August 28th, 1996 Report on Air Academy School District Microwave and Spread Spectrum System by David Hughes, Principal Investigator National Science Foundation Wireless Field Tests Overview The 14,000 student, 3,000 staff, Air Academy School District 20, with 28 seperate schools and administrative sites, which lies in the northern part of Colorado Springs, has just completed installing a nearly total wireless internal network linking 20 of its sites, to serve its schools, with both internal communications between schools, and to and from the Internet. For both academic, and administrative data communications purposes. The economics are impressive. Only two full-service bids were recieved to network all the schools and sites to each other and the District Headquarters, as well as provide internal school servers and LANs connecting the schools' existing computers. One bid was for a telephone company all fiber T-1 wired links between the schools, the servers and LANS, for at $1.5 million installation, and then $75,000 a year in recurring monthly service costs, with 5 year contracts. Or $375,000 every five year contract period. The other bid, was for $601,000, no communications-cost wireless links between the buildings, and the servers and LANS in the school buildings. In this bid, all the wireless equipment (radios, antennas, cabling) represented approximately one third, or $200,000 of the cost. When completed in August, 1996, this installation provided a minimum of 2Mbps to every school, and 10Mbps between key schools and the district headquarters. Cost Comparison Telephone Company Vendor Installation Wired T-1 (1.54Mbs) Wireless E-1 (2Mbps and 10Mbps) Installation $1,500,000 $601,000 10 years 750,000 ($75,000/year) 0 ---------- --------- $2,250,000 $601,000 Of course the District chose the Wireless option, and it was installed over an 18 month period, ending in August of 1996, in time for the 96-97 school year. The vendor was the local company 'Open Minds.' The installation of the wireless has given District 20 T-1 or higher speed data communications to and between all but 4 schools. Three school sites that are close by other, wirelessly linked schools, and are on ground owned by the District are linked by T-1 fiber laid by the contractor - which, of course, incurs no costs. Two elementary schools are so distant and hidden from line of sight, that, at the present time they are using dedicated dial-up line (28.8 modems) for their IP access. Thus only two school buildings are using US West lines. All the rest are wireless or local fiber. The Wireless network uses a mix of 8 Microwave (23Ghz range, site licenced) 10Mbs radios, ($16,000 the pair) in 4 'backbone' links, and 30 spread spectrum 2MBps radios (about $6,000 a pair) in both the 900Mhz and 2.5Ghz FCC Part 15 frequency ranges, to reach all schools. The hub is the District headquarters site, which is in turn linked to the Internet via two T-1 wired circuits to the MCI Internet POP in downtown Colorado Springs. With the $200,000 cost of the wireless component of the District network, connecting up 20 school-sites, the cost per school was approximately $10,000. The first year's operation of the initial links (several schools had one full year of operational use of a 2Mbps link) saw no failures. And the link margin on the 10Mbps Microwave radios - which were licenced to the District for operation at .15 watts which would give 16 miles range, was so robust at the 5 miles they are operating over, there has been no degradation from weather, including severe storms. And given the total capacity of the links, the slowest observed Internet speed from a school has been 256Kbs. Ample bandwidth for Internet multi-media. In short, School District 20 has a reliable, economical, high-bandwidth, Internet and Intranet, wirelessly linked wide area network that has ample bandwidth room for expansion and extension. It initally cost one fourth that of a wired telephone company-supplied network, and with no subsequent costs except routine maintainance in the future. It is a classic case of what a somewhat sprawling modern Suburban school district can do with wireless. The Evolving Network Story As is commonly observed in US school districts, getting to the current point has been incremental, even a bit ad hoc at times, and 'learn as you go.' District 20 is in the newer suburbs of northern Colorado Springs, which is also home to the Air Force Academy, Hewlett-Packard, and a series of other high technology firms. Accordingly the population served by the district is well educated and comfortable with technology. Computers had been introduced into the District incrementally as far back as the early 1980's. And some telecommunications was being used by the mid and late 80's from school-based computer bulletin-boards, to Internet links at Air Academy High School (on the Academy grounds, serving children of staff and faculty - not cadets). The District, however, only had two 'techs' - one handling the growing number of PCs and the other the Administrative computer system. They were overburdened as the technological demands grew. One highly experimental 'Magnet School' - Mountain View School was establish, with Rich Pattison as the Principal, and there was focused many of the experimental efforts combining technology and modern education. It rapidly because a showcase, and was high 'telecommunications' conscious, even before the nationwide move to 'The Internet' started