Simulation and analysis of dispersion compensation schemes for 100 Gbps PDM–OFDM optical communication system

In this paper, the implementation of 100 Gbps optical communication system exploiting polarization diversity at transmitter and receiver is developed and investigated with pre-, post- and symmetrical dispersion compensation schemes by using dispersion shifted and dispersion compensated fibers through simulations to optimize high data rate optical transmission. Motivation to the current analysis is to compare all 3 compensation schemes and it's found that the pre compensation technique is superior to post and symmetrical compensation techniques in 100 Gbps PDM–OFDM communication system. On examination of symmetrical and post dispersion compensation schemes, it's found that the later is superior to the previous in this case. A 100 Gbps coherent optical OFDM workplace has been discovered in which two 50 Gbps data streams are combined into one wavelength by polarization beam combiner. By comparing one can get a promising system to the symmetrical high capacity access network with high spectral efficiency, cost effective, good flexibility.     

Comparison of various dispersion compensation techniques at high bit rates using CSRZ format

In this paper, the dispersion compensation techniques are compared on the basis of eye opening, eye closure, bit error rate and Q-factor. These techniques are applied to CSRZ system, which operates at bit rates of 2.5, 5, 10, 15 and 20 Gbps bit rates. The technique using fiber Bragg grating (FBG) for dispersion compensation is the best technique as this technique gives larger values of eye opening at 10 and 20 Gbps bit rate, smaller values of eye closure at 10 and 20 Gbps, minimum value of BER at 15 Gbps and maximum value of Q-factor at 15 Gbps when compared with other techniques. The RDF technique is the next best technique since this technique gives maximum value of eye opening when other techniques give almost similar values of eye opening at 15 Gbps, minimum value of eye closure at 15 Gbps, minimum value of BER at 15 Gbps and maximum value of Q-factor at 15 Gbps when compared with other techniques. The DCF is the next best technique as this technique gives maximum and minimum values of eye opening and eye closure at 20 Gbps (next best to FBG at 20 Gbps).     

50 km bidirectional FTTH transmission comparing different PON standards

In this paper, a bidirectional Fiber To The Home (FTTH) is proposed where WDM transmitter is used as a seeding source with wavelength of 1550 nm. The system utilizes a Travelling wave Semiconductor Optical Amplifier (TSOA) with injection current 0.15A. 50 km range FTTH architecture is demonstrated for both downstream and upstream channels. We investigated the impact of different data rates on upstream and downstream data. The BER results show that the performance of our scheme is good for 10 Gbps system for downstream transmission as it accommodates 64 ONUs. From simulation results show the BER of 9.95e-009 is reported at 15 Gbps but only in case of 32 ONUs. Similarly, in case of upstream transmission, Q-Factor of 15.04 dB is reported for 32 ONUs. So this scheme is a practical solution to meet the data rate of the optical links simultaneously in tomorrow's PON access networks.     

Performance comparison of pre-, post- and symmetrical-dispersion compensation techniques using DCF on 40 Gbps OTDM system for different fibre standards

Various factors like polarization mode dispersion, non-linear effects, Kerr effect, second and third order dispersion impose limit on the performance (transmission distance, pulse broadening) of Optical Time Division Multiplexed (OTDM) transmission system. In this paper, the performance comparison of 40 Gbps OTDM transmission system with pre-, post-, and symmetrical-dispersion compensation techniques for different fibre standards has been carried out. It has been observed that for pre compensation, ITU 655 [D = 3.78 ps/nm/km] came to be best suitable fibre with the dispersion compensating fibre length of 2.36 km for maximum reach of 3000 km. For post- and symmetrical-compensation, the behaviour of alcatel [D = 8 ps/nm/km] is almost similar with maximum transmission distance of 3200 and 3050 km respectively.     

