Wireless Broadband Internet System White Papers

Applying Radio Frequency (RF) engineering as part of your business plan.

These days many are considering starting a business offering wireless broadband Internet service. These are commonly known as wireless hotspots, wireless broadband or Wireless Internet Service Providers (WISP’s). This is an exciting time for wireless broadband and there are many opportunities to make a good business plan and money. While there are plenty of places to gather information about a given market, it’s potential for customers and their demographics, there has been too little attention placed on the radio system design and how it could maximize your investment. Many people throw up a wireless access point and hope it reaches the customers they want. While this will work for a small coffee shop or restaurant, it is not the best plan of action for anyone considering offering services to multiple customers over a larger area. This type of service would be considered outdoor wireless broadband. In this article, we attempt to explain the importance of transmitter selection, antenna selection, base station and antenna location, customer premise equipment considerations, and FCC type acceptance.

Access point transmitter selection.
    The core of your coverage plan is your access point; you don’t want to skimp here. A little more money spent up front can improve your overall system performance and customer satisfaction. It will also keep maintenance and downtime to a minimum. Most people would think that more power is better. While power does carry the signal farther, this is a two-way communication, so your customer has to be able to get their signal back to your base station as well. This is referred to as a balanced path. A standard access point will cover a small area about as far as a city block; this range can be increased significantly with outside antennas and bi-directional amplifiers, but they don’t always need to be used.
        Outside antennas on a high location will carry a signal much farther than off the shelf consumer home systems. They can also pick up interfering signals from farther away. Careful site surveys in advance will give you an idea if this could be a problem.
       Bi-directional amplifiers in conjunction with an outside antenna will give the best distance performance but they have drawbacks. While you can now get your signal out a much greater distance, most amplifiers will raise any interference or noise levels as well. These can create a situation where you might not be able to maintain a connection to the base station even though you receive it at your location just fine. If your signal is not strong enough at the base station to overcome the level of noise at the amplifier, then you can’t connect.

Access point antenna selection.
Outside antennas come in various shapes and sizes. They have different performance patterns and gain. Omni directional antennas work great to cover uniformly in all directions but they also pick up interference in those same directions. This can be minimized by choosing an antenna with less gain or performance. Your coverage area will be smaller but it could help eliminate an interfering signal or signals.

There are also situations where you need to focus coverage in a particular direction. This might be to get a stronger signal in a particular location such as a mall or you might have a concentrated customer base in that region. Directional antennas focus the signal in a specific direction with more power. On the receive side you also get better performance and limit the direction from which you are likely to receive interference. Many times this technique can block out undesirable signals that otherwise kept a base station from functioning well.

Example of an omni directional antenna with local terrain.
Click on thumbnail for full image.

Same site with directional antenna to focus coverage to the South.

Base station/antenna location.
Just as in real estate, the three most import factors in choosing the transmitter site are location, location, and location. The proper site will allow you to cover the most customers and install as few transmitters as possible. The relationship to the local terrain and the ultimate mounting height of the antenna are the key points. Fortunately, most WISP solutions require minimal antenna arrays, and in most cases avoid any major zoning problems. Good locations don’t necessarily need big towers to work well. With the proper site selection, you could easily install an antenna on a rooftop or chimney and not be subject to any zoning review. Favorable ground elevation can do wonders for base station performance.

Customer premise equipment considerations.
While it would be nice to have a system that worked so well a person could just power up their laptop with a wireless card and get connected, this is not cost effective or practical on a large scale for an outdoor WISP system. We therefore have to put some thought in to the type of equipment that will be located at the customer site. If you invest in an outside antenna and amplifier at your base station, you can further increase your range and potential customer base by using high gain antennas at the customer premise. The customer will only need to focus their wireless energy in the one direction that faces your base station; any energy in other directions is wasted. Installing devices at a customer site with external antennas will give them more power to connect from a much greater distance.

This map shows a sample transmitter range where the customer uses off the shelf devices.

Same transmitter range using client equipment with external 3.5ft 24dbi dish antennas.

