Riding shotgun with a cell-tower troubleshooter


Bob Anderson drives his US Cellular mobile unit carefully, with one eye on the road, the other on his computer screens, and his mind on problems he hopes the company’s customers will never discover. “Most of what I’m looking at is changes in statistics. I want to know if a site is dropping more calls or if traffic has gone down more than usual,” says Anderson, assistant performance engineer with the company. “My job is to see if we have issues before the customer has an issue. We want to get to it before the customer calls customer service with a complaint.” Along with one other performance engineer, Anderson covers the more than 110 transmission sites US Cellular has in New Hampshire and southern Vermont. Today, on a mid-morning ride from Manchester to Bedford, he is accompanied by the company’s sales director, Jim Holmes, and a reporter to see how the monitoring system works. “The monitor on the dash is to monitor the legacy system,” he says, with a nod toward the small rectangular screen atop the dashboard of the minivan. The analog-based legacy system is being phased out in favor of a relative newcomer that Anderson and Holmes refer to as “CD May.” “Code Division Multiple Access,” says Anderson, explaining how young “CD May” came into the system less than two years ago, supplanting old “TD May” (Time Division Multiple Access) as the dominant cell phone technology. “Back in the analog days, when you made a call, you were assigned a channel exclusively to you,” Holmes says. “When the first generation of Multiple Access came along it was time division, a sharing of resources and time domain.” Multiple users could access the same channel, one after another, in rapid-fire sequence. Then code division marked further progress in multiple access, Anderson says. “Picture yourself in a crowded room where everyone is talking, but one person is talking in a code that only you can understand. That’s how ‘CD May’ works and capacity increases with that,” he says. By allowing multiple access simultaneously to the same channel, the newer technology makes it possible to serve more customers with a smaller share of the spectrum, says Holmes, making more minutes available at lower rates. Voice quality also is improved, he says. Even customers with the older legacy system are benefiting from the shift in technology. “We’re moving so many people to our new system that we’re not seeing many problems with the legacy system,” says Anderson. The occasional malfunctions are generally in the handoff of a call from one tower to another, he says, or in a backlog where customers have trouble accessing the network. “Sometimes we’ll have to go in and change the channel to reduce interference,” Anderson says. Anticipating problems Driving from Manchester over to Bedford, Anderson maintains an ongoing call from one of the cell phones affixed to the dash. “It goes to a test site in Manchester with a loop back to me,” he says. The call enables him to monitor the CDMA system on a screen set up next to him and to see which of the six towers in the area are engaged in transmitting his call. The screen, powered by a computer behind the driver’s seat, also provides information about the strength and decibel level of the signal. A computer keyboard next to him enables Anderson to log the results. “On a dirt road in a rural area, I have four sites active,” he says, while driving through a heavily wooded area in Bedford. “Now I’m back to six” he announces a moment later. “My receive level is 96.” The power received, measured in decibels per milliwatt, is recorded in negative numbers. The higher the number, the more power is required for the signal to reach its target. As the number tops 100, Holmes comments on the effect of the terrain and foliage on transmission. “Back in the days of the analog phone, that would cause static,” he says. Yet relatively few complaints about cell phone reception have to do with car calls, Anderson says. “I don’t get many calls about mobility issues. Most are about home or office reception. That depends on building penetration. Fortunately in this part of the country, there are a lot of wood buildings.” On the other hand, there are a lot of trees, contributing to “foliage deflection,” he says. Anderson’s monitor also records the “frame erasure rate” during a call. “Normally, if that’s between zero and 2, the calls are very clear,” he said. “Between 2 and 5, you notice some voice quality issues. A number over 5 would be a performance issue. Typically you can drive around the area and never see it go above 2.5.” When the numbers on his screen indicate a problem, or when an alarm goes off at one of the tower sites, Anderson will call one of the company’s field engineers in the area before heading out to the site. Most of the problems occur in rural areas where the towers are further apart, he says. “On a typical day, I’ll catch maybe two to three issues,” Anderson says. Customer problems, requiring him to visit residential or business locations, occur less frequently. “I usually get one or two a week,” he says. “We give them priority. We get to them as soon as possible.” Anticipating problems, the company often brings mobile transmitters to events drawing huge crowds and a heavy concentration of cell phone use. “Usually we have enough capacity, but it broadens the field,” Holmes says. “When we have NASCAR races going on up in Loudon, we often bring in mobile sets for that.” Back in Manchester, Anderson pulls into the Manchester Commons shopping center on South Willow Street and drives over to a tower located behind a row of stores. He goes inside and checks the readings on the various instruments. “I look for anomalies in the data. A higher level of drop-off or increase in traffic could be related to a site issue,” he says. Holmes, meanwhile, points out the greater volume of computer hardware needed for the old legacy system than for the more efficient CDMA. The tower also is equipped with a back-up power system of 1800 amps to keep the calls routed during a power outage. “It’s like having 24 car batteries,” Holmes says. By his own count, Anderson drives anywhere from “zero to 360” miles a day. On days he is not on the road, he is “sitting in the office, looking at stats or working on projects.” Anderson, who has been in the cellular communications industry for more than 20 years and with US Cellular for the past 10, says the business is “constantly changing.” “There’s never a dull moment. I get a lot of good feedback from the people I work with and from customers. It just kind of grows on you.” And, as a troubleshooter in the communications business, he never gets too far away from his cell phone and computer. “I’m not on call per se, like the field people are,” he says of off-duty hours when emergencies may arise. “I do take calls — except when I’m playing golf,” he laughs. “There has to be some sacred time.” But even the fairways are an imperfect sanctuary from the growing demands of the cellular communications industry. “I do check my messages between the ninth and tenth holes,” Anderson says.