Preamble: I don't have that much experience with lower level computer networking yet.
I am currently trying to wrap my head around the workings of the WLAN protocol. While I am starting to get the hang of how the communication between AP and stations works with the different management packets and the protocol for data fragments I am currently still not really seeing how the data is passed to the outside world.
From my understanding if a station S wants to send data to the host 188.8.131.52 (which is neither the AP nor any other station in the network) it will create some IEEE 802.11 data packets (lets assume that data needs to be fragmented into 2 data packets) and encrypt them and send them to the AP. The AP will identify the station, get its current key and decrypt it.
But what next? For example, what will my router send over my fiber cable? And how does it work with fragmentation? As far as I understand there are some rules for fragmentation in WLAN, but what if the connection between my router and its next hop could transfer much more/less? Will it do some buffering or splitting in the router?
I think all of the questions above boil down to the question in my title: What does an access point do when it receives a packet that is addressed for the outside world?