RESEARCH ACTIVITIES
As our department has evolved over the past few years, we have developed research programs in new and exciting areas and we hope to continue in this direction. Our close affiliation with a number of research groups such as the Rsoft design group, USA has given us new dimensions for setting up state-of-art research laboratory on soliton transmission Light wave communication field. The thrusts areas of
research in communications and signal processing include:
- Optical soliton transmission system
(long-distance, high-speed optical transmission)
| Research Work | “Analysis, Simulation and Performance Evaluation of Optical Soliton Transmission Networks” |
| Faculty | Dr. Manoj Kumar, Professor & Head |
| Status: | Executed |
The term soliton (formed from Latin solitarius – solitary) is one of the fundamental unifying ideas in modern theoretical physics and mathematics. An impressive practical implementation of the soliton concept has been achieved in fiber optics, where soliton pulses are used as the information carriers to transmit digital signals over long-haul. Optical soliton research, full of innovative spirit, has recently arrived at the stage of a first real-world implementation of the soliton concept in communication systems. Realization of soliton-based transmission will clearly demonstrate how the results of the fundamental soliton theory can be successfully exploited in very important practical applications.
Practical and research interest is directed mostly towards two main goals: development of effective high capacity long-haul transmission systems and the upgrade of existing terrestrial fiber networks. There are two principal approaches to overcome these limitations: in the first (that can be called ‘linear’) both the chromatic dispersion and nonlinearity are considered to be detrimental factors while in the second, the nonlinear and dispersive effects are counter balanced (such systems can be called ‘nonlinear’). Nonlinear effects that are detrimental in the ‘linear’ systems can be used to improve transmission characteristics of optical communication systems.
- Our investigations have been focused to suggest alternative optical soliton based designs that are suitable for already installed optical transmission links. Based on our investigations, it is recommended that one of the promising ways to upgrade installed optical network is to exploit the 1.3 mm optical window, where the step-index fibers have their zero dispersion wavelength, using wide-bandwidth polarization-insensitive SOA’s. The pattern effect and the impact of chirp on pulse propagation after amplification have been investigated. The observations are based on modeling and simulation optical soliton transmission link. Optical soliton pulse transmission over distances of the order of several hundreds of kilometers has been shown with and without initial chirp.
- We investigated that the Kerr non-linearity stabilizes solitons against splitting due to birefringence. The birefringence induced time delay between X and Y polarization components reduces to 200 ps from 440 ps when the Kerr non-linearity is taken into account at polarization angle and fiber length of 631.72 km (10 soliton periods) & 1264.344 km (20 soliton periods) for both the linear and nonlinear soliton transmission.
- Our research goal was to realize long-haul, large capacity optical transmission by taking advantage of optical nonlinear effects, including optical solitons and nonlinear techniques for generating ultra short optical pulses. The soliton is a wave that exists in nature that can propagate over long distances without any distortion of its waveform. We have developed several novel path-averaged long-haul soliton transmission techniques, such as the use of path averaged soliton, dispersion-managed (DM) soliton, loss-managed soliton transmission systems. By adopting these techniques, we can increase the transmission capacity and upgrade installed terrestrial or submarine cables
The investigations demonstrate the robustness of path-averaged soliton in a long-haul transmission link of 17,000 km at a bit rate of 10 Gbps. It has been investigated that relatively stable pulses can propagate over longer distances in long-haul dispersion-managed soliton regime in a fiber link with loss and periodic amplification by keeping the average dispersion small but non-zero. It has been shown that the dispersion management is achieved through soliton pulse narrowing in anomalous dispersion fiber and broadening at DCF. In conclusion, we have reported that the pulse propagation in dispersion-managed soliton transmission link is similar to conventional transform-limited soliton transmission link.
- We have also carried out performance evaluation of the Optical Soliton Transmission Systems under the influence of various linear and non-linear fiber parameters & performance measures. Performance evaluation has been carried out for the different modulation formats viz. NRZ, RZ Soliton, RZ Raised Cosine and RZ Super Gaussian.
Simulations for data formats Return to Zero (RZ), Non Return to Zero (NRZ), RZ-Soliton, Duobinary and their subcategories has been done with and without ideal dispersion compensation for optical communication systems. The results show that in general dispersion compensation improves timing jitter. RZ-Rectangular pulses show the smallest value of jitter without compensation. It has been observed that the RZ-Raised cosine and Soliton gives minimum jitter after ideal compensation. It has been reported that the BER performance of optical communication system using duobinary data format is 10-8 and 10-37 before and after dispersion compensation respectively. Further the comparative study show that the timing jitter is lowest in case of RZ-Soliton (0.0127 ns) after dispersion compensation and 0.0135 ns for RZ-Rectangular data format before dispersion compensation.
| Research Work | “Performance Analysis of Data Formats in Optical Soliton Transmission Link under the impact of Chirp and Third Order Dispersion” |
| Faculty | Mr. Jagjit Singh Malhotra, Assistant Professor |
| Status: | Executed |
This research work is focused on the Performance Analysis of NRZ, RZ, CRZ and CSRZ data formats in Optical Soliton Transmission Link under the impact of Chirp and Third Order Dispersion. The objective is to analyze the performance of these data formats using performance metrics viz BER, Q factor, Eye opening etc. The results obtained so far indicate that performance of CRZ and CSRZ under the given system is better as compared to NRZ and RZ data formats. However CSRZ has yielded so far best results.
| Research Work | “Performance evaluation of various types of optical fiber and erbium doped fiber amplifier for optical fiber communication systems” |
| Faculty | Ms. Kiran Ahuja, Lecturer |
| Status: | Executed |
This research work aimed at evaluation of different types of fibers on the basis of BER, Q factor, Jitter and also find out the best fiber based on these factors. Performance analysis of EDFA has been carried out on the basis of gain, noise figure, doped length.
Digital Communication through Wireless Channels
Our research goal is to effectively characterize the propagation channel for the design of effective transmitters, receivers and communication protocols. Various optimal diversity combining and adaptive modulation techniques are analyzed for their performance in the multiplicative fading & ISI channel. Various fading mitigating techniques such as OFDM, MIMO, Space-time coding are also being analyzed.