FCC type acceptance.
In talking about external antennas, amplifiers, access points and customer terminals, I offer this word of caution. Most business plans are formulated using the unlicensed radio spectrum and the inexpensive equipment available. All of these devices are allowed under FCC part 15 rules in the US. These are guidelines for power limits and effective radiated power output. There is a temptation to buy different components from different sources and put together a solution that technically works and within the power output rules for part 15, but the rules also state that the device/ complete system must be type accepted. That certification is achieved using specific components, feed lines, amplifiers, and antennas. Once you substitute a different antenna or other component, you are no longer in compliance with FCC part 15 rules. This applies for the customer premise equipment as well. You can’t just add an inexpensive external antenna to an off the shelf product to increase it’s performance and still be legal. If you supply customer equipment, it would be in your best interest to sell only type accepted solutions. Many manufacturers produce type-accepted devices for outdoor systems discussed in this article. Their costs are far less than the fines the FCC can levy on you if they inspect your business and find you have non type-accepted equipment in service.

In conclusion, we hope to have shown that with some good RF planning you can more accurately forecast what your costs will be to start a wireless broadband system and the predicted coverage area you will offer service. In times where investment dollars are scarce, better pre-planning can eliminate a trial and error approach to developing a successful system.

Leading Edge or Bleeding Edge - Determining When a Wireless Site Fits Your Business Plan

WiFi is a very real and exciting opportunity where tech savvy entrepreneurs are redefining our world before our eyes. Buzzwords like Wireless Broadband, Wi-Fi, WiMax, Access Point, BTS, 802.11a, 802.11b, 802.11g, 802.11n, WAP, Hot Spot 2.4Ghz, 5Ghz, 5.8Ghz, CPE, Backhaul, Mesh, Open Source and COTS are all around us. Many are considering joining the ranks of the Wireless Internet Service Providers or WISP’s. Hey, this is not rocket surgery, right? Nope, rocket surgery is easier, much easier. You can see the rocket.

If you fail to plan, plan to fail. It is not enough to just mesh your acronyms, understand the hardware, crack open a box; plug it in, and your Rupert Murdock’s next apprentice. This is business; remember the basics, do the homework. Things like; a business plan, network design, equipment, installation, integration, software specification and cost analysis is just the start and hardly enough to determine if you have a winning return on investment (ROI) model. Back in the days of Wing Commander and dial-up ISP’s it was relatively easy to predict who you could provide services to. You merely did research on available phone number exchanges and calling areas. As long as people had a telephone, ring-ring cha-ching, they were potential customers.

Now, just because your barber and broker have mastered the buzzwords (sort of) and the spectrum is unlicensed, it does not mean that it is open mike night at the Grand Ole Opry… yet. In the wireless broadband world if you want to maximize that opportunity, you will need to conduct some very advanced field and propagation studies on both radio system range and market penetration. Then after defining the realistic sufferable degradation of your network and understanding the implication of the resulting demographics you may just begin to see the rocket. Predicting the coverage area is a complex and critical task. Contrary to your barber and broker’s best advice this in not plug and play technology and not as simple as reading what the manufacturer says is the maximum range. These numbers are usually under ideal conditions and the most favorable of base station sites. In reality, you must look at many factors.

First you should consider the terrain or topography of the area where you want to offer service. Hey, “I know this,” you say “higher is better, line of sight, right?” The proper answer is, “Yes”, “No”, “Maybe” and “it depends”. Hills, mountains, morphology, clutter, time of year, weather and their proximal impact to your base station and customer sites should be well defined. This can be a very challenging, expensive and unnerving problem to solve, especially after you have started to build your network and have live customers on line.
Second, the equipment to be used and its performance to cost analysis. This needs to be considered for both the base station site as well as the customer premise equipment (CPE). The combination and performance of these will greatly affect both the footprint of your site as well as the capital required to acquire each customer and can change your ROI in a heartbeat.
The third factor is demographics. Once you have the first two well in hand, there are some interesting methods to integrate or define the realistic range of your site, Geographic Information Systems (GIS), Census data and equipment used. Once these layers have been peeled back a study of the demographics of this area can reveal information like population, number of households, income level and wireless competitive market value analysis, existing ISP’s, legacy and incumbent technologies. Having this data goes a long way towards determining site viability based on your particular business model. Now that’s a rocket! Scalpel!

Let’s look at each factor in more detail:

Terrain and Topography

Hills and mountains can be used to your advantage in a properly designed system. They can isolate a whole group of customers focusing on only those you wish to serve with a particular site. Since many WISP’s operate in the unlicensed radio spectrum, frequency management is critical. Not only do you have limited resources but you also have to share it with all other part 15 devices (in the US). Using the terrain to contain a signal to a limited area will allow you to reuse those same frequencies in another area. This same technique can also help to minimize the areas where you pick up interfering signals. Doing this in conjunction with narrow beam directional antennas can keep your options open for growth, expansion and spectrum mitigation in the future. You may have to be creative and flexible when coexisting and managing your allotted spectrum.

