![m-ary threshold detector optisystem m-ary threshold detector optisystem](http://cdn.optiwave.com/wp-content/uploads/2013/06/Optical-System-DPSK-transmitter-using-DPSK-modulator-and-receiver1.jpg)
Similarly, the estimation of pure OSNR is altered by the influence of XPM. However, as soon as the system exceeds the reference parameter space or if different system conditions refer to similar state models, the estimation becomes unreliable. As the parameter space can be reduced to typical operation points of the system, a reference-based method comparing the actual system state to a set of known system states delivers respectable results. Although there is a systematic separation of deterministic signal components and noisy distortions, the identification of individual deterministic distortions like CD or PMD is not possible, nor is the identification of different noise sources. In conclusion, OPM from the state model of MLSE equalizers in direct detection systems is elaborate and only allows for limited access to individual channel parameters. Hauske, Maxim Kuschnerov, in Optical Performance Monitoring, 2010 10.2.5 Conclusion
![m-ary threshold detector optisystem m-ary threshold detector optisystem](https://slideplayer.com/slide/13023600/79/images/10/QPSK+with+carrier+channel.jpg)
We conclude the chapter by presenting our view on the future of short-reach transmission systems.įabian N. We then introduce advanced DD systems where novel transmitter and receiver designs are employed, so as to enable ultra-high interface rates for short-reach applications. In this chapter, we review the principles of conventional DD systems and discuss their limitations. Nowadays, typical transmission distances for DD systems range from few meters to about 100 km. The applications of DD systems were then limited to cost-sensitive short-reach applications such as metro transports, intra- and interdatacenter interconnects, and passive optical networks. Later, core networks transitioned to coherent systems, as they offer higher receiver sensitivity and better spectral efficiency, and therefore are more suitable for long-distance transmission at interface rates of 100 Gb/s and beyond. Schematic structure of a typical transceiver used in a direct-detection system.Īt the time when the required rates per transceiver interface were 10 and 40 Gb/s, DD systems were widely deployed for various kinds of fiber communication systems ranging from short-reach metro connections to long-reach links in core networks.