Very high packet loss UDP with Apple Iphone 4

[jonshouse]

ESP8266 Seems to have a power management or fundemental low level network bug when peered with an Iphone 4

UDP Broadcast packet transmission from an ESP8266 to Iphone4 result in >75% packet loss.

To reproduce use:
AT+CIPMUX=1
AT+CIPSTART=4,"UDP","255.255.255.255",48899

Now send 1 packet per second using AT+CIPSEND

Not all the Iphones seem to suffer as badly, but the Iphone4 is the worst.

On the Iphone4 run a UDP receiver, note the VERY large packet loss. Other devices (including Ipad) show a much lower packet loss.

Using another peer (at the same time) with the ESP module and run a packet sniffer, I find a PC laptop at 1 meter gives a packet loss from the same sender of almost zero, an Iphone at the same distance (1 meter) will give very high packet loss. Note this is only true for UDP broadcast packets.

Thanks,
Jon

[Triacon]

Hi
Just some thoughts. When developing an IOT device with IOS controller app we also found that there was problems with high UDP packet loss.
And this wasn't with an ESP8266 but a CC3000, so I would guess that the problem is in IOS, as is also suggested by the fact that the PC got all the packets.
IA quick google also show other people having the same problems.
Kind regards
Jimmy

[jonshouse]

so I would guess that the problem is in IOS

Yes, I thought the same at first. But then I tested Iphone to Iphone, Ipad to Iphone etc and found very low packet loss.

It seems (so I am told) that the Wifi module advertises a power saving mode that then fails to fully comply with, I dont know enough to prove this one way or the other but it does fit with the tests I have done. For example ESP8266 peered with the newer Android device also seems to suffer high packet loss, nothing apple in that equation.

I picked ESP8266 with Iphone4 as this has the highest packet loss, around 75% go missing !

If I program the Iphone to send a dummy UDP frame every few ms with calling recvfrom() then the packet loss rate drops back to almost zero. See "usehack" referemce in the UDP demo I made to argue with Apple.

http://www.jonshouse.co.uk/UDP-TESTS.tar.gz

Thanks,
Jon

[freerock]

Jon,

Excellent information, thank you! This is exactly what I have been trying to figure out with the UDP packet loss I have been seeing.

Kevin