Wi-Fi transmits frames outside BlockAck window

This condition is triggered in wifi-manager-example.cc: https://gitlab.com/nsnam/ns-3-dev/blob/661c12280bc38128010b4b643222b8687ea2697d/src/wifi/model/mac-low.cc#L2379

It means that transmitter sends frames outside the BA window, and the window advanced not because of BA request. It should not happen normally.

It happens because:

1. MpduAggregator::GetNextAmpdu incorrectly calculates BA window start. Instead of asking BA manager, it tries to extract this sequence from the first packet in A-MPDU. If there are outstanding frames, it is not correct. See MR !49 (closed)

2. QosTxop does not check if the window is stalled. The sequence may be outside the window in NotifyAccessGranted: https://gitlab.com/nsnam/ns-3-dev/blob/661c12280bc38128010b4b643222b8687ea2697d/src/wifi/model/qos-txop.cc#L256 Also, if TXOP is enabled, it may happen in QosTxop::StartNextPacket: https://gitlab.com/nsnam/ns-3-dev/blob/661c12280bc38128010b4b643222b8687ea2697d/src/wifi/model/qos-txop.cc#L975 I don't have fixes for these cases, and there may be others.