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In Good Voice

By Bob Chapin

Top-quality test and measurement procedures help CDMA operators realize the full potential of their network, in terms of both reliability and voice quality. And that means more satisfied customers generating more revenue for the operator. Bob Chapin

CDMA is arguably the best digital wireless technology for voice quality. So say many wireless industry engineers. This is a major benefit in a highly competitive market environment where superior voice quality can be the essential differentiator.

In order to assure the highest level of network performance and to maximize the benefits of this marketing differentiator, it is imperative that both network operators and terminal manufacturers incorporate the best and most accurate test and measurement equipment and techniques available. Test equipment in the hands of a skilled field and service technician has the capacity to deliver on the promise of CDMA for network operators.

There's certainly more than enough competition in the marketplace to encourage a continuing attention to voice quality. When wireless telecommunications infrastructure and handset manufacturers began strategizing the development and implementation of the next generation of wireless services, the demands of the marketplace called for multiple digital RF standards. While Europe chose a single digital standard, the U.S. instead nurtured the development of three different digital standards: TDMA, CDMA and an Americanized version of the GSM standard.

At first, Europe's GSM seemed a natural winner. It was an operationally proven standard that had already received wide acceptance throughout Europe and was in the process of being implemented globally. America, however, has long preferred its own home-grown technologies. Consequently, TDMA was rushed into service in the early 1990s by a small group of US cellular operators who were desperate for an increase in bandwidth to handle their burgeoning subscriber numbers.

Technology of choice

The implementation of TDMA was followed three years later by CDMA, which many industry experts have long called their technology of choice. GSM was finally pioneered in the USA in 1996 by wireless industry veterans such as George Schmitt, who had launched GSM in Germany while with AirTouch International.

The choices available to system operators allowed equipment vendors to differentiate their hardware from that of their competitors, which in turn allowed them to differentiate their services and voice quality. But all this effort only pays off when system operators and handset vendors deliver what subscribers want: superior voice quality and reliability. It is the job of the field engineers and service center technicians to deliver the goods, and it is the test and measurement equipment that allows them to perform their jobs.

Digital technology has forced a radical increase in the functionality and sophistication of test equipment, both for base stations and handsets. The very nature of digital technology has resulted in today's test equipment being much more dependent upon software and far more automated than analog test equipment. Several factors are behind this:

  • digital technology is far more complex than analog and test equipment must be able to respond to these new technical engineering requirements;
  • several technologies must now be addressed (GSM, TDMA and CDMA), often with the same equipment. Some test equipment is now capable of evaluating more than one technology, often a combination of analog with a digital standard;
  • the actual process of testing is very different from what it was in the old days of analog. Two issues are involved here: wireless system buildouts are moving so rapidly that operators want equipment that can accomplish the task very quickly and effectively, while at the same time the skill sets of the average field technician are far lower than in the past, due to the rapid growth of the industry and a lack of experienced labor;
  • while one field technician used to be responsible for perhaps ten sites, today one person now has to cover as many as 20. Consequently, the new digital test and measurement equipment has to be highly automated, easy to use and extremely reliable.

Manufacturers of wireless test and measurement equipment currently produce a full array of infrastructure products and handsets based on the three major digital standards and market them to system operators, positioning each with a different set of features, benefits and values. High-end field units can cost up to $39,000 while high-end mobile units go as high as $50,000. This is pretty pricey. It is rumored that CDMA operator Sprint PCS in the United States has invested some $100 million in its testing program.

Competitive issue

Is voice quality a real competitive issue among digital operators? "Oh yes," says Wayne Leuck, executive director of engineering for USWest Wireless LLC, a CDMA-based PCS operator in the western USA. With 15 years in wireless technologies, Leuck has experienced the transition from IMTS (improved mobile telephone service) via analog cellular to digital. Once USWest had divested itself of USWest NewVector, its cellular operation, and was capable of focusing on the new PCS technologies, it selected CDMA. "Our company is built from the ground up," says Leuck. He believes his system has to be perfectly optimized to provide the level of quality CDMA offers.

USWest Wireless has taken control of its build-out and its test and measurement programs. So committed is the company to getting it right the first time and keeping it right, it has taken two bold and dramatic steps to assure optimization of its network. First, it determined it wanted to be able to test and measure its system from moving vehicles. Together with Tropper Technologies of Chicago, USWest designed and built much of its own test equipment, incorporating proprietary PC-based software programming that analyzed a series of wireless phones mounted in the vehicle.

The concept was predicated upon the belief that by conducting post-process evaluation of collected data back at the office you would miss a lot of opportunities. In fact, environmental or usage conditions may by then have changed enough to invalidate post-process findings. According to Leuck, post-process evaluation also leads to a major mistake commonly committed by operators, that of making network-wide changes based upon data collected in just one or two areas. "We optimize our network by site," he adds.
USWest's second big decision was to have its own engineers install and optimize the Lucent Technologies network equipment. The company found that its technicians and engineers learned about the network faster by doing their own installation, testing and measuring.

David Whipple, R&D project leader for Hewlett-Packard, agrees that CDMA's voice quality can be a marketing differentiator against competitive digital networks. TDMA is three years older than CDMA in its vocoder technology, he points out, and by today's standards, CDMA's more recent vocoder technology provides superior voice quality. "Older TDMA has pretty bad voice quality," he says, "but the network and handset must be optimized."

"One of the reasons CDMA works so well is all the feedback contained in the control of the link, particularly the power control," says Whipple. Power levels are properly maintained so that the vocoder is always running at error rates that achieve good voice quality. With digital wireless, it becomes a capacity versus voice quality issue when there are problems with the network. "Deployment problems directly affect voice quality in TDMA," says Whipple. "While in CDMA they directly affect the capacity of the system."

