Recently in Cellular Category

I was staying at a friends house in Austin a few weeks ago. We pulled out of the driveway to head to the airport for the flight home. Just before we drove off I realized I didn’t have my iPhone. “Hang on, I forgot my phone.” Then I looked up and saw it lying in the driveway. Yikes! Apparently, as we were loading up the car, my iPhone fell under the car (Ford Edge SUV actually....). When we backed out, we drove right over the phone. It was screen up with a rubber case (iPhone condom from inCase - http://www.goincase.com/products/detail/protective-cover-cl59051/2). I retrieved the phone. The screen was not cracked, but the phone was inert.... dead.... “Shit !” I pushed every button. Nothing. I followed the reset process. Nothing. As we drove to the airport, I was trying to wrap my head around the idea of flying back home and sitting around airports all day without the iPhone. I began rationalizing spending $399 for another iPhone. (I doubt Apple will replace a flattened iPhone.) For some reason we both decided that we should try plugging the phone into power at the same time. I connected the iPhone, not expecting much. After a few seconds the iPhone started booting up!!!! The phone started working again. No problems. The phone was on and fully charged before we ran over it. I am not sure why it shut itself off... Maybe there is a panic function that shuts off the phone when it is subjected to extreme stress like this. Before the pancake incident, the main button was a little sticky. Now it works flawlessly. The phone should last for another few months, when the new iPhone 3.0 is available.

WIth Apple's World Wide Developers Conference this week there are many predictions being thrown around. I have no special inside knowledge, but can't resist throwing my guesses into the mix. Yes - Apple will announce a new iPhone at the WWDC this week. It will have improved technical specifications... a camera with better resolution, video capability, 802.11n Wi-Fi, faster processor, bigger memory etc... But the new iPhone won’t be marketed that way... Apple doesn’t allow itself to be put on the “mine is bigger than yours” technology treadmill. The new iPhone will be marketed as something like : “... and now the world’s first video phone in your pocket...” Put the camera on the same side as the main screen, add video capability, add iChat.... We already have Skype for the iPhone. Voila - pocket video phone. The only challenge is the impact on AT&T’s network in the US.... Perhaps it will start out as Wi-Fi only like Skype for the iPhone.... Whatever Apple does, the new iPhone will be sufficiently cool that I will have to get one soon after it comes out. Oh.... one more thing. Steve makes an appearance during the keynote. He may the the “one more thing” of this keynote.

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.

We tested performance (delay, uplink throughput, downlink throughput) and availability (percentage of tested locations with service with the advertised service area) for ATT (Cingular), Sprint and Verizon cellular data networks in a number of North American cities during the NWBR. We tested one or more of these 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. Great disparity of service was noted with several small towns (Galt CA and St. Cloud FL) having no 3G service at all (and hence barely averaging 100 kpbs of data service) from any service provider while larger, growing metro areas (Tempe AZ) had an abundance of high performance cellular data providers (with downlink service approaching 1000 kbps). When available, the three major cellular providers offered a similar grade of performance averaging about 200 kbps on the uplink and about 500 kpbs on the downlink. No measurements ever exceeded 1000 kbps.

Network	Delay (msec)	Uplink (kbps)	Downlink (kbps)	Total Availability	3G Availability
ATT (Cingular)	318	195	473	75%	59%
Sprint	330	215	559	96%	90%
Verizon	366	179	494	92%	70%
Average	340	195	507	89%	73%

On average, Sprint offered the highest performance with the greatest availability. ATT and Verizon both offered a slightly poorer grade of performance but the availability for these two networks is far more interesting. Cellular networks do not offer a single grade of service ... where available, 3G service is offered but when there is no 3G capacity left, the networks fall back to offering 2G service instead. This fallback results in an almost 3x decrease in upload performance and over a 5x decrease in download. For Sprint, almost all our testing locations offered 3G service and only in 6% of the those locations did the offered service fall back to 2G. For both ATT and Verizon, in about 25% of the locations with service - we could not get 3G service but rather fell back to 2G service. And in the case of ATT, this exacerbated the already poor availablity with only 75% of the tested locations could we get service at all! As we will see when we look at the results for WiFi networks, with the proper client modem selection, WiFi network uniformly outperform and can achieve availability of 85% - not dissimilar to the average availability of 89% for cellular data.

We have been curious about how real wireless networks perform - both in the enterprise and in metropolitan areas. We have also been impressed by how few third party measurements at scale have been performaned for both applications of wireless networks. Most of our knowledge about how these networks really deliver service is either based on anecdotal reports or the marketing information from the service providers and equipment vendors. So we decided to test and obtain some real, non-partial information. We went out and tested over 136 wireless networks in 22 North American cities from July 2006 through early 2008. We devised an network independent testing regime that mimics the behaviour that ordinary users of these services would observe - testing packet delay, upload and download throughput (using industry standard tools) and percentage of the claimed service area in which we could actually get service. We tested in the following cities (some twice to reflect major changes in the networks between tests): Anaheim CA (2x), Brookline MA, Chico CA, Cuperino CA, Daytona FL, Eugene OR, Foster City CA, 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, Santa Clara CA, Sunnyvale CA, Tempe AZ, and Toronto ON (2x). Where we could find them, we tested cellular data networks from ATT (nee’ Cingular), Sprint and Verizon; pre-WiMax networks from ClearWire and WiFi networks from a variety of ISPs. The data clearly shows that all these technologies can deliver similar levels of service when properly built out. Subsequent blogs will address individual lessons learned for each of these network technologies.

This blog is the combined thoughts of Ken Biba and Phil Belanger ... two pioneers of wireless networking and arguably two of the co-inventors of the networking systems we think of as WiFi:

1. Minimal licensing.
2. Sharing of scarce radio spectrum.
3. Robust technologies that survive (and often prosper) in a severe radio environment.
4. Dirt cheap.
5. Ubiquitous.
6. High performance.

Look for us to be posting product critiques, technology thoughts and the results from our ongoing measurements of both enterprise and municipal networks. Over the last 18 months, we have done extensive studies of many of the foundation myths of deploying large scale wireless networks in both large enterprise and metropolitan environments. We will be reporting on those studies here and many of the implications of those studies on future use of unlicensed technology for providing mission critical network services. The Novarum Wireless Broadband Review surveyed and measured over 100 deployed municipal WiFi, cellular and pre-standard WiMax networks and comprises the largest available database of experience about these networks. We will be using this large experience base to inform our comments ... rather than mere opinion. We look forward to your comments.