Add/drop applications in fiber ring networks based on a reconfigurable optical add/drop multiplexer in a re-circulating loop

A periodic add/drop system in a fiber ring network was investigated using a reconfigurable optical add/drop multiplexer (ROADM) in a re-circulating fiber loop. After seven cascaded add/drop nodes at every 150 km along the transmission, at bit error ratio (BER) equals to 10⁻⁹ and data rate of 10 Gbps, we observed a 2.5 dB power penalty for the passing through channels with 1050 km transmission distance, and 0.3 dB sensitivity penalty variation for the periodic add/drop channels at every 150 km, respectively.     

A novel approach for simultaneous millimeter wave generation and high bit rate data transmission for Radio over Fiber (RoF) systems

We propose a novel method for simultaneous transmission of OC-192 (9.95328 Gbps) digital data and 60 GHz RF generation in a Standard Single Mode Fiber (SSMF) link utilizing Stimulated Brillouin Scattering (SBS). The system comprises of a 1550 nm DFB Laser diode, Mach Zehnder modulator (MZM), 50 km SSMF and Optical receiver. The receiver includes laser diode for optical pump, a regenerator for data retrieval and a RF bandpass filter for RF generation. This system requires minimum number of RF and optical components for the generation of 60 GHz RF. The remotely generated 60 GHz RF signal may be used for wireless transmission of data. The entire link is simulated in Optisystem software to analyze the system performance.     

Influence of modulation formats performance of the combined modulation in WDM-PON system

Different modulation modes of DPSK and OOK are separately employed in the upstream and downstream link, after the comparison with different modulation formats in the downstream including the codes of non return-to-zero (NRZ), return-to-zero (RZ) and inverse return-to-zero (IRZ), the symmetric rate of 10 Gbps with 20 km transmission is realized without the dispersion compensation. It can be shown that in the combined modulation mode with the downstream of IRZ code, higher extinction ratio in the downstream and better performance of dispersion tolerance in the upstream could be achieved, enhancing the overall property of the transmission system.     

Simulation of fiber to the home triple play services at 2 Gbit/s using GE-PON architecture for 56 ONUs

This paper evaluates and compares FTTH (Fiber To The Home) GEPON (Gigabit Ethernet Passive Optical Network) link design for 56 subscribers at 20 km reach at 2 Gbps bit rate. A 1:56 splitter is used as a PON (Passive Optical Network) element which creates communication between a Central Office to different users and. A boosting amplifier is employed before fiber length which tends to decrease BER and allows more users to accommodate. This architecture is investigated for different values of data rate from a CO (Central Office) to the PON in terms of BER (Bit Error Rate). The simulation work reports BER of 4.5246e−009 at 2 Gbit/s systems for the case of 56 users and if we further increase data rate of system say 5 Gbps, then we observe a sharp increase in BER. Similarly in the variation of BER with respect to transmission distance, we observe that BER shows an increase in its value as transmission distance increases.     

Optimization of free space optics parameters: An optimum solution for bad weather conditions

Free Space Optics Systems (FSO) is one of the most effective solutions, especially for atmospheric turbulence due to the weather and environment structure. Free space optics system suffers from various limitations. A well-known disadvantage of FSO is its sensitivity on local weather conditions-primarily to haze and rain, resulting in substantial loss of optical signal power over the communication path. The main objective of this article is to evaluate the quality of data transmission using Wavelength Division Multiplexing (WDM) with highlighting several factors that will affect the quality of data transmission. The results of these analyses are to develop a system of quality-free space optics for a high data rate transmission. From the result analysis, FSO wavelength with 1550 nm produces less effect in atmospheric attenuation. Short link range between the transmitter and receiver can optimize the FSO system transmission parameters or components. Based on the analysis, it is recommended to develop an FSO system of 2.5 Gbps with 1550 nm wavelength and link range up to 150 km at the clear weather condition of bit-error-rate (BER) 10⁻⁹.     

The generation of optical duobinary signal using electroabsorption modulator for optical access networks

We generate the duobinary signal by utilizing the intensity modulation characteristic of the electroabsorption modulator and the phase characteristic of phase shifter for the high-speed transmission system. In addition, compared to those commercial 10 Gbps OOK modulators, lower cost, better performances and easier integration can be achieved by using these duobinary modulators.     

