WARP Project Forums - Wireless Open-Access Research Platform

Hi. everyone:

I am using a 802.11 reference design v1.2.0.
I want AP can transmit a frame (e.g beacon)at the specific time and STA can also do the  wlan_mac_low_poll_frame_rx() at the same time to receive it. just like synchronization

※ Our testing environment is using cable to replace antenna. and the cable connect 2 warpv3.

first, I modified something in v1.2:
     1. I add a timer at CPU low. so that i can use the scheduler to transmit a frame(here i use beacon(i create it at TX packet buffer 6) , and turn off beacon frame at CPU-high).
     2. I extend the beacon interval from 100us to (1min or 10sec)
     
In the original v1.2.0, the beacon go through lots of processing like enqueue, dequeue.....before PHY-TX transmit it. I want beacon to be transmitted every min. if I just extend beacon interval to 1min, it create the beacon packet every min but  it's not the way i want.  (here it's my guess, is that correct??) That's why i make this change.

Second, I record some variable:
    1. the delay of the beacon in scheduler (this one : sched_ptr->delay)
    2. the target of the beacon in scheduler(sched_ptr->target)
    3. num_coarse_checks in timer_handler()
    4. the reset value of Load register
    5. the value of Timer counter register
i add this 5 variable at the tail of the association response. when STA receive all this info,  CPU LOW  wil wait a value K
(I refer the formula you do synchronize-->timestamp_diff = mpdu_ptr_u8)->timestamp - (mpdu_info->timestamp) + PHY_T_OFFSET, so the value i assume it's
(K = the value of Timer counter register -  PHY_T_OFFSET)

then,
it will change the way CPU-LOW do wlan_mac_low_poll_frame_rx() & wlan_mac_low_poll_ipc_rx()

the original v1.2 ↓
while(1){
        //Poll PHY RX start
        wlan_mac_low_poll_frame_rx();

        //Poll IPC rx
        //wlan_mac_low_poll_ipc_rx();       
    }

the way i modified↓ (using scheduler to trigger)

wlan_mac_schedule_event_repeated(SCHEDULE_COARSE, (delay receive from ass_resp * SLOW_TIMER_DUR_US), SCHEDULE_REPEAT_FOREVER, A function);

A function(){
wlan_mac_low_poll_frame_rx()
wlan_mac_low_poll_ipc_rx()
}

here is my problem:
  1.if the beacon interval is very small, it seems like no problem, but when i extend longer like 10sec or 1min, the synchronization may not success. is there better way to
improve? or the value K i calculated it is not the good way??

2.from now on, the CPU-LOW I used DCF. or i should use NOMAC to reach my purpose??