Manivasakan Rathinam

We propose and demonstrate a generalized framework for performance limit evaluation and comparison of multihop optical repeated and regenerated links. The model developed is implementation agnostic and applies to multihop optical links of varied forms, including fiber, free space, and underwater links. The framework estimates the best-case performance gains of deploying an all-regenerative link over an all-repeater link for any given implementation. The implementation-independent technique is then illustrated using guided and free-space optical links. An abstract model is developed first with the evolution of signal, noise power, and bit error rate down the link compared and contrasted for both cases. The model is then evaluated using physical parameters for a typical fiber optic intensity-modulated direct detection link, and the obtained all-regenerator link performance advantage is translated to extra reach and lower transmission power requirements. Further, certain approximations are provided to reduce computational complexity and improve the analytical tractability of the procedure, which could be particularly helpful when employed in specialized hardware or for dynamic reconfiguration networks. Finally, the framework's versatility is established by employing it in analyzing an ideal free-space link and comparing amplify and forward links against decode and forward counterparts. Similar results are also reproduced on a commercial optical link simulation suite. Detailed literature on link analysis is provided for fiber, free space, and underwater links, bringing out their similarities. We conclude by elaborating on various current and emerging application domains and certain limitations of the proposed technique.

Long haul optical links provides the backbone for most of today's communication and the Internet in general. The throughput of an optical link witnessed a major breakthrough with the advent of optical amplifiers in the early 1990s. These optical amplifiers with their large bandwidth facilitated the introduction of Wavelength Division Multiplexing (WDM) and a bandwidth explosion followed. Though they provide good gain and large bandwidth, all while keeping the information in optical domain; optical amplifiers do add noise of its own to the data, which when cascaded over long distances starts to limit the link length. Optical-Electrical-Optical (OEO) regenerators are used to clean and regenerate the signal but are expensive and adds potential delays in the link. In this paper we investigates their theoretical performance differences and highlights the advantages of all regenerators link over all repeaters ones. We undertake this analytical study to investigate the absolute theoretical gains of implementing an all regenerator link which is to serve as a baseline, or a precursor, for further investigations on the advantages of all optical regenerative link. Here we derive the performance limits of an all regenerator systems and compare it with its amplifier/repeater counterparts. Noise evolution in all repeater links and BER accumulation for both are illustrated. We illustrate general optical link BER curves and compare all repeater/regenerator link performances against input power for single and multiple hops. We also translate the BER advantage of all regenerator link to longer link reaches or lower power requirements. The later is repeated for different target BER too.