3,661 research outputs found
Blind frame synchronisation for Block code
Publication in the conference proceedings of EUSIPCO, Florence, Italy, 200
Spread spectrum-based video watermarking algorithms for copyright protection
Merged with duplicate record 10026.1/2263 on 14.03.2017 by CS (TIS)Digital technologies know an unprecedented expansion in the last years. The consumer can
now benefit from hardware and software which was considered state-of-the-art several years
ago. The advantages offered by the digital technologies are major but the same digital
technology opens the door for unlimited piracy. Copying an analogue VCR tape was certainly
possible and relatively easy, in spite of various forms of protection, but due to the analogue
environment, the subsequent copies had an inherent loss in quality. This was a natural way of
limiting the multiple copying of a video material. With digital technology, this barrier
disappears, being possible to make as many copies as desired, without any loss in quality
whatsoever. Digital watermarking is one of the best available tools for fighting this threat.
The aim of the present work was to develop a digital watermarking system compliant with the
recommendations drawn by the EBU, for video broadcast monitoring. Since the watermark
can be inserted in either spatial domain or transform domain, this aspect was investigated and
led to the conclusion that wavelet transform is one of the best solutions available. Since
watermarking is not an easy task, especially considering the robustness under various attacks
several techniques were employed in order to increase the capacity/robustness of the system:
spread-spectrum and modulation techniques to cast the watermark, powerful error correction
to protect the mark, human visual models to insert a robust mark and to ensure its invisibility.
The combination of these methods led to a major improvement, but yet the system wasn't
robust to several important geometrical attacks. In order to achieve this last milestone, the
system uses two distinct watermarks: a spatial domain reference watermark and the main
watermark embedded in the wavelet domain. By using this reference watermark and techniques
specific to image registration, the system is able to determine the parameters of the attack and
revert it. Once the attack was reverted, the main watermark is recovered. The final result is a
high capacity, blind DWr-based video watermarking system, robust to a wide range of attacks.BBC Research & Developmen
A Novel Beamformed Control Channel Design for LTE with Full Dimension-MIMO
The Full Dimension-MIMO (FD-MIMO) technology is capable of achieving huge
improvements in network throughput with simultaneous connectivity of a large
number of mobile wireless devices, unmanned aerial vehicles, and the Internet
of Things (IoT). In FD-MIMO, with a large number of antennae at the base
station and the ability to perform beamforming, the capacity of the physical
downlink shared channel (PDSCH) has increased a lot. However, the current
specifications of the 3rd Generation Partnership Project (3GPP) does not allow
the base station to perform beamforming techniques for the physical downlink
control channel (PDCCH), and hence, PDCCH has neither the capacity nor the
coverage of PDSCH. Therefore, PDCCH capacity will still limit the performance
of a network as it dictates the number of users that can be scheduled at a
given time instant. In Release 11, 3GPP introduced enhanced PDCCH (EPDCCH) to
increase the PDCCH capacity at the cost of sacrificing the PDSCH resources. The
problem of enhancing the PDCCH capacity within the available control channel
resources has not been addressed yet in the literature. Hence, in this paper,
we propose a novel beamformed PDCCH (BF-PDCCH) design which is aligned to the
3GPP specifications and requires simple software changes at the base station.
We rely on the sounding reference signals transmitted in the uplink to decide
the best beam for a user and ingeniously schedule the users in PDCCH. We
perform system level simulations to evaluate the performance of the proposed
design and show that the proposed BF-PDCCH achieves larger network throughput
when compared with the current state of art algorithms, PDCCH and EPDCCH
schemes
Near-Instantaneously Adaptive HSDPA-Style OFDM Versus MC-CDMA Transceivers for WIFI, WIMAX, and Next-Generation Cellular Systems
Burts-by-burst (BbB) adaptive high-speed downlink packet access (HSDPA) style multicarrier systems are reviewed, identifying their most critical design aspects. These systems exhibit numerous attractive features, rendering them eminently eligible for employment in next-generation wireless systems. It is argued that BbB-adaptive or symbol-by-symbol adaptive orthogonal frequency division multiplex (OFDM) modems counteract the near instantaneous channel quality variations and hence attain an increased throughput or robustness in comparison to their fixed-mode counterparts. Although they act quite differently, various diversity techniques, such as Rake receivers and space-time block coding (STBC) are also capable of mitigating the channel quality variations in their effort to reduce the bit error ratio (BER), provided that the individual antenna elements experience independent fading. By contrast, in the presence of correlated fading imposed by shadowing or time-variant multiuser interference, the benefits of space-time coding erode and it is unrealistic to expect that a fixed-mode space-time coded system remains capable of maintaining a near-constant BER
Testing communication reliability with fault injection : Implementation using Robot Framework and SoC-FPGA
Taajuusmuuttajia käytetään teollisuudessa laajasti, sillä merkittävän osan teollisuuden sähkönkulutuksesta muodostavat oikosulkumoottorit, joita ajetaan taajuusmuuttajien avulla. Taajuusmuuttajiin on mahdollista kytkeä optiokortteja, jotka lisäävät taajuusmuuttajaan valvonta-, ohjaus- ym. toiminnallisuuksia. Nämä kortit kommunikoivat sarjaliikenneväylän kautta taajuusmuuttajan pääyksikön kanssa.
