Mobile Radio Telephony in the U.S.

In 1946, the first public mobile telephone service was introduced in twenty-five major American cities. Each system used a single, high-powered transmitter and large tower in order to cover distances of over 50 km in a particular market.

The early FM push-to-talk telephone systems of the late 1940s used 120 KHz of RF bandwidth in a half-duplex mode (only one person on the telephone call could talk at a time), even though the actual telephone-grade speech occupies only 3 KHz of base-band spectrum.



The large RF bandwidth was used because of the difficulty in mass-producing tight RF filters and low-noise, front-end receiver amplifiers. In 1950, the FCC doubled the number of mobile telephone channels per market, but with no new spectrum allocation. Improved technology enabled the channel bandwidth to be cut in half to 60 kHz. 


By the mid 1960, the FM bandwidth of voice transmissions was cut to 30 kHz. Thus, there was only a factor of four increase in spectrum efficiency due to technolgogy advances from World War II to the mid 1960s. Also in the 1950s and 1960s, automatic channel trunking was introduced and implemented under the label IMTS (Improved Mobile Telephone Service).

With IMTS, telephone companies began offering full duplex, auto-dial, auto-trunking phone systems. IMTS is still use in the USA but is very spectrally inefficient when compared to today's US cellular system.

Evolution of Mobile Radio Communications

A brief history of the evolution of mobile communications throughout the world is useful in order to appreciate the enormous impact that cellular radio and Personal Communication Services (PCS) will have on all of us over the next several decades. It is also useful for a newcomer to the cellular radio field to understand the tremendous impact that government regulatory agencies and service competitors weld in the evolution of new wireless systems, services, and technologies.

While it is not the intent of us to deal with the techno-political aspects of cellular radio and personal communications, techno-politics are a fundamental driver in the evolution of new technology and services, since radio spectrum usage is controlled by governments, not by service providers, equipment manufacturers, entrepreneurs, or researchers. Progressive involvement in technology development is vital for a government if it hopes its own country competitive in the rapidly changing field of wireless personal communications.

Wireless communications is enjoying its fastest growth period in history, due to enabling technologies which permit widespread deployment. Historically, growth in the mobile communications field has come slowly, and has been couple closely to technological improvements. The ability to provide wireless communications to an entire population was not even conceived until Bell Laboratories developed the cellular concept in the 1960s and 1970s.

With the development of highly reliable, miniature, solid-state radio frequency hardware in the 1970s, the wireless communication era was born. The recent exponential growth in cellular radio and personal communication systems throughout the world is directly attributable to new technologies of the 1970s, which are mature today.

The future growth of consumer-based mobile and portable communication systems will be tied more closely to radio spectrum allocations and regulatory decisions which affect or support new or extended services, as well as to consumer needs and technology advances in the signal processing, access, and network areas.

Introduction to Wireless Communication Systems

The ability to communicate with people on the move has evolved remarkably since Gugliemo Marconi first demonstrated radio's ability to provide continuous contact with ships sailing the English Channel. That was in 1897, and since then new wireless communications methods and services have been enthusiastically adopted by people throughout the world.

Particularly during the past ten years,the mobile radio communications industry has grown by orders of magnitude, fueled by digital and RF circuit fabrication improvements, new large-scale circuit integration, and other miniaturization technologies which make portable radio equipment smaller, cheaper, and more reliable.

Digital switching techniques have facilitated the large scale deployment of affordable, easy-to-use radio communication networks. These trends will continue at an even greater pace during the next decade.

Welcome to Wireless Communications Technology Blog

Welcome to Wireless Communications Technology Blog @ http://wireless-communications-technology.blogspot.com/

We will be writing about Wireless, Mobile, GSM, CDMA, 1G, 2G, 2.5G, 3G, 4G, Bluetooth, WLAN, LAN, Radio, GPRS, EDGE, Telephone, Cell, Model, Modulation, Multiple Access, Equalization, Diversity, Coding, AMPS, Channel, Traffic, Link Budget