Monday, April 18, 2011

NBN is Missing the Point: Wireless Waves Ride on Wires and Fiber.

Among the latest misguided arguments is the recent scuffle over wireless vs. fiber in Australia, where proponents of wireless broadband fear that the national emphasis on a fiber-backed network will impede their mission to provide wireless broadband to the rural areas. And this is misguided why, you might ask? Because, the fiber back-bone built out by the NBN will serve to bolster wireless broadband, not impede it.

The truth is, without fiber, wireless would be weaker, if it were viable at all.

Wireless is a local-loop solution.
To get data from New York to Los Angeles, packets ride on the back of copper cables, twisted pairs, and most recently: fiber optic cables. Where does wireless come in? Wireless performs best moving those packets from the terrestrial network to the end user. Network engineers agree that moving data thousands of miles from hub to hub is the easy part. But it's the last leg of the journey that gets tricky. Often called the "local loop" or the "last mile," from network hub to end-users can be costly and time consuming to deploy when trenches and cables are required. This is where wireless broadband comes in most handy.

But wireless travels at the same speed, right?Theoretically, radio waves travel at the speed of light. And, if you consider the latency added by fiber optic refraction or copper cable resistance, perhaps wireless signal would win in the land-speed record. But there are some major challenges in an end-to-end wireless network. First, spectrum limits the total amount of data that can be transmitted. If you imagine each distinct range of spectrum as one usable "cable" over which to transmit data, then the nation would have fewer than 1000 cables over which to transmit data. Compare that to the current grid of over 100,000 discreet channels of fiber and cable which span the country and you can see wireless suffers a great bandwidth deficit.

The shortest distance from A to B...More importantly, however, wireless (for the most part) is a line-of-site medium. This means that the simple curvature of the earth presents a problem, as a truly straight line from New York to Los Angeles would actually fall over a thousand feet below the earth's surface. Bouncing off the atmosphere is a precision game and hardly reliable. Not to mention, over long distances, interference from other radio sources (storms, personal devices, and the sun, to name a few) degrade the signal.

So, to move a data packet from end-to-end without ever hitting a wire requires the use of tools called repeaters. Repeaters simply pick up the signal and re-transmit it immediately. When you add the computing time required by each repeater, even if micro-seconds, that would be required to reach New York from Los Angeles, the latency of the signal is now far greater than a pure fiber network. Of course, fiber hits repeaters of sorts, too. The difference is, however, that fiber suffers little-to-no degradation of signal in between. What's being repeated is a pure packet, unadultered by solar flares or car stereos. The net impact of incremental degradation as it repeats hundreds of times is the net effect of playing the telephone game with grade-school children.

Can't we all just get along?The truth is, without a strong terrestrial network, fixed wireless broadband is not much of a solution all by itself. Wireless broadband is a local loop solution, more cost effective and quicker to deploy in most situations than its wired alternatives. But for the long distances, terrestrial networks are our most valued partner.

Labels: Copper Cable, Fiber Optic, Fixed Wireless Broadband, NBN, radio waves, Rural Broadband