ISSN : 1796-203X
Volume : 2    Issue : 3    Date : May 2007

Alternatives for In-Service BER Estimation in All-Optical Networks: Towards Minimum Intrusion
Carolina Pinart
Page(s): 56-63
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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.

Index Terms
Performance monitoring, all-optical, WDM, physical impairments, service quality