Well, in 802.11 polling is to do QoS.
It send the frames in allways in a specific time, no one in 0.1 nano, the other 0.3 before another in 0.2..... it´s allways like 0.2, 0.2, 0.2..... i don´t know if it´s in frequency or the packges but it´s something like this....
i´m right??