History and Importance of Cell Broadcast

By nature, all radio systems are multi point to multi point systems, unless you force them not to be so, by adding elaborate protocols. Cellular phone networks are radio networks and are therefore naturally suited to Broadcasting.

Back in 1897 Guglielmo Marconi called his invention the “Wireless Telegraph”, because he wanted his customers to visualize the use to which the system would be put. In order to make radio behave like a telegraph network, Marconi had to introduce a regime of call signs and traffic procedures to control the flow of traffic. As far as any sender of a telegram was concerned, the telegram was delivered from point to point, so the illusion was complete.

However in 1919 Peter Eccersley (who later became a founder of the BBC) proposed deliberately ignoring such protocols in order to intentionally ‘Broadcast’ speech and music for the purpose of ‘information and entertainment’. This did cause a momentary regulatory, administrational and intellectual property rights storm, but as they say, the rest is history.

The word ‘Broadcasting’ was borrowed from a farming technique whereby sewers of seed throw handfuls of seeds at random, not paying attention to where it may land, like your broadcast lawn spreader. (This is in contrast with seed drilling as is used in modern farming).   

In a precise parallel with Marconi’s brilliant marketing strategy, the cellular industry calls its product the ‘Mobile Phone’ so that customers will more easily relate to, what is actually, a sophisticated ‘trunked full duplex radio’ system, (clearly calling it that would sell less phones).

Nevertheless the fact remains that signals are broadcast from a base station, but reception is intentionally limited by means of protocols resident in the terminal (the phone). A simple change in those protocols would enable any terminal to pick up Broadcasts from any base station.

This point was not lost on the ETSI’s GSM committee, (who, 100 years after the invention of radio) added a feature called ‘Cell Broadcast’ to the GSM standard. This is contained in standards GSM 03.49 and others. Technologically this was successful and had been demonstrated in Paris by 1997. By now all GSM phones and base stations have the feature latent within them, though sometimes it is not enabled in the network.

The IS95 CDMA standard also provides for an exactly similar feature which they called ‘SMS-CB’, which is also a Broadcast method, added to the paging channel. Later still the ETSI’s 3GPP group also added the Cell Broadcast feature to the third generation WCDMA UMTS standard.

However in the USA, network owner policy was, to protect their investment in the legacy analogue systems. This was done by making the digital D-AMPS system, closely back compatible with the first generation analogue system. This did indeed stretch out the usefulness of first generation analogue infrastructure way beyond the stage when most other countries had abandoned it in favor of second generation.

However it left Americans with a technologically more backward asset than that of less developed neighbors. By 1993 Vietnam had a more advanced mobile system than America, when it adopted GSM. Among other things there is no packet radio service, SMS capability, or Cell Broadcast with this technology. Roaming was also very poor.

Though The Cellular Emergency Alert Systems Association it technology neutral, it would respectfully point out that there is no technical or natural reason why Broadcasting of emergency alert messages should not be done over a mobile phone network. Furthermore GSM, CDMA and UMTS have such feature resident within them, which have been proven to work very well.

There are four important points to recall about the use of Cell Broadcasting for emergency purposes.

• It is already resident in most network infrastructure and in the phones, so there is no need to build any towers, lay any cable, or write any software or replace terminals.

• It is not affected by traffic load; therefore it will be of use during a disaster, when load spikes tend to crash networks, as the London bombings 7/7 showed. Also it does not cause any significant load of its own, so would not add to the problem.

• It is geo scalable, so a message can reach hundreds of millions of people across continents within a minute.

• It is geo specific, so that government disaster managers can avoid panic and road jamming, by telling each neighborhood specifically, if they should evacuate or stay put.

In short, it is such a powerful national security asset, that it would be inexcusable not to seize the chance to put an existing technology, to the benefit of the safety of the American citizen. Indeed, providing for the common defense is one of the prime duties that the constitution places on the federal government.  

Mark Wood, Hon. CTA CEASa.