Thursday, March 24, 2005

Can Gigabit Hotspots Be Far Off?

Even while attention is being focused on WiMAX as the next big breakthrough in wireless networking, the capabilities of 802.11 WiFi have been quietly creeping up and up. Speeds have already increased one order of magnitude to over 100 Mbps in commonly available equipment. Combinations of new technology are now pushing that second order of magnitude toward the 1 Gbps level. Let's review how far we've come and why Gigabit WiFi hotspots may not be out of the question.

Our benchmark is 802.11b, the now ubiquitous standard that offers 11 channels in the 2.4 GHz band with 11 Mbps of bandwidth. Then came 802.11a which boosted that to 54 Mbps on the 5 GHz band. The 2.4 GHz band technology was then boosted by 802.11g to the same 54 Mbps bandwidth as "a." The "a", "b" and "g" technologies are the standards currently available. But why stop there?

No sooner was the 802.11g standard introduced, when a non-standardized "Super G" by Atheros Communications doubled the speed again to 108 Mbps. Super G has a number of enhancements that include sending data in bursts, bundling data frames together, and compressing data for transmission. It also uses a controversial technique called "dynamic turbo" that bonds 2 of the 11 available WiFi channels to create a double channel with twice the capacity. It's controversial because doubling up reduces the number of networks that can be operating in a given area. In practice, the limited range of WiFi is often confined to a single office, restaurant or dwelling with a few users, so it may make no difference at all.

Another technique that improves on the original wireless network performance is MIMO, the smart antenna technology called Multiple-Input Multiple-Output. MIMO sticks with one channel, but sends out at least 2 independent datastreams from two different antennas on that channel. That also doubles the bandwidth from 54 to 108 Mbps. The "pre-n" hardware you can buy now runs at that speed. However, MIMO isn't limited to only two datastreams. With sufficient processing power to sort out the jumble of signals arriving at the receive antennas, a 4X4 MIMO structure consisting of 4 transmitters and 4 receivers can boost throughput 4 times to 216 Mbps.

Now, combine MIMO with channel bonding and you are getting close to half a gigabit per second. Include the other enhancements of Super G and you are probably past that mark.

So, what's next? Larger MIMO structures? Bonding in more channels? Moving back to the 5 GHz band and spreading out to 100 MHz with Orthogonal Frequency Division Multiplexing (OFDM)? Actually, that might be it. Siemens demonstrated an experimental gigabit per second wireless system at the end of 2004 using these techniques. It was a lab demonstration, but now that we know it works...

Well, you know how fast technology can get to market once we know it can be done.

Meanwhile, if you really need GigE or similar bandwidth and don't mind a small fiber optic cable in lieu of wireless, let our GigaPackets service get you the best SONET and GigE price quotes for your demanding IT applications.

Click to check pricing and features or get support from a Telarus product specialist.

Follow Telexplainer on Twitter