An access point includes an antenna module, a wireless network module and a processor, wherein the processor includes a plurality of Modulation and Coding Scheme code (MCS) codes supported by the electronic device. When the access point operates in a training stage for determining at least one optimal antenna adapted to the electronic device, the processor uses a specific MCS code from the plurality of MCS codes to transmit the plurality of training packets to the electronic device via the antenna module and the wireless network module without switching the other MCS codes for determining the at least one optimal antenna adapted to the electronic device.