Ever since mobile telecommunications standards were first laid down in the 1980s (the First Generation or 1G), there has been a continuous effort to increase the data rates available to the end users. Once certain levels of data rates are achieved by the industry, they set even higher targets, driven of course by the ever increasing demand by the users.
1G, 2G, 3G and 4G basically refer to these standards that were successively laid and met by the telecommunication sector (both the industry and the academia). The current thrust is towards reaching the 5th Generation of mobile communications. Behind each of these generations, there have been one or more breakthrough technologies that helped achieve the quantum inter-generation leaps in the data rates. I will elaborate upon those below:
First Generation (1G):
Modulation Scheme – Analog FM modulation
Multiple Access Scheme – FDMA with Frequency Division Duplexing
Examples: AMPS (Advanced Mobile Phone Services)
Second Generation (2G):
Digital Communication introduced
Still designed only for phone calls (using phones to access internet was still unthinkable) ~ 10 kbps
Multiple Access Scheme – FDMA, TDMA (for GSM) and CDMA
Examples: GSM (Global System for Mobile Communication) and CDMA (Code Division Multiple Access)
Realization dawned that people wanted phones for both voice and data and thus this intermediate standard was introduced.
Recall how you used to access internet using GPRS (General Packet Radio Service). Up until 2G, only circuit switched networks were in use which were unsuitable for internet. With the advent of GPRS, packet switching was introduced which was more suited for internet.
Examples: GPRS ~ 50 kbps
EDGE (Enhanced Data for GSM Evolution) ~ 200 kbps
Third Generation (3G):
This time the target was to be able to provide sufficient data rate for both voice and mobile internet ~ 384 kbps
Examples: WCDMA (Wideband CDMA), CDMA 2000 and UMTS (Universal Mobile Telecomm Standard)
This is what most of urban India currently uses. HSDPA/HSUPA (High Speed Downlink/Uplink Packet Access) are the standards used and they offer data rates of 5-30 Mbps.
Fourth Generation (4G):
In essence, Mobile Broadband. They now want to offer you broadband-like data rates on mobile devices ~ 100-200 Mbps.
The key technologies that have made this possible are MIMO (Multiple Input Multiple Output) and OFDM (Orthogonal Frequency Division Multiplexing). For those who are from engineering background, MIMO leverages spatial multiplexing to provide diversity gain while OFDM is more adept at managing channel distortion and ISI.
The two important 4G standards are WiMAX (has now fizzled out) and LTE (has seen widespread deployment). LTE has only recently been introduced in India.
Gigabit Internet (Woah!)
This is what the academia and the industry is working towards now but seems are affecting peoples. Expected to arrive in 2020.
Key technologies to look out for: Millimeter Wave Mobile Communications, Massive MIMO