Review Paper

Topics: Modulation, Quadrature amplitude modulation, Multiplexing Pages: 16 (5588 words) Published: April 11, 2013
Amanpreet Kaura, Kamaljit Singh Bhatiab
a,b Department of Electronics Engineering, Sri Guru Granth Sahib World University, Fatehgarh Sahib, India

To design optical OFDM using low bandwidth electronics and optoelectronics components,also low loss comb-line combiner using the IFFT,lightware centralized Bidirectional hybrid Acess network and also with remodulated ONUS and a coherent receiver OLT ,various technique to control PAPR(peak to average power ratio),different types of modulation methods with pre-emphasis technique, an idea abot MAMSK-OFDM technology for next generation,putting the Doppler shift into usuage into intelligent transportation system,comparison between different types of modulation scheme and OFDM,directly modulated signal transmission over fiber in WDM –PON S. H. Lee 2011 (et.Al) a new low-cost solution using orthogonal transmission of non-return-to zero and carrierless-amplitude-and-phase format data to realize a coarse OFDM transmission system. demonstrated at 37.5Gb/s.When lower speed laser drive electronics were used low cost future Ethernet system will developed.This new system had used 2 ASK namely NRZ and Quadrature carrierless amplitude and phase codes ,which have frequency distribution .Link capacity increased due to NRZ and CAP signals. This scheme was simpler and easy to implement. It allowed the increase of link Bandwidth using existing Ethernet grade component.[1]

A. K. Mishra1 2011 (et.Al) The generation of comb spectra was essential for optical OFDM transmitters. The dual drive Mach-Zehnder at one arm modulator with a 12.5 GHz sinusoidal and at the other arm with a 25 GHz sinusoidal separately. with 12.5 GHz spacing Up to eight optical subcarriers and a spectral flatness of < 1 dB could be produced.Lower drive voltage swings were required than other techniques. The modulated optical subcarrier fields are multiplexed to a compound field employing a lossless optical inverse Fourier transform circuit.This circuit strongly suppresses intersubcarrier cross-talk.Min. component count to produce densely and optical subcarrier channel comb line maintained the phase relation between generated subcarrier. [2]

Yu-Ting Hsueh, 2011 (et.Al) The first lightwave-centralized WDM-OFDM-PON architecture with OFDM re-modulation and a coherent-receiver-OLT was shown. downstream and re-modulated upstream Both 10Gbit/s OFDM-16QAM was successfully transmitted over 25km-SSMF with 10dB power-margin and negligible re-modulation and also transmission penalties.WDM to meet Large Capacity,Low Latency and High Security .Reuse of downlink for uplink transmission had taken place.Downlink and uplink frequencies were modulated in different format in order to avoid crosstalk like DPSK/OOK or RZ/OOK. OFDM/OOK had proved to be a new efficiently act source[3]

Ming-Fang Huang 2011 (et.Al) radio-over-fiber systems employed multiwavelength generation and the carrier-reuse technique.Due to bidirectional transmission backscattering over single fiber link Rayleigh can be reduced, because of different range of frequencies for downlinks and uplinks.For the wired transmission over 25-km single-mode fiber (SMF-28), power penalties were less than 0.5 dB for 11.29-Gb/s OFDM-16 quadrature amplitude modulation (16QAM) downlink and also for 5.65-Gb/s OFDM quadrature phase-shift keying. Moreover, successful access network transmissions were had been of the main problem faced was Rayleigh backscattering (RB) in WDM/PON .it had utilized simple modulator to realize successful hybrid bidirectional transmission with low (RB) interference and without additional light source in upstream[4]

Michela Svaluto Moreolo 2011(et.Al) peak-to-average power ratio (PAPR) The selective mapping (SLM), interleaving and partial transmit sequence (PTS) techniques for transmitting real-valued OFDM signals were adopted. In...
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