January 2009 Archives

Metro WiFi Does Work

| 0 Comments | 0 TrackBacks
The great lesson we were supposed to have learned from the first generation of metro WiFi networks was - they don’t work and no one wants to use them. Both lessons are false .. though we have many examples of networks that have done either or both. Let’s look at the WiFi networks we examined in the NWBR - which ranged from the some the early networks in the surge of metro WiFi exuberance to some of the later, more mature networks. And for this example, I want to look at them using the results from high power 802.11g clients, that use power levels and antennas better than most laptops (and all PDAs) - though still much less than the power used by cellular data or WiMax modems. Note also that our measurements indicate that new generation of 802.11n WiFi laptop clients perform very similarly to these numbers as well.
Client Delay (msec) Uplink (kbps) Downlink (kbps) Availability
Worst 338 106 337 50%
Best 63 2062 2949 100%
Average 113 767 1286 85%
With similar client modems, averaged over good and bad networks, WiFi networks deliver almost 3x better performance than cellular networks and materially better performance than pre-WiMax networks - with a similar levels of availability of service over the promised coverage area for all three network technologies. Municipal wireless in the unlicensed bands DOES work - at least as well as licensed wireless technologies such as cellular and WiMax.
Client Delay (msec) Uplink (kbps) Downlink (kbps) Availability
Average Cellular 340 195 507 89%
Average pre-WiMax 174 169 1124 83%
Average WiFi 113 767 1286 85%
If we look at the best, and most recently deployed networks - Minneapolis and Toronto - we see performance and availability superior to all the cellular data networks (by a factor of 3!) and pre-WiMax networks we measured - by at least a factor of 2.
Client Delay (msec) Uplink (kbps) Downlink (kbps) Availability
Best Cellular 192 612 980 100%
Best pre-WiMax 190 164 1129 100%
Best WiFi 63 2062 2949 100%
The measured performance suggests that WiFi networks materially outperform cellular data networks AND pre-WiMax networks - and do it with similar service area coverage. In addition, WiFi networks offer the added bonus of offering a lower grade of performance, and coverage area - to the commodity WiFi network clients packaged in laptops and smartphones.