Duobinary Modulation Format for Optical System- A Review

Abstract

ABSTRACT:In metropolitan optical networks, with the increasing growth and demand for capability, high bit rate transmission has recently become an important part of communication. Duobinary modulation is more efficient format for transmitting high speed optical signals over bandwidth limited channel. The duobinary modulation format for long haul and WDM transmission links is the one that has a narrow spectral width, low susceptibility to fiber nonlinearity, large dispersion tolerance and good transmission performance and has a simple and cost-effective configuration. KEYWORDS:Amplitude Shift Keying (ASK), Duobinary Modulation (DM), Mach Zender Modulator (MZM), NonReturn-to-Zero (NRZ), Phase-shift Keying (PSK), Return-to-Zero (RZ). I.INTRODUCTIONOptical duobinary format has attracted much attention in latest years, since optical duobinary signals have a higher spectral efficiency and better tolerance of chromatic dispersion than the standard non-return-to-zero (NRZ) signals due to the narrower spectral bandwidth [1]. Optical duobinary is a proficient modulation format which is known to increase the spectral efficiency [2]. Duobinary modulation format have been proposed to increase the transmission capacity by improving the bandwidth efficiency of the limited amplifier bandwidth to reduce channel spacing with the narrow spectral width of modulated signals in DWDM systems [3]. The high dispersion tolerance of this modulation scheme can eliminate the accurate dispersion compensation [4]. Due to its large dispersion tolerance, the duobinary modulation is appropriate for optical metro area networks (MANs) [5]. Its simple implementation, high chromatic dispersion tolerance and enhanced spectral efficiency are all attractive characteristics for wavelength-division-multiplexed transmission systems [6]. Duobinary modulation is an attractive candidate because it is spectrally efficient (~0.8 b/s/Hz) [7]. Compared with the standard non-return-to-zero (NRZ) format, optical duobinary modulation also has higher threshold for the onset of Stimulated Brillouin Scattering (SBS) [8]. To improve the transmission capacity, the duobinary modulation format has been very attractive due to a narrow spectral width and a high tolerance to the chromatic dispersion [9].Lender el at.[10] demonstrated a new approach to digital data transmission, termed duobinary and correlative, substantially increases speed over any band-limited media owing to correlation between signal states. Specific codes are used with or without carrier modulation. In the error detection process, it has been observed that with this type of system it is unnecessary to introduce redundant digits into the original data stream. Price and Mercier el at. [11] analysed a reduced bandwidth optical digital intensity modulation with improved chromatic dispersion tolerance. In this a simple optical modulation scheme using a lithium niobate MZ modulator driven by a three level drive waveform is proposed. The two-level intensity modulated optical signal obtained possesses a smaller ...

Utilization of 10 Gbps DWDM System with Duobinary Modulation into Passive Optical Network

“…If there is even number of zero-level signals in between, polarization remains the same polarity. The main disadvantage of optical duobinary modulation is polarization mode dispersion (PMD) which can strongly impair the performance of system, especially when working at high bit rates (40 Gbps and more) [18], [19].…”

Transmitter Aperture Diameter Effect in 40 Gb/s Inter-Satellite Optical Wireless Communication System

“…In addition, it has the capability to work in various electromagnetic bands, such as infrared (750-1560 NM) and ultraviolet (200-280 NM). [26], [27], [28]. Last, it reduces the area of the payload and weight of the satellites, since the components required are compact and lightweight, in contrast to RF based satellite communication as shown in Figure 2 [29], [30], [31].…”

Research of M-PAM and Duobinary Modulation Formats for Use in High-Speed WDM-PON Systems

“…Another way to improve capacity of limited bandwidth is by using duobinary modulation format. Transmission capacity will be increased in comparison with NRZ, utilization of DB will increase the transmission capacity by improving the bandwidth efficiency and reducing channel spacing with this modulation format [12]. Duobinary modulation format is type of proficient pseudo-multilevel modulation format, and therefore is the area of interest due to its increased spectral efficiency.…”