Friday, January 25, 2013

Mobile TV

How the Service deployed

We first have to download the Mobile TV application and then register to a particular TV channel. For example imagine that you are going to register for the channel TenCricket. Content providers main server is in India alongside with a customer database. Our customer attached to the SGSN and the normal procedure going to the internet will take place as usual. When he clicks “subscribe for a channel”, his request will reach the server located at India as a HTTP request. To do that authentication part should be handled by our Fire Wall and according to the request server will take necessary actions. Then the server will send an HTTP/XML request to our External Charging Gateway (ECG) to check the details of our customer. Refer the image below for further details.
ECG will direct it to OCS to check for the balance of the customer. We can directly charge prepaid customers in OCS if they have got enough balance. For postpaid customers OCS will generate a CDR (Call Detail Record) and send it to OFCS for billing him later. After that OCS will send a response back to ECG indicating the status. It will forward again to Main server.
If the charging process of the customer succeeded he will be given separate RTP (Real Time Protocol) addresses for video and audio (i.e. RTP://video, RTP://audio) for that channel. 
            E.g.: RTP://

You can’t see above addresses or you can’t identify them. Because when the addresses

assigned you will see a “Play” button in the Mobile TV interface. When you press the button above mentioned two addresses will be opened through mobile’s default player. 
Company prefer customers under 3G coverage but even with a 2G coverage (will depend on traffic, weather, etc.) you may able to get an uninterrupted service. This application requires at least 248kbps (3G) or 64kbps (2G). There are 3 profiles defined for the convenience of the customer.
     1.      MPEG4 (video),AAC (audio) – specially for older mobiles
          2.      H.264,AAC – high (i.e. android phones)
          3.      H.264,AAC – low (for customers in 2G coverage)

Giver URLs were all internal private IPs. Because we don’t need to use over internet bandwidth for streaming. That is handled using an Encoder as shown below. After successful subscription from the main server side Encoder will send a unicast RTP addresses (mentioned above) for the customer. Now customer can watch the TV channel. For streaming only bandwidths between mobile and Encoder will be used.
When we get the content from a content provider (i.e. Sky TV) we have to get it as shown in the image. Because the switching room is isolated from outside world to protect it from lightning and etc. It will only get power from outside. So we connect roof top cabin and switch using fiber. This much of security measurements taken in order to protect all the high cost equipment located inside the room.

How the charging happens

To charge a particular customer we need to get his mobile number through the main server in India. In order to pass that information; we send a HTTP enriched header request to the server which consist of following details.
  •          MSISDN
  •          Bearer (2G or 3G)
  •          SGSN ID (We don’t allow this service to roaming customers. If a customer is roaming his SGSN ID will be different from ours. So we can restrict him by looking at this ID)

Why the Main Server is not in Sri Lanka (Can’t we set up it in Sri Lanka)

Major distribution points of the content provider are not located in Sri Lanka. If we are going set up those facilities here in Sri Lanka, the cost will be high. It is not hard (very easy) to configure and get connected with existing facilities. We only have to get the authentication done because we have to connect through public internet. Authentication will be done using IPs, ports, usernames, passwords, etc. only when we subscribe we have to communicate with the Main Server. Especially as I mentioned above while we stream, it is controlled inside our network.