[Bloat] Bufferbloat on 4G Connexion

[David Lang]

On Wed, 23 Oct 2019, Rich Brown wrote:

> I only have a 30,000 foot understanding of this work, but it seems the use of AQL (Airtime Queue Limit) maps better onto the vagaries of 4G/5G radio transmissions than BQL. Specifically, having a measurement of the actual time it takes to transmit a packet might give additional information about the current link speed, with the potential for adjusting the codel target, etc.

The key thing in both BQL and AQL is that instead of treating all packets the 
same, you account for how long it will take to transmit them.

In Wifi, your transmission rate can vary by a factor of 1000x (1Mb to over 1Gb 
per second), so just counting bytes as BQL does is no longer good enough.

how much does the actual over-the-air transmission rate vary in 4G? I'd bet that 
it varies less than wifi does because wifi must retain compatibility with the 
earliest equipment while 4G no longer supports 2G protocols.

is it just a matter of each phone getting a smaller slice of the airtime when 
things get busy? or does the actual data rate for that slice of airtime 
decrease as well?

David Lang