Applying its linear fiber optics technology, Ortel Corp. is providing wireless networks a vital supplement for communicating in environments that are limited by physical barriers, like underground transit.
Together with Andrew Corp., Ortel will help provide clear communications for cellular customers in Hong Kong’s Mass Transit System, the company announced. The subway, which covers much of the city and the Kowloon, China region, transports 2.5 million people each day, nearly one-third of the city’s population, said Hal Zarem, Ortel’s wireless communications business manager.
The firm’s linear fiber optic technology allows cellular radio signals to convert to optical signals and back to radio without distortion for callers. “It sounds as good as any cellular call ever does,” Zarem commented.
Andrew Corp. is providing system design, which includes its Radiax coaxial cable, and implementation.
The transit system will receive two key benefits from the project, Zarem said. “It’s an important customer service issue. They expect professionals to ride the subway.” Also, the enhanced communications system is a revenue-generating source for the Hong Kong transit system. To link the subway’s communications system with outside cellular networks, Hong Kong cellular service providers must “lease” the capacity from transit operators to connect their customers.
When a cellular phone user in the subway makes a call, the handset’s radio signal is picked up either by the nearest antenna or by a leaky coaxial cable, Andrew’s Radiax cable, Zarem noted. The cable also acts as an antenna. Holes along the cable capture signals, which radiate to a fiber optic transmitter, wherein a laser component converts the radio signal to an optical signal. That signal travels through optical fiber to the nearest base station, above or below ground, noted Zarem. In the base station a fiber optic receiver equipped with a photo diode component converts the optical signal back to a radio signal and communications resume as a typical cellular call. The process is reversed for incoming calls.
The companies are in the early stages of implementation, Zarem said, and the system is scheduled to be completed in a few years. The technology allows digital and analog signals to be transmitted, Zarem added, and is compatible with both paging and personal communications services radio signals, in addition to cellular. Currently, Hong Kong’s wireless standards include Global System for Mobile communications, Code Division Multiple Access and Advanced Mobile Phone Service.
Andrew, based in Orland Park, Ill., and Ortel in Alhambra, Calif., will implement a communications system similar to Hong Kong’s for the Bay Area Rapid Transit in San Francisco, Zarem noted. The companies recently completed a project at the new Denver International Airport, facilitating in-building cellular and two-way radio communications.
Ortel earlier this year introduced its Series 5800 fiber optic antennas, which provide in-building cellular communications. Licensed manufacturers of Series 5800 include Ericsson Inc., marketing the product as IndoorCell, and Allen Telecom Group, with ActiveLite.
