The demands being made on mobile operators' backhaul connections are well documented. Running 2Mb leased lines, or multiples of the same, doesn't cut it when you may be looking at tens of megs coming off the RAN. Fibre may take too long to arrive, or may never materialise at all. If you have spectrum for Microwave links, you again may face capacity challenges in upgrading to service the bandwidth intensive services on the RAN.
This is why - ten years after a raft of mega-investments in free space optics companies withered and died - one company is once again pushing Free Space Optics (FSO) as the answer to mobile operators' link capacity requirements.
The company is fSONA, and its CEO Andrew Grieve says that it is currently in trials with a few operators looking at using its optical wireless technology to move traffic from the RAN to the core.
The advantages of FSO is its capacity, up to 2.5Gbps, and its flexibility - it is a transmission layer technology so can be protocol independent. It is particularly well suited to dense, urban areas, Grieve claims. The disadvantage is that previous installations "have just not worked" according to Grieve, because solutions were poorly engineered and over-promised.
FSO, which uses lasers to carry optical bandwidth connections, can be affected by fog, by physical obstructions (it needs line of sight), and by atmospheric conditions such as high humidity or hot air.
Grieve said that fSONA's products had been designed to overcome many of these problems, by working in the 1550nm wavelength and a range of other technical solutions.
The question is, will the operators go for it? Grieve himself said that Vodafone Group's technical office, for instance, doesn't want to know. But some of Vodafone's regional technical teams are more willing to hear fSONA out, so the company is hoping to build out a bridgehead, and then make their case from initial trials.
The objections from operators are technical, based on the "poor legacy" of FSO, Grieve said. But they are also because the operators are used to RF planning, and RF tools, etc. FSO is not a radio technology, and is more akin to fibre.
It's possible that operators may use FSO as an interim solution between where they are now, and deploying full fibre. They could then redeploy the links or retain them for redundancy in the same locations, Grieve said.
Currently the company has a few hundred links out in the market, including in central and Latin America. It is also on the approved Federal suppliers' list for AT&T and Verizon, which adds credibility, Grieve claimed.
There are, of course, a range of competing solutions for the next generation of backhaul, from millimeter-wave, to point-to-multipoint microwave, to high capacity microwave solutions, as well as fibre.
FSO has had a tough time over the past decade. Could it be that its time has finally come? Grieve certainly hopes so.
As you may know, Mobile Backhaul will form the theme for Mobile Europe's next Insight Report - published in our August/September issue. If you would like to get involved in the report, please email me on firstname.lastname@example.org.
Keith Dyer, Editor