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

Amit Nevo Amit.Nevo at hallo.co.il
Tue Feb 14 07:05:01 EST 2012


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?

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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