Wszystkie pola: wysocki, J. J. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Walsh-chirp sequences for wireless applications
Autorzy:: Wysocki, B. J.
Wysocki, T. A.
Zepernick, H.-J.
Powiązania:: https://bibliotekanauki.pl/articles/309560.pdf
Data publikacji:: 2001
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: spread spectrum communications
polyphase spreading sequences
multi-access interference
Walsh sequences
aperiodic correlation functions
Opis:: This paper deals with a new method to design polyphase spreading sequences for DS CDMA wireless applications. The method is based on weighting symbols of the orthogonal Walsh sequences by the complex factors being symbols of baseband chirp sequences. The resulting sequences possess good aperiodic correlation properties, while maintaining the orthogonality. Because of the parametric design, the sequences can be optimized to achieve desired characteristics.
Źródło:: Journal of Telecommunications and Information Technology; 2001, 3; 24-28
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:: On a method to improve correlation properties of orthogonal polyphase spreading sequences
Autorzy:: Wysocki, B. J.
Wysocki, T. A.
Powiązania:: https://bibliotekanauki.pl/articles/307741.pdf
Data publikacji:: 2003
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: spread spectrum communications
orthogonal sequences
wireless communications
wireless LAN
correlation
Opis:: In this paper, we propose a simple but efficient method for improving correlation properties of polyphase spreading sequences for asynchronous direct sequence code division multiple access (DS CDMA) applications. The proposed method can be used to reduce the mean square value of aperiodic crosscorrelation or the mean square value of aperiodic autocorrelation, the maximum value of aperiodic crosscorrelation functions, merit factor or other properties of the sequence set. The important feature of the method is that while it modifies correlation properties of the sequence set, it preserves sequence orthogonality for perfect synchronization, if this is the property of the original sequence set.
Źródło:: Journal of Telecommunications and Information Technology; 2003, 2; 99-105
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:: 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

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Skocz do pozycji: 4.

Tytuł:: Load-balanced route discovery for mobile ad hoc networks
Autorzy:: Abolhasan, M.
Lipman, J.
Wysocki, T. A.
Powiązania:: https://bibliotekanauki.pl/articles/309094.pdf
Data publikacji:: 2006
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: ad hoc routing
MANET
load balancing
on-demand routing
protocols
Opis:: This paper presents flow-aware routing protocol (FARP), a new routing strategy designed to improve load balancing and scalability in mobile ad hoc networks. FARP is a hop-by-hop routing protocol, which introduces a flow-aware route discovery strategy to reduce the number of control overheads propagating through the network and distributes the flow of data through least congested nodes to balance the network traffic. FARP was implemented in GloMoSim and compared with AODV. To investigate the load distribution capability of FARP new performance metrics were introduced to measure the data packet flow distribution capability of the each routing protocol. The simulation results obtained illustrate that FARP achieves high levels of throughput, reduces the level of control overheads during route discovery and distributes the network load more evenly between nodes when compared to AODV. This paper also describes a number of alternative strategies and improvements for the FARP.
Źródło:: Journal of Telecommunications and Information Technology; 2006, 1; 38-45
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

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

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Skocz do pozycji: 6.

Tytuł:: Simulating capture behaviour in 802.11 radio modems
Autorzy:: Ware, C.
Wysocki, T. A.
Chicharo, J.
Powiązania:: https://bibliotekanauki.pl/articles/309552.pdf
Data publikacji:: 2001
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: wireless local area networks
ad hoc networks
capture models
medium access control protocol
fairness
Opis:: Simulation plays an important role in the performance evaluation of MAC protocols. Building simulation models which are able to accurately model physical behaviour is fundamental to the outcome of such techniques. Through both qualitative and quantitative comparison of experimental trace data against simulation results obtained using delay, power, and hybrid capture models, this paper investigates the performance of various packet capture models in the simulation analysis of the 802.11 PHY and MAC layer protocols. We illustrate these models are unable to accurately describe the fairness properties of the experimental data. A new model is proposed, Message Retraining, to describe the operation of an 802.11 receiver. We illustrate that the Message Retraining reception model is able to model the fairness characteristics obtained with an IEEE 802.11 radio modem more accurately than the previous capture models.
Źródło:: Journal of Telecommunications and Information Technology; 2001, 3; 46-54
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:: Transmitter diversity antenna selection techniques for wireless channels utilizing differential space-time block codes
Autorzy:: Tran, L. C.
Wysocki, T. A.
Mertins, A.
Seberry, J.
Powiązania:: https://bibliotekanauki.pl/articles/309431.pdf
Data publikacji:: 2006
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: differential space-time modulation
differential space-time block codes
diversity antenna selection
MIMO system
Opis:: The paper deals with transmitter diversity antenna selection techniques (ASTs) for wireless channels utilizing differential space-time block codes (DSTBCs). The proposed ASTs tend to maximize the signal-to-noise ratio (SNR) of those channels. Particularly, we propose here the so-called general (M,N;K) AST/DSTBC scheme for such channels. Then, based on this AST, we propose two modified ASTs which are more amenable to practical implementation, namely the restricted (M,N;K) AST/DSTBC scheme and the (N + —N,N;K) AST/DSTBC scheme. The restricted (M,N;K) AST/DSTBC scheme provides relatively good bit error performance using only one feedback bit for transmission diversity purpose, while the (N+ —N,N;K) AST/DSTBC scheme shortens the time required to process feedback information. These techniques remarkably improve bit error rate (BER) performance of wireless channels using DSTBCs with a limited number (typically 1 or 2) of training symbols per each coherent duration of the channel. Simulations show that the proposed AST/DSTBC schemes outperform the DSTBCs without antenna selection even with only 1 training symbol.
Źródło:: Journal of Telecommunications and Information Technology; 2006, 2; 79-96
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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