Alternatives for In-Service BER Estimation in All-Optical Networks: Towards Minimum Intrusion

Combining the existing approaches for optical intelligence and the speed and capacity of light is undoubtedly the only viable strategy for building future-proof, highspeed networks. Future optical networks are also expected to provide added value through service quality. However, the performance parameters included in current service level agreements (SLA) require the termination of a channel (wavelength) at an optical-electrical (O/E) conversion point to measure them. In all-optical networks, this is associated with higher cost. Therefore, the optimal monitoring solution for all-optical networks will be one that implements the minimum amount of O/E conversions required to measure or estimate the SLA parameters. This is very challenging due to the complex relations of electrical and optical parameters. Taking the bit error rate (BER) as the key performance parameter to quantify the reliability of a transmission system, this paper discusses the applicability of in-service BER estimation strategies used in current (opaque) optical networks to an all-optical framework. From this discussion, it is derived that link bit error checks are not cost-effective in an all-optical network. Then, we compare different alternatives for low-cost, real-time BER estimation with different levels of O/E conversions and apply the least intrusive of them to a use case consisting of an all-optical networking laboratory testbed. Through this example, we show that the combination non-intrusive monitoring of OSNR and packet statistics results in a viable estimation of the BER and at also provides additional, valuable information of packet metrics.