Atheros HAL: Long Distance Links Notes
This is just a placeholder page for now, documenting what's required to support long distance links (and half/quarter rates) using net80211/ath/ath_hal.
Madwifi timing patch: https://dev.openwrt.org/browser/trunk/package/madwifi/patches/424-timing.patch?rev=15713
What needs to be figured out:
- The slot, IFS timings and RTS/CTS timeout values
- .. as a function of distance
- .. as a function of regulatory domain
- .. as a function of channel operation and mode
Then where that calculation should live
- .. in net80211?
- in if_ath ?
- in the HAL?
- Is it per-radio?
For HT40/HT20/half/quarter modes
- .. making sure the mac clock calculation is correct
- .. what about supporting half/quarter rates in 5ghz fast clock modes? (the PLL values are hard-coded, rather than allowing for half/quarter clk)
- .. AR9130/Howl and half/quarter rates? Same deal, hard-coded PLL values
- .. what about supporting long distance links in 5ghz fast clock modes?
- .. the Kiwi code (upcoming) has hard-coded override values for the slot/timing/timeout registers since the MAC clock isn't 44MHz (11g); figure out how to make them adjustable
- .. need to craft PHY tx rate arrays for 11na/11ng half/quarter modes
- .. does net80211 need to be taught about 11na/11ng half/quarter modes? (what channel set does IEEE80211_MODE_HALF / IEEE80211_MODE_QUARTER assume? It only supports OFDM rates at least, even in 11g mode.)
- .. ath_rate_sample needs to be taught about 11na/11ng half/quarter modes?