Re: [Discuss-gnuradio] RAW source

[Activecat]

On Thu, Jun 19, 2014 at 9:32 PM, Sara Chérif <address@hidden> wrote:

Sorry , I forgot to say that some packets coming from Twinkle are SIP & ARP packets not only RTP.

Hence , I think I need to receive RAW packets in GNU Radio ( as I have different type of packets:  RTP , ARP , SIP packets)

Note that :

I use 4 laps & 2 USRPs.

1st & 4th lap has twinkle softphone & I will make a call between them.

2nd lap has an OFDM TX implemented by Gnuradio.

3rd lap has an OFDM RX implemented by Gnuradio.

First and 2nd laps are connected by Ethernet cable.

3rd & 4th laps are connected by Ethernet cable.

One USRP is connected to the 2nd lap , the other USRP is connected to the 3rd lap.
2nd lap(GNUradio ,ofdm tx)  will receive the packets from 1st lap(Twinkle) using RAW socket (as I think ) .

2nd lap will send the packets to the 3rd lap by the USRPs.

3rd lap ( Gnuradio , ofdm rx)  will send real time voice packets to 4th lap (Twinkle) using RAW socket(as I think).

Hi Sara,

What you need is only a wireless bridge.
A wireless bridge allows you to connect one network (1st and 2nd lap) to another (3rd and 4th lap) over the airwaves (which is USRP-to-USRP), rather than having to run wire from one room (2nd lap) to another (3rd lap).

I would say you only need to work at the OSI layer 1 (physical layer).  In this case you can ignore the UDP, RTP etc as far as gnuradio is concerned.

In alternative you may implement the wireless bridge using 802.11, but it is not mandatory for you to work at OSI layer 2.

So you may rephrase your question as "how to build wireless bridge using USRPs ?"

Then you may want to work in either transparent "repeater" mode or "bridge" mode. In either case you don't need to work at layer 3 or above.

The basic requirements are just that, you need the USRPs to setup wireless link at full-duplex, and make sure the bandwidth of the wireless channel is sufficient for few concurrent VoIP calls.

Anyway, I may be wrong.