Don't Rush W-CDMA Migration

The North American CDMA vendor's group has proposed a wideband CDMA (W-CDMA) system based on cdmaOne. Although it is different from the European ETSI W-CDMA proposal, the group is trying to harmonize its system with Japan's ARIB W-CDMA. In early 1998, W-CDMA was chosen as the IMT-2000 radio technology. But many operators deploying cdmaOne are wondering why they should buy into the future CDMA system. After all, how can they make money if they have to keep investing in technology changes?

Evolution is a natural and inevitable trend. cdmaOne improvements will occur, just as improvements have occurred for analog and GSM. AMPS and GSM evolved for about 10 years before another revolutionary system caught up. Likewise, the cdmaOne system must evolve first, then eventually a revolutionary W-CDMA system will replace the cdmaOne narrowband CDMA in order to enhance system performance.

Because developing any new system involves considerable risk, the W-CDMA specifications must come after extensive trials, validations and modifications are complete. Only then will the specifications deliver a feasible and low-risk system.

W-CDMA developers must be patient enough to discover what today's cdmaOne system can offer and put their efforts toward finding ways to improve it. The industry could apply existing cdmaOne enhancement technologies such as microcells, smart antennas and distributed antennas to the future W-CDMA.

The problem is that non-cdmaOne vendors and service providers are letting political issues get in the way of these developments. To achieve a global IMT-2000 standard, we all have to make concessions and create harmony in the process.

During the evolution to a W-CDMA system, the industry will have to address several issues. For example, although subscriber units are capable of receiving many traffic channels, the reverse link needs a software radio for multichannel transmission from the subscriber unit.

The industry also needs a new power-control algorithm and a new protocol for the series-to-parallel and parallel-to-series data streams. Wideband linear amplifiers and wireless wideband ATM switches must be developed for W-CDMA along with filter technology to improve coverage and reduce interference, and a proper spectrum bandwidth for spectrum efficiency.

The wireless industry needs to address backward compatibility, standalone systems, the time frame for developing IMT-2000 and intellectual property right issues. Despite these challenges, there are technical areas of W-CDMA that have common ground across the CDMA camps. For example, W-CDMA would use direct sequence as the spread-spectrum scheme, have multiple spectrum bands served within a single-mode system and provide international roaming capability.

Four elements will be key to a successful W-CDMA solution:

* Domestic and international input should guide the development of regulations and laws.

* Schools and research institutes must develop and train engineers and technicians to operate these new technologies.

* Vendors and carriers need to resolve conflicts of interest. Vendors usually are focused on selling more equipment, but carriers only want the best-performing equipment for market deployment.

* Both vendors and carriers must serve the public's interest. As the evolution of cdmaOne leads to new multimedia services, the industry should develop new features according to customers' needs.

During this early phase we need to learn the ups and downs from cdmaOne. CdmaOne could become a high-speed data system -- a model for W-CDMA. As cdmaOne evolves, we should see how well it does. During the second phase, we should choose proper technologies and spectrum bandwidths for W-CDMA.

In the end, W-CDMA should be a true global system. For that to happen, it must be the only standard system used worldwide. It should expand and grow easily, achieve optimum spectrum efficiency and avoid drastic changes from the cdmaOne system. Everyone has to work together to get the best revolutionary W-CDMA for the future.