Aussie unis plan high-speed fibre research testbed

Three leading Victorian universities are planning to create a joint testbed for research that could significantly boost the capacity of fibre backhaul networks, a senate inquiry heard last week.

Under the plan, a dedicated 10 Tbps fibre testbed would be established between the city campuses of the University of Melbourne and RMIT, with a link to Monash’s main Clayton campus in Melbourne’s southeast.

The network would be used to subject recently-developed fibre optic modulation techniques to real-world conditions, and trial new signal processing methods that promise to improve fault tolerance from interference.

If successful, the network promises to lead to increased capacity on existing long-distance and undersea fibre optic backhaul links.

Monash University researcher Arthur Lowery told iTnews “the time was right” for the collaboration.

“There are six leading academics at Monash, RMIT and Melbourne, all known worldwide for their work in long-haul optical communications, who want to collaborate in building optical networks using optimal combinations of optical and electronic signal processing,” Lowery said.

The researchers published a joint research paper on the techniques last year, and implementing a test-bed would allow them to test the techniques against real-world conditions.

“We’ve each got equipment that packs a lot of information into the same fibre that we’ve been trialling in our laboratories,” Lowery said.

“But when you use that same equipment to send signals from A to B to C outside, you get degradation due to natural conditions, and so we’re interested in testing how signal processing can be used to correct for some of that degradation."

The researchers are aiming to get the testbed up and running later this year.

“We’re scoping at the moment, getting quotes and then we’ll ask for funding,” Lowery said.

“There’s a lot of dark fibre installed around town, so we hope to get this off the ground very quickly. Because of new appointments, we now have people in all three universities who are very keen to collaborate with one another, and take their lab work into the field –one step closer to commercialisation."

While there are existing fibre optic links between the major Victorian universities, the researchers have opted for their own dedicated fibre network to prevent their experimental techniques from causing interference with real data.

“We’re doing experiments with flexible networks, using different types of modulation – both new and old modulation techniques,” Lowery said.

“A key question is whether new and old can co-exist in the same fibre. Obviously, no-one wants existing customers disadvantaged when adding new wavelengths to a system.

“That is, we need to turn our techniques off, to see how much things improve when they are on. When they are off, we will probably impair the 'real data' channels, hence our need for a 'quarantined' link.”

The research involves adding photonic integrated circuit filters to commercial Australian-made reconfigurable optical add-drop multiplexers (ROADMs) in order to boost their throughput by reducing interference.

“The research includes sending signals in multiple wavelengths down a single strand of fibre as superchannels, then developing methods to mitigate fibre nonlinearity, which causes cross-coupling,” Lowery said.

“We're also interested in switching signal channels that have been affected by the environment, changing their polarisations and relative timing. For example, can we de-skew them before multiplexing them together?

“The polarisation of the light is also affected by the environment (heat and vibration), which causes cross coupling in polarisation-multiplexed systems, and fading when polarisation-dependent loss is present.

“We have provisionally patented some new signal processing methods to mitigate these issues, and we want to show them working in the field.”

The techniques promise to boost capacity on existing backhaul links without the cost of laying new fibre.

“There are very few fibre links between cities and towns, and these techniques will allow them to be upgraded without replacing fibres. This is especially important for undersea links, where increasing data capacity could be almost pure profit,” Lowery said.

“We hope the end result is to reduce transmission costs for telco operators and make better use of installed infrastructure around rural Australia by pushing more data down existing fibre links.”