Real Measurements of Municipal Wireless Technologies: WiFi, WiMax and Cellular

Two of the important issues in large scale wireless have been:

1. Can a given technology provide a usable data communications service and
2. How much does it cost to deploy such a service.

A useful network service provided at an affordable price are necessary preconditions for a successful network offering. Many of the early muni WiFi networks were hampered by the double whammy of both a poor service AND the higher cost to deploy than expected. In seeking to answer this, Novarum structured its’ Wireless Broadband Review to provide some of this information. During 2007 and early 2008, we tested cellular, WiFi and pre-WiMax networks in these cities: Anaheim CA (2x), Brookline MA, Chico CA, Cupertino CA, Daytona FL, Eugene OR, Galt CA, Longmont CO, Madison WI, Minneapolis MN, Mountain View CA (2x), Palo Alto CA, Philadelphia PA (2x), Portland OR (2x), Raleigh NC, Rochelle IL, St. Cloud FL (2x), Santa Clara CA, Sunnyvale CA, and Tempe AZ (2x). In several cities we tested twice to detect changes in traffic and improvements in network service over time and experience. We discovered that, on average, all of these networks have similar performance and coverage, but that the best of the WiFi networks substantially outperformed the best of either the cellular AND pre-WiMax networks. Our test was an apples to apples comparison of performance (delay, uplink throughput, downlink throughput) and availability (percentage of tested locations with service within the advertised service area) for all of the major network technologies:

1. ATT (Cingular), Sprint and Verizon cellular data networks
2. A number of metro WiFi networks using equipment by BelAir, SkyPilot, Strix, Tropos, and
3. Four of ClearWire’s pre-WiMax networks.

We tested outdoor coverage in an average of 20 locations per city - testing all networks with the same traffic load and in the same location and time. One of the important determinants of good performance is a good client modem - and we tested with a variety of client modems. For today’s thoughts, we’ll look at standard USB external modems for each of the cellular data networks, a higher power WiFi modem (noting that current 802.11n modems appear to perform on par with these higher power clients), and a desktop directional CPE for the pre-WiMax ClearWire networks (no portable device was available) at the time. We would expect the WiMax modem (AC powered, directional antenna) to have the advantage in performance. To our surprise, with similar client modems, averaged over good and bad networks, WiFi networks delivered almost 3x better performance than cellular networks and materially better performance than pre-WiMax networks - with similar levels of availability of service over the promised coverage area for all three network technologies.

Network	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 WiFi network, we see performance and availability superior to the best the cellular data networks (by a factor of 3!) AND the best of pre-WiMax networks we measured - by at least a factor of 2.

Network	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 demonstrate that WiFi networks materially outperform cellular data networks AND pre-WiMax networks - and do it with similar service area coverage. And likely lower deployment costs.