TDMA slot(bh)

[Adrian Chadd]

The whole point here is that DBA is used to control the start of the
slot times, and SWBA is used to only send out actual beacon frames in
multiples of that.

normally you'd have SWBA be just before DBA, and and they'd have the
same interval.

Here DBA is used primarily to gate the start of the slot time for that
particular device, and it only bothers sending the beacon frame every
'tdmaswba' DBA intervals. The beacons are used to announce that the
device is there and to update RTT estimates; it's not doing anything
like gating broadcast traffic.



-adrian


On 18 February 2015 at 09:55, 子文 <u8j9 at 163.com> wrote:
> Dear Adrian
>    In HAL_INT_SWBA handler of ath_intr funtion . What means tdmaswba? I found the tdmaswba default is five  and when it decrease to zero ,the ap  will send out the beacon package. From here I fell every SWBA is the start of the slot?
>
>
>
>
> --
> 发自我的网易邮箱手机智能版
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>
> 在 2015-02-19 01:28:38，"Adrian Chadd" <adrian at freebsd.org> 写道：
>>Yup.
>>
>>DBA gates the actual beacon transmit - if there's no beacon in the
>>slot, then it's fine.
>>
>>SWBA is the software timer that fires just before DBA, so the software
>>stack has a chance to program the hardware with a beacon and let the
>>hardware get the packet DMA -> TX FIFO setup all correctly so that
>>when it's DBA time (ie, time to /transmit/ the beacon), it's already
>>ready to go.
>>
>>
>>-adrian
>>
>>
>>On 18 February 2015 at 09:09, bh <u8j9 at 163.com> wrote:
>>> Dear Adrian
>>>       In ath_intr , there are a variable which decrease every swba, so when the variable swbaintalval is zero, ap will send beacon .So I  think the period of swba is slot time,  ap will send beacon every five slot, the beacon interval is five slottime?
>>>
>>> Adrian Chadd <adrian at freebsd.org>编写：
>>>
>>>>On 18 February 2015 at 07:55, bh <u8j9 at 163.com> wrote:
>>>>> Dear
>>>>>     The default slotcnt=2 , becntival=5.For ap  it will generate SWBA every  slot,it will send beacon every five slots, beacause ap fire  the DBA timer in every slot, so it will send data package  in every slot. Is my above understanding correct?
>>>>
>>>>It generates SWBA every beacon interval, which is calculated in
>>>>ath_tdma_bintvalsetup().
>>>>
>>>>Master stations beacon 20 times a second with the default config
>>>>specified by the wiki.
>>>>
>>>>
>>>>-adrian