Startup Promotes Switchless Networks
Called Pipistrelle Ltd. (Website still under construction), the company is still in its early stages. It's waiting for a technology license from Lockheed Martin Corp., which covers the basic architecture. Lockheed also intends to license the technology to a newly minted startup in Florida (name unknown) to cover the American market.
Lockheed developed the technology some time ago but didn't want to commercialize it for telecom networks, according to Pipistrelle's managing director Dick Winchester. And rather than give the idea to a company already in the communications business, it decided to encourage startups that would be solely focused on what it calls "fiber-optic bus wavelength division multiplexing" (FOBWDM).
The main feature of FOBWDM is that it's all optical, meaning that there are no electronics in the path of the data. That allows the core infrastructure of the network to be protocol- and data-rate-independent. Winchester claims that FOBWDM is suitable for speeds up to and including 40 Gbit/s.
Being a bus system, it means that the data does not need to be routed to a particular destination. It is broadcast through the system, and when it passes through the destination node, it gets recognized by the equipment and picked up. As a result, FOBWDM doesn't require switches or routers.
Instead, what's called an "optical bus interface module" (OBIM) is placed at each node in the network. This contains passive splitters that tap signals traveling on the network and place new signals into circulation.
An OBIM feeds signals into an interface card, which contains some kind of magic to ensure that all the signals on the network are kept up to strength optically. "You would think that the signal-to-noise ratio would worsen, but in fact it doesn't," notes Winchester. This observation was made on a demonstrator network built at Lockheed's plant in San Diego, he adds.
On a small scale, the FOBWDM idea has already proven itself. Lockheed has put the idea into practice as the communications nervous system inside two NP-3 testbed aircraft. However, putting communications systems comprising roughly 100 feet of cable into military aircraft is an entirely different thing from building a national or regional network covering hundreds of miles. Winchester claims that it would be possible to build a FOBWDM that covered the entire U.K. but can furnish little evidence to prove that it would work as advertised.
Pipistrelle also faces the not insignificant hurdle of convincing people to buy into a rather radical idea that would require drastic changes in their network infrastructures.
By its nature, the bus network is bidirectional -- signals travel in both directions along the fiber. That immediately rules out the possibility of using Erbium Doped-Fiber Amplifiers (EDFAs) in the network, since they contain isolators that only permit signals to pass in one direction. Therefore, most existing fiber plant is unsuitable for FOBWDM.
Other startups that have challenged mainstream technology, such as, for example, CodeStream Technologies with its OCDMA (optical code division multiple access) modulation scheme, have met with resistance, even though there may have been certain advantages to the technology (see CodeStream Goes Under).
Right now, Pipistrelle comprises only three people: Winchester and two others, whom he is not at liberty to name, since they haven't left their present employers. The company is registered at Insch in Aberdeenshire, Scotland, "where the air is clearer and houses are considerably cheaper." It remains to be seen if this batty idea will fly. The first task, apart from waiting for the license agreement, is to identify where the opportunities are for FOBWDM networks.
— Pauline Rigby, Senior Editor, Light Reading