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From: | Marcus Müller |
Subject: | Re: [Discuss-gnuradio] RAW source |
Date: | Thu, 19 Jun 2014 16:12:23 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 |
Hi Sara, in the stack of usual VoIP systems, there is no such thing as a "RAW" package. What you seem to want is the common transport layer for ARP, SIP and RTP to go over the air. I'm not really sure why you would want ARP, as that is something two VoIP devices usually can't communicate over (because it's one layer under the internet layer, and basically only exists for local networks); ARP is only necessary when you want to know the ethernet MAC address belonging to an IP address, which you don't need to do in your case; just tell your routing table that packets for that other IP address have to go over your wireless link... Aside from ARP, the common layer would be IP. Problem here is that all of your protocols are two-way protocols: you cannot just send packets in one direction and hope everything will work, there has to be some back channel. How would your TX soft phone know the other end picked up your call? So what you must do is two-fold: 1. Implement a link-layer, and instruct your operating system to transport the IP pakets over that and 2. implement a back channel. Notes: 2.: this might need another OFDM channel in the opposite direction, or, with some firewall/ low level routing magic, another ethernet link, just used for the back channel. 1.: there's still gr-digital/examples/ofdm/tunnel.py from the "old" OFDM framework, which has become somewhat infamous :) but looking at that code, you should be able to figure out how to use your OFDM implementation with TUN/TAP devices. Also look at gr-ieee802-11, which *is* a working OFDM layer with a TAP (that's ethernet layer) device interface. Greetings, Marcus On 19.06.2014 15:32, Sara Chérif 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). > > If I want only to make a call & send and receive the voip real time packets > , Do I have then to write a specific block as this mentioned decoder ? > > Thanks in Advance. > > > 2014-06-19 15:33 GMT+03:00 Marcus Müller <address@hidden>: > Hi Sara,>> >> _______________________________________________ >> Discuss-gnuradio mailing list >> address@hidden >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> > > > > _______________________________________________ > Discuss-gnuradio mailing list > address@hidden > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio |
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