Wireless Coverage Map for High Speed Internet System using the terrain to contain the signal
Image © 2004 by Wirelessmapping.com
Here is an example of a site that uses a mountain to block the signal from going to the West. This is one technique for containing a signal to a particular area and minimizing the direction from where you can receive interference.

Equipment Selection

One key factor in designing a wireless broadband system is a balanced path. Essentially that is to say that WiFi communication is a two way street and data packets have to be exchanged in both directions. It is not good for your base station site to broadcast over great distances if your clients cannot talk back to it. The range of your system will be limited to the talk back range of the client devices. If your business plan relies on devices such as PCMCIA cards or built in radios such as the Centrino laptops, you may have extremely short range and a limited client base. If you plan to have maximum range and reach the most customers possible, then you must consider incorporating CPE equipment that employs some sort of outdoor antenna and/or bi-directional amplifier solution. There are many different sources and prices for CPE equipment and it will vary based on the technology you chose for your base station systems. Be sure that your solution is FCC type accepted as a complete system, this includes the combination of radio and antenna. Mixing and matching antennas and radios from different sources will not always be a certified solution. The better performing units will have the radio and antenna integrated on the customer unit or have the radio located as close to the antenna as possible. This minimizes any feed line loss between the radio and antenna and gets the most energy possible over the air; this also applies to the received signal. Many times an integrated unit will be powered via the Ethernet cable, this makes an installation at your customer site easier since you won’t have to drill big holes for the antenna line and you only have to worry about an Ethernet cable. Units with the most antenna gain will help for those clients located farthest away from the base unit to get a good link.

On the base station, antenna selection and the use of bi-directional amplifiers should be considered. Panel or sector antennas can be very useful with the additional gain they offer and the directional pattern they employ. With a directional pattern, you can point the signal where you need it and isolate the directions from where you will receive interference. When considering the use of bi-directional amplifiers, it is true that your output signal is stronger and goes farther. On the downside it will amplify the weak client signals and the noise from other devices using the same spectrum. If the use of these devices gets the signal from your clients to your base receiver at a stronger level than the noise, it is worth installing the amplifier. To maintain a good quality of service you want to have as much signal at both ends of a link as possible, when the noise levels fluctuate, the customer still maintains connectivity. Here are some examples of the differences to expect based on CPE unit selection.

RF Propagation Coverage Map for an amplified wireless hotspot
Image © 2004 by Wirelessmapping.com
This is an example of the coverage you can expect (shown in green) with an outdoor 802.11b access point and antenna system using standard wireless clients like PCMCIA cards. A bi-directional amplifier was used at the base station in this case.

Map of Wireless Service Area for a WISP using amplifier and high gain CPE antennas
Image © 2004 by Wirelessmapping.com
This is the same outdoor site with amplifier. The difference shown is the effect of having client units using outdoor antennas with gain in the 16 to 18-dbi ranges. You can clearly see the increase in service area.

The selection of CPE units can change your coverage area a great deal affecting your financial forecast. It will add from $200 to $500 in additional cost to each customer access point when outdoor customer premise units are used. Additionally you must calculate installation and customer support costs.

Basic Demographics

Of all the factors in choosing proper base site locations, demographic data and its real world footprint should be well defined considered and understood before proceeding with construction. Once the range for a transmitter has been determined, knowing the population and number of households within this area is crucial. Most individuals can find basic demographic information about a particular city or town; the problem with this data is that it rarely coincides with the smaller area that the wireless transmitter covers. Producing demographic reports specific to the coverage of the site arms business owners with the information they need. The bottom line is you need to know if the market has enough potential customers to support the new system. Being able to show this same data will also help determine if the investment in outdoor CPE terminals will increase the potential customer base enough to warrant the expense. The chart below illustrates a sample of these demographics for the coverage maps used in this article:

Distance from Site	Number of Households	Broadband Penetration %	Percent of Broadband Marketshare	Potential # of Customers	Population
.5km	491	50	15	36	938
3km	1244	50	15	93	2496

This example assumes there are other broadband options for consumers in the market. While the market share and broadband penetration rates are estimates, you can easily adjust that data for your market. The real key here is knowing the actual number of households and population of the area you will be able to serve.

