22 research outputs found
Experimental Error Performance of Modulation Schemes Under a Controlled Laboratory Turbulence FSO Channel
This paper experimentally investigates the performance of different modulation schemes under the atmospheric turbulence conditions for free space optical communication links. The experiments were carried out in a dedicated and controlled indoor atmospheric chamber. The turbulence environment was created by introducing hot air, while the temperature profile was monitored throughout the chamber to maintain a constant environment. By evaluating the error performance of different modulation schemes under identical conditions, it was observed that pulse position modulation offers the best performance, followed by subcarrier intensity modulation under weak turbulence environments
Open University Malaysia : way forward in Science and Technology education
One of Malaysia’s national agenda is to move towards a scientific and progressive
society. Government strategies for Malaysia described in this paper highlights the
importance of life long learning in achieving its national agenda. Open University
Malaysia as a pioneer in open and distance education has a role in promoting life long
learning in Malaysia. This paper highlights the key features of the university i.e. blended
learning mode and e-learning platform which offers various benefits that could provide
supports for creating an innovative society. In the context of science and technology,
creating an innovative society means creating manpower with good foundation in basic
science knowledge and science skills, a sense of appreciation of contributions and
innovations in science and technology, positive attitudes and awareness on ethical issues.
This paper proposes strategies to invest in the future by retraining man-power, promoting
basic science and increasing the quality of technical courses. (Authors' abstract
10 Mb/s visible light transmission system using a polymer light-emitting diode with orthogonal frequency division multiplexing
We present a newly designed polymer light-emitting diode with a bandwidth of ∼350 kHz for high-speed visible light communications. Using this new polymer light-emitting diode as a transmitter, we have achieved a record transmission speed of 10 Mb/s for a polymer light-emitting diode-based optical communication system with an orthogonal frequency division multiplexing technique, matching the performance of single carrier formats using multitap equalization. For achieving such a high data-rate, a power pre-emphasis technique was adopted
Experimental demonstration of data-dependent pilot-aided phase noise estimation for CO-OFDM
We demonstrate a novel phase noise estimation scheme for CO-OFDM, in which pilot subcarriers are deliberately correlated to the data subcarriers. This technique reduces the overhead by a factor of 2
Multi-band carrier-less amplitude and phase modulation for bandlimited visible light communications systems
Visible light communications is a technology with enormous potential for a wide range of applications within next generation transmission and broadcasting technologies. VLC offers simultaneous illumination and data communications by intensity modulating the optical power emitted by LEDs operating in the visible range of the electromagnetic spectrum (~370-780 nm). The major challenge in VLC systems to date has been in improving transmission speeds, considering the low bandwidths available with commercial LED devices. Thus, to improve the spectral usage, the research community has increasingly turned to advanced modulation formats such as orthogonal frequency-division multiplexing. In this article we introduce a new modulation scheme into the VLC domain; multiband carrier-less amplitude and phase modulation (m-CAP) and describe in detail its performance within the context of bandlimited systems
A 10 Mb/s visible light communication system using a low bandwidth polymer light-emitting diode
In this paper we experimentally demonstrate a 10 Mb/s error free visible light communications (VLC) system using polymer light-emitting diodes (PLEDs) for the first time. The PLED under test is a blue emitter with ∼600 kHz bandwidth. Having such a low bandwidth means the introduction of an intersymbol interference (ISI) induced penalty at higher transmission speeds and thus the requirement for an equalizer. In this work we improve on previous literature by implementing a decision feedback equalizer, rather than a linear equalizer. Considering 7% and 20% forward error correction codes, transmission speeds up to ∼12 Mb/s can be supported
Exceeding the nonlinear-shannon limit using Raman laser based amplification and optical phase conjugation
We demonstrate that a combination of Raman laser based amplification and optical phase conjugation enables transmission beyond the nonlinear-Shannon limit. We show nonlinear compensation of 7x114Gbit/s DP-QPSK channels, increasing system reach by 30%