Verizon technician discusses testing local cell phone networks

The increase of cellular phone usage nationwide over the last few years has pushed communications companies to continually upgrade the range and quality of their cellular services in order to serve their growing customer bases.

To do so, cellular providers typically upgrade the existing networks or build new cellular towers, as many companies have already done on campus just within the last year.

The necessary sites are determined by so-called "drive tests" that assess quality and availability of wireless service in populated areas and on widely traveled roads.

Last week, The Daily Pennsylvanian went on a drive test of West Philadelphia with William Madden, a baseline technician for Verizon Wireless.

DP: What exactly do you do?

WM: I work for Verizon Wireless as a baseline technician. We're the "Can You Hear Me Now?" guys that you see on Verizon's television ads. I serve Southeastern Pennsylvania, Delaware, parts of Maryland and New Jersey -- basically, the tri-state area. I drive on highways all around my area and test wireless service from Verizon and all our competitors.

DP: What do you look for?

WM: I look for two types of failures: ineffective attempts, or non-service, and dropped calls. Sometimes we have random failures happen, but it's like any technology; there's always a few bugs. What we look for is consistency in errors, and then we can fix that by adding more cell sites and towers.

DP: How do the tests work?

WM: I have a number of different phones, and the equipment -- which anyone can buy -- dials numbers for each phone. The software then "speaks" one of the pre-programmed Harvard sentences that approximate all inflections of the English language, and male and female voices. Each call lasts roughly 2 1/2 minutes, which we have found to be the average length of a cell phone call from our billing records.

We track successful calls and failed calls. At the same time, we track the recorded signal strength [or RSSI] and the signal-to-noise ratio, so we can quantify what kind of service people are getting. A good RSSI number is from 30 to 80 decibels. If you get any higher than that, service is not too good. It becomes more choppy and is likely to drop out. For just Verizon lines, we also test that the phone can receive calls from the switch, and not only call out.

DP: How do you plan your routes, and how does your data get displayed from these routes?

WM: All my routes are designed to go by the most heavily traveled roads, according to highway statistics from the Department of Transportation. I just do roads, but there are other system performance engineers who test specific places of high usage, rather than roads. The computer keeps track of the RSSI and eventually I can deliver the data in maps of routes with the range of the RSSI drawn out. From there, we can locate search areas of weak service to which we should add more towers or upgrade our equipment. We have added generators or batteries at all our sites and towers, because we like to maintain our commitment to system reliability and redundancy.

DP: What kind of standards does Verizon use?

WM: Verizon uses mostly Code Division Multiple Access, rather than the Global System for Mobile Communications standard used by some of the other companies. CDMA uses spread-spectrum techniques that allow each user blocks of frequencies called channels. We work mainly in the 850 to 900 megahertz range. As CDMA originally came from the military, all calls are also scrambled with 64-bit encryption. Verizon is also slowly phasing out analog service in favor of digital, as analog is expensive to maintain and digital is much more reliable. Also, people speculate that digital is safer anyway, as the higher wattage in the analog phones are thought to be bad for the head.

DP: How is service in the city and on campus compared to elsewhere?

WM: Of course, we try to maintain good coverage in all areas. In cities, however, you have lots of interference from buildings and also cars, and because digital cell phone signals are lower power -- only 0.3 watts -- we need a lot more cell sites to serve everyone. We have a lot of cell sites in Philadelphia.

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