Test and Measurement for Future Networks

Mario Larose

Test and measurement evolves in anticipation of advanced components, emerging protocols and streamlined network architectures.

It’s no secret that telecommunications carriers are reducing their capital expenditures because of a more competitive landscape. Consequently, these carriers will not necessarily deploy new optical networks. However, they will upgrade existing networks by adding dense wavelength division multiplexing (DWDM) channels, lighting dark fibers and increasing data transmission rates.

Also, the traditional boundaries defining the physical, optical and protocol layers of optical networks will blur as DWDM networks simplify their topology. From a protocol perspective, we foresee hybrid systems like SONET-Ethernet growing in importance, especially in the metropolitan-access areas.

In coming months, expect to see more hybrid field-testing platforms capable of testing the physical, optical and protocol layers with a single box. Photos courtesy of Exfo.

Testing requirements will be influenced greatly by the emerging implementation of protocol-independent DWDM networks capable of dynamic bandwidth assignments. A good example of this is enterprise networks, which are deployed to provide data storage area networks.

These trends will fuel the emergence of comprehensive physical-, optical- and protocol-layer test equipment for long-haul, metro and access networks. Already appearing are portable testing platforms that can operate multiple field-interchangeable modules for high-end DWDM testing, characterization of polarization mode dispersion, high-fiber-count testing, as well as optical time-domain reflectometry and optical loss testing. Similarly, performance management equipment has emerged to support a wide variety of protocols, including asynchronous transfer mode, SONET, synchronous digital hierarchy, Ethernet, Gigabit Ethernet and data transmission rates from 64 kb/s to 10 Gb/s.

The progressive hybridization of test and measurement equipment won’t stop there. Expect to see early this year field-testing platforms that will enable field technicians to be far more efficient and cost-effective by seamlessly carrying out physical-, optical- and protocol-layer tests with a single box in their hands.

On the optical component and system manufacturing side, the slowdown in network deployment and the resulting buildup of inventories have directly affected vendors. Leading manufacturers, however, cannot afford to curb spending on research and development in their quest to design next-generation solutions that will keep them one step ahead of the competition. As a consequence, new production lines of increasingly complex optical components — such as arrayed waveguides, optical hybrids and integrated optics — will be required. These components require fast-measurement test stations to provide positioning feedback for fiber termination on the devices.

Slowing network deployments won’t stem the research and development that keeps manufacturers ahead of their competition. Hence, test and measurement will help development of next-generation arrayed waveguides, optical hybrids and integrated optics.

Furthermore, the trend toward 40-Gb/s systems is no longer a matter of if but when. Whatever the time line, 40-Gb/s data rates will place enormous pressure on manufacturers to find highly accurate and quick instruments for measuring polarization mode dispersion in the femtosecond range. Measurements must be obtained in femtoseconds because even the smallest effects of polarization mode dispersion from individual components have a cumulative effect on the overall performance of high-speed optical networks.

We’re already beginning to see analyzers that enable simple, fast and repeatable measurements of very small dispersion effects in narrowband DWDM channels and broadband components.

Chromatic dispersion is another limiting factor. As a result, we can expect new generations of test equipment to measure this physical phenomenon on deployed networks and individual components.

Besides more sophisticated instruments for 40-Gb/s testing, users are demanding instrumentation with greater ease of use and shorter testing cycles. Vendors will continue to introduce simplified, single-button automated test systems that enable nonexperts to characterize complex optical parameters in less than a minute on the production floor.

In summary, the increasingly competitive environment is driving telecommunications carriers as well as optical component and system manufacturers to extract the greatest possible value from existing optical networks through enhanced solutions. The challenge for test and measurement vendors is to support these customers in their quest to develop next-generation solutions with innovative products that are highly accurate, are fully reliable and that, by design, save time.

Meet the author

Mario Larose is responsible for marketing and customer service activities at Exfo. He holds a bachelor’s degree in engineering physics from École Polytechnique in Montreal and an MBA from the Université du Québec à Montréal.