In a wireless 802.15.4 communication system, a method and system are provided for switching between a predetermined protocol transmission mode and a high-speed transmission mode by including signaling mode information in a data packet (330, 340) to instruct the receiver device (300) to demodulate at least a data payload using the predetermined transmission mode if the signaling mode information comprises a first predetermined value, and to demodulate at least the data payload using the high-speed transmission mode if the signaling mode information comprises a second predetermined value. The signaling mode information may be included in the SFD field of an 802.15.4 SHR structure to instruct the receiver how to demodulate or process the data packet, or may be included as desired anywhere in the data packet to instruct the receiver how to demodulate or process one or more subsequent data packets.