Best regards.
Siyu
2017-06-07 14:02 GMT+08:00 Bastian Bloessl <address@hidden
<mailto:address@hidden>>:
Hi,
On 06/07/2017 03:04 AM, zhan siyu wrote:
Thanks. I just wonder why. Because I meet some performance
problem. I thought it maybe caused by my misconfiguration of the
gr-ieee802-11 code. Now, it seems not.
I'm a bit confused why the fact that the transceiver is not
configured through iwconfig ruled out any configuration issues, but
great that all seems to be set up now.
However, theoretically, as my current sample rate is 10M and
BPSK. So the coding rate should be 10M/2 = 5M b/s. The
throughtput should be around 5M/8 = 625K B/s. Assuming the 12%
head cost, so the data throughput should be 625 * 88 % = 550K
B/s. But as my experiment shows, the throughput is only 150K B/s.
I'm new to the communication. Is my calculation right ?
BPSK 1/3 is 3Mbit/s gross at 10MHz. The overhead per packet has to
be subtracted, i.e. the actual maximum rate depends on the frame size.
If it were right, then what might cause the gap?
Since you don't explain what you are doing, this is very hard to
tell. You would reach this theoretical throughput only if you send
frames back-to-back (which probably only works if you pregenerate
the sample stream). But also a WiFi card will insert inter-frame
space, so that the actual throughput will not match the theoretical
maximum physical layer throughput.
Best,
Bastian
One more question, I didn't run the volk_profile. Does it matter?
Best regards.
Siyu
2017-06-07 4:23 GMT+08:00 Bastian Bloessl <address@hidden
<mailto:address@hidden> <mailto:address@hidden
<mailto:address@hidden>>>:
Hi,
On 06/06/2017 03:55 PM, zhan siyu wrote:
Hi all,
I just found I can't use the iwconfig tap0 rate 20M to
setup the
bandwidth of the tap0. The error message is :
Error for wireless request "Set Bit Rate" (8B20) :
SET failed on device tap0 ; Operation not
supported.
But in their video , it can be set in this way. May I
know how
to solve it ?
The WiFi transceiver is attached to the tun/tap interface,
which is
a virtual Ethernet device. This device doesn't support
WiFi-specific
configuration through iwconfig.
If you wanted this level of integration, you would have to
write a
kernel module that attaches the transceiver to a virtual
WiFi card.
Some group already did that, but they didn't release the
source code.
Best,
Bastian