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Proposal for Wireless Networking Micro-conference at Linux Plumbers Conference 2014 in Düsseldorf, Germany…

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Wireless Networking Microconference Notes

Welcome to Linux Plumbers Conference 2014.

The structure will be short introductions to an issue or topic followed  by a discussion with the audience. A limit of 3 slides per  presentation is enforced to ensure focus and allocate enough time for  discussions. 

Please use this etherpad to take notes. Microconf leaders will be giving a summary of their microconference during the Friday afternoon closing session.
Please remember there is no video this year, so your notes are the only record of your microconference.


1:30 -- What's missing for Miracast? -- David Herrmann
miracast = wireless display, essentially
demo - using laptop as sink (projector), phone as source
software built using wpa_s
few ms delay (demo with game)
low framerate (30fps)
his software also implements the source side
his implementation shows up the data as a separate GPU which is problematic for the current UI stack, Wayland helps here
different USB wifi devices failed horribly, demo using Intel PCIe, only one USB (Atheros) worked at all
why separate GPU - why not use virtual output from GPU? should be supported and let the GPU encode the stream? implementation is also providing userspace APIs to bypass decode/encode

what really is missing?
 - supplicant that works - e.g. P2P_DEVICE support can cause spurious errors
 - NetworkManager/Connman support for P2P (the latter is WIP)

1:45 -- Extremely high speed and high coverage home wifi -- Avery Pennarun
2:00 -- Cloud-based wireless packet capture, sharing, analysis, and diagnosis -- Avery Pennarun
"How we're doing WiFi @Google Fiber"
problem of selling gbit service - wifi is too slow, WAN faster than LAN
no longer a question of whether customers will be disappointed or not, just a matter of how disappointed :)
wifi speeds drop with distance - so now APs in each TV box; this causes problems roaming - measures latency in http session, can do DNS queries
new version will record & upload the data for customer support purposes
other tool: isoping to measure upstream/downstream latency/jitter - upload pcap (radiotap headers) and show 802.11 data graphed
q: bufferbloat, how does it affect you?
a: when things are going well the systems often can't even catch up with the wan link so not a problem there; solutions to bufferbloat all on ethernet so far but wifi is really what they need, where it's a much harder problem
network stack may have to be changed to deal with more dynamic queues due to changing stations/link conditions

2:15 -- Break

2:30 -- AP Group Features -- Helmut Schaa
AP group is a set of APs managed centrally, a lot of problems could be solved with such a framework if it were to exist
proposal to create a new protocol specific to hostapd for cooperation between APs

2:45 -- "Minstrel-Blues" - Practical Joint Rate und Power Control in Linux mac80211 with todays 802.11b/g/a/n Chips -- Thomas Huehn
rate control algorithm that incorporates tx power adjustment to reduce interference
modifications to minstrel, working w/ ath5k & ath9k
new mac80211 driver flags for power control capabilities
current work to extend to minstrel_ht

3:00 -- generalized firmware coredump support  -- Johannes Berg
framework merged in 3.18
register a buffer or method for access
creates device_coredump device class in sysfs
implemented in iwlwifi
not specific to wifi drivers

3:15 -- Break

3:30 -- randomized MAC address scanning -- Johannes Berg
originally from Apple (keybote), helps with privacy concerns
implementation in hostapd
When to randomize?  randomization breaks some use cases
only when not associated?  pre-association exchanges
should not be enabled by default -- end user option?  probably...

3:45 -- Batman mesh -- Simon Wunderlich
overview of l2 mesh technology, generally used w/ wireless networking
mesh connection based on ad-hoc links
protocol decisions based on packet loss (OGMv2)

4:00 -- 802.11s mesh -- Kathy Giori
new life for 802.11s, QCA acquired copyrights from Cozybit for firmware (could be used in ath10k)
some implementations can work better by breaking the spec slightly -- will we accept patches?  (likely yes, not guaranteed)

4:15 -- regulatory -- Luis Rodriguez
efforts to push CRDA functionality into the kernel
timing issues exist w/ userland implementation, some use the in-kernel static database instead
use in-kernel signing infrastructure to validate rules database BLOBs coming from userland
en/developers/summits/duesseldorf-2014.txt · Last modified: 2015/01/26 09:49 (external edit)