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Broadband Stimulus

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There is a portion of the American Recovery And Reinvestment Act that will fund programs to accelerate the deployment and use of broadband in the United States. In particular, the NTIA's Broadband Technology Opportunities Program (BTOP) and the Department of Agriculture's Rural Utility Services (RUS) grants and loans will go to fund programs "in unserved, underserved, and rural areas and to strategic institutions that are likely to create jobs or provide significant public benefit". These programs are handing out billions of dollars in the next 18 months and will likely have thousands of applicants for the much needed stimulus money. How will these agencies do it? It is a daunting task and efforts are already underway. The first open public meeting was held earlier this week and two more will be held in the coming weeks. At this point there are more questions than answers. How are these agencies going to work together? Who is eligible to receive a grant? How will the success of the program be measured overall? What does "underserved" mean? For that matter - what does "broadband" mean? In the new era of transparency and accountability, grant applicants will have to explain how they are going to execute their program, deliver the claimed benefits, and measure the results. For the wireless broadband piece, this brings us right back to the basics. What are the technical requirements to support a given application - coverage, throughput, latency and overall system capacity? In order to support multiple different applications, what are the system level requirements? What performance is required to deliver an acceptable user experience? Perhaps it is time to dust off our Novarum lessons from the first round of Municipal Wireless. We can not afford to repeat those mistakes again.
IEEE 802.11n is the new international standard for wireless Local Area Networks, incorporating new smart antenna technologies (MIMO - Multiple In and Multiple Out) permitting a 5x performance and 2x coverage improvement for WLANs. While this new technology is now becoming the de facto standard in consumer and enterprise networks, it has not yet made an appearance in outdoor, metropolitan scale networks derived from WiFi technology. Many of these same MIMO techniques are being incorporated in both WiMax and in LTE for cellular. Sadly neither is being produced in much volume as yet and fixed WiMax networks do not incorporate MIMO technology. There has been much dispute about whether the specifics of 802.11n designed for indoor networks would apply to outdoor networks and bring the economy of scale of 802.11 to outdoor applications. We (Novarum) decided to test the effects of .11n on outdoor performance. We found dramatic improvements in using indoor 802.11n technology outdoors - so much so that 802.11n has become the recommended baseline for new network deployments. First, let’s review the key pieces of technology incorporated in 802.11n and how it might affect outdoor performance.
Maximal Ratio Combining Receiver combines signal from multiple paths to maximize SNR. We can see a 3-4 dB receiver link budget improvement even to legacy clients. Dramatically improved receiver signal strengths and dramatically reduced packet error rates. More reliable use of higher level encoding methods increasing link performance.
Transmit Beam-forming Modulate phase and amplitude from multiple antennas to create phased antenna array pointing increased performance at the destination node. 7-8 dB gain possible with omnidirectional antennas Decreased inteference, increased capacity, decreased deployment cost. Likely directional antenna performance with omnidirectional antennas substantially increasing network performance and decreasing deployment cost.
Spatial Multiplexing Use the redundant paths created by multipath to increase throughput by transmitting data in parallel paths. Probably not compelling outdoors since high SNR needed for parallel data paths. However, increasing reliability by taking advantage of multipath around deep fades.
Channel Bonding 20 and 40 MHz channels in both 2.4 and 5 GHz bands 20 MHz channels legacy compatible while 40 MHz channels double throughput, mostly useable in the 5 GHz band.
Protocol Improvements Packet aggregation Modest overhead reduction and performance improvement for streaming media and bulk transfers
Cost Reduction Indoor WiFi network demand is for low cost, dual band (2.4 and 5 GHz) simultaneous radios at commodity prices The availability of these dual band 3x3 MIMO chipsets drives the cost of multiradio outdoor units down
In the course of Novarum’s Wireless Broadband Review in 2007 and 2008, we examined over 25 deployed WiFi networks (including all major vendors), 46 deployed 3G cellular networks and 4 fixed pre-WiMax networks. In the case of the WiFi networks, we noted the dramatic effects that client selection had on network performance, coverage and ultimately user satisfaction. We both examined 802.11n clients against the installed multivendor base of 802.11g infrastructure and constructed our own testbed from early outdoor 802.11n components to evaluate the effect of 802.11n when deployed in the infrastructure itself. It is important to recognize that in almost all outdoor WiFi networks, the client access uplink is the weakest link in the communication chain. Legacy 802.11b/b clients experience VERY high packet retry rates of between 100 and 1000% and there are often deep multi-path fades of between 10-30 dB within a few tens of feet. The WiFi protocol is VERY good at masking these effects - instead they are most commonly seen indirectly - by lower throughput and higher delay variance. These effects are seen even for deployments of very high access node density of 50 nodes per square mile or more. These deep fades and very high packet retry rates made mobility difficult, dramatically effect throughput, make packet delay variance so high as to make streaming media difficult and materially decrease the overall capacity of these networks. The improvements that 802.11n provides outdoors astonished us - particularly for a technology that has been disparaged as inappropriate for outdoor deployment. Deploying IEEE 802.11n technology has dramatic effects outdoors - both with legacy systems and even more compellingly with green fields deployment. Let’s summarize the facts of what we found in Novarum’s experiments:
  • 100% throughput improvement of 802.11n WiFi clients with legacy 802.11g outdoor infrastructure;
  • 100% throughput improvement of legacy 802.11g WiFi clients with new 802.11n outdoor infrastructure;
  • 200% throughput improvement of 802.11n client with 802.11n outdoor infrastructure;
  • Similar coverage of 802.11n clients and infrastructure in the 5.4 GHz band as for legacy 802.11g clients and infrastructure in the 2.4 GHz band - making the 5.4 GHz band useful for client access;
  • 25% decrease in access latency and a dramatic improvement in latency variance;
  • a low power 802.11n client has the same throughput and coverage as a high power 802.11g with 10x the power and antenna; and
  • coverage to smartphones at low power and with poor antennas dramatically improves.
These results have a dramatic impact on outdoor wireless networks - bringing the benefits of MIMO technology at consumer price-points. We can expect that 802.11n technology will dramatically improve outdoor WiFi networks.
  • 4-800% increase in system capacity and throughput
    • 2-300% improvement in spectral efficiency through increased link budgets, reduced packet errors, increased modulation rates and improved fading performance
    • effective client access to the 200 MHz of the 5.4 GHz band
  • 802.11n clients dramatically improve legacy 802.11g networks and new 802.11n networks dramatically improve legacy 802.11g clients.
  • Streaming media applications will perform as we expect and will be much easier to deploy.
  • Better backbone designs by reducing the interference of the backbone mesh through beam-forming antennas rather than omnidirectional broadcast.
  • Decreased deployment cost due to decreased node cost. Possibly dramatically.
While not optimally designed for outdoors, 802.11n will SUBSTANTIALLY increase the performance and customer satisfaction of outdoor wireless networks. We can expect the first product announcements of outdoor WiFi networks incorporating 802.11n shortly and can expect that all major vendors of outdoor WiFi equipment to be shipping by the end of 2009. Novarum recommends that all new outdoor WiFi networks use 802.11n products in their infrastructure and strongly recommends 802.11n clients wherever possible.
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.

