An apparatus has a first communication module that is compatible with a first wireless communication technology, and a second communication module that is compatible with a second, different, wireless communication technology. Transmissions by each communication module may contribute to interference at the other communication module. In one example, a Block Acknowledgement Request is transmitted by the apparatus during a downlink period of the second communication module so that the Block Acknowledgement transmitted in response is received during the downlink period. In another example, the apparatus calculates a maximum size of A-MPDU to receive and notifies an access point of that maximum size. In a further example, the apparatus, having notified an access point of operation in a power save mode, polls the access point for buffered frames at the start of a downlink period of the second communication module.