Conclusion

This article is not meant to cover every detail of proper site design and analysis, especially in the area of radio frequency engineering. I hoped to Increase your knowledge base as a high-end techno consumer, get your arms around this leading edge technology, and understand that there are many options to consider when deploying an outdoor wireless broadband system. There are well defined tools and techniques that can help you make smart choices about site selection and market conditions before you expend capital and start construction. This should be welcome news to investors and potential WISP entrepreneurs alike. Whether you are building your own network or hiring outside consultants, securing this data and truly understanding your real world market impact should be the cornerstone of your business plan. If you don’t believe me, just ask your broker and barber. Now how about that beautiful singing voice of yours, can you hear me now….?

www.wirelessmapping.com

Broadband Market Demographics

Less than 5% of towns in the US with a population of 10,000 or less have access to broadband technology. High-speed (broadband) Internet access in many rural locations and areas beyond the reach of Cable and DSL (Digital Subscriber Line) is virtually unavailable. Current broadband technologies are simply not being expanded to rural populations because the costs associated with rapid expansion of cabled high-speed access are exorbitant, and reliance on telecom exchange carrier facilities slows infrastructure expansion. This lack of connectivity in rural communities adds to a nation-wide "digital divide", or a perceived gap between those who have current broadband technology and those who do not.

US Broadband Penetration 45.2% - US Internet Penetration Nearly 75% - March 2004 Bandwidth Report

Overall, broadband grew by 2.14% in February, with 45.15% of Internet-connected U.S. households enjoying a high-speed connection. 54.85% of US home users dial into the Internet with "narrowband" connections of 56Kbps or less.* Nearly 75% of U.S. households have Internet access at home, according to a Nielsen//NetRatings survey. The charts below, derived from Nielsen//NetRatings, show trends in connection speeds to the Internet for users in the United States.

Home Connectivity in the US

As of February 2004, most users in the US connect to the Internet using dial-up modems of 56Kbps or less. 44.4% use 56Kbps modems, 7.6% use 28/33.3Kbps, and 2.9% use 14.4Kbps modems. In total, 54.85% of home users in the US connect to the Internet at 56Kbps or less (see Figure 1).

Graph Showing Broadband Growth in the US

Figure 1: Web Connection Speed Trends - Home Users (US)
Source: Nielsen//NetRatings
Broadband Growth in the US

Broadband penetration in US homes increased by 2.14% in February. As of February 2004 broadband penetration was at 45.15%, up from 43.01% in January. This is higher than the average increase in broadband of .75% per month from October 1999 to December 2003. Extrapolating the data provided by Nielsen//NetRatings, broadband share in the US should exceed 50% by June of 2004 (see Figure 2).

Broadband Connection Speed Trend - Home Users (US)

Home Users Broadband Connection Speed Graph

Figure 2: Broadband Connection Speed Trend - Home Users (US)
Extrapolated by Web Site Optimization, LLC from Nielsen//NetRatings data.

Work Connectivity in the US

Most workers in the US enjoy high-speed connections to the Internet. Most use a high-speed line such as a T1 connection, and share bandwidth between computers connected to an Ethernet network. The speed of each connection decreases as more employees hook up to the LAN. As of February of 2004, of those connected to the Internet, 77.2% of US users at work enjoy a high-speed connection, up 2.1% from 75.1% in January. 22.8% connect from work at 56Kbps or less (see Figure 3). As more users get access to high-speed connectivity at work, they desire the same performance for their home systems. This also illustrates a large market potential for business class customers. These are a longer sales cycle as most are under long term contracts with their existing high-speed providers. They are very interested in switching to services at the lower prices offered by wireless carriers but typically don’t switch until they are out of the obligated contract periods for the current services.

Graph of Web Connection Speeds in the Workplace

Figure 3: Web Connection Speed Trends - Work Users (US)
Source: Nielsen//NetRatings
U.S. Internet Penetration Nearly 75%

Nearly three out of four U.S. households with a phone line have access to the Internet, according to a February 2004 Nielsen//NetRatings survey. In the United States, 204.3 million people have access to the Internet, or 74.9 percent of the population. Internet access was 66% in February 2003, a nine-percentage point rise in one year.

For more information on these articles or to request maps for your system go to www.wirelessmapping.com.