The difference between 2G, 3G, and 4G networks

There have been a number of technology changes in the wireless space such as those commonly referred to as 2G, 3G, and 4G. 2G is generally referred to those radio interface technologies that replaced analog transmission modes. These technologies are much more efficient than analog in terms of carrying customers and voice traffic. They also are able to carry or transmit SMS and some data. 2G technologies are commonly associated with the terms GSM and CDMA.

3G technologies are associated with 1xEVDO, EDGE, WCDMA, and HSPA/HSDPA. These technologies enable the transmission of data at greater speeds and throughput than 2G radio interfaces. They can also carry many more customers than 2G technologies. They are able to do this by packing more bits of information into the RF carrier, yielding greater traffic carrying capability.

4G technologies can carry even more customer voice calls and data calls than is achievable by 2G and 3G networks. 4G technologies accomplish this by combining some of the best techniques used in analog, 2G and 3G radio protocols. More specifically, first generation radio technology uses frequency multiplexing to transmit the voice information. 2G uses unique time slots or unique codes to pack the data or intelligence for transmission. 3G radio technologies use time and code for packing the transmission payload. 4G radio technologies combine the use of frequency, time, and codes to obtain maximum transmission capacity and throughput. Other techniques are used to improve the spectral efficiency of the 4G technologies in addition to its use of frequency, time, and codes. One of these techniques uses multiple transmit and receive antennas in a concerted way to improve coverage range.
What's next in terms of increasing radio transmission capabilities? There are a number of things being looked at. One that could substantially increase capacity is using the mobile devices to relay information to the system. As an example, I have some information to transmit. You and your device are located closer to the cell site than I am. Our devices communicate to each other and your device relays my information to the base station rather than my device trying to communicate to the cell site. Obviously there are number of issues with this, not the least of which is privacy and security. However, when there are many mobile devices in the system, each turns into a relay station increasing overall system capacity.