Re: [Discuss-gnuradio] MAC layer questions

[Andre Puschmann]

On 07/06/2011 07:33 PM, Morgan Redfield wrote:
> I'm still working on my MAC, and there's a lot of room for
> improvement. At the moment, I get throughput of about 1kbps. What kind
> of throughput are you getting?

In a setup of two nodes we have a end-to-end throughput (measured using
iperf using TCP as transport protocol) of around 150-200 kbps. But that
certainly depends on physical layer parameters as well. At the moment we
use a sampling rate of 1Mbps and Bpsk modulation.
Parameters still need to be fine-tuned (SIFS, DIFS, etc.), so there is
definitely room for improvements. What PHY are you using?

Regards,
Andre



> 
> Andre and George, thanks for pointing me to those papers. I'll look
> through them and see if I can figure out any ways to improve my MAC.
> 
> Morgan
> 
> On Tue, Jul 5, 2011 at 4:30 AM, Andre Puschmann
> <address@hidden> wrote:
>> On 07/01/2011 03:16 AM, Morgan Redfield wrote:
>>> Hi,
>>>
>>> I've been working on building a CSMA/CA MAC for the past couple of
>>> weeks. I built it in Python, and used ofdm/tunnel.py as a guide. It's
>>> working now, but I don't think it's very efficient. I ended up having
>>> to relax a lot of timing parameters to get it working, so my
>>> throughput is pretty bad. I also get a lot of dropped packets. I think
>>> this is also because my timing isn't very accurate, and I end up with
>>> more collisions than I would expect.
>>>
>>> I was wondering if anyone else had had any luck building a CSMA/CA
>>> MAC. I saw a few posts on the mailing list from several years ago
>>> about people who were working on it, but I don't see any example code
>>> anywhere. I also checked out CMUmacs on CGRAN, but that relies on a
>>> deprecated version of GNURadio.
>>>
>>> Is my best bet to rewrite the MAC as a block in C++? Can anyone tell
>>> me what kind of speedup that's likely to get me?
>>>
>>> Thanks,
>>> Morgan Redfield
>>
>> Hi Morgan,
>>
>> we are also working on a CSMA/CA MAC here using a SDR software called
>> Iris (I know that's the GNU radio list but problems are pretty much the
>> same in terms of timing). The implementation is still not perfect but we
>> got some nice results already.
>>
>> May I ask you about the throughput of your system? I would really like
>> to compare them with our setup.
>>
>> There is also another paper titled "An IEEE 802.11 MAC Software Defined
>> Radio Implementation for Experimental Wireless Communications and
>> Networking Research" which might be of interest for you.
>>
>>
>> Regards,
>> Andre
>>
>>
>> --
>> André Puschmann
>> Ilmenau University of Technology, Integrated Communication Systems Group
>> Phone: +49 3677 69-4132, Fax: +49 3677 69-1614
>> Email: address@hidden, Web: http://www.tu-ilmenau.de/ics
>> Office: Zuse Building, room 1071
>>
>>
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-- 
André Puschmann
Ilmenau University of Technology, Integrated Communication Systems Group
Phone: +49 3677 69-4132, Fax: +49 3677 69-1614
Email: address@hidden, Web: http://www.tu-ilmenau.de/ics
Office: Zuse Building, room 1071