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now that our wireless devices are being used for both voice and data, indoor coverage is becoming more important.

Taking It Inside

Tuesday, April 15, 2003

When cellular phones were first introduced in the U.S. they were large, bulky devices installed in automobiles or carried around in a sack (bag phones). Wireless networks provided coverage on major highways, then to streets inside cities, suburbs and finally into rural America. No one thought that indoor coverage was expected or even important. Even back then, wired phone service was cheap enough so when you were inside a building you just asked to use a wired phone and made your call.

Today we carry small handheld phones and while most of the wireless network operators have done a good job of extending coverage indoors in many areas, there are still a large number of buildings where wireless phones only work near windows if at all. You can still ask to use a wired phone and the cost of a call is certainly less than it was in the early 1980s. But now that our wireless devices are being used for both voice and data, indoor coverage is becoming more important.

But how are wireless network operators going to provide indoor coverage when no one, it seems, wants a wireless tower in their neighborhood or even on top of their office building. Part of the answer is that there will be an explosion of in-building cell sites and/or repeater systems. Companies such as AT&T Wireless, Verizon, Sprint PCS and Nextel are approaching major companies and offering to install both an in-building repeater or cell site and Wi-Fi systems for "free" if the company will commit to switching all of their wireless users over to their network on a long-term contract.

What about companies and even individuals who don't have enough phones to make it worthwhile for a network operator to install an in-building cell-site or repeater system? Well, there are other ways to get an in-building repeater system.

A Real-World Example

My wireless network operator of choice happens to be Verizon Wireless. I have found that this network provides the best overall coverage for me while I travel extensively in the U.S. I have both a phone and a Sierra Wireless PC Card for the Verizon CDMA2000 1X network. So far I have only been out of range of the Verizon network on one or two occasions this past year. However, when we purchased our new home in Santa Barbara, California, much to my dismay, I discovered that I did not have Verizon coverage. I could stand in the driveway and make a call if I held the phone just right but when I moved from that spot I had no coverage.

I soon discovered that the Santa Barbara City Government makes it really tough for wireless network operators to build new towers. Sprint PCS, which is preparing to offer service there, is having to build a number of "towers" that are only about twenty feet tall and look like old-style street lamps. So for the past year or so I have been trying to find a way to help Verizon to be able to erect a cell site that would cover not only my home but the entire community. So far the City has stood firm.

While at the CTIA Wireless 2003 show I saw an exhibit by Spotwave ( showing a product it calls "SpotCell." I contacted the company to learn more about SpotCell and after a few discussions, they kindly offered to come visit my home and see if they could install a Verizon repeater system for me. The criterion for their system to work is that there has to be a signal of at least -100 dbM (a pretty weak signal to be sure, but a signal nonetheless).

Since we are in the process of adding on to the house this turned out to be a good time to try SpotCell. If it worked I could run the wire between the two units in the walls prior to the drywall being installed. The Spotwave folks showed up to run a coverage survey and they determined that I could get a Verizon signal that was better than -100 dBM, but they also discovered that AT&T Wireless had a cell site hidden on a telephone pole about a quarter of a mile from my house that could prove to be a problem because of its strong signal. But we decided to give it a try.

Last week UPS delivered a Spotwave box and the next day an installer arrived. The SpotCell consists of two pieces: a donor unit, which is the outside "smart antenna" and the coverage unit, which is the antenna that goes inside and radiates the signal. Since these systems "repeat" a licensed wireless system, permission has to be granted by the operator in order to set one of these up but the folks at Verizon were gracious and their approval was quickly forthcoming.

Both units are small. The donor unit is in a beige plastic housing that measures 14" x 11" that is 4" thick. The coverage unit is 7.5" x 5.5" and 2.5" thick. It turns out that a typical installation is so easy that it can be done by anyone who has ever put in their own DirecTV satellite system. The "kit" includes the two units, the coax cable that runs between them, the power supply and a slew of different types of mounting hardware.

The actual installation of my system took only about an hour including drilling the studs and running the coax and ground wire. In most installations there is an indicator light on the donor unit. You mount the unit and then turn it until the light glows green rather than red. Once this is done you turn the system on and, like magic, the inside of your home or business is flooded with wide-area wireless coverage from your wireless operator of choice. My installation required a little "tweaking" to null out the AT&T Wireless signal and get the best Verizon Wireless signal. The Spotwave folks have developed some really great software with which they can not only "see" the signal strength of the chosen network, they can see the signal strength of the other network. Using this software they were able to optimize the signal from Verizon and null out the AT&T Wireless signal. (The unit we installed operates on the 850-MHz cellular band but Spotwave makes units for PCS channels as well.)

Once we set the donor unit in the best location and turned on the coverage unit I had full coverage in my entire house as well as outside in the driveway. As we ran our coverage survey I learned how "smart" this system is. It is constantly measuring the incoming signal and adjusting the output signal so that full two-way coverage is maintained. It is also designed to minimize any interference to the other cellular operator (in this case AT&T Wireless). The day after the system was installed one of our sub-contractors showed up with an AT&T phone and was able to use his phone in the driveway without any problems or interference.

While it only took one coverage unit to provide all the coverage I need, Spotwave also makes a unit that can feed two coverage units to provide coverage over a wider area or on two separate floors. The folks at Spotwave are working closely with wireless operators to make sure they are aware of each installed unit. Again, since they are operating on licensed spectrum, the wireless operator not only needs to be notified of any unit that is installed, it must give its permission for the installation.

Spotwave's devices are, generally, being purchased by wireless network operators and installed at no charge or for a small fee depending on the circumstances. Spotwave is also working with other distribution channels. The way the units are packaged, and as easy as they are to install, they could even sell SpotCells at retail if it weren't for the licensing issue.

Today, the SpotCell 100 costs $3,000 but I believe that wireless network operators will either give them away or make them available for a lot less. This is a great way to inexpensively provide voice and data coverage inside buildings that now lack coverage. It would be really great to have in-building repeaters that provided access to all of the networks at once, but since each network operator controls its own licensed spectrum, I don't think that this would be practical except for large facilities such as airports or convention centers.

Meanwhile, the Spotwave solution is simple yet elegant. The system has been developed to be installed quickly and easily and it works for both voice and data. I want to thank the folks at Spotwave for providing this unit for my use. Now I have Verizon coverage inside my house and firsthand experience with SpotCell's ease of installation and can attest to the fact that this is a really simple and inexpensive solution for in-building coverage problems.

Andrew M. Seybold

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