Publication | Legaltech News
Nervous System: When Mobile Telephones Had Steering Wheels
The era of mobile telephony started much longer ago than one might imagine. On June 17, 1946, a man driving through the streets of St. Louis made a telephone call from his car—and thereby made history.
The driver, an engineer working for Southwestern Bell, was testing new carphone technology that Bell Labs and Western Electric had spent many years developing. Although the technology facilitated a mobile caller on the road to place or receive a call, this was not the cellular service we know today.
To facilitate this new era of mobile telephony, the Federal Communications Commission (FCC) had allocated six channels of high-frequency radio spectrum around 155 MHz. Enough interference existed between those channels, though, that in practice there were only three viable channels. This high-frequency spectrum was also vulnerable to interference from physical objects, meaning that the radio transmitters and receivers had to have a line-of-sight connection.
Analog radio communications in the 1940s had no options for simultaneous bandwidth-sharing. This meant that only three calls could be carried on the network at the same time, and those calls would suffer poor audio quality and frequent dropped connections.
Users commonly waited up to an hour for their turn to use the service. To place a call using the mobile service, they had to connect through a live switchboard operator. Once connected, the handsets operated like walkie talkies, where the mobile user had to depress a key to speak.
A mobile phone of this type cost around $2,000 (which in 1946 was pricier than buying the car itself) and weighed 80 pounds. The device consumed so much power, it was challenging to use at night since the phone diverted energy from the vehicle’s headlamps. Using the system required a hefty monthly subscription and a per-call fee.
By 1948 this mobile telephony was available in only a few dozen major cities and highway corridors and used by only a few thousand customers.
In the years that followed, the mobile network improved substantially. The FCC allocated more radio spectrum, and the telephony providers engineered ways to implement more narrowly defined channels. The push-to-talk feature was overcome, making calls more like ordinary phone service, and the need to connect through an operator was removed.
By 1964 there were 1.5 million mobile phone users. Even though the service cost up to twenty times as much as regular phone service, there were still long waiting lists for subscriptions.
The system was still straining to accommodate simultaneous users. At best, a city might be able to have around forty subscribers because that was the upper limit technologically possible for simultaneous users. The key to opening up mobile telephony to the masses was the transition to cellular technology.
This new technology involved the FCC allocating a block of frequencies to a provider, which would then subdivide its allocation into seven sub-groups. A single radio tower had coverage for approximately three miles—so the three-mile range around a given tower was its “cell” of coverage. Each tower would be tuned to one of the seven frequency sub-bands, so that any overlap between two adjacent towers would be using different frequencies and therefore minimize interference. The seven frequency groups and three-mile radius for each tower allowed for a network of coverage that encompassed any given region without any two adjacent cells using the same frequency.
To provide continuous service to a mobile user moving through such a network, the system would manage handoffs from one tower to another as the phone moved across the various cells. To accomplish the handoff, the phone would need to switch its frequency at the moment of changeover, which took a fraction of a second. This would produce a mildly annoying hiccup in voice communications but was a long enough interruption to disconnect any data transfer over a modem. For cell providers to allow data users to move freely between towers, more improvements would be needed.
The first successful trial of cellular service took place in Chicago in 1978, with ninety employees of Illinois Bell serving as test subjects. By the end of 1978, the trial was expanded to paying customers. Although considered a success, the experiment led Bell to overhaul the technology, rendering the entire 1978 cell network obsolete. The first commercial cellphone service launched in 1980.
Cell service in the early 1980s was an expensive status symbol. The first commercially available cellphone was a Motorola device that cost just shy of $4,000. On top of the hardware costs, a typical user would expect to pay $3,000 for the setup, $45 a month for the subscription, and a per-minute fee ranging from $0.24 to $0.40 depending on the time of day. These fees would be meaningful even in today’s dollars; they were serious expenses in the early 1980s.
Additionally, the upper limit of forty or so concurrent users per tower remained in place for analog cellular service. The cell concept substantially scaled service up from the 1940s era system, but any further increase in the user base would require some method of packing multiple simultaneous users into the same channel.
This required technical trickery that could be accomplished only through the advent of digital cellular service. The various bandwidth-sharing gimmicks that have evolved over the years (from to 2G to 5G and beyond) are a story for another day.
The views and opinions expressed in this article are those of the author and do not necessarily reflect the opinions, position, or policy of Berkeley Research Group, LLC or its other employees and affiliates.