Using one USRP


#1

Hi

I am trying to implement a cognitive radio system for dynamic spectrum
access. I am trying to implement it in GNU radio. But the problem is
that i
have only one USRP at the moment with Basic RX and TX daughterboards.
The
setup consists of Station A transmitting to Station B.
In order to be able to use the licensed spectrum, the transmitter must
know
which channels are free in the vicinity. Thus it has to do a parallel
detection of spectrum as well—receiver mode.

The Transmitter first senses the spectrum for some time say 10ms and
then
transmits on the free frequency for say 90 ms before sensing the
spectrum
again and so on.

Thus the following questions arise:

  1. Can the Station B be implemented on the same USRP when the Station A
    is
    only transmitting[not sensing(recieving)]?
  2. What effects would this have on the Data Rates and any problem with
    the
    USB interface?

Is there any built in example within gnuradio with which i can test the
simultaneous transmission and reception from the BasicTX to the BasicRX
respectively on the same usrp?

Regards,
Ali


#2

Hi Ali - Check out the following MS thesis, by a ex-colleague of mine
here at ND:

Practical Implementation of a Cognitive Radio System for Dynamic
Spectrum Access

< http://etd.nd.edu/ETD-db/theses/available/etd-07252008-162749/ >

It sounds similar to what you’re talking about, and certainly worth a
look-through IMHO. - MLD


#3

Michael D. wrote:

Hi Ali - Check out the following MS thesis, by a ex-colleague of mine
here at ND:

Practical Implementation of a Cognitive Radio System for Dynamic
Spectrum Access

< http://etd.nd.edu/ETD-db/theses/available/etd-07252008-162749/ >

It sounds similar to what you’re talking about, and certainly worth a
look-through IMHO. - MLD

Sounds like an interesting paper but the website requires a Notre Dame
password to download the file.

Matt


#4

Sounds like an interesting paper but the website requires a Notre
Dame password to download the file.

I apologize; I didn’t realize that website was password protected (it
didn’t ask me :wink: Here’s another:

< http://www.nd.edu/~jnl/pubs/crohas-ms-nd-2008.pdf >


#5

Hi Ali,

I have done the similar as a part in my thesis as well. But I used two
USRPs
to serve as receiver and transmitter. When u try to listen on a daughter
board using same USRP and transmit simultaneously ( which I tried ) you
do
not receive the transmitted signal. I did not dwell much on this because
I
had two USRPs to serve as two users. I know that both tramsitter and
receiver programs can be run using two daughter boards. But the
receiver in
this case seems to receive only signals send from other USRPs. But
signals
Transmitted from a diiferent antenna/daughter board on same USRP was not
received
. I used this isolation for my benefit to run a scanner
simultaneously to detect signal from while transmission is going on. I
do
not know if this isolation can be removed by changing some parameters. I
do
not have access to my boards now will try it next week and let you
know.But
I would recommend you to search the archive there are some related
discussions.
Thank you
Swapna

2009/3/20 ali siddiqi removed_email_address@domain.invalid


#6

Michael D. wrote:

Sounds like an interesting paper but the website requires a Notre
Dame password to download the file.

I apologize; I didn’t realize that website was password protected (it
didn’t ask me :wink: Here’s another:

< http://www.nd.edu/~jnl/pubs/crohas-ms-nd-2008.pdf >

hi, i had read the thesis but there is no OFDM used in this project… is
there any others thesis or document that explain on how to generate
the OFDM using GNU Radio?


#7

Michael D. wrote:

Hi Ali - Check out the following MS thesis, by a ex-colleague of mine
here at ND:

Practical Implementation of a Cognitive Radio System for Dynamic
Spectrum Access

< http://etd.nd.edu/ETD-db/theses/available/etd-07252008-162749/ >

It sounds similar to what you’re talking about, and certainly worth a
look-through IMHO. - MLD

Hi.

I have read this thesis and it is very instructive.

This thesis appears to use the transmit/receive_path that comes with the
downloadable gnuradio package to transmit and receive.

I am wondering: did the person who wrote this thesis write and develop
transmit/receive_path, with this later being incorporated into gnuradio,
or the other way around?


#8

Hi Raj - Alice Crohas’ MS thesis sounds similar to yours. She used 2
USRP1’s, one doing RX-audio, and the other doing the RX-sample and the
TX-audio. We discussed trying to do simultaneous RX/TX using the same
daughtercard on a given USRP, or different daughtercards on the same
USRP, but decided against either for various reasons. Her eventual
setup used just two USRPs: two antennas and two daughtercards – one
each per USRP. The RX-audio was not smooth (it had gaps where the TX-
audio was stopped to do RX-sample), but listening was not unpleasant;
with a little added buffering on RX, she could have made the RX-audio
smooth (but added in a small latency to the transmission, which for
the purposes of what she was doing would have been just fine) – this
wasn’t necessary for the MS, but it would have been nice for our
demos. Good luck on your projects. - MLD


#9

On Apr 1, 2009, at 11:26 PM, William Sherman wrote:

did the person who wrote this thesis write and develop
transmit/receive_path, with this later being incorporated into
gnuradio,
or the other way around?

Other way around; she just used what was available from GNU Radio at
the time and modified it to meet her needs. - MLD


#10

Michael D.-3 wrote:

OFDM modulation so that i can notch the subcarier in the channel instead


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#11

Michael D.-3 wrote:

smooth (but added in a small latency to the transmission, which for
the purposes of what she was doing would have been just fine) – this
wasn’t necessary for the MS, but it would have been nice for our
demos. Good luck on your projects. - MLD

regarding the thesis by Alice Crohas, in page 32. do anyone know how she
manage to obtain the ROC graph? how the experiment is done is not really
clear explained.

in spectrum sensing with experimental work, how do we obtain the
probability
of false alarm and probability of detection graph? what is the proper
method
and how do we plot the ROC curve. thanks.

Adib


Mohd Adib Sarijari
Universiti Teknologi Malaysia
www.fke.utm.my
www.utm.my

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