Re: [Discuss-gnuradio] gr-ieee 802.11 and commercial AP (late ACK packets)

[Marcus Müller]

From a CPU and thus, SDR _software_ throughput, point of view, the E310 certainly isn't more powerful than a modern laptop + B2xx; latency might be a bit shorter, though, but in the end, you're making the most important point here:

If you need to eradicate the nondeterministic behaviour of general purpose operating systems running on general purpose computing hardware (such as Linux or Windows on a PC or the Zynq's ARM), you can only do two things:

1. Have enough leeway for timing, so that you're *always* faster than you need to be, or

2. doing the timing-sensitive stuff directly on dedicated realtime environments, which in this case means the FPGA.

Cheers,

Marcus

On 03/29/2017 10:27 PM, Saulo Queiroz wrote:

An interesting question is whether more powerful SDR (e.g. E310) should manage to do that (DATA+SIFS+ACK).

RFNoC may facilitate the FPGA design...

2017-03-29 17:19 GMT-03:00 Bastian Bloessl <address@hidden>:

Hi,

On 03/29/2017 01:11 PM, sumitstop wrote:
> Hi,
>
> With gr-ieee 802.11, I know that SIFS cannot be respected becz of USB delays
> (B210), but what we can also try is that : sending ACK packet before all the
> layer-2 retries are exhausted ! Instead of sending ACK withing 10 microsecs.
>
> In this way, the throughput will be down for sure but the device can
> communicate with a commercial 802.11 AP.
>
> I was wondering if anyone tried like this and I can get some heads up.
>

It's not only about sending fast enough, but mainly about sending at the
right point in time (i.e. immediately after a frame). Since the SDR
doesn't do channel sensing on the FPGA, this is at least not
straightforward.

Best,
Bastian

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--

Saulo Jorge bq
- "Beware of bugs in the above code; I have only proved it correct, not tried it." 

Donald Knuth.

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