A communication apparatus is provided. A processor camps on a first cell, which is associated with a first radio access technology (RAT) and belongs to a first wireless network, via a radio transceiver module, and further camps on a second cell, which is associated with a second RAT and belongs to a second wireless network, via the radio transceiver module. The processor constructs a first packet switch connection with the first wireless network via the first cell to perform data transfer in the first wireless network, measures a first data transfer throughput of the first wireless network when performing the data transfer via the cell, and determines to perform the data transfer in the second wireless network via the second cell when a theoretical data transfer throughput corresponding to the second RAT is higher than the first data transfer throughput.