Theses and dissertations (Engineering and Built Environment)
Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/10
Browse
2 results
Search Results
Item Comparative analysis, design and optimisation of a 48 channel DWDM system using various design parameters(2019) Mohan, Jerrin Zachariah; Sokoya, Ayodeji SokoyaIn the current era, there is an ever-growing demand for data hungry applications and services that need large amounts of bandwidth to send digital information at very high speeds. In order to meet this challenge for higher bandwidth capacity, Dense Wave Division Multiplexing (DWDM) is used as the strategy to transmit multiple high-bit rate channels at extremely narrow channel spacings over a single fiber core. However, this gives rise to detrimental transmission impairments such as linear effects and non-linear effects. The dissertation minimises the impairments by optimally designing a new DWDM system that produces a detectable and acceptable quality of signal at the receiver. In this dissertation, a comparative analysis is performed on the simulative design of a 48-channel DWDM system that has a 25 Gb/s bit rate and a 100 km transmission distance. The research mitigates the effects of transmission impairments such that an error-free matched communication link is produced for equally spaced (ES) channels of 100 GHz, 50 GHz, 25 GHZ and 12.5 GHz and 6.25 GHz. Various design parameters are used to create the comparative analysis model to optimise the 48 channel DWDM network. The design is simulated using the Optisystem simulation platform and the signal analysis is based on the bit error rate (BER) and quality (Q) factor of the received signal’s eye diagrams. It is established in the desertion that modified networks with matched active components has ES frequency channels that are aligned to each other and has a higher optical signal to noise ratio (OSNR) than mismatched networks. The maximum signal power and OSNR of the 3-erbium doped fiber amplifier (EDFA)-post symmetric compensation technique is always higher than the 1-EDFA post compensation technique for all channel spacings in any type of network. Modified duobinary return to zero (MDRZ) when compared to non-return to zero (NRZ) and return to zero (RZ) has a greater dispersion tolerance, higher fiber non-linearity tolerance and a higher acceptable signal transmission over longer distances with the least amount of errors. The optimised design parameter configurations produce the highest signal performance (highest Q factor > 6 and lowest BER > 10-9) and the highest bandwidth efficiency for the RZ Modulation (at 100 GHz, 50 GHz and 25 GHz channel spacings) and MDRZ Modulation (at 12.5 and 6.25 GHz channel spacing).Item Energy-efficient PLIA-RWA algorithms for transparent optical networks(2017) Mutsvangwa, Andrew; Nleya, BakheThe tremendous growth in the volume of telecommunication traffic has undoubtedly triggered an unprecedented information revolution. The emergence of high-speed and bandwidth-hungry applications and services such as high-definition television (HDTV), the internet and online interactive media has forced the telecommunication industry to come up with ingenious and innovative ideas to match the challenges. With the coming of age of purposeful advances in Wavelength Division Multiplexing (WDM) technology, it is inherently practicany possible to deploy ultra-high speed all-optical networks to meet the ever-increasing demand for modern telecommunication services. All-optical networks are capable of transmitting data signals entirely in the optical domain from source to destination, and thus eliminate the incorporation of the often bulky and high-energy consuming optical to-electrical-to-optical (OEO) converters at intermediate nodes. Predictably, all-optical networks consume appreciably low energy as compared to their opaque and translucent counterparts. This low energy consumption results in lower carbon footprint of these networks, and thus a significant reduction in the greenhouse gases (GHGs) emission. In addition, transparent optical networks bring along other additional and favourable rewards such as high bit-rates and overall protocol transparency. Bearing in mind the aforementioned benefits of transparent optical networks, it is vital to point out that there are significant setbacks that accompany these otherwise glamourous rewards. Since OEO conversions are eliminated at intermediate nodes in all-optical networks, the quality of the transmitted signal from source to destination may be severely degraded mainly due to the cumulative effect of physical-layer impairments induced by the passage through the optical fibres and associated network components. It is therefore essential to come up with routing schemes that effectively take into consideration the signal degrading effects of physical -layer impairments so as to safeguard the integrity and health of transmitted signals, and eventually lower blocking probabilities. Furthermore, innovative approaches need to be put in place so as to strike a delicate balance between reduced energy consumption in transparent networks and the quality of transmitted signals. In addition, the incorporation of renewable energy sources in the powering of network devices appears to gain prominence in the design and operation of the next-generation optical networks. The work presented in this dissertation broadly focuses on physical-layer impairment aware routing and wavelength assignment algorithms (PLIA-RWA) that attempt to: (i) achieve a sufficiently high quality of transmission by lowering the blocking probability, and (ii) reduce the energy consumption in the optical networks. Our key contributions of this study may be summarized as follows: Design and development of a Q-factor estimation tool. Formulation, evaluation and validation of a QoT-based analytical model that computes blocking probabilities. Proposal and development of IA-RWA algorithms and comparison with established ones. Design and development of energy-efficient RWA schemes for dynamic optical networks.