On the carrier generation and HD signal transmission using the millimeter-wave radio over fiber system

The dual sideband optical carrier suppression (DSB-OCS) technique is employed in the optical carrier generation for 40 GHz radio over fiber (ROF) system. A dual electrode Mach-Zehnder modulator (DE-MZM) with the minimum transmission bias (MiTB) technique is employed to build the system. The results show that, a 40 GHz carrier is successfully generated with the amplitude up to −29 dBm and signal to noise ratio (SNR) of 35 dB and a high definition (HD) signal is successfully transmitted using the system. Finally, the bit error rate (BER) measurement is carried out for the system with 1.25 Gbps OOK signal showing an error free 40 GHz ROF system with almost no penalty between the back to back and 20 km fiber for a BER of 10⁻⁹.     

Realization of free space optics with OFDM under atmospheric turbulence

Free space optics (FSO) technology provides a promising solution for future broadband networks, offering high data transmission compared to RF technology. This work is focused on investigating the performance of an FSO system with OFDM and QAM. A 10 Gbps data stream is transmitted using a 4-level QAM sequence through the FSO system under different atmospheric conditions. Results indicate that the integration of SOA prolongs the maximum achievable distance with acceptable SNR to 185 km under clear weather conditions whereas under atmospheric fog, the maximum distance is extended to 2.5 km.     

Enhanced colorless and broadcast capable symmetrical 10-Gbps bidirectional transmission in WDM-PON using RSOA and EAM

Here we proposed a novel architecture of wavelength division multiplexed-passive optical network (WDM-PON) in which the downlink unicast data, broadcast data and uplink unicast data transmission is possible with the symmetric data rate of 10 Gbps. At remote node (RN) cyclic wavelength routing property of array waveguide grating (AWG) and power splitting capacity of power splitter is used in the architecture so that broadcast channel can be overlaid on downlink unicast channels. At ONU carriers sent from central office (CO) is reused for upstream data transmission with the help of integration of a reflective semiconductor amplifier (RSOA) and an electro-absorption modulator (EAM) so there is no need of extra laser sources at ONUs which makes them colorless. EAM can be operated at very high speed; a modulation bandwidth of tens of GHz can be achieved. Broadcast channel causes a limited interference with downlink and uplink unicast channels so it does not affect the system performance. Since each channel has different wavelength so NRZ data is used which eliminates expensive DPSK receivers and detection becomes very easy. Simulation is performed with all channels having data rate of 10 Gbps having acceptable performance.     

Adaptive unsaturated OFDM multimode fiber communication technique based on zero padding

In order to overcome the deterioration of system performance induced by the subcarriers at or near the deep fading nulls in high frequency band-pass regions of multimode fiber, we first propose adaptive unsaturated OFDM technique based on zero padding in this paper. In our proposed method, the subcarriers with low SNR (at or near deep fading nulls) are turned off by zero padding, and data originally transmitted by those subcarriers will be transferred to new subcarriers with high SNR which have been created at high frequency by the adjusting of IFFT points. The results show that the technique proposed can accomplish transmission of 10 Gbps data rate over 1 km multimode with the BER of 4.61e−3 when the OSNR is 20 dB.     

Application of Turbo codes in optical OFDM multimode fiber communication system

In this paper, Turbo Code is proposed in optical OFDM multimode fiber communication system in order to decrease the bit error rate (BER) of the system, which is mainly affected by the deep nulls of the magnitude response of multimode fiber in the high frequency region (above 3 dB). A simulation system in SIMULINK is established. Based on the system, the BER of the system with Turbo Code is compare to the systems with another two typical coding schemes including convolutional code (CC) and serially concatenated code (SCC) which uses a concatenation of convolutional and RS codes when transmitting 10 Gbps data over various length multimode fibers. Different transmitting rate is also considered. The results show that Turbo coded system has a lower BER than the other two systems and the Turbo coded system can transmit 10 Gbps data to the distance of 300 m with BER below 1e−6.     

