Imagine and Explore ….

There is a common miss-perception about what 3G service is and its relation with GPRS. This writing is not going into the how 3G works in detail, but I hope it can help any non-technical people understand what is 3G and how we can utilize 3G service.

If my guess is right, the first thing that come up on your mind after hear word “3G” is a technology that make you able to do video call, you can see your friend in your phone screen while calling him/her. You are not wrong if you think like that because video call is the easiest thing to recognize about what “3G” is.

In correct definition, 3G is actually only a matter of radio technology in telecommunication world. With 3G radio, we can have broader bandwidth and more service variation for end user. In general, for end user services, we can have two kinds of services, circuit-switch (CS) based services and packet-switch (PS) based services.

First, for the CS based services, the only difference from 2G services is video call. With 3G, you can still able to do any other normal services like voice call, SMS, USSD, etc without any different method to use it. There are many new services and applications coming with the availability of video call feature. You can do video call to your friend in one-to-one or one-to-many connections (video conference). You are also able to call to a special phone number that pointed to TV streaming services, etc.

Regarding video call, some of you must have questions in your head. What is the video codec used there? How much bandwidth is required for each call? How is the QoS mechanism? Etc. Video call is require fix 64kbps bandwidth in the network. Since video call is CS based service, each call is requiring 1×64 kbps fixed channel which is make the QoS can be always guaranteed for each call. If you are using TDM, the total bandwidth for each call is 64 kbps, but if you are using ATM AAL2, you will need around 84 kbps because of ATM headers and if you put video call of IP transport, you will need around 170 kbps. Why does video call need very high bandwidth? Is there any compression there? Video call is a handset feature, there is nothing to do in the network except for providing the bearer. There is no compression in the network, video call data is treated same as normal CSD (circuit switch data) in the network.

The different thing is happened for voice call. In 3G, AMR (adaptive multi rate codec) based codec for voice is supported as basic feature. With AMR you can compress the bandwidth required for each voice call up to 12 kbps, dependent on the nature of how the caller speaks. If the compression can reach 12 kbps, the transport requirement for voice call is actually around 19 kbps for ATM network and 23 kbps for IP network.

But please remember that 3G is not only video call, you can find out some phone that support 3G but have no camera at all so you can not do any video call. With this type of phone, you will able to connect to 3G radio network but only for PS based services which I will try to explain after this.

Ok, now is the time for PS based services. PS based services in telecommunication is based on GPRS (general packet radio services), no matter what is the radio technology, whether using 3G radio or 2.5G radio. Packet data service in 3G is not different with GPRS service that we know and maybe you have used currently. From end user perspective, there is no difference at all about how to use the services. The difference is only occur in radio part, with 3G radio, with the new coding mechanism, we can have data throughput up to 384kbps for normal 3G network or up to 14 Mbps if the 3G network has HSDPA (high speed downlink packet access) feature enabled.

By having this new data throughput, let say we only have normal 3G network which is only 384 kbps, we are able to do many thing over there. You can watch TV streaming in your phone like in CS based service but with better quality because in PS based service, there is no fixed channel allocated for each connection. The bandwidth required for each streaming is depend on what is the codec used in the streaming server. Of course, you also able to use this high speed GPRS connection for any type of internet based services, you can do VoIP call using skype maybe. If your operator supports, you can also able to do any video call using GPRS to normal CS-based users by using video gateway. You connect to the video gateway using SIP or H323 and video gateway will convert to normal CS based video call.

I think I already have to long posting here, if you want to know more about 3G in detail, you can put a question in the comment form of just contact me.

-rendo-

Without any expectation, I was looking for how to get IMSI number from SE M600i phone. As far as I knew before, there is no serial port profile in SE UIQ based phone so I can’t put at+cimi command via serial port connection as I usually did in any normal phone.

From Google, finally i found that although there is no serial port bluetooth profile in UIQ based phone, we still able to do AT-Command via dial up networking(DUN)-bluetooth profile as well as DUN related virtual serial port if we are using USB connection.

After got the info, I tried to connect to M600i first by using secureCRT via serial com port that associated with DUN-bluetooth profile (In Windows, You can find this com port number from control panel –> phone and modem options) and put at+cimi command. The result was the phone truly answer my command with correct IMSI number.

And to follow my curiosity, i tried to connect my FMA (float mobile agent freeware) to M600i with new setting. I change the com port setting in FMA to my virtual com port that associated to DUN bluetooth profile. The connection was successfully established and FMA could reterieve all my SMS messages, call logs, contact list.

But there are some limited behaviours, 

1. phone contact and sim contact were giving same results.
2.  we could not update the contact list from FMA

but at least i’m able to send,receive and backup my sms from FMA. It is enough for me.

-rendo-