[USRP-users] GSM900 2G Implementation using USRP2-N200

Josh Blum josh at ettus.com
Tue Feb 14 12:34:18 EST 2012



On 02/14/2012 04:05 AM, Amit Nevo wrote:
> Thomas, Ban and All,
> 
> Thanks for your answer.
> 
> Just to verify my understanding:
> Assuming we receive simultaneously multiple channels (upto 8x124 -
> theoretically)  from the 1GBE link, can we modulate these channels onto 124
> different sub-channels frequencies ( 200KHz spaced) of same 25MHz BW, by
> Digital Processing/Embedded DSP in FPGA device and later transmit them
> simultaneously on 900MHz carrier?
> 

Have you ruled out the possibility of implementing the filter bank on
the PC? There is a nice, efficient polyphase filter bank already in
gnuradio. I recommend experimenting with it. It would certainly be less
work than implementing the processing inside the FPGA.

-Josh

> Amit Nevo
> 
> 
> 
> Amit.Nevo at hallo.co.il
> -----Original Message-----
> From: Thomas Tsou [mailto:ttsou at vt.edu] 
> Sent: Thursday, February 09, 2012 8:17 PM
> To: Amit Nevo
> Cc: usrp-users at lists.ettus.com
> Subject: Re: [USRP-users] GSM900 2G Implementation using USRP2-N200
> 
> On Thu, Feb 9, 2012 at 7:17 AM, Amit Nevo <Amit.Nevo at hallo.co.il> wrote:
>>
>> Hi all,
>>
>> I consider a GSM900 2G implementation using the USRP2-N200.
>>
>> I would like to know how many channels/AFRCN/sub carriers (of 8 slots
> each) does the USRP2-N200 support?
> 
> With 25 MHz of bandwidth of the N200 you can digitize the entire
> (non-extended) GSM900 uplink or downlink if that's what you're interested
> in. As Ben said, the device views samples and bandwidth and not specific GSM
> channels.
> 
>> If the number of supported channels is more than 1, what is the technique
> that the USRP2-N200 use to transmit multiple channels on single transmitter?
>>
>> If the answer is single channel, is there a USRP type that support more
> than one channel?
> 
> Multiple channels can be supported using a channelizer / transmultiplexer
> with a single device. Support for that capability in the open version of
> OpenBTS is forthcoming.
> 
>   Thomas
> 
> 
> 
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