Maximizing 802.11b throuput

Christian Zoffoli merlin at studiobz.it
Fri Mar 14 08:42:21 EST 2003


André Luiz Ribeiro Moutinho wrote:
> Hi,
> 
> I am implementing a realtime video streamming application using
> 802.11b in order to transmit video data.
> Transmitting MJPEG 320x240 at 30fps and 40% quality results a
> 3Mbit/s total bandwith. When I try to increase the video data
> bandwith (for instance, rising JPEG quality), the radio channel starts
> failing to transmit all video information. I would like to know what
> is the REAL 802.11 data transmittion throuput (4 or 5Mbit/s ??) and
> what could be done in order to maximize the data throuput. For instance,
> trying to optimize the transmitted data block size.
> I need to use the maximum data bandwith available in order to transmit
> the maximum mount of video sessions possible.
> 
> Thanks a lot,
> 
> Andre Moutinho
> 


I have a ~ 5.30 MBps on this setup:

(Channel 1)

O----------------0<-------------->0-------------------0
Sender          router1  wvlan  router2              receiver

####

5.20 + 5.10 Mbps  (Channel 1 + Channel 9)  [same antenna, single pol, 
without load balancing]

Note:
* on the left side I have 2 special filters 5+4 cels each and a single 
antenna
* on the right side I have 2 std filters 5 cels and 2 antennas (without 
the right filters I can't branch 2 channels with a right separation).

O----------------0<-------------->0-------------------0
                  O<-------------->O
Sender          router1  wvlan  router2              receiver

####

7.4 - 8 Mbps  (Channel 1 + Channel 9)  [same antenna, single pol, with 
load balancing TEQL ]

Note: ...same as ^


O----------------0<-------------->0-------------------0
                  O<-------------->O
Sender          router1  wvlan  router2              receiver


####

The big problem on your setup is the lack of DMA trasfer between the 
card and the processor. I hope in the next generation (aka 802.11g/a 
cards) and obviously in the hostap driver.

Does anyone know a way to sincronize the cards (2 cards transmitting at 
the same time) ?

Regards,
Christian




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