GSM Radio Technology Evolution Path

• The new mobile datacom services will differ from the second generation GSM data services in several ways. Perhaps the most essential changes take place in the radio access technology. For example, they support much higher bit rates over the air interface, which is basically made possible by more efficient channel coding and the ability to use multiple time slots. In addition, General Packet Radio Service (GPRS) will bring packet switched communication to GSM. The following chapters describe the GSM Radio Technology evolution steps.

History of cellular Communications

• In a separate segment of communications, another revolution was taking place—cellular telephones. In the late 1970s AT&T Bell Laboratories began working with several leading United States and Japanese companies to create a cellular telephone system based on dividing coverage areas into small cells and reusing frequencies. Previous mobile telephone technologies operated on limited numbers of channels, thus limiting the number of users in any given coverage area to a very small number.
  
• The result was low user use and costly service and equipment. A core group was created to develop a standard called the Advanced Mobile Phone Service (AMPS). In December 1983, AMPS was launched in Chicago, Illinois with great fanfare. It proved immensely popular. Now before someone says, “Hey, wait a minute, AMPS wasn’t the first cellular system!,” let’s give that credit to the Nordic Mobile Telephone (NMT) system.
  
• NMT was launched in 1981 in Scandinavia, but in terms of market size, AMPS potential market in the United States was vastly larger. AMPS quickly spread to other countries in North and South America, Korea, and Australia. A similar standard, Total Access Communications System (TACS), was developed in the United Kingdom as well.
• Today, there are many competing standards in mobile telephones worldwide. In fact the word “mobile” means something entirely different today than it did in 1983. The majority of cellular telephones sold today are hand-held, not permanently installed in vehicles. Each competing standard is incompatible with others on the basic technology used, but to the end user, all cellular telephones should perform the basic functions expected. (Even though many new carriers would like to distinguish themselves from “cellular” companies by calling themselves “PCS” companies, we consider both as cellular applications.
• This is not to say that companies with PCS spectrum in the 1900 MHz band may or may not have some advantages over carriers with traditional spectrum allocations in the 800 MHz band. But because many carriers own spectrum in both bands this is a moot point.)
• Cellular radio got its name from the physical layout of a system in a pattern resembling a honeycomb figuratively. Each cell site operates on a different frequency so that neighboring cells do not interfere with one another. However, frequencies can be re-used if they are separate by sufficient distance. This is referred to as the re-use pattern.