GSM modem from scratch

[madhan_2005]

Guys I want to design a GSM modem just for knowledge purposes. I want to build the unit from scratch. I have a fair understanding of GSM architecture and GMSK protocols but i havent seen any diy guys attempting to do a modem from scratch. I don't understand that. I will try to build the unit in my FPGA. But even for that I need a good resourse that tells me more deeper than the high level architecture to the low level programming involved in it. Any resources you can point me to.

And also can you suggest me some good baseband ICs and LNAs that i can use to build a working GSM unit?

 

[sky_123]

Google reveals **broken link removed**.
Still, going from even that massive task to a complete modem is still another similarly sized huge leap. And it requires skills in
many subject areas. That's why there are no DIY projects for this. I'd give up before I'd start : )

 

[madhan_2005]

I too have seen that . i am going through it right now. But what i need is not the high level protocol. i want the low level protocol which explains about the encryption encoding etc and all the tasks to be carried out during communication. And my take is if another can do the program then so can me...I am just doing it for knowledge .It doesnt matter whether i finish it or not. both will give me some knowledge. So can anybody point me to some good technical refrences? also the gsm reference paper can also be of great help to me. but i cant find it...

 

[sky_123]

You've still not grasped the extent of work you need to do; when I said massive, I really meant it. There is no single low level protocol.
There are many, all layered on top of each other, and without them, you've got something that won't function. It is described in a few
tens of thousand of pages on the 3gpp website.

 

[madhan_2005]

man you are not getting my point. even if i research 1% of it its success for me. Its just a hobby project. It may take years for me to complete it or even start it but i like the challenge of it. better try than do nothing. and one more question are you involved in communications industry because by your talks it seems you know about gsm. so if you are can you point to to the gsm white papers it would be of much help.
thank you...

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or else is there any solution for gsm like a gsm baseband chip that i can use for this?i cant seem to find any chip that does this in internet without NDA. If there is no other go can i sign the NDA of baseband processors for my personal work saying that i am researching something?

 

[sky_123]

I pointed you to the papers. There you'll find the high level down to the low level docs. I'm not involved in that industry, but I've had to look into it
in the past. After several years of it, I had probably read 0.1% (if I'm being generous to myself) of the information relating to mobile, and I
wouldn't even know how to begin this huge task.
Regarding NDA, I don't think you'll find an issue, most firms will supply the info as long as you sign an NDA. However, these chips are complex -
the purpose of the NDA isn't always trade secret related. It's to do with getting their teams confident in getting you all the information you need
for your design to be successful, i.e. data sharing. Nevertheless that's a big commitment for a firm since they're tying up resources to help you.
Nothings impossible, so you may find companies helpful. (I wouldn't know which companies to approach, maybe other people know better than me).

 

[madhan_2005]

thanks for the info. these baseband processors are supplied by only some companies like

MediaTek
Broadcom
Icera
Intel Mobile Communications- former infineon wireless division
Qualcomm
ST-Ericsson
(all taken from wiki)

as you see these are all huge firms. will they supply datasheet to me?or are there other companies that i can approach?anybody can help me?