Transmission transparency and potential convergence of optical network solutions at the physical layer for bit rates from 2.5 Gb·s-1 to 256 Gb·s-1

In this paper, we investigate optical network recommendations GPON and XG-PON with triple-play services in terms of physical reach, number of subscribers, transceiver design, modulation format and implementation cost. Despite trends to increase the bit rate from 2.5 Gb s1 to 10 Gb s1 and beyond, TDMPONs cannot cope with bandwidth requirements of future networks. TDM and WDM techniques can be combined, resulting in improved scalability. Longer physical reach can be achieved by deploying active network elements within the transmission path. We investigate these options by considering their potential coexistence at the physical layer. Subsequently, we analyse the upgrade of optical channels to 100 Gb s1 and 256 Gb s1 by using advanced modulation formats, which combine polarization division multiplexing with coherent detection and digital signal processing. We show that PDMQPSK format is suitable for 100 Gb s1 systems and PDM-16QAM is more beneficial at 256 Gb s1. Simulations are performed in the OptSim software environment

System Performance and Limits of Optical Modulation Formats in Dense Wavelength Division Multiplexing Systems

In this paper we investigate in OptSim software environment the system performance of intensity and phase modulation formats for different network scenarios and dense wavelength division multiplexing grids. OptSim employs the Time Domain Split Step method to implement the signal distribution equation in a fiber. We investigate intensity formats, such as Non Return to Zero, Return to Zero, Carrier- Suppressed Return to Zero and DuoBinary, and phase modulation formats like Differential Phase-Shift Keying and Differential Quadrature Phase-Shift Keying. The main goal is to compare these formats in terms of bit error rate, Q-factor, optical reach and grid limitations for transmission rates 10, 40 and 100 Gbps per channel and discuss the possibilities of increasing their spectral efficiency. We also focus on other advanced solutions such as the polarization division multiplexing combined with phase modulations, coherent detection and advanced digital signal processing which mainly benefits in spectral efficiency, optical signal to noise ratio and chromatic dispersion tolerances

Benefits and limits of modulation formats for optical communications

This paper is focused on benefits and limits of intensity and phase modulation formats used in optical communications. The simulation results are obtained using OptSim software environment, employing Time Domain Split Step method. Non-Return to Zero, Return to Zero, Chirped Return to Zero and Carrier-Suppressed Return to Zero formats are compared in terms of Bit Error Rate and spectral efficiency to find the limits for selected transmission network topologies. It is shown that phase modulation formats offer many advantages compared to intensity formats. Differential Phase-Shift Keying and mainly Differential Quadrature Phase-Shift Keying improve the Bit Error Rate and transmission reach, among others. A promising solution is the application of Polarization Division Multiplexing Quadrature Phase-Shift Keying, which primarily benefits in spectral efficiency, estimated reach, optical signal to noise ratio and chromatic dispersion tolerances