4G/LTE - SON

SON(Self Organizing Network)

SON stands for Self Organizing Network. What does this mean ? Ideally it means that just add a eNB wherever you want to put and just connect power and switch on, it would configure all of its configuration by itself and makes itself ready for service.

If you think a whole mobile network as a single PC, SON is like 'Plug-and-Play' functionality. (just Plug a any hardware (e.g, Keyboard, Printer etc) and it would play).

Normally when a system operator construct a network, they go through following steps.

i) Network Planning

ii) Bring the hardware (e.g, eNB) to the locations determined at Network Planning Process

iii) Hardware installation

iv) basic configuation

v) Otimizing parameters

Ideal goal of SON is to automate large portions of step i) and all of step iv), v) meaning that the installed system do all of iv), v) by itself.

In more formal way, SON framework can be illustrated as follows.(This illustration is from from nomor research - Self-Organizing Networks (SON) in 3GPP Long Term Evolution )

But we know from experience that any Fancy idea takes very long time to be fully implemented and adopted by everybody and sometimes the idea would disappear even before it is realized. SON itself is at its very early stage (as of now, May 2012 at least). I would say it is at the stage of doing only a portion of step iv).  I personally don't think SON concept would disappear but it would take pretty long time to be realized at the level of Plug-and-Play of our PC component.

You may have a question "Why we need this kind of idea ?", "Why we want to achieve this ?"

Typical answers that I can think of is

• i) Generally as the data rate of a technology gets higher, the cell coverage (range) gets smaller. It means we need to deploy more eNBs. and especially in LTE, we would see a lot of pico cells and femoto cells even inside of our house (If you take presentation or workshop for femto cell, you would hear a lot of about SON). So it would be practically impossible or highly costly to send specialized engineer to install and configure all of those hardware.  If we can make the hardware configure itself, we can have less skilled person just setup the hardware at any location and power on, or we can just deliver the hardware (e.g, femtocell) to a home and let them just plug in the power.
• ii) Normally as new (advanced) technology introduced, number of configuration parameters gets exponentially increased, so manual tuning of all those parameters whould gets more and more difficult as we have new technology.
• iii) Now we have all the different technologies (CDMA, GSM, WCDMA, LTE) are running simulteneously and in many cases these technologies interact each other. This makes the mannual optimization almost inpractical.

Major Goals for SON

Major Goals for SON is to achieve meeting the following two use cases. (This is defined in 3GPP TR 36.602)

• Providing optimal coverage : User should be able to get access to a network any time/ anywhere if they want. Once a UE get connected to a network, it should be able to maintain the connection as long as they want and the quality of service should be at least default quality.
• Providing optimal capacity : A network should be able to support as many subscribers as possible with enough service quality.

For now (as of ETSI TR 136 902 V9.3.1 (2011-05)), Achieving 'Optimal Converage' is at higher priority than achieving 'Optimal Capacity'.

Use Cases for SON

Following is the list of Use Case described in ETSI TR 136 902 V9.3.1 (2011-05). Each of these items is huge item. Basically 3GPP describes 'what is to be achieved' but does not describe 'how they can be described'. Most of the items are up to network operator and hardware manufacturers. (I will keep updating details as find time)

Further Readings :

• For further details of SON, I strongly recommend to see this presentation : LTE/LTE-A SON for Femtocells 
• Another articles I want to recomment is Further Enhancements of LTE

Presentations on YouTube :

• A Unified View on Self-Organizing Techniques for Heterogeneous Networks [Part I]
• A Unified View on Self-Organizing Techniques for Heterogeneous Networks [Part II]