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Chapter 54
Wireless Communications for Voice and Data

Andres Liana, Jr.

Use of wireless technologies has become one of the fastest-growing communications applications around the world. Recent innovations have greatly increased the availability of the telephone in many parts of the world, yet wireless communications have been around since the early 1900s. Back then, radio served as the principal means of mass communication and, like TV, was the principal means of public entertainment. During World Wars I and II, wireless communications allowed combat forces to communicate. Today, law enforcement agencies, marine agencies, and transportation companies, among many others, use wireless communications to manage deployed resources.

In the 1950s, the Rural Electrification Administration considered wireless radio technology as a means of supplying telephone service to rural populations. This experimentation proceeded through many iterations but was largely abandoned during the mid-1980s as cellular technology emerged.

Today, radio communication is thought of as a new innovation because of its growing ubiquity and its support for personal communications, data, and information collection. Lower costs have made it possible for users to enjoy cellular telephones, personal digital assistants (PDAs), and a host of other devices to simplify the conduct of commerce. Wireless technology has improved intra- and intercorporate communications, enabling more cost-effective control of such business resources as deployed sales forces and technical service personnel.

WIRELESS TECHNIQUES: A STRATEGY FOR WORLDWIDE VOICE COMMUNICATIONS

Cellular Voice

Great strides have been made in the adaptation of cellular radio as a means of supporting local telephone service. In many undeveloped countries there is little or no infrastructure to support telephone services. For this reason, it is not uncommon in some parts of South America, Asia, Russia, and Eastern Europe for a subscriber to wait as long as one year to get local telephone service. Because of this situation, wireless subscriber penetration has grown at about 45% per year. For example, Motorola, Inc. recently reported that it had orders for 150 wireless systems for 21 provinces of China and the three municipalities of Beijing, Shanghai, and Tianjing an area with a combined population of more than one billion people. As a result, wireless local loop (WiLL) systems are being installed around the world at an accelerated rate to reduce the time to service.

Wireless Radio

Wireless radio is being installed in place of traditional central office systems that require expensive extended copper wire external networks. Service providers are finding that wireless radio central office systems are convenient, fast, and less costly than traditional central office switching systems. Because there are no copper wires to string and no wire plant to maintain, subscribers can enjoy telephone service as soon as the radios are turned on.

Building a traditional central office system with a stationary copper landline network costs between $1,250 and $1,750 per subscriber, depending on terrain and labor. A Motorola WiLL system can be installed for between $800 and $2,000 per subscriber. About 80% of these costs are the construction of cell sites, which can also be used for other forms of wireless communications, such as personal communications systems (PCSs).

Wireless PBX Systems

In companies where operations are widespread, such as chemical and heavy equipment manufacturing, it is often necessary for first-line supervisors and other key employees to cover a lot of terrain in a day. Often these personnel are in high demand and maintaining contact with them is difficult. For these applications, private branch exchange (PBX) manufacturers have developed wireless radio frequency (RF) systems that can be integrated into the architecture of a PBX system.

Lucent Technologies (Basking Ridge, NJ), Ericsson Messaging Systems (Woodbury, NY), Intercom Computer Systems, Inc. (Woodbridge, VA), Northern Telecom, Inc. (Richardson, TX), Mitel Corp. (Kanata, ON, Canada), and Siemens-ROLM Corp. (Alpharetta, GA) offer systems that integrate into their PBX architectures. These systems are integrated through the PBX line cards and support the same line appearances as any hard-wired single line or electronic station set. A base radio operating in the unlicensed frequency range together with a series of antennae spaced around the user’s facility comprise the basic network. Low-powered mobile handsets are used with these systems to avoid interference with other frequencies operating in the same area.

Wireless PBX Add-On Systems. Motorola and Spectralink have developed wireless PBX add-on systems similar to those developed by the PBX manufacturers. The Motorola InReach design concept is slightly different because it was developed as an extension to a cellular operator’s service offering. InReach handsets can be used either as a cellular terminal or a PBX station set.

For example, when a user enters an InReach-equipped building, the handset can function as an electronic desk telephone. The handset provides access to all of the features on the PBX, including access to the corporate and public network. When the user leaves the building, the handset can then be used to access the cellular network and functions as a mobile handset.

Wireless add-on PBX facilities are expensive because of the addition of a base radio module and antennae infrastructure to the established internal PBX network. A typical midrange (i.e., 75 × 45O line) PBX system, when configured with a wireless add- on system, can easily double the cost of the basic PBX system. However, as PCS and other handheld terminal-based services proliferate, the costs for PBX wireless systems will continue to decline.


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