The result, even with deployment problems, is that CDMA subscribers will continue to receive clear voice quality, even though the system may not allow as many calls to go through. CDMA operators can enhance the throughput of calls by making certain the network is optimized by conducting drive tests using the latest test and measurement equipment.

Conducting on-site tests of base stations quickly and effectively is a necessity in many parts of the world. Base stations can pose a particular problem for the operator, especially in areas of the globe that incorporate co-location or the sharing of sites in order to comply with local zoning requirements. With multiple systems operating on the same tower or building, operators have no way of knowing who might have been climbing around their equipment, perhaps tripping over cables or re-orienting the direction of an antenna.

As a system is built out, the costly process of reconfiguring the network must be accomplished. This not only means having to drop in additional sites, but also having to re-orient existing antennas and even adding additional hardware to the site. Having reliable, one-button base station test equipment permits operators to move quickly in order to keep their subscribers talking.


USWest Wireless has made the commitment that all its technicians' vehicles will be stocked with the same basic test equipment. Leuck notes that some operators keep only a few vehicles fully equipped because of the huge costs involved, but it is his belief that each truck needs to be fully equipped in order to keep the system optimized. By developing much of its own software and test equipment, USWest has dramatically reduced the cost factor, allowing it to fully equip its technicians.

Another issue concerning operators is being able to effectively test mini-sites and those that are located in difficult-to-access areas. Like USWest's mobile test vehicles, several manufacturers have developed drive-by testing equipment that determines if additional analysis is necessary. Because the CDMA signal can use three different antenna sites simultaneously while determining which to choose during a soft handoff, sophisticated testing equipment from companies such as Hewlett-Packard is necessary to test the system. These devices make it easier for technicians to test large numbers of sites over shorter periods of time, which is more cost-effective for the operator.

The question of whether or not a service problem is the result of a network problem or a handset problem drives engineers and technicians crazy. Subscribers on the other hand are not very knowledgeable about the technology-and operators shouldn't expect them to be so. Frankly, subscribers don't care if they are using CDMA or GSM, and many don't even consider that they are using RF technology. Most just see the device as a phone, a means of communication, and all they want is for it to work, with good quality and reliable service.


When a problem does arise, the subscriber's first thought is usually that there must be something wrong with the handset. This response is quite different from that originally experienced with analog equipment. With analog handsets, subscribers would hear hissing and the call breaking up as they experienced poor coverage or a handoff to another base station. With CDMA, the error correction functionality within each handset is so good that the subscriber is never aware of a problem until the call is dropped, apparently instantaneously and for no obvious reason. "There must be something wrong with my phone," thinks the subscriber as he stares at it, shakes it and grumbles.

When this occurs, the operator is faced with a no-win situation. With the phone apparently inoperable, the subscriber isn't generating revenue through the use of airtime or enhanced services. Dissatisfied subscribers cost operators huge amounts of revenue due to lack of usage and churn. Additionally, the operator is often faced with the prospect of sending the phone back to the manufacturer to have it tested, at a cost of upwards of $50, while having to provide a new phone or loan one to the subscriber. All this incurs added costs, including courier shipment of the questionable phone to the manufacturer and the new phone to the subscriber.

The problems don't end there. Once the questionable phone is returned to the operator with the manufacturer's seal of approval, it is the reluctant owner of a used phone. Depending upon the conditions of the marketplace, the phone may be worthless. Who will pay for a used phone when they can purchase a new one for very little, or even get it free? The operator can be forced to unload the phone not only for free, but might also have to add a period of free airtime or enhanced services as part of the package. Industry insiders report some operators holding as much as $8 million-worth of used phones that came back to them for servicing.

Operators of cdmaOne networks may be interested to learn of a possible solution to this problem being trialed in European markets by Wavetek. Although it has only recently been put through its paces, Will Foster, marketing director of the recently merged Wavetek Wandel & Goltermann, Inc, now the world's second largest communications test company, reports a positive response to a trial of a simple testing device that allows wireless subscribers to test their own handsets.

When a subscriber suspects there may be a performance problem with his handset he need only visit a conveniently located, user-friendly touch screen console, which can be installed at the operator's direct or indirect retail distribution centers. Embedded in the console is a handset testing device manufactured by Wavetek that quickly analyses the handset and provides the subscriber with a "Go" or "No go" reply.


According to Foster, the device gives customers confidence that the operator can help them. It also differentiates the service from that of competitors on grounds other than price. And, crucially, being able to inform a subscriber that his phone is in proper working order gets him back on the network much more quickly so that he can generate more billable usage.
While Leuck of USWest acknowledges that the state of the art in test and measurement equipment has made major strides since the days of analog, he insists that the end result-optimizing your CDMA network-is still dependent upon well-trained and experienced technicians and engineers. "You can't just hire people and throw them in the truck," he says. "In the digital world you have to do a lot of thinking." The equipment is highly automated and more user-friendly than ever but, says Leuck, "You still have to figure out what the test equipment is telling you, and there are a lot more parameters going on than in analog."

In today's highly competitive wireless marketplace, CDMA operators have the ability to demonstrate to their subscribers that their technology of choice delivers the clearest voice. By implementing the highest test and measurement quality controls, supported by well-trained technicians and engineers, operators can position their voice quality as a meaningful marketing differentiator.

Bob Chapin is a principal of Wireless Marcom, LLC, a strategic marketing and communications company specializing in wireless communications enterprises. He is the former editorial director of Cellular Marketing, Satellite Communications and Global Communications magazines. He can be reached on-line at