Communication Networks/History of Networking
The cellular concept of space-divided networks was first developed in AT&T in the 1940's and 1950's. AMPS, an analog frequency division multiplexing network was first implemented in Chicago in 1983, and was completely saturated with users the next year. The FCC, in response to overwhelming user demand, increased the available cellular bandwidth from 40Mhz to 50Mhz.
The second generation (see below) started in the early 1990's with the advent of the Digital European Cordless Telephone (DECT) system, and the Global System for Mobile Communication (GSM). Data networks were also developed such as HiperLAN and the IEEE 802.11 working group, which produced the 802.11 legacy standard in 1997. The 802.11a and 802.11b revisions were standardized in October 1999.
The third generation started with the CDMA2000 standard in Korea, and UMTS in Europe and FOMA in Japan. The IEEE 802.15 WiMAX specification was approved in December 2001.
It is often instructive to break the history of wireless networking up into several specific generations.
First Generation (1G)
The 1G wireless generation comprised of mainly analog signals for carrying voice and music. These were one directional broadcast systems such as Television broadcast, AM/FM radio, and similar communications.
Second Generation (2G)
2G introduced concepts such as TDMA and CDMA for allowing bi-directional communications among nodes in large networks. 2G is when some of the first cellular phones were made available, although communications were restricted to very low bit-rates.
The second generation is frequently divided into sub-sets as well. "2.5G" represented a significant increase in throughput capacity as digital communications techniques became more refined. "2.75G" is another common pseudo-generation that saw an additional increase in speed and capacity among digital wireless networks.
Third Generation (3G)
3G is the current generation, and represents the combination of voice traffic with data traffic, and the advent of high-bandwidth mobile devices such as PDAs and smartphones. Spectrum Band Freq. varies depending on the mobile technology standard adopted in the system. Current HSDPA deployments support down-link speeds of 1.8, 3.6, 7.2 and 14.0 megabit/s and the HSPA family with up-link speeds up to 5.76 Mbit/s.
Fourth Generation (4G)
The 4G generation, which is a theoretical future generation, will see the ubiquity of broadband data connections and universal Internet access. These networks, many of which are being designed around the WiMAX (IEEE 802.16) specification.