in education. In 1994 a District committee was formed to look into networking the schools. It included a parent, Mike Willett, who has an engineering technical background, ran a small, self employed firm that did both consulting and installation of a variety of technologies in the region, but volunteered much time and expertise to the School District. The committee was initially focused on giving all schools, students and faculty, access to the district's automated Library DYNX computer system, which resided at the District Headquarters. It was Willett who suggested the committee look at wireless as an alternative to telco wired, for the District. The Finance Director of the District, a committee member, authorized the purchase of 4 Solectek 2Mbps radios to test with. They cost about $5,900 apiece. Willett and the committee put up the radios, linking them to Unix servers in the two schools, three miles apart. They invited the City of Colorado Springs Radio section to come out and help them evaluate the throughput. Even though they were put up during a rain, which caused some problems until the connectors where blown dry, they performed perfectly during a test period, and the committee got serious about doing a cost benefit analysis. By this time Willett's expertise was being recognized, and the committee asked him to bid on the project when they put out a public RFP. Willett's small company 'Open Minds' was the only one that bid a wireless solution. While a telephone company also made a full service bid, all other bids were only for a 'part' of the project - links between schools, servers, and lan connections inside the schools. Willett had not expected to be involved with the project except as an interested, technical-volunteer, parent. He had to think twice before tackling such a big job. And he had to do a lot of radio 'site survey' work before putting in his bid. The Site Survey Challenge The low hills which characterize the district's area required careful site survey, and in several cases would require the radios to be set up to cross the valley from one school to another, then halfwayback to a school in a low spot, to preserve line of sight links - an important requirement for spread spectrum operating in the 2.4Ghz radio frequency range. The longest link was to be 6.4 miles. Willett, with expertise in Unix, LANS, as well as radio, used an ingenious method to determine how high an antenna had to reach to give true line of sight betweem points where the roofs were not mutually visible. He inflated a 4 foot balloon with helium, and had someone extend its rope - knotted every 10 feet - high, then bring it down until he could just see the balloon from the other site, then measure the distance by the rope knots, to determine antenna height. In order to reach all but the two most distant schools, the final radio topology looked bizarre. With 6 'Z' shaped legs crisscrossing the district. Then by using two, sometimes four radios at selected sites - some at different frequencies (900Mhz and 2.5Ghz) to prevent local, adjacent radio, interference, he was able to calculate the required number of radios. (in the end, 30). He also looked for other (than Solectek) vendors and settled on Karlbridge 2Mbps radios (with Wavelan technology common to many wireless radios) that cost under $3,000. He also planned on, (before the FCC revised its antenna rules for Part 15) buying, seperately, Chris Craft antenna sets with yagi 11dB gain for the 900 Mhz radios. Then, seperately again, he planned on Gandalf $1,500 TCP-IP routers to place between the radios and the servers in each school, which themselves were Sun Unix systems that would double as LAN servers and Internet gateways. 'Open Mind's' bid was so low, and the projected economics of high speed links was so favorable to wireless, he was awarded the job in the fall of 1994, with work to start in early 1995. Which job, unfortunately grew as the committee got more into its coming reality. Besides the Library access, they wanted e-mail. Then add between-school Administration communications to the network. Then Internet. Then web access and web site software. Willett realized that high bandwidth would eventually be needed. The 18 month installation was characterized by a highly flexible management style, where Willett kept upgrading the technical abilitites of the network as he learned of better solutions, and district personnel helped on roofs to put up antennas. The District did not quite fullfill its informal agreement to do some of the roof-piercing work (lots of drop cables have to be laid to the hubs and routers), so he picked up that slack. (he states he would charge more for that aspect if he had it to do over again) But at the point of this writing, he is still under the original bid budget - even though there has been substantial upgrading from the original plan. One major change in the original plan came when Willett realized that the project could afford 4 pairs of new Microwave radios to create a network 10Mbps 'backbone' from the District Headquarters to four sites - three high schools and one middle school, from which could radiate the 2Mpbs spread spectrum radios. But Microwave requires FCC licencing, specific to sites and other radio emanations. Because there would have to be 4 seperate radios at the 'base' location, physically close to each other with the potential for interference, the licence, and purchase, was requested for 4 seperate