Every year, technology professionals connect, educate and learn about the latest trends at Penton’s International Wireless Communications Expo (IWCE). This great event, originally founded in 1977 as the “National Business Radio Dealer Conference,” has become one of the largest industry shows for two-way radio manufacturers. Last year, the Expo welcomed over 350 vendors and more than 7,000 tech buyers. Approximately 75 countries outside the U.S. were represented at the convention, making IWCE truly a global affair.
FDMA (Frequency Division Multiple Access) and TDMA (Time Division Multiple Access) technologies are used in P25 and in business and industrial digital radios (P25 Phase I & NXDN™ for FDMA; P25 Phase II & DMR for TDMA).
The basic difference between FDMA and TDMA is the definition of a channel and how it is used.
In FDMA, a particular bandwidth (e.g. 6.25 kHz) at a particular frequency (e.g. 150.000 MHz) is used to define a channel. This is the way channels have been allocated in analog land mobile radios (LMR) for decades. All information is contained in the channel – compressed to the smallest frequency footprint. Analog radio bandwidth has recently shrunk from 25 kHz to 12.5 kHz, which is about the limit for analog technology without seriously degrading radio voice quality. With digital technology, channel bandwidth can be compressed to a spectrum-efficient 6.25 kHz by using vocoders and error correction.