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Chapter 1: History of Radio Communications A gentleman named Heinrich Hertz was the discoverer of electromagnetic waves, the technical foundation of radio itself By 1880, Hertz had demonstrated a practical radio communication. system This is the origin of the term hertz, the unit of frequency.
Guglielmo Marconi developed the worlds first commercial radio service in 1898 His first customer was Lloyd's of London, and the first radio link covered about 7.5 miles and provided information about incoming shipping. This link was a data communications-only link. It was the first ship-to-shore communications system.
The first human voice transmission via radio was accomplished by Reginald Fessenden in December 1900 This first voice radio link was 1 mile long. The demonstration took place in Maryland and marked the beginning of radio telephony The first cellular telephone system didn't go into operation until 83 years later.
In 1901, Marconi produced the first long-distance transatlantic radio transmission.
On Christmas Eve in 1901, Fessenden. transmitted the world's first radio broadcast The transmitter was located at Brant Rock, Massachusetts and good-quality voice and music was received by ship and shore operators within 15 miles of Brant Rock.
From 1910 to 1912 mandatory 24-h ship-to-shore communications were established by the United States, Great Britain, and other maritime nations as a direct result of two ships sinking: the Republic in 1909 and the Titanic in 1912. This requirement was derived from the first attempt at regulation of the radio industry: the Radio Act of 1912.
In 1915, a team of BellTelephone engineers, using the giant antennas at the US Navy station at Arlington, Virginia, were the first to span an ocean with the human voice. This was a milestone in international radio telephony as voice radio transmissions were received in France, Panama, and Hawaii. By 1918, 5700 ships worldwide had wireless telegraphy installations.
1.1 Mobile Radio SystemsThe development of the mobile radio system can be divided into two parts: Phase I produced the earliest systems, and Phase II began after the FCC's classification of what it termed "Domestic Public Land Mobile Radio Service."
The first use of mobile radio in an automobile instead of a ship was in 1921. The Detroit Police Department implemented a police dispatch system using a frequency band near 2-MHz This service proved so successful that the allocated channels in the band were soon utilized to the limit In 1932, the New York Police Department also implemented the use of the 2-MHz band for mobile communication.
In 1934, the FCC allocated four new channels in the 30-40 MHz band, and by the early 1940's a significant number of police and public service radio systems had been developed. By the late 1940s, the FCC made mobile radio available to the private sector along with police and fire departments.
1.1.1 Mobile Telephone Service (MTS)In 1946, Bell Telephone Labs inaugurated the first mobile system for the public, in St. Louis. This system was known as Mobile Telephone Service (MTS). Keep in mind that at this time AT&T still owned and operated the majority of the public switched telephone network (PSTN). Three channels in the range of 150 MHz were put into service, operating at frequencies between 35 and 44 MHz An MTS highway system to serve the corridor between Boston and New York began operating in 1947. MTS transmissions (from radio towers) were designed to cover a very large area, using high power radio transmitters. Often the towers were placed at geographically high locations. Because they served a large area, they were subject to noise, interference and signal blocking.
MTS was a half-duplex, "push-to-talk" system; therefore MTS offered communications that were only one way at a time. An operator was needed to connect a customer to the landline local exchange carrier (LEC) network.
In 1949 the FCC authorized non-wireline companies known as radio common carriers (RCCs) to provide MTS, An RCC is a wireless carrier that is not affiliated with a local telephone company. Prior to 1949, all mobile service was supplied by the wireline telephone companies. This marked the birth of competition in the telecommunications industry.
1.1.2 Improved Mobile Telephone Service (IMTS)In 1965, almost 20 years after die introduction of M174 the Bell System introduced Improved Mobile Telephone Service (IMTS), the successor system to MTS. IMTS was the first automatic mobile system: it was a full-duplex system, eliminating the push-to-talk requirement of the older MIS system. IMTS allowed simultaneous two-way conversations. A key IMTS advantage was that users could dial directly into the PSTN. IMTS narrowed the channel bandwidth, which increased the number of frequencies allowed. Because the cell site locations were high-output-power stations, one radio location could serve an entire city.
Between the landline phone company and the WC, nineteen 30-kHz channels were authorized in the 30-300 MHz band, which is the VHF band The FCC also authorized twenty-six 25-kHz channels in the 450-MHz band (the UHF band). With full-duplex systems such as IMTS, two radio channels arc needed for each conversation: one channel to transmit and one channel to receive.
As with MTS, IM17S radio towers were still installed in high places (e.g., tall buildings) and the system was still designed to cover large geographic areas, up to 50 mi in diameter Because of limited capacity, eventually IMTS operators prohibited roaming in their markets. Roaming refers to placing calls in markets other than a user's home market. Roaming will be discussed in a later section.
Trivia: The IMTS system was designed so that only 50% of the calls were completed during the busy hour. Service was often poorer than that in some metropolitan areas. This was a result of the fact that very few radio channels existed for IMTS service.
1.2 AMPS: The American Cellular Standard
Advanced Mobile Phone Service (AMPS), is the American analog cellular standard. In 1970, several key developments occurred:
- The FCC set aside new radio frequencies for land-mobile communications. These frequencies were UHF television channels in the 800-MHz band that had never been used.
- That same year, AT&T proposed to build the first high-capacity cellular telephone system It dubbed the system AMPS for Advanced Mobile Phone Service and selected Chicago as the first test city
Trivia: At that time, AT&T never anticipated the growth potential of the apparently pent-up demand by the general public for widespread availability of mobile communication services. They estimated only 1 million cellular customers would exist by the end of the century Today, there are over 30 million wireless customers in the United States alone!
However, at that time the FCC, bowing to intense pressure from radio common carriers, determined that the cellular industry should have two carriers per market, and 333 channels were allocated per carrier, per market. This marked the birth of the A band and B band carrier concept (see Chapter 2, "Cellular Market Regulatory Structure"). The number of channels was later increased to a total of 832 total cellular channels, 416 channels per carrier per market. This change was brought about by cellular industry pressure on the FCC to relinquish reserve spectrum to relieve capacity and congestion problems.
In 1977, while the FCC realized it had to create a regulatory scheme for the new service, the Commission also decided to authorize construction of two developmental cellular systems: one in Chicago licensed to Illinois Bell, and a second serving Baltimore and Washington, DC, licensed to a non- wireline company. American Radio Telephone Service (an RCC).
Once the regulatory framework was decided upon by the FCC, the fun commercial cellular system began operating in Chicago on October 13, 1983. The very first commercial cellular telephone call was made at Soldier Field in Chicago to a descendant of Alexander Graham Bell in West Germany. The second system was activated a short time later in the Baltimore/Washington, DC corridor in December 1983. It was these systems that gave rise to the fastest-growmg consumer technology in history an industry that adds about 28,000 customers per day....