May 5, 2007

Just a little bit about 3G

The following is a snap from my presentation made for English classes (which isn`t my native language). SO the topic or the heading is simple: 3G networks
It just covers the basics, so for deeper explanations check Wiki or Sergey Gershtein`s opinion (translated from Russian using Google translation) - also see Sergey`s blog for other topics.

Firstly lets make it clear what are these G-s about:
  • 1G - analog telephony system (NMT - developed in 80-s in Scandinavia)
  • 2G – stands for GSM, most common at the moment
  • 3G – besides voice it enables video-to-video calls, video on demand, music and internet services

To start with, 3G is quite different from 2G, the main difference is that 2G is circuit switched while 3G is both packet-switched and circuit switced.

What does it means? - Well, on a case of circuit switching the connection is established and kept through one certain route (through nodes – antennas). On a case of packet-switching there are packets of data used - packets are transferred through different routes.

Moving on to Planning a network - planning begins with preparations as researches are made for :
population working and living in specific area
vehicular traffic through and in the area
areas of concerts and sports events
Also landscape and locations of buildings shouldn`t be misnoticed.

There are 3 fundamental basis that should be considered on planning a network:
Coverage, capacity and QoS (Quality of Service), the trick is to find an optimal balance between these 3 parameters.
Firstly, Coverage – only places where high data traffic usage is predicted (as densely populated areas) will be covered at present.
Secondly, Capacity – Video on Demand services require. that there is a node after at least every 3 km, that`s the main reason for coverage limitation at the moment.
Thirdly, QoS – it is paramount compared to 2G systems - data rates might be high or low, depending on which service is used. So there are different levels of QoS (switching between different QoS)

After the network has been built and it`s fully functional, traffic analysis is essential.
For example:
Quantifiable traffic is calculated: = Call time / 1 hour

So if the subscriber makes 2 calls in hour (lets take an average length of a call 120 s) ... = 240 / 3600 = 66mErl of traffic generated by that user (Erl - Erlang - a unit for traffic measurment). If user density in a region is known, then the traffic density can be calculated and expressed as Erl / km2

Main Source:
UMTS Network Planning and Development: Design and Implementation of the 3G CDMA Infrastructure by Chris Braithwaite and Mike Scott


Digital Nomad said...

This is a great post, and explains this very well. Do you do guest posts?

Tim said...

Nomad, thanks for the nice words!

Actually I have seriously thought about doing guest posting. You would be interested ? My e-mail is

Cheers =)

Plantronics said...

So is the 4g that some of these providers are coming out with true? IS there a big difference from 3g to 4g?