Telephone technology has evolved by leaps and bounds. It is important to understand some of the key terminology used when discussing cellular phones and other mobile devices.
A Brief History
How many readers remember when we had basic black home telephones with rotary dials that were connected to multi-user party lines? Remember picking up the phone and listening to someone else’s conversation or having to actually talk to an operator to place a local or long distance call? We have come a long way since Alexander Graham Bell conducted the first successful bi-directional transmission of speech in 1876. Those classic words spoken to his assistant “Mr. Watson, come here, I want to see you,” and Watson’s subsequent reply are the origins of modern telephone communications. (Incidentally, Bell also made what is considered the first long distance call; it went about ten miles!) No one at that time could envision how the telephone would forever change the world. Obviously, no one could predict what would happen just sixty years or so later.
Sometime during the late 1940s the idea of using mobile phones was introduced. The technologies available at that time limited their use to police cars, emergency vehicles, and taxies. In 1973, Motorola demonstrated the first handheld mobile phone (cell phone) which weighed in at over four pounds! Later in 1983, they introduced the First Generation (1G) of cell phones; only voice communication was supported. Since they relied upon analog technology, considerable static and noise interference was common. Due to their high cost and bulky size, they were considered as status symbols rather than as effective communication devices.
That all changed in the 1990s when the Second Generation (2G) of cell phones made their appearance. These cell phones relied upon digital technology and that advancement over analog technology allowed for faster and less noisy calls. Cell phones began to shrink in size as more energy efficient batteries and advances in miniaturizing electronic components became commonplace. Smaller cell phones, lower prices, and widespread demand caused a literal explosion in the cell phone industry and in their use.
Most users today have cell phones that rely upon Third Generation (3G) digital technology. Unlike 2G phones which could only transmit voice data (phone calls), 3G technology is capable of transferring all types of data including e-mails, text, and instant messages. 3G technology also supports WIFI and Internet access.
Manufacturers are currently going forward with plans to develop a Fourth Generation (4G) technology for cell phones. Developers are building upon and expanding the current technologies to provide faster information and data transfer and faster access to the Internet.
Cellular Technology Overview
As we enter the realm of 4G, cell phone technologies and access schemes remain fairly constant as does the associated terminology or acronyms. A brief discussion of both is provided below.
A. Cell Phone Technology and Access Schemes:
- CDMA: Code Division Multiple Access. This access scheme breaks a designated frequency into code for customer usage, thereby making efficient use of the available bandwidth. Widely used in the United States, it is becoming more common in other countries. CDMA was originally a military communications technology that Qualcomm converted to civilian use. CDMA handsets normally do not contain a SIM card. Data is stored either in the handset’s memory or on an SD card (SD/Mini-SD/Micro-SD). Handsets use either a hexadecimal or decimal ESN to identify themselves to the network.
- FDMA: Frequency Division Multiple Access. Access schemes divide the designated frequency into various usable components.
- GSM: Global System for Mobile Communications. GSM uses TDMA technology and SIM cards to track user information. GSM is probably the most common cell phone technology in world-wide use today. Handsets generally contain at least one SIM card which usually contains encryption keys to provide user authentication. The handsets use a fifteen digit IMEI and a fifteen digit IMSI to identify the user and the handset to the network respectively.
- iDEN: Integrated Digitally Enhanced Network. This technology, referred to as push-to-talk, allows the handset to be used both as a cell phone and a two way radio. The handsets use a small portion of the available frequency spectrum to communicate with the network and normally contain a SIM card.
- TDMA: Time Division Multiple Access. This access scheme breaks the designated frequency into time slots to utilize the bandwidth more effectively. In combination with FDMA, they make up the entire GSM access scheme.