Metro WiFi Does Work

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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.

Performance of Cellular Data Networks

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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.

Rural Internetification Project

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One of the smaller towns we tested in the NWBR was Rochelle, IL - a farming town of 10,000 people about 75 miles West of Chicago. In this case the ISP providing wireless internet service was the city itself through the Rochelle Municipal Utilities organization - along with power and water. It was an interesting experience going to the small office, right next store to the window where a citizen would pay their electric bill, to shop and sign up for Internet service ... with a variety of recommended CPE devices displayed on the wall. One the key items we argue about in building municipal networks is ownership - who should own and operate the network? And here in Rochelle was a rather good wireless network that was built by the town. And clearly where other options for broadband access offer poor performance or do not exist (The city started by offering dial-up Internet access and the wireless cellular carriers offer spectacularly poor wireless data products - the city’s networks offers roughly 20x the performance of the sadly 2G wireless cellular networks in the town.) This reminded me of the Rural Electrification Project (that had originally sponsored bringing electricity to Rochelle after WWII) - (from Wikipedia): In 1936 the Rural Electrification Act was enacted. Also, the Tennessee Valley Authority is an agency involved in rural electrification. The Rural Electrification Administration (REA), a former agency of the U.S. Department of Agriculture, was charged with administering loan programs for electrification and telephone service in rural areas. The REA was created in 1935 by executive order as an independent federal bureau, authorized by the United States Congress in 1936, and later in 1939, reorganized as a division of the U.S. Dept. of Agriculture. The REA undertook to provide farms with inexpensive electric lighting and power. To implement those goals the administration made long-term, self-liquidating loans to state and local governments, to farmers' cooperatives, and to nonprofit organizations; no loans were made directly to consumers. In 1949 the REA was authorized to make loans for telephone improvements; in 1988, REA was permitted to give interest-free loans for job creation and rural electric systems. By the early 1970s about 98% of all farms in the United States had electric service, a demonstration of REA's success. The administration was abolished in 1994 and its functions assumed by the Rural Utilities Service. The Rural Electrification Administration (REA) was an agency of the United States federal government created on May 11, 1935 through efforts of the administration of President Franklin D. Roosevelt. The REA's task was to promote electrification in rural areas, which in the 1930s rarely were provided with electricity due to the unwillingness of power companies to serve farmsteads. America lagged significantly behind European countries in rural electrification. Private electric utilities argued that the government had no right to compete with or regulate private enterprise, despite many of these utilities having refused to extend their lines to rural areas, claiming lack of profitability. Since private power companies set rural rates four times as high as city rates, this was a self-fulfilling prophecy.[1] Under the REA program there was no direct government competition to private enterprise. Instead, REA made loans available to local electrification cooperatives, which operated lines and distributed electricity. By 1939 the REA served 288,000 households, prompting private business to extend service into the countryside and to lower rates. By the end of the decade, forty percent of rural homes had power, up from around 10% in 1930. From 1949, the REA could also provide assistance to co-operative telephone companies. In ten years, rural electrification increased from 10% of rural homes to 40% by 1940. So why can’t we use this already successful model of the Rural Electrification Project as the basis for government deploying broadband, particularly in less developed areas? While some of the early attempts at municipal wireless were not considered successful (Philadelphia, for example) they had the clear effect of dropping the local cost of wired broadband access. Competition beyond the entrenched monopolies of DSL and cable is a good thing.