Modeling and simulation of FBG based OCDMA-IsOWC system

Photonics have evolved from protracted fibers to dominant wireless system to look at the use of hybrid optical-wireless communication system into space technology. Inter-satellite optical wireless communication (IsOWC) systems, one of the important applications of optical-wireless communication, will be deployed in space in the near future. A significant improvement in BER at 5 Gbps is achieved along with the maximum length of ISL link between the two satellites by incorporating OFDM scheme in IsOWC systems than that of conventional IsOWC systems [9]. The work is further extended in this paper to prolong the ISL link with acceptable BER at 10 Gbps between two satellites in space by employing code division multiple access (CDMA) scheme due to its robustness against narrowband interference and an inherent low power spectral density. In this work, we have designed a model of FBG based CDMA-IsOWC system to establish a prolonged ISL link at data rate of 10 Gbps with SNR of 20 dB. Further, a comparison is also reported between our proposed FBG based CDMA-IsOWC system and OFDM-IsOWC system.     

Colorless gigabit WDM-PON link using injection locking and electro-absorption transceiver

In this paper, a novel colorless wavelength division multiplexing-passive optical network (WDM-PON) system using injection locking and electro-absorption transceiver (EAT) is proposed and demonstrated experimentally. This system has advantages, high data transmission, small downlink signal effect to uplink signal and less polarization sensitivity, compared to the system using reflective semiconductor optical amplifier (RSOA). Downlink signal modulates the right side carrier of the double side band signal by using injection locking. EAT functions as both photo detector in downlink signal and modulator for uplink signal, simultaneously. A possible cross absorption modulation effect from the EAT is analyzed experimentally. Bidirectional transmission of 1.25 Gbps and 622 Mbps for downlink and uplink, respectively, were verified through 23 km standard single mode fiber (SSMF).     

160 Gbps S-band WDM transmission system over 1400 km using ITUT-652a and ITUT-655 fibers with low dispersion accumulation

Dispersion accumulation with the distance effects optical WDM system's performance severely. For every modulation format used there is a limit on maximum transmission distance due to dispersion accumulation. So dispersion compensation is required. But dispersion compensation can be avoided to a large extent by alternatively using different fiber standards. In this paper it has been proposed that the dispersion accumulation can be reduced to a large extent by alternatively transmitting in S-band and using fiber standards ITUT-652a and ITUT-655. To validate the claim, performance of a 16 channel 10 Gbps WDM system with the proposed method has been analyzed in terms of BER and Q-factor. And it has been observed that with the proposed scheme without any dispersion compensation the system performs well up to 1400 km.     

Transmission of 4× 40/10 Gbps in a WDM-PON using NRZ-DQPSK/ASK modulation

In this paper we demonstrate the feasibility to deploy a wavelength division multiplexing passive optical network (WDM-PON) of a 30 km standard single-mode fiber (SSMF-28) carrying 160 Gbps data in downstream and 40 Gbps through the uplink. The developed method is based on the comparison between two WDM-PON systems of 4 channels with the same characteristics, using two different formats of modulation in OLTs. The first system uses the NRZ-ASK in the downlink direction, while the second uses the NRZ-DQPSK.     

A novel non-coherent spectral OCDMA system using one-dimensional expanded Hybrid codes for two-code keying

We propose leveraging one-dimensional expanded Hybrid codes (1-D E-Hybrid codes) for two-code keying (TCK) in spectral amplitude coding (SAC) optical code division multiple access (OCDMA) networks. Compared with the existing work, the proposed system can utilize all codes and provide a larger code size to support more simultaneous users. The numerical results demonstrate that the 1-D E-Hybrid codes for TCK outperform the existing 1-D approaches in terms of bit error rate (BER), and the data transmission rate can achieve 2.5 Gbps.