high RTT in 40 MHz channel width

[Jose Núñez-Martínez (CTTC)]

Hi all,
just to clarify, results are ms. And stations are in IBSS mode.

BW 20 MHz: TCP 0.9ms UDP 1.1ms
BW 40 MHz: TCP 7.7ms UDP 1.3ms
BW 80 MHz: TCP 3.5ms UDP 1.3ms

Behavior with 40MHz and 80MHz channel bandwidth is really weird taking 
into account there are no retransmissions. Anyone facing this kind of 
problem?

Thanks,
Jose

On 04/29/2016 07:12 PM, Iñaki Pascual wrote:
> Hi,
>
> I am measuring TCP and UDP latency (actually RTT) and I am getting too 
> high values when working with channels with 40MHz (also with 80MHz) 
> width.
>
> I am using hping3 for testing and these are the RTT avg values:
>
> BW 20 MHz: TCP 0.9 UDP 1.1
> BW 40 MHz: TCP 7.7 UDP 1.3
> BW 80 MHz: TCP 3.5 UDP 1.3
>
> I have tried different channels with similar results. According hping 
> there are no packet loss and with wireshark I don't see any 
> retransmission.
>
> I am using:
> driver: ath10k_pci
> version: 4.2.0+
> firmware-version: 10.1.467-ct-com-full-014-96d543
>
> Any ideas?
>
> Bests,
>
> Iñaki
>
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-- 
Jose Núñez-Martínez, PhD
Senior Researcher   email: jose.nunez at cttc.cat
COMNET Division     Web: http://networks.cttc.cat

Centre Tecnològic de Telecomunicacions de Catalunya (CTTC)
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