Communication between sora and commercial 802.11a RRS feed

  • Question

  • Hi!


    I have some problem when I tried to communicate from commercial laptop to sora with 802.11a/b mode. 

    I tested using ping. (I unblocked the ICMP in Windows firewalls at both sora and my window lap-top)


    Here are my settings.

    2 laptops (MAC-book, WINDOW) and 1 sora machine.

    (I generate ad hoc network from MAC-book)



    BSSID: sora-mmlab



    Associate to : sora-mmlab (MAC-book)



    BSSID: manually set to “sora-mmlab” (both registry key and sdr.inf are modified)

    I changed the sources file for 44MHz sampling rate. (we use usrp xcvr2450)

    Followings are command that I used.  

    (11b setting)

    dot11config -c 3

    dot11config --rxpa 0x0000

    dot11config --rxgain 0x1400

    dot11config --txgain 0x1F80


    (11a setting)

    dot11config -c 36

    dot11config --rxpa 0x0000

    dot11config --rxgain 0x1400

    dot11config --txgain 0x1F80



    I checked sora machine can hear 802.11 signal since I can check the BSSID (sora-mmlab) in the beacon signal using oscilloscope when I use channel # 3 in both 11a and 11b. (use dot11config –d). However, when I use channel # 36 for 11a, it does not sense any signal and noise.

    (I’m confused that channel #3 is possible setting for 802.11a??)


    Ping results:

    Ping from MAC-book to WINDOW is fine, and vice-versa.


    But ping from MAC-book to sora is impossible, and vice-versa.

    Between WINDOW and sora is also impossible.


    Using tcpdump at MAC-book, I checked that there is a problem with ARP. MAC and WINDOW are always looking for who has the ofsora). but there is no response. It means that MAC do not know sora (no association from sora to MAC-book).

    (There is no difference when I initiated ad hoc network w/ WINDOW machine)


    When I configured static ARP table, I could check sora try to send a ping packet to other nodes (through oscilloscope). But there is no answer from other nodes.

    I also try with iperf with static ARP table setting, but there is also no response between sora and commercial 802.11.



    Please let me know what should I do to success ping test from commercial 802.11 to sora or vice-versa, or what did I miss…



    Jiho Ryu


    Jiho Ryu
    Friday, May 27, 2011 6:58 AM


  • Hi Jiho,

    1. Channel 36 is not supported by default. To enable, you should modify the firmware in USRP adapter. However, this is not critical to your problem since you can also use channel 3 to test 802.11a.

    2. I guess the "sora-mmlab" is SSID, instead of BSSID. BSSID has the same format as MAC address and are randomly generated from SSID. I suggest you to change your SSID to "sdr", because we have implemented an algorithm which adaptively changes Sora's BSSID when Sora hear a beacon with the SSID "sdr".

    3. Instead of directly going to TCP (or ping), I suggest you to try broadcasting first. You can use iperf and you should try broadcasting in both directions (Sora to WiFi card and WiFi card to Sora). The broadcasting test will help you find out the proper gain setting.



    Thursday, June 2, 2011 5:41 AM