A method comprising: receiving downlink data via a radio interface of a second access point; causing uplink feedback information to be transmitted via a radio interface of a first access point, the uplink feedback information being associated with the received downlink data, wherein: • a protocol entity is responsible for reliable downlink data transmission via the radio interface of the second access point only, wherein the protocol entity is a packet data convergence protocol entity, a stream control transmission protocol entity, or a radio link control protocol entity, • another protocol entity is dedicated for handling downlink data transmissions via the radio interface of the first access point only, • the first access point is associated with a first network and the second access point is associated with a second, different, network, wherein the first network is a cellular network and the second network is a wireless local access network, • the first access point and the second access point co-operate in radio aggregation, and • the uplink feedback information is acknowledgment feedback information for the downlink data transmission via the radio interface of the second access point. receiving downlink data via a radio interface of a second access point; causing uplink feedback information to be transmitted via a radio interface of a first access point, the uplink feedback information being associated with the received downlink data, wherein: • a protocol entity is responsible for reliable downlink data transmission via the radio interface of the second access point only, wherein the protocol entity is a packet data convergence protocol entity, a stream control transmission protocol entity, or a radio link control protocol entity, • another protocol entity is dedicated for handling downlink data transmissions via the radio interface of the first access point only, • the first access point is associated with a first network and the second access point is associated with a second, different, network, wherein the first network is a cellular network and the second network is a wireless local access network, • the first access point and the second access point co-operate in radio aggregation, and • the uplink feedback information is acknowledgment feedback information for the downlink data transmission via the radio interface of the second access point. • a protocol entity is responsible for reliable downlink data transmission via the radio interface of the second access point only, wherein the protocol entity is a packet data convergence protocol entity, a stream control transmission protocol entity, or a radio link control protocol entity, • another protocol entity is dedicated for handling downlink data transmissions via the radio interface of the first access point only, • the first access point is associated with a first network and the second access point is associated with a second, different, network, wherein the first network is a cellular network and the second network is a wireless local access network, • the first access point and the second access point co-operate in radio aggregation, and • the uplink feedback information is acknowledgment feedback information for the downlink data transmission via the radio interface of the second access point.