iPhone 11 Airdrop speed

imp3rator

macrumors 6502
Original poster
Dec 25, 2019
263
173
I use airdrop between iphone 11 and macbook pro 2019 - average transfer rate is 33 MegaBytes/s - so it's like 802.11n network transfer speed. I didn't connected to wi-fi network so it was in ad-hoc mode. Why they didn't use 802.11ac network speed (about 70 megabytes/s) ?

Do you have a higher transfer speed rates via airdrop than 30-40 Megabytes / s ?
 

cynics

macrumors G4
Jan 8, 2012
11,586
1,884
AirDrop always uses its Ad-hoc mode regardless of current network connection. Like all non infrastructure mode networks there is a lot of overhead (computational overhead, contention overhead, protocol overhead, packet loss, etc)

Apple then does their security thing with two authentication checks (first is a glance, second is thorough) for the contact you are going to AirDrop with, sets up a firewall around the newly created network and encrypts all the data thats sent via 2048-bit RSA encryption.

Considering Wifi-Direct and other Ad-hoc system max throughput, 33 MBps isn't that bad (I could be wrong but isn't wifi direct 250 Mbps?).

This is my MBP sending my iPhone 11 a large single file (many smaller files have a lot more overhead) with the iPhone sitting on it.
Screen Shot 2020-03-13 at 11.12.31 PM.png

476 Mbps

I wouldn't expect much higher than 20-30 MBps in more realistic use though. Wifi broadcast between two low power device is anemic at best. Inches make a difference in transfer rate and that makes the transmission more susceptible to interference. Wifi routers naturally broadcast and receive wifi signals 20-30x better just due to their hardware and design (exposed antenna arrays) plus they used 20-30x more power on top of that. Even with an iPhones wifi maxed its got a lot going against it when it comes to making an ad hoc wifi network.

Excluding security the priorities of the AirDrop protocol were latency to establish transfers and then throughput. If it doesn't work immediately people give up, I know I have. But generally it sees the client via an authentication process, establishing communication to authenticate the client thoroughly, establishes a wifi network, secures it, transfers the file, closes the connection all in a matter of seconds. For photos and small video transfers its perfect. Large files will admittedly leave you wanting more though.
 
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imp3rator

macrumors 6502
Original poster
Dec 25, 2019
263
173
Wow this is best explanation thus far. But what is the fastest way to transfer data to / from iphone ? Because usb 2.0 (lightning) is similar to 30 MB/s as airdrop... If lightning supports usb 3.0 - probably 200 MB/s will be average...
 

cynics

macrumors G4
Jan 8, 2012
11,586
1,884
Wow this is best explanation thus far. But what is the fastest way to transfer data to / from iphone ? Because usb 2.0 (lightning) is similar to 30 MB/s as airdrop... If lightning supports usb 3.0 - probably 200 MB/s will be average...
Afaik AirDrop lol
 

imp3rator

macrumors 6502
Original poster
Dec 25, 2019
263
173
So buying a 512GB for using e.g. half 256GB as handy flash drive is useless (and quite expensive) - it is good only for synchronized or one-time stored content (video, music etc.)

USB Flash drive 512GB is for 72 EUR and give better speed in USB-C (USB 3.1).

I just doing research about that.
Am I right ?
 

imp3rator

macrumors 6502
Original poster
Dec 25, 2019
263
173
OK i tested some scenarios.

Airdroped 3,5 GB mkv file - peak 65,5 MB/s, average 45-50 MB/s (so 400-500 mbit data transfer for encrypted connection is really quite good as you mentioned)
Airdropped mp4 file - saved automatically to photos - save from photos to vlc folder (because of subtitles)
Airdropped .srt file - automatically opened vlc after transfer but subtitles is not saved in folder. So I must transfer subtitles via VLC Wi-Fi transfer with same name.

And one "bug" in VLC - if you resize movie into display - subtitles is below screen and you can not set position...

EDIT : I found that

"The expanded LTE connectivity on the iPhone 6 and iPhone 6 Plus is improved to LTE Advanced, with support for over 20 LTE bands (seven more than the iPhone 5s), for up to 150 Mbit/s download speed, and VoLTE support. Wi-Fi performance has been improved with support for 802.11ac specifications, providing speeds up to 433.0581 Mbit/s—which is up to three times faster than 802.11n"

EDIT 2 :
So iphone 11 support Wifi 6 (802.11ax) but macbook pro 2019 not :rolleyes:
 
Last edited:

cocoua

macrumors 6502
May 19, 2014
328
147
madrid, spain
AirDrop always uses its Ad-hoc mode regardless of current network connection. Like all non infrastructure mode networks there is a lot of overhead (computational overhead, contention overhead, protocol overhead, packet loss, etc)

Apple then does their security thing with two authentication checks (first is a glance, second is thorough) for the contact you are going to AirDrop with, sets up a firewall around the newly created network and encrypts all the data thats sent via 2048-bit RSA encryption.

Considering Wifi-Direct and other Ad-hoc system max throughput, 33 MBps isn't that bad (I could be wrong but isn't wifi direct 250 Mbps?).

This is my MBP sending my iPhone 11 a large single file (many smaller files have a lot more overhead) with the iPhone sitting on it.
View attachment 899020
476 Mbps

I wouldn't expect much higher than 20-30 MBps in more realistic use though. Wifi broadcast between two low power device is anemic at best. Inches make a difference in transfer rate and that makes the transmission more susceptible to interference. Wifi routers naturally broadcast and receive wifi signals 20-30x better just due to their hardware and design (exposed antenna arrays) plus they used 20-30x more power on top of that. Even with an iPhones wifi maxed its got a lot going against it when it comes to making an ad hoc wifi network.

Excluding security the priorities of the AirDrop protocol were latency to establish transfers and then throughput. If it doesn't work immediately people give up, I know I have. But generally it sees the client via an authentication process, establishing communication to authenticate the client thoroughly, establishes a wifi network, secures it, transfers the file, closes the connection all in a matter of seconds. For photos and small video transfers its perfect. Large files will admittedly leave you wanting more though.
very impressive, thanks

I work with large video recordings on iPhone and I'm annoyed iPhone has so slow data transfer
protocols, USB2 or WIFI, is incomprehensible and a shame.
 
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