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Modulation Formats (modulation + formats)

Distribution by Scientific Domains

Engineering	50%

Selected Abstracts

Analysis of the effects of Nyquist pulse-shaping on the performance of OFDM systems with carrier frequency offset

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 1 2009
Peng Tan
An exact method for calculating the bit error rate (BER) of an uncoded orthogonal frequency-division multiplexing (OFDM) system with transmitter Nyquist pulse-shaping over AWGN channels in the presence of frequency offset is derived. This method represents a unified way to calculate the BER of this system with different one- and two-dimensional subcarrier modulation formats. The precise BER expressions are obtained using a characteristic function method. The effects of several widely referenced Nyquist pulse-shapings, including the Franks pulse, the raised-cosine pulse, the ,better than' raised-cosine (BTRC) pulse, the second-order continuous window (SOCW), the double-jump pulse and the polynomial pulse on intercarrier interference (ICI) reduction and BER improvement of the system with carrier frequency offset are examined in the AWGN channel. The dependence of the BER on the roll-off factor of the pulse employed for a specific system in the presence of frequency offset is investigated. Analysis and numerical results show that the Franks pulse exhibits the best performance among the Nyquist pulses considered in most cases. Copyright © 2008 John Wiley & Sons, Ltd. [source]

DVB-S2, the second generation standard for satellite broadcasting and unicasting

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 3 2004
Alberto Morello
Abstract DVB-S2 is the second-generation specification for satellite broadcasting developed by the DVB Project in 2003 and needs to be seen in conjunction with the world-famous DVB-S specification which was finalized in 1993. It benefits from more recent developments in channel coding (LDPC codes) combined with a variety of modulation formats (QPSK, 8PSK, 16APSK and 32APSK). When used for interactive point-to-point applications like IP-based service navigation, it may implement adaptive coding and modulation (ACM), thus allowing the transmission parameters to be optimized for each individual user, dependent on path conditions. Backwards compatible modes are available, allowing existing DVB-S services and Set Top Boxes (STBs) to continue working during any transitional period. Copyright © 2004 John Wiley & Sons, Ltd. [source]

40 Gb/s DBPSK and DQPSK formats for transparent 50 GHz DWDM transmission

BELL LABS TECHNICAL JOURNAL, Issue 4 2010
Sethumadhavan Chandrasekhar
Today's dense wavelength division multiplexed (DWDM) long haul and metropolitan networks are being upgraded from 10 Gb/s to 40 Gb/s, to support the growing traffic demands. Reconfigurable optical add/drop multiplexers (ROADMs) allow for transparent networking at 50 GHz channel spacing. This paper addresses the challenges to support 40 Gb/s by examining two promising modulation formats, namely, differential binary and quadrature phase shift keying (DBPSK and DQPSK). We investigated several variants for reception of the two formats and present performances under optical filtering, crosstalk, and polarization mode dispersion. We also discuss ROADM node architectures that have bearing on overall system performance. © 2010 Alcatel-Lucent. [source]

8 Tb/s long haul transmission over low dispersion fibers using 100 Gb/s PDM-QPSK channels paired with coherent detection

BELL LABS TECHNICAL JOURNAL, Issue 4 2010
Jérémie Renaudier
100Gb/s end-to-end broadband optical solutions are attractive to cope with the increasing demand for capacity. Polarization-division-multiplexed (PDM) quaternary-phase-shift-keying (QPSK) paired with coherent detection has been found to be promising for upgrading optical legacy systems based on 50GHz wavelength slots thanks to its high spectral efficiency (2bit/s/Hz) and its tolerance to linear effects. One of the major concerns for the deployment of such a solution is the transmission reach, mainly limited by nonlinear effects. This limitation can be exacerbated over non-zero dispersion shifted fiber (NZDSF) due to low local chromatic dispersion of the transmission fiber. The aim of this paper is first to report on the benefits brought by combining coherent detection techniques with advanced modulation formats as compared to conventional direct detection schemes for optical fiber communications. Digital signal processing paired with coherent detection is described to point out the efficiency of a coherent receiver to combat noise and to mitigate linear impairments. We then report on nonlinear tolerance of 100 Gb/s coherent PDM-QPSK through an 8 Tb/s transmission over a dispersion-managed link based on low dispersion fibers. © 2010 Alcatel-Lucent. [source]