The Growth Period

A wireless carrier's concern for its network reliability does not change according to the size of its operation. A small local wireless provider cares just as much about its reliability as its large national counterpart, and so do its subscribers. However, as your subscriber base, coverage and call volume increase, network reliability issues arise. Wireless carriers that have lived through this growth can offer insight into a few of the network reliability challenges that come with it.

Increase Reliability as You Increase Subscribers Although a large subscriber base is every carrier's dream, you must maintain an acute awareness along the way of how more customers will affect your network. Anticipated subscriber growth was the primary motive behind Omnipoint's effort to upgrade its interconnect, said William A. Diaz, Omnipoint vice president of network engineering and operations. He advised other wireless carriers that are planning for growth to put their resources into this part of the network because it is the single largest recurring cost for any wireless operator.

"We have more and more subscribers on the network, and we can't afford to have a single point of failure anywhere," Diaz said. "We recognize that we have to spend money in the right places. One of the right places is our network interconnect."

If the switch is not placed at the right location, he explained, it could cost you anywhere from $50,000to $150,000 extra per month millions of dollars each year. The money he saves by improving recovery makes up for the significant dollars he spends on those improvements. Lately, the company has poured a bundle into intelligent dual wire centers and alternate routing. Omnipoint's goal is to start pushing recovery further and further into the interoffice facilities network, Diaz said. As a rule of thumb, the company designs interconnect enhancements to handle growth for 18 months to three years. One way it has done so is by installing OC3, OC12, and OC48 SONET rings. The switch location usually contains an OC48 bidirectional SONET ring, Omnipoint's standard for its entrance facility. The company also has introduced an alternate serving wire center, so the intelligence that was traditionally located in the serving wire center now also is located in another area. Its next step is to move toward an intelligent dual wire center, which will improve its ability to take on a major hit.

Earlier this year, the company's recovery was tested when World-Com experienced a major fiber cut on the East Coast that affected 900 DS3s. Although Omnipoint was not the only wireless carrier affected, it survived better than Diaz had expected.

"One of the reasons was the improvements we have been making," he said.

He suggested that smaller wireless carriers move away from point-to-point architecture and go with a very small SONET architecture to keep the network reliable in the face of subscriber growth. SONET and fiber allow carriers to start small, yet they are still able to scale, Diaz pointed out.

"That doesn't mean you have to put up OC48s," he clarified, "but maybe you could at least consider OC3s or OC12s."

Expanded Coverage: A Logistical Challenge Not only should you think about how a bigger subscriber base may affect reliability, but as your network coverage expands, other challenges surface, said Keith Surratt, GTE Wireless director of technical services.

"You must recognize that you have to change some of your logistics as far as where you place your resources so that you can respond to problems that you cannot deal with remotely," he said.

If your network covers 200 square miles, he said, you will place your field forces differently from the way you would if it covered 2,000. A larger network requires you to get closer to potential points of failure in case you need to fix a problem manually. That means situating employees so drive time is reduced when restoring service-affecting situations.

For instance, when GTE Wireless had only a small system in the Ohio area, it had little equipment in its Pennsylvania markets. Once the network grew to where the company had substantial equipment in Pennsylvania, it had to place people there as well because drive time from Ohio was more than two hours.

"Sometimes when you grow from small to large, you have to sit back and think about what changes need to take place," he said. "Otherwise, it can overcome you."

Tom Holmen, Ericsson vice president of customer support, said one way to overcome the logistics challenge when your coverage grows is to use the personnel of companies that already cover other areas. Utility companies, for example, have the same types of resources and can be an asset in this situation.

Increased Call Volume Without attention to network growth management, increasing call volume (greater traffic) may decrease reliability, said David Lowry, Aerial Communications CTO. The central issue is that carriers need to anticipate having adequate resources where and when needed. Network capacity is directly influenced by both the temporal and geographic distribution of customer usage. If you have a certain pattern of usage spread across a group of cell sites, a change in pattern could have an adverse affect on your capacities and your ability to serve the same number of subscribers, Lowry said. In addition to the busy-hour traffic patterns, you also must take into account seasonality issues, such as the holiday buying season or heavy tourist periods. Aerial manages traffic distribution in terms of the time and geographic dimensions using standard traffic engineering methodologies to project increased volume. That way, the carrier can add capacity in advance of an increase of traffic demand.

