What is 3G?

Ok, so my posts are usually a bit more detailed than this, but I was looking at the Google Search stats for 2012 and it seems the question "What is 3G" was the 3rd most searched "What is..." type question (1st was love and 2nd was iCloud in case you are wondering). So here is my attempt to explain the mysterious 3G..

3G refers to the 3rd Generation mobile technology standard. But if we are talking about the 3rd Generation, what were the 1st and 2nd?

The 1st Generation was based on analogue technology (like your FM radio) and appeared around the 1980's in a few countries. The mobile phones were enormous, the batteries even bigger (sometimes external to the handset) and they were very expensive. I imagine very people reading this post ever used a 1st Generation analogue mobile phone. 1st Generation networks are a thing of the past now and none exist anymore (at least in the so called "developed" countries).

The 2nd Generation was based on digital technology (like your digital TV) and appeared around the beginning of the 1990's. The most popular 2G standard is called GSM (Groupe Speciale Mobile) and is still incredibly popular today. I imagine the vast majority of people reading this post have used and are still using GSM. 2G technology standards were initially developed to support voice calls. The transfer of data was a bit of an after thought and the GSM standard was further enhanced with GPRS (General Packet Radio Service) and then EDGE (Enhanced Data rates for GSM Evolution).

So now we come back to 3G. The 3rd Generation was also based on digital technology and appeared around the beginning of the 2000's. The most popular standard is called UMTS (Universal Mobile Telecommunications System) and it too has proven incredibly popular. The main benefit of UMTS over GSM is that is supports much higher data rates so the web browsing, downloading, tweeting etc happen much faster. The UMTS standard was further enhanced with HSDPA (High Speed Downlink Packet Access) and HSUPA (High Speed Uplink Packet Access) to further increase the data rates possible. Of course if all you are interested is making voice calls and sending some text messages, there is not much benefit in 3G as 2G will do that just fine.

So 1G has disappeared and we are left with 2G and 3G. Most phones today support both standards and most operators, support both networks. These can be thought of as layers, like the graphic above. A dual standard phone will have a preference to camp on the 3G layer (point 1 above). When the 3G layer is not available (typically 3G networks use higher frequencies and thus don't propagate as far) the mobile will transition to the 2G layer. This can happen both in idle and during a voice call or data session (point 2 above). Once 3G coverage improves the mobile will re-select back to the 3G layer.

As an end user you can tell which standard/layer you are using by looking at the icon next to the signal strength bars on your phone. Unfortunately the actual icon itself is not standardised so mobile phone manufacturers usually pick from a collection. The possibilities are:

For 2G it is typically "2G", or sometimes just "G" or sometimes "E" (for EDGE), or "O" if you are using an iPhone (Apple, go figure..)

For 3G it is typically "3G", or sometimes "H" (for HSDPA/HSUPA), or "3G+" (again for HSDPA/HSUPA), or even "H+" (for some further enhancements to HSDPA)

A bit confusing, but you get the idea.

We are now at a time where 4G networks have started appearing. These are based on a standard called LTE (Long Term Evolution) and support even higher data rates. This can be thought of as just another layer on the graphic above, and a 4G capable phone will have a preference to camp on the 4G layer and when that is not available on the 3G layer and when that is not available on the 2G layer.

That is my attempt at answering "What is 3G?". Hopefully it makes some sense!