[USRP-users] Loading USRP X3x0 by baseband processing functions

Marcus Müller marcus.mueller at ettus.com
Thu Oct 9 13:19:02 EDT 2014

Hi Birhane,

On 09.10.2014 19:04, Birhane Alemayoh wrote:
>> However, a complete GSM stack is a big thing, and I don't see much use in
>> implementing it in FPGA rather than host code, especially since working GSM
>> base stations already exist (openBTS).
> My system is supposed to capture and process downlink and uplink GSM
> signals in real time from the air using this X310 device.
OpenBTS [0] does that with USRPs on a host.
>  My system is
> shall work under frequency hopping environment which requires strict real
> time requirement. 
> We believe that this requirement is difficult to handle
> by processing the signal in the host. 
It is. But it has been done :)
> This is the reason why we prefer to
> write FPGA code.
Wow, that's dedication. I'd *definitely* spend more time making sure
things can't be done in host code than spending manyears of development
on FPGA hardware.
Since you're asking us for advice, I'd expect you / your company to be
not very experienced in the implementation of communication standards on
FPGAs -- deciding early you want to do *everything* in the FPGA this
early into your development doesn't sound very wise. Re-inventing the
wheel actually sounds bad. And not looking up the capabilities of
openBTS with USRPs instead of believing requirements are hard to meet
with software sounds like a mistake, but one that is easily corrected ;)

> So what do you comment/recommend for this?
Doing what all the industry has been doing for 20 years: Doing only the
really necessary part of processing in hardware, and moving higher level
functionality to general purpose processors. Seriously, look at the
Osmocom BB project [1]: Even the Motorola C115 [2] brick of a cheap
consumer mobile phone does its baseband processing in software.
Seriously, I think it will be easier to instantiate a general purpose
CPU in the FPGA and just run the baseband processing software on there
rather than doing everything in real FPGA hardware.
> Thank you

Hope you find the links I share helpful!


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