Sarjaliikennelinkissä, kuten taajuusmuuttajan väylällä, voi syntyä virheitä, jotka häiritsevät tietoliikennettä. Sen takia sarjaliikenneprotokolliin on luotu virheentunnistus- ja -korjausmekanismeja, joilla pyritään varmistamaan virheetön tiedon kuljettaminen. Luotettavuutta testaamaan voidaan väylälle generoida virheitä siihen tarkoitetulla laitteella.
Tässä diplomityössä luotiin taajuusmuuttajia valmistavan yrityksen, Danfoss Drivesin (aik. Vacon), pyynnöstä häiriögeneraattorijärjestelmä. Järjestelmä koostuu SoC-FPGA-piirillä luodusta virheitä syöttävästä laitteesta, PC-työkalulle luodusta testirajapinnasta sekä Ethernet-kommunikaatiosta niiden välillä. Laite kytketään väylään, ja testirajapinta tekee testaajalle mahdolliseksi luoda mukautettavia testejä ja ajaa testejä käyttäen Robot Framework -testiympäristöä.
Diplomityössä tutkittiin ensin sarjakommunikointiväylien yleisimpiä virheentunnistus- ja korjauskeinoja sekä SoC-FPGA-piirien sekä työssä käytetyn Robot Frameworkin ominaisuuksia. Järjestelmä suunniteltiin ylhäältä-alas-periaatteella ensin tunnistamalla kolmen edellä mainitun komponentin päärakenne päätyen lopulta yksittäisten ohjelmafunktioiden logiikan suunnitteluun. Tämän jälkeen laite ja testirajapinta toteutettiin C- ja Python-ohjelmointikielillä käyttäen suunnitellun kaltaista kommunikaatiota näiden kahden komponentin välillä.
Lopulta järjestelmä testattiin kaikki komponentit yhteen kytkettynä. Varsinainen injektorilogiikka, joka luo virheitä väylään, ei ollut työn loppuun mennessä vielä toimittavan tahon puolelta valmis, joten järjestelmää ei voitu testata todellisessa ympäristössä. Työssä luodut osuudet voidaan kuitenkin myöhemmin kytkeä kokonaiseen järjestelmään.
Työn tärkeimpänä johtopäätöksenä on, että tavoitteiden mukainen järjestelmä saatiin luotua ja testattua toimivaksi mahdollisin osin. Jatkokehityskohteeksi jäi mm. kokonaisen järjestelmän luonti ja testaus oikeaan kommunikaatioväylään kytkettynä.Frequency converters are widely used in industry because a notable part of the industrial electricity consumption is by electrical induction motors driven by frequency converters. It is possible to connect option boards into a frequency converter to add monitoring and control features. These option boards communicate with the main control unit of the frequency converter over a serial communication link.
In a serial communication link, e.g. in a frequency converter, it can occur faults that interfere with the transfer. Hence, error handling mechanisms are used to secure transmission of the data without errors. A fault injector device, which generates errors into the data travelling in the link, can be used to test the communication reliability.
In this master’s thesis, an error generator system was created for a company, Danfoss Drives (previously Vacon), manufacturing frequency converters. The system consists of a fault injector device created with a SoC-FPGA, a testing interface for a PC tool, and an Ethernet-based communication between these two. The device is connected to a serial communication link, and the testing interface makes it easy for a tester to create and run modifiable fault injection tests using a Robot Framework test environment.
At the beginning of the thesis, the most common error detection and correction mechanisms in serial communication and properties of SoC-FPGAs, and Robot Framework were studied. Following this, the system was designed with top-down approach, first identifying the main structure of the components, and finally ending up in designing the logic of individual functions. After this, the device and the testing interface were implemented in C and Python using the designed Ethernet communication between them.
After the implementation, the system was tested with all the components combined. The actual fault injection logic was not ready by the end of the thesis, so the tests were not run in a real environment. However, the work is done so that the implemented parts can be later used in a complete system.
The most important conclusion is that the system was created and tested to meet the requirements with applicable parts. Further development includes creating a complete system and testing it with a real communication link
VocaLiST: An Audio-Visual Synchronisation Model for Lips and Voices
In this paper, we address the problem of lip-voice synchronisation in videos
containing human face and voice. Our approach is based on determining if the
lips motion and the voice in a video are synchronised or not, depending on
their audio-visual correspondence score. We propose an audio-visual cross-modal
transformer-based model that outperforms several baseline models in the
audio-visual synchronisation task on the standard lip-reading speech benchmark
dataset LRS2. While the existing methods focus mainly on the lip
synchronisation in speech videos, we also consider the special case of singing
voice. Singing voice is a more challenging use case for synchronisation due to
sustained vowel sounds. We also investigate the relevance of lip
synchronisation models trained on speech datasets in the context of singing
voice. Finally, we use the frozen visual features learned by our lip
synchronisation model in the singing voice separation task to outperform a
baseline audio-visual model which was trained end-to-end. The demos, source
code, and the pre-trained model will be made available on
https://ipcv.github.io/VocaLiST/Comment: Submitted to Interspeech 2022; Project Page:
https://ipcv.github.io/VocaLiST
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