As the commercials say - 5G(Fifth Generation) networking is here. Why is that a big deal? One appealing aspect: How do you like getting multi-gigabit bandwidth to your mobile device(s)?
How does that work? For the first time in commercial mobile networking history a vast untapped spectrum has been made available for mass user consumption in the millimeter wave length range; in the 5G world it is refered to as "mmWave". The spectrum in mmWave links makes possible the multi-Gbps data rates on the 5G cellular networks.
The problem with mmWave links is they are, like most high-frequency signals, susceptible to blockage. Basic obstructions like trees, snow, rain, buildings, etc interfere with the signal. A technique called beamforming helps but doesnt solve the problem entirely.
To put this in context: Think of having a link that is very high speed but is constantly fluctuating in capacity. Then the question is: "How does TCP congestion control work in this kind of setup?"
In this talk Feng Li, Jae Won Chung and Jamal Hadi Salim[1] will present results of a study to evaluate how various Linux TCP congestion control algorithm implementation fare over mmWave links. The authors claim this is _the first ever_ such study on a real commercial 5G network! The study was carried on the Verizon 5G deployment network.
Feng et al will present data on comparing popular TCP congestion control algorithms, including NewReno, Cubic, BBR and BBRv2 (prepatch) etc. The results show that the performance of TCP on mmWave links is still highly dependent on the combination of TCP algorithm and socket buffer sizes.
Without a doubt mmWave links impose new challenges on future transport layer design and the authors hope this talk will incentivize more discussions in the community.
[1] Refered to in the third person.
More info: https://netdevconf.info/0x14/session.html?talk-preliminary-evaluation-of-TCP...
Reminder, registration is now open and early bird is still in effect. https://netdevconf.info/0x14/registration.html
cheers, jamal