Re: [Discuss-gnuradio] The low performance of gr-ieee-802.11 running on b210 ????

[Cristian Rodríguez]

2017-05-16 10:51 GMT-05:00 zhan siyu <address@hidden>:

Hi Cristian,

Thanks for your email. As to my experience, at first you need to make sure the two computers can receive each other's packet sent by usrp. Then you 'd better use wireshark to capture the packets and analyze. I didn't do any modifications on the grc file. Actually, I am learning the code and trying to modify it to satisfy my requirements but I 'm still reading it and I don't have ability to modify it right now.

Hi Siyu.

Thanks for your message.

I am engaged of working over IEEE802.11 over USRP B210 so i think if you are doing the same, we can share all information about it, so the learning curve is smoother.

I opened a thread called "IEEE802.11 transceiver - problems sending data" in which i explain my problem. If you could read it and give me a hand it would be very helpful for me.

 

Btw, I'm interested on your words about you solved the overrun errors by changing some transport parameters. It's new to me. Although I haven't had this error, I 'm curious about it. Could you share it with me ?

About the transport parameters it is the reference page transport_udp_sockbufs. i modified the next two:

• recv_frame_size: The size of a single receive buffer in bytes
• num_recv_frames: The number of receive buffers to allocate

Thus, i can manage more samples. It is basically, increasing the buffer amount and the size of each one.

You define it in the USRP source parameter: device Arguments.

If you want to put several of them, you have to separate by a semicolon.

-------------------------------------------------------------------------------------------------------------

On the other hand, it is courious for me that you haven't had overflows. Could you please share me the next information?

• Your pc characteristics (I7?, RAM?, USB ports?)
• Your Kernel and Ubuntu version (it can be done by typing: uname -r (kernel) and lsb_release -r (ubuntu) )
• The USB controller version (By typing lspci)

I ask for it because the solutions that people in the forum gave me were: my pc is too slow, but it is not (i have i7 4710HQ (up to 3.5 GHz), My kernel version (but it is, for me, ok) and my USB controller (at this point i'm not sure what is good and what isn't)). Then wiht that info i could migrate to your kernel and controllers version.

I know you are thinking but you already solved it, but i'm not pretty sure about receiving all packets yet. Then i would prefeer trying to solve the thing with my computer.

Thanks in advance for your time to read it.

Best regards,

Cristian

Best regards.

Siyu Zhan

2017-05-16 22:16 GMT+08:00 Cristian Rodríguez <address@hiddencom>:

Hi all.

I was reading about your implementation Siyu and i am trying to do the same (ieee802.11 over USRP B210 - intel i7) but i haven't been able to. Could you indicate me what you did. It would help me a lot.

I had overruns and i solved it by changing the transport parameters. I have the transceiver in only one pc. I run it and I try to do a ping but the ping just is received for the transceiver. It is not answered, then i don't achieved comunication.

If you could share me your .grc file would be great too, if you maybe modified some important parameteres or something in the flowgraph.

Thanks a lot.

Best regards,

Cristian

2017-05-09 16:37 GMT-05:00 Marcus Müller <address@hidden>:

Hi Siyu,

well, transceiver performance depends effectively on bit error rate of the underlying transport – and that error rate might be limited by noise, by interference, or by effects like clipping and saturation, overly large clock offset and much more. I'd say: add a time and a frequency sink to your receiver flow graph, and watch the statistics! Analyze what might be going wrong. In a first approach: Play with the TX and RX gains, carefully.

To be completely honest, how well that transceiver works is something no-one outside your lab can assess – you'll have to start diagnosing things yourself :)

Best regards,

Marcus

On 09.05.2017 22:11, zhan siyu wrote:

Hi all,

Recently, I bought two b210 usrps. And I just successfully setup the usrps to run the gr-ieee802.11, written by Bastian. I used 2 desktops connected to usrp and run the transceiver.py program. I can ping from one to the other. I 'm so excited as I finally made it. However, I used the iperf to test the throughput between two computers through the 802.11p. The result is too low, only around 120kb/s , as shown by the log of iperf server side. No overrun or underrun errors. The sample rate is 10M. The OS of my computers is ubuntu 16 and cpu is i7. Also, the %cpu is only 310% as shown by the top command. The distance between two usrps is about 0.5 meters.  Is the performance too low ? I think it should be much higher. But how can I improve it ? Where is the bottleneck ? 

Can anyone help me ? Thanks ahead.

Best Regards.

Siyu

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