frequency 'channels.' It took several months for the FCC licence to come through, which set back the project a little. (originally it was hoped the work could be done in 1 year. It took 18 months from such 'upgrading' delays) Technically, the Microwaves were fitted with "Etherswitches" by Willett, feeding them into an Ethernet Hub, from which the Gandalf router was attached, as well as were the Spread Spectrum radios with their 10Base T connectors. So Ethernet was the 'bridge,' TCP-IP the protocol, through the Sun Unix systems, to the school workstations. Willett also heavily 'engineered' all sites, both physical antenna setups, and radio link margin (robustness) with thoroughly wrapped, sealed, and wrapped again connectors exposed to weather, solid antenna footing against wind, and with ample lightning arrestors deployed near the antennas. And ranges between radios well within their design limitations. The installation was engineered to provide a mean operational life of 10 years. At the Administration Building While this network deployment was going on, Rich Pattison, the once-Principal accepted the position of being the District's Technology Director in the summer of 1995. With a growing staff. And a strong belief in the soundness of the wireless network solution. At the District site - the gateway to the Internet, the District has installed firewall software to control access to and from the Internet. While there was investigation into linking the entire system to the Internet wirelessly, either through a long distance and ISP company called Telephone Express, or through MCI, these organizations did not show an interest in the ultimate economics that the wireless was offering. So the District had to settle for two T-1 lines that gives a total of 3Mbps bandwidth to and from the outside, (but with the latency of only T-1 for top speed). At a cost of $1,800 a month per line. So the T-1 'internet connection' point to point to the large national Internet provider costs $42,000 a year, while the 'internal' T-1 network to 20 schools costs nothing per month. (If the US West portion of the link to MCI were wireless, the cost would go down by perhaps $15,000 a year). The two schools that are currently linked only by dedicated dial-up lines are linked to the net by coming into a 32 port terminal server installed next to the router at the District Headquarters by 28.8 modems. The terminal server is capable of accepting modems for future faculty, student, dialup from their home computers. (There is little development in the District of the concept of home <--> school dialup, much less wireless, for homework and class preparation by teachers). The Web Server software on all the schools' computers is NCSA public domain code. The District has the capability of supporting a Web Site on the 'public' (MCI link) side of the firewall, as well as giving limited access to the web sites at the schools from the outside. But mainly, the web sites at the schools are accessible only from within the school, or from other schools of the District. The funds for the whole operation came from the District's Capital Improvement Budget. There was no problem with the School Board on the decisions, or budget allocation. The Associate Superintendent of the time, Donna Nicholson gave the project, growing out of the Magnet School experiments, strong support when the initial, crucial, decisions were being made. It was simply not either a controversial decision to have an entire school district come to depend on wireless links, nor particularly well understood. In fact, although this is as classic and impressive a case of the use of advanced, and extremely economical, telecommunications technologies for education as we have observed, there has been virtually no local news about the project. It remains to be seen how this wireless network, only recently fully deployed, holds up through a full academic year. We will revisit the Air Academy School District 20 before this NSF Project is over in the fall of 1997, and report on their year's experience. And in particular how this bandwidth is being used in the classroom by teachers and students. Bandwidth wide enough to support multimedia - animated graphic, sound, image, and text communications - applications, simlutaneously from many workstations. Already the network permits the district-wide sharing of the central Library resources, access to data and CD's, a complete internal e-mail communications network, ability for each school to establish a Web site, and visit that of all other schools of the District, as well as controlled-access to outside Internet sites, as well as the Administration of the District, including facility maintainance. And while TCP/IP is the principal protocol used over the net, already the installers have proven that they can, if desired, share AppleTalk, Novell, and even HP-3000 proprietary protocols used in the district. If anything, reflecting Mike Willett's technological judgements, the network is over-engineered for the current requirements. Thus he does not seem interested in bringing lesser bandwidth radios (56 and 115Kbs) to the small remote schools. But there is no question that the network can handle, reliably, all the network load that the district can generate for the forseeable future. At a very low original, and continuing, cost. Air Academy School District is fully into the advanced "Information Airways" of the future. Dave Hughes dave@oldcolo.com