94
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Concept of Joint Functioning of Access Control Systems
Autorzy:: Strelbitskyi, Mykhailo
Mazur, Valentyn
Prokopenko, Evgenii
Rachok, Roman
Mul, Dmytro
Powiązania:: https://bibliotekanauki.pl/articles/2200963.pdf
Data publikacji:: 2023
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: access control model
concept
information system
telecommunication system
modernization
Opis:: Modern integrated information and telecommunication systems are upgraded on a continuous basis. Such systems contain both new and old components. The approaches to developing individual components of access control systems are different in the majority of cases. As a rule, modernization of outdated but efficient systems that have been operating without any failures for long periods of time is economically unfeasible. Such an approach requires that different subsystems function based on shared data. This necessitates the coordination of various access control systems in order to ensure proper information security levels. This article examines how joint functioning of various versions of access control systems deployed in IT and telecommunication spheres may be achieved at the stage of their modernization. Potential ways in which information flows may bypass the security policies of one of the access control systems concerned are determined. The authors discuss traditional access control models. For role-based and thematic access control models, specific hypotheses are formulated to comply with security policies when different versions of access control systems work together. The structure of the model assuming that different versions of access control systems operate jointly has been developed. Based on the model, the necessary and sufficient conditions are determined under which unauthorized information flows are prevented. The security theorem for the joint functioning of different versions of access control systems is presented and proved. The results of the study showed that the methodological basis for coordinating access control models applicable to information and telecommunication systems undergoing modernization consists in observing, separately, the equality of information flows between shared objects in each of the versions of the access control systems. The approaches developed in this article can be extended to combined access control systems.
Źródło:: Journal of Telecommunications and Information Technology; 2023, 1; 30--36
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Protocols for Wireless Sensor Networks: A Survey
Autorzy:: Kochhar, A.
Kaur, P.
Singh, P.
Sharma, S.
Powiązania:: https://bibliotekanauki.pl/articles/958098.pdf
Data publikacji:: 2018
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: cross-layer
Medium Access Control
protocols
Wireless Sensor Networks
Opis:: This paper presents a survey on the MAC and network layer of Wireless Sensor Networks. Performance requirements of the MAC layer are explored. MAC layer protocols for battery-powered networks and energy harvesting-based networks are discussed and compared. A detailed discussion on design constraints and classification of routing protocols is presented. Several routing protocols are compared in terms of such parameters as: energy consumption, scalability, network lifetime and mobility. Problems that require future research are presented. The cross-layer approach for WSNs is also surveyed.
Źródło:: Journal of Telecommunications and Information Technology; 2018, 1; 77-87
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: How the Role-Based Trust Management Can Be Applied to Wireless Sensor Networks
Autorzy:: Felkner, A.
Powiązania:: https://bibliotekanauki.pl/articles/307588.pdf
Data publikacji:: 2012
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: access control
role-based trust management
trust
wireless sensor networks
Opis:: Trust plays an important role in human life environments. That is why the researchers has been focusing on it for a long time. It allows us to delegate tasks and decisions to an appropriate person. In social sciences trust between humans was studied, but it also was analyzed in economic transactions. A lot of computer scientists from different areas, like security, semantic web, electronic commerce, social networks tried to transfer this concept to their domains. Trust is an essential factor in any kind of network, whether social or computer. Wireless sensor networks (WSN) are characterized by severely constrained resources, they have limited power supplies, low transmission bandwidth, small memory sizes and limited energy, therefore security techniques used in traditional wired networks cannot be adopted directly. Some effort has been expended in this fields, but the concept of trust is defined in slightly different ways by different researchers. In this paper we will show how the family of Role-based Trust management languages (RT) can be used in WSN. RT is used for representing security policies and credentials in decentralized, distributed access control systems. A credential provides information about the privileges of users and the security policies issued by one or more trusted authorities.
Źródło:: Journal of Telecommunications and Information Technology; 2012, 4; 70-77
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 11.

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

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Skocz do pozycji: 12.

Tytuł:: Model of User Access Control to Virtual Machines Based on RT-Family Trust Management Language with Temporal Validity Constraints - Practical Application
Autorzy:: Lasota, K.
Kozakiewicz, A.
Powiązania:: https://bibliotekanauki.pl/articles/309357.pdf
Data publikacji:: 2012
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: RT-family languages
security model
user access control
virtualization environment
Opis:: The paper presents an application of an RT-family trust management language as a basis for an access control model. The discussion concerns a secure workstation running multiple virtual machines used to process sensitive information from multiple security domains, providing strict separation of the domains. The users may act in several different roles, with different access rights. The inference mechanisms of the language are used to translate credentials allowing users to access different functional domains, and assigning virtual machines to these domains into clear rules, regulating the rights of a particular user to a particular machine, taking into account different periods of validity of different credentials. The paper also describes a prototype implementation of the model.
Źródło:: Journal of Telecommunications and Information Technology; 2012, 3; 13-21
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 13.

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

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Skocz do pozycji: 14.

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

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Skocz do pozycji: 15.

Tytuł:: Quality of Variable Bitrate HD Video Transmission in New Generation Access Network
Autorzy:: Makowski, P.
Powiązania:: https://bibliotekanauki.pl/articles/308077.pdf
Data publikacji:: 2014
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: congestion in access network
quality of experience
streaming
variable bitrate
Opis:: Article presents influence of multiplying variable bitrate high definition (HD) video streams in an access network link on Quality of Service (QoS). The aim of a conducted study is to define key parameters influencing Quality of Experience (QoE). Numerous simulations were performed and indicators like packet loss, delay, jitter, frame loss and bandwidth utilization were observed. Moreover, two independent algorithms were used to indicate QoE values of video streams. These are SwissQual VQuadHD and Telchemy VQMon applications which provided credible full reference and no reference algorithms, respectively. In the article evaluation of accuracy of no reference algorithm is performed. In future work it is planned to build analytic model of VBR video transmission and to undertake more thorough research of transmitting multiplied HD video streams in an access network using various QoS policies and optimizing size of buffers.
Źródło:: Journal of Telecommunications and Information Technology; 2014, 1; 21-26
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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