Increasing call volume also necessitates that you dynamically grow your signaling network to handle more messages. Lowry said Aerial is not as concerned about this possible problem because its GSM technology offers more flexibility to allocate additional signaling capacity on the radio network.

"You can add virtually as many signaling channels as needed," he said.

In addition to the technical resources, such as switching components, transceivers and circuits, you also must track the human resources essential to support growing networks. You have to increase the number of technicians as a function of the size of your network.

"It takes time to acquire those types of resources," he said. "Unlike base-station equipment, you can't go out and buy it. You have to develop it in most cases. Anticipating will help achieve the desired quality performance standards."

Aerial prepared for a growing call volume when it designed its network for the build-out of its footprint. It included large intrinsic expansion capacities within the existing cell-site infrastructure. The carrier essentially has modular expansion capabilities so it can avoid having to build significant numbers of additional cell sites to meet its capacity requirements.

Anticipating that growth is Lowry's main suggestion to smaller carriers. To prepare, you should make sure you anticipate having the appropriate resources necessary to maintain and operate your network to the planned reliability level. That is not always the case, he said, because start-up carriers tend to focus on the near-term coverage without anticipating growth capacity.

Large, established carriers also often are ill-equipped to manage their networks. Experienced, knowledgeable personnel are key to ensuring reliability during a growth spurt, but network-management software increasingly is having to take their place.

"Companies that used to have a large organization of planners and engineers and support people don't have them any more," said Dave Cox, Tekelec network switching division director. "They've offered them early-retirement packages and gotten rid of them one way or the other. They're coming to us and saying, 'Can you do more?' So we think that testing, monitoring, surveillance and intelligent-network elements are going to become even more important in the traditional markets because of downsizing and streamlining."

Tom Holmen, Ericsson vice president of customer support, noted that building a reliable network requires a large capital investment, which is easier to make when you have a big subscriber base and more cash flow. The deck is stacked against small carriers when it comes to money, he said, but that does not mean a small provider can't build a reliable network. One way to overcome that challenge is to rent resources from a manufacturer, rent space in a network-management center or piggyback on a larger operator.

"Investments in network-management centers can be split between various operators so you don't have to do all the investment yourself," Holmen said. "You still can get the same economies of scale even if you are a small operator."

Another way to improve reliability while keeping overhead down is to look for highly automated, all-in-one network-management tools that require as few personnel as possible. Fortunately, vendors are providing more turnkey solutions in response to the growing number of start-ups, which often are venture capitalists.

"They're basically people with deep pockets, but not a lot of experience," said Dave Cox, Tekelec network switching division director. "What we've seen as a vendor is (that) they don't want to build up these huge organizations to support, maintain and monitor. They want to pay somebody else to do it."

The result is sophisticated equipment that tests more network elements yet requires fewer people.

"Test, surveillance and monitoring equipment are going to become paramount to those types of customers because they don't want that huge base of people," Cox said.

In the drive to make wireless more user-friendly for subscribers, carriers got short-changed. Subscribers got graphical user interfaces, caller ID and detailed bills to manage their usage. But when it comes to network management, well, let's just say the tools haven't always been so user-friendly.

That's understandable, considering how tall the order is: the ability to look into SS7 messages from end to end of the network, all in real time and with point-and-click interfaces.

But network-management tools are steadily becoming more user-friendly even as they become more sophisticated. Vendors such as Inet, Tekelec and WatchMark offer turnkey packages that pull raw data from throughout the network and compile it into accessible, graphical displays.

That ability to see at a glance how the entire network is performing is important not only for ferreting out delays and congestion but also for planning. If one cell site is displayed in red because it's maxed out with traffic while another across town is blue and quiet, it's easy to decide which site justifies an upgrade.

"Beyond technical complexity, what's also emerged is more of the business aspects of running the network," said Kevin Keough, Inet vice president of marketing. "People look at the systems not only to see that bits and bytes are going around correctly but also to try to make money and save money in terms of the business applications of their network."

Such software can help carriers understand usage patterns to develop enhanced services that not only capitalize on those patterns but also track usage of those services for billing and antifraud.

"What started out as an operations tool has crept more into the business aspects of running the operation," Keough said.

And in network management, the best defense often is a good offense.

"We've been very reactive as a carrier," said Ed Evangelista, Cellular One network engineering manager in San Francisco. "I think that's true for all carriers. We build our network based on growth but not on trending. So sometimes we don't know whether we're making the most efficiencies in scaling our capital build-out."