Wireless communications are becoming increasingly popular in today?s fast paced world. Mobility, portability, and instant access (via the Internet) to unlimited information have become the mantra of businesses and individuals alike. The evolution of wireless communications has been incredibly quick and the future of this technology is unlimited. The impact of this technology on our lives will be tremendous and allow us to do things we never imagined.
What Is Wireless Communication?
There are two types of cellular technology: 1) circuit-switched cellular, and 2) Cellular Digital Packet Data (CDPD). One of circuit-switched cellular?s biggest advantages is its nationwide availability. Another advantage is the ability to send voice and data over the cellular phone network. Circuit-switched cellular is ideal if the application requires the exchange of long text messages, large files, or faxes because it typically charges by the minute of connect time, not by the number of bytes transferred. A practical application for this technology is the transfer of data from a laptop by means of a cellular modem and phone. The initial cost to outfit a laptop to connect to a cellular network is about $400. A disadvantage of this type of service is the long set-up time each connection requires (about 30 seconds).
Cellular Digital Packet Data is best suited for transaction processing and database queries. This service offers fast call setup (about 5 seconds), and is inexpensive for short messages, such as sending e-mail. The main disadvantages of CDPD are the expense of large file transfers, and the limited availability of the service (currently it is available in about 40 cities nationwide).
Private Packet Radio
Private packet radio, though not as common as cellular, offers businesses widespread connectivity. The two major private packet radio providers in the U.S. are Ardis and RAM Mobile Data. These services can be connected to from virtually anywhere in the country. Private packet radio offers quick call setup and is well suited to communications that generate short, bursty messages, such as e-mail, database queries and point of sale applications. Since private package radio has been around for several years, there are many applications that use the network. Some of the commercial applications being used handle messaging, scheduling, electronic filing of expense reports, and even allow for insurance agents to process accident claim forms from a customer?s house or office (Salamone 96). The disadvantage with private packet radio, like CDPD, is that it is expensive for large file transfers.
The fundamental problem that wireless communications faces is that none of the major wireless data services is ideal for all applications. The stumbling blocks to widespread adoption of data connections for laptops and personal digital assistants (PDAs) include the lack of compatibility between services, the cost of the services, and the size and price of wireless modems.
History of Wireless Communications
Radio telephones have been used for decades, but have not been widely available due to limited system capacity. The breakthrough that addressed this capacity problem was the development of the cellular concept, which allows frequency reuse. Needless to say, the use of wireless communications has increased exponentially since that breakthrough. The evolution of wireless systems can be divided into several stages: 1) the preprevailing stage, 2) the first generation analog system, 3) the second generation digital system, and 4) the third generation system (to be discussed later). The promised services, the required technologies, and the developmental timetable are summarized in Table 1 (see appendix A).
The preprevailing stage occured during the 1950?s and the 1960?s. Land Mobile Radio systems such as police communication and taxi dispatch systems were developed. Navigation radio for ship and aircraft, and portable radio telephone for the battlefield were other applications. The sending and receiving equipment was bulky and expensive in this early stage of development.
First Generation System
The first generation wireless system is based on analog technology and was developed in the 1970?s and 1980?s for public use. The price of the hardware was reduced rapidly and the demand for wireless services grew quickly in this stage. The cellular concept was adopted and several technologies such as spatial channel reuse and cell splitting were developed to improve system capacity. The growth of the service demand in the first generation analog system outpaced the system capacity in some areas. Digital communication technologies became mature enough for commercial use, and led to the second generation digital wireless system.
Second Generation System
The second generation system was built in the 1980?s and the 1990?s, and featured the implementation of digital technology. The system capacity is several times higher than the traditional analog system. More service features were introduced, service quality was improved, and the cost was significantly reduced. The demand for wireless communications services has grown tremendously with the development of the second generation system. The growth rates in various parts of the world are from 20-50%. The existing capacity in some market areas are now close to saturation. The practice of mobile voice communications also stimulated the market in other personal communication services. Portable computing and wireless data communication have become not only attractive but also feasible. With the development of technologies, the integration of both wired and wireless, voice and data services will be achieved in the coming years (Li 1212).
Local Wireless Networks
A brief discussion of network history and architecture will be helpful in demonstrating the impact wireless communications have had and will continue to have on computing. The first generation of wireless LANs were designed to operate with workstations, and are not suitable for battery operated portable computers. The next generation wireless LANs are developing around the lap-top, palm-top, and pen-pad computers. Wireless connection is the natural medium for the portable computing devices that are growing in popularity. “In this environment researchers are thinking of new concepts such as ad hoc networking (Fig. 1 Appendix A), nomadic access (Fig. 2 Appendix A), and mobile computing that leads to the fusion of the computer and communications in a ubiquitous computing environment” (Chase 89). Typical applications of this process include a wireless campus or a wireless battlefield in which a user (student/soldier) can move withing a local area with continuous access t!
o the computing and information facilities. “There?s not much left that mobile computers don?t do as well or better than desktop systems. And when the remaining challenges are solved mobile technology will significantly change the face of computing” (Reinhardt 100). The fusion of computers and wireless communications, in this case LANs, will indeed have a considerable impact on the future, and will drastically change the way in which we do things.
The Future of Wireless Communications
Third Generation System
Personal Communication Systems (PCS) are considered to be the next major step in the evolution of communication systems. According to the defintion given by the U.S. Federal Communications Commission in its Notice of Inquiry, PCS is the system by which every user can exchange information with anyone, at anytime, in any place through any type of device, using a single personal telecommunication device. The underlying vision for the emerging mobile and personal communications services is to enable communication with a person at any time, at any place, and in any form (Li 1210). The main features of PCS are: 1) Multimedia services with high quality, 2) Multiple environments, 3) Multiple user types, 4) Global roaming capability, 5) Single personal telecommunication number (PTN), 6) Very high capacity, 7) Universal handset, and 8) Service security. The enabling concepts for providing universal personal communications include terminal mobility (provided by wireless access),!
personal mobility (based on personal numbers), and service portability. Personal mobility is based on the use of a unique personal identity (personal number). Service portability refers to the network capability to provide subscribed services at the location designated by the user.
Terminal mobility is associated with wireless access and requires that the user carry a terminal and be within the radio coverage area. “The scope and applications of terminal mobility are rapidly expanding through advances in wireless access technologies and miniaturization of mobile terminals” (Pandya 44). Digital Cordless Telecommunication Systems are intended to provide terminal mobility in residential, business, and public access applications where the users can originate and receive calls on their portable terminals as they change locations and move about at pedestrian speeds within the coverage area. This type of system would lend itself to an academic environment where students could access information from the library, professors could give lectures, and assignments could be turned in without an actual physical building, classroom, or office. The range of applications often associated with Personal Communication Systems is illustrated in Figure 3 of Appendix A.!
A Current Trend
Power paging is the current trend in wireless services and is paving the way for PCS. In actuality power paging is a bit of a misnomer, in that the terminal is more of a computing device than standard pagers. “Motorola has made a bid for leadership in the two-way wireless market with the announcement of Memos, an ambitious, client/server-based messaging platform” (Matzkin 31). Memos provides both a complete operating environment and an open development environment. This device will offer wireless Web access and a lot of messaging options, including e-mail, fax, and voice messaging. All of this while fitting into the palm of your hand.