Best of the ISP-Lists

Fixed Wireless Technology

Adding Laser to the WISP

Members of the ISP-Bandwidth list dispute the value of using lasers for point-to-point connections. Although the bandwidth is more than adequate at 155 Mbps, there are drawbacks to the technology.

[June 18, 2002]

On the ISP-Bandwidth list in May, JR inquired,

"Does anyone have experience with wireless products that use lasers to connect two points? They claim 155 Mbps with no distance restriction. What are the pros and cons?"

Some respondents explained that laser still has significant limitations:

[RB warned] "Free space lasers cannot penetrate snow or thick fog. Because variations in temperature cause high buildings to move, tracking systems are often required. Finally, most systems are point-to-point, and hence offer poor economics. However, for customers who can tolerate some outages, it may be okay. Terabeam recommends that their customers get an RF backup: I would recommend a landline backup if the economics work."

[RD added] "The market for this stuff seems pretty weak. Plaintree is doing free space optics, and just laid off 75 percent of their staff."

JB noted that cost can also be an issue:

"We tried one in Mexico city. With all the pollution there, we got five miles without problems. The biggest TV company in the country tested it and accepted it from a technical point of view, but the client declined the solution because the lasers were very expensive. Currently, we're looking at solutions that use radio frequencies."

Others discussed the potential for improvements in the technology:

[FM offered] "It has its problems, but they will be overcome soon by modern technology. Even now, with their current performance, the freedom from licensing is worth the consideration. In many parts of the world, licensing is difficult or impossible. If the need is there, there will be a technical solution."

[RB countered] "I can't share your faith that technological improvements will eliminate the problems with free space lasers. Technological progress just doesn't guarantee a solution to every problem. You need more than faith in technological progress to convince me that free space lasers will eventually be able to peer through smoke and snow."

LC suggested that, in many parts of the world, laser is already the best option available:

"There are several laser suppliers in Eastern Europe, and especially in Israel (the weather is ideal for it). Countries with corrupt and/or national telecom monopolies and fiber infrastructures that are weak to non-existent are good markets. For short urban links, even in bad weather, the one-time price compared to laying fiber (or renting fiber) is very attractive. And there are no punitive frequency/operator licensing fees for 'light' as there are for RF and physical networks. The very high expense (both legal and corrupt) of network operator licensing and of laying cable has made air optical viable in all of Europe. Compared to nothing (no link at all), a few atmospheric perturbations are certainly acceptable."

—End