Re: [Discuss-gnuradio] RAW source

[Sara Chérif]

Thanks very much Activecat

I have some last questions please :
1- Does the block " Socket PDU" can be used instead of a socket ? It don't understand what is the importance of this block ? what does it take as input ? I know it takes "Pdus"= "Async message " but also I don't understand what is the block that must precedes the socket PDU.

 

2- Do I have to write a code for socket ?or simply I can write ,in the "UDP source" block in Gnu radio(2nd lap) , the IP address & port number of the Ethernet connection (of 2nd lap) receiving from Twinkle(1st lap) ?

Or the UDP source is an interface to socket and So there must exist an external code of socket ?

Thanks in advance

2014-06-21 19:43 GMT+03:00 Activecat <address@hidden>:

On Sat, Jun 21, 2014 at 7:31 PM, Sara Chérif <address@hidden> wrote:

Thanks Marcus Müller , Marcus D. Leech , Activecat.

yes , we can call this "Ethernet to wireless bridge using GSM RF channel ". I have some questions, please :

1- Can I use both UDP source & TCP source  in this way :

  Can I connect output of" UDP source" & output of "TCP source" to input of "Socket PDU " and connect output of "Socket PDU "   to the input of the "PDU to tagged stream " block ?  What is wrong in this connection ?

2- But when I connect the output of TCP or UDP source to the Socket PDU , I got an error ! what does the Socket PDU block take as an input?!

3- Also when I connect output of "TCP or UDP source" to "PDU to tagged stream " I got an error , what must be the input of the PDU to tagged stream block ?! Does the "PDU to tagged stream " is used here instead of the "stream to tagged stream" block  and has same role?

4- Does the block " Socket PDU" can be used instead of a socket ? It don't understand what is the importance of this block ?

 
5-  Is there any flags so that when signaling packets are coming (SIP or ARP)  : TCP source is enabled while UDP source is disabled  ?
  And the inverse happens when there is RTP packets coming?

Note that , in network settings in Twinkle soft phone , there is a port number for RTP different from port number of SIP & we can change these ports numbers , I don't know if this may help me .

6- Do I have to write a code for socket ?or simply I can write ,in the "UDP source" block in Gnu radio(2nd lap) , the IP address & port number of the Ethernet connection (of 2nd lap) receiving from Twinkle(1st lap) ?

7-  If there is no new packets coming , I want to send zeros instead of repeating the sent packets ? How Can I do this ?

i.e: I want to insert 8 bits zeros after each ofdm symbol as a guard band : I tried to insert " pad source " block to do this , after the IFFT block  and before the cyclic prefixer block

 , but it is not allowed to connect 2 inputs to the cyclic prefixer also I don't know how to use the pad source to insert these zeros & I don't know if there is a block to concatenate between the zeros coming from the pad source & the output of the ifft block .

Thanks in advance .

Looking at above questions, you doesn't seem to understand OSI 7 layers model.

You said this is a "wireless bridge".
If you have decided to have gnuradio (with USRPs) working at layer 2, then you no longer need to consider TCP, UDP, RTP etc.

Even if you decided to have gnuradio working at layer 3, you also no need to handle TCP, UDP, RTP etc.

If you want to have gnuradio (with USRPs) working at layer 7, then you this will be very complicated and the resulting setup will be very application specific, i.e. you will need to handle each application one by one. This approach is unnecessarily complicated and hence not recommended.

An analogue to this:

Says, now you have a PC that you want to connect to internet. In another room you have a DSL router which is already connected to internet. Currently the PC has no connection to the DSL router, it is standalone.

To connect the PC to the DSL router, you have few options:

Option 1:  Use Ethernet Extender
The Externet Extender do not need to understand any IP address, TCP, UDP, HTTP etc.

In this case the Ethernet Extender is working at OSI layer 1.  The Ethernet Extender doesn't even need to care about the MAC address, right ?
 

Option 2: Use a bridge

The bridge need a MAC address but does not need any IP address.  It will perform packet switching based on MAC addresses. It doesn't need to look at the IP addresses of the packets, no need to talk about the TCP, HTML etc.
In this case the bridge is working at OSI layer 2.

Option 3: Use a router

If the IP address of your PC is in different subnet from the Ethernet port of the DSL router, then you need put another router between the PC and the DSL router. The default gateway of the PC is pointing to the interconnecting router.
In this case the router is working at OSI layer 3.   The router doesn't need to understand any HTTP protocol, right?

Option 4: Use a proxy server
The HTTP proxy server needs to understand HTTP traffic, know the contents of each website etc in order to perform filtering and caching.  In this case the proxy server is working at OSI layer 7.

Now let's come back to your question.

As you already decided to have gnuradio working at layer 2, why you still need to care about the UDP, TCP, RTP etc ?