Why Network Clients Matter!

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It was clear from the beginning of the NWBr that the proper choice of client device makes all the difference in the complete system performance of a municipal wireless network ... and in particular the user experience. Cellular and pre-WiMax (and mobile WiMax when delivered) networks precisely specify the client and test its performance. These clients are much more rigorously controlled and, in general, have much high transmit power and better antennas with less noise than WiFi clients. In the process of the NWBR we have tested many client devices to see the effect of client devices on network performance - testing them in the same networks in the same locations, at the same time ... to more accurately assess the difference. We tested the following clients:
  1. Standard 802.11g laptop client - approximately 30 mW output power
  2. A high power 802.11g laptop client - approximately 200 mW output power
  3. A first generation 2x2 MIMO 802.11n client - approximately 30 mW output power. Current .11n clients should have even better performance.
  4. First generation iPhone smartphone WiFi client.
Let’s first examine the average performance of these clients across all the networks in which they were tested.
Client Delay (msec) Uplink (kbps) Downlink (kbps) Availability
Average Laptop 157 481 1030 64%
Average High Power 113 767 1286 85%
Average .11n 115 845 1712 82%
Average iPhone 422 231 810 45%
The clear performance advantage of the higher power client and for the 802.11n clients leaps out. Both deliver average megabit performance with approximately 85% outdoor availability - availability comparable to both the best of cellular and pre-WiMax with superior performance. The lower performance of both the standard laptop client and the iPhone client is understandable with the low power iPhone still showing a rather amazing 45% availability on average. The difference a good infrastructure network makes is clear when we look at the best performance by each of these clients. Our top three performing networks (Minneapolis, Toronto, and St. Cloud) all deliver outstanding performance but the single best performances were by the laptop, high power AND .11n clients in Minneapolis - delivering multimegabit performances that leave both cellular and pre-WiMax in the dust - while delivering avaiailability uniforming over 80% - including 100% for the high power client. The St. Cloud network delivered the best performance and availability combination for the iPhone client with 75%.
Client Delay (msec) Uplink (kbps) Downlink (kbps) Availability
Best Laptop (Minneapolis) 74 457 3090 80%
Best High Power (Minneapolis) 63 2062 2949 100%
Best .11n (Minneapolis) 77 1939 3237 82%
Best iPhone (St. Cloud) 415 158 831 75%
Some conclusions:
  1. A modern WiFi network designed with appropriate access node density ( greater than 40 nodes/mi^2) can deliver performance and coverage that outperforms cellular and pre-WiMax.
  2. The increasing usage of 802.11n in client devices will only improve the quality of already installed networks ... increasing performance, coverage and user satisfifaction.
  3. All the WiFi network infrastructure we tested was 802.11g compatible, often without diversity antennas for the uplink from clients. As infrastructure vendors move from .11g to MIMO .11n we can only expect these performance gains to increase even more.

Novarum Wireless Broadband Review

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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.

Welcome!

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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.