[orbit-user] Radiotap header parsing

[Guillaume Jourjon]

Hi,

I think you are not using the latest version of both the trace_oml2 and 
oml2-server during your experiment. Indeed, when I'm running the same 
experiment using the latest debian packages (oml-client and oml-server) 
from http://pkg.mytestbed.net/ubuntu I obtain the following results:

CREATE TABLE trace_oml2_radiotap (oml_sender_id INTEGER, oml_seq 
INTEGER, oml_ts_client REAL, oml_ts_server REAL, tsft INTEGER, rate 
INTEGER, freq INTEGER, sig_strength_dBm INTEGER, noise_strength_dBm 
INTEGER, sig_strength INTEGER, noise_strength INTEGER, attenuation 
INTEGER, attenuation_dB INTEGER, power INTEGER, antenna INTEGER, 
sourceMAC TEXT, dstMAC TEXT);
INSERT INTO "trace_oml2_radiotap" VALUES(1, 1, 30.6524909995496, 
0.565649, 1375296379, 2, 2412, -87, -98, 11, 4, 47111, 42447, -125, 
1,'00:22:55:ee:b2:90','ff:ff:ff:ff:ff:ff');

In this example let me explain everything:
- oml_sender id = 1 means that this is the first client using oml that 
connect to the server;
- oml_seq = 1 means that this is the first measurement for this table;
- oml_ts_client is the timestamp made by the client but re-interpreted 
by the server that's why you can have some negative values sometimes;
- oml_ts_server is the timestamp representing the server time when the 
server received this measure;
- tsft is the Time Synchronization Function timer from the wireless 
frame in microseconds, it is supposed to be an unsigned 64 bits int but 
we are supporting this type yet. It will be fixed soon;
- rate is Tx/RX data rate and the unit is 500Kbps. In this example 
therefore I have a rate of 1Mbps;
- freq is the frequency in MHz, in our example we have a frequency of 
2.412 GHz (I'm using 802.11g);
- sig_strength_dBm and noise_strength_dBm are the signal and noise 
strength in dBm;
- sig_strength and noise_strength are the signal and noise strength in dB;
- attenuation is the wireless transmit attenuation;
- attenuation_dB is the wireless transmit attenuation in dB;
- power is the transmit power expressed as dBm;
- antenna is the unitless indication of the Rx/Tx antenna for this packet.

I hope that helps you a bit.

Best Regards,

Guillaume



Akash Baid wrote:
> Hi,
>
> I am using the trace_oml2 application of OML2 for libpcap sniffing. I 
> was wondering if someone can help me out with understanding (parsing) 
> the received radiotap data. The schema and an example row entry from 
> the database is :
>
> /oml_sender_id INTEGER, oml_seq INTEGER, oml_ts REAL, tsft INTEGER, 
> rate INTEGER, freq INTEGER, sig_strength_dBm INTEGER, 
> noise_strength_dBm INTEGER, sig_strength INTEGER, noise_strength 
> INTEGER, attenuation INTEGER, attenuation_dB INTEGER, power INTEGER, 
> antenna INTEGER, sourceMAC INTEGER, dstMAC INTEGER/
> /
> /
> /"1"// //"16777216"// //"99.76406667032279"// //"-2113757635"// 
> //"369098752"// //"1812529152"// //"-1426063361"// //"-1627389953"// 
> //"201326592"// //"0"// //"0"// //"0"// //"0"// //"33554432"// 
> //"1957724087"// //"1857060791"/
>
> So I am trying to guess for example how the freq = 1812529152 
> corresponds to channel 1 and so on. Also I am getting some negative 
> numbers for oml_ts, tsft; what is the significance of that? Would 
> really help if someone can point me to the appropriate documentation.
>
> Thanks
> Akash
>