Both IEEE 802.15.4 and 802.15.4a standards allow for dynamic channel allocation and use of multiple channels available at their physical layers but its MAC protocols are designed only for single channel. Also, sensor's transceivers such as CC2420 provide multiple channels and channel switch latency of CC2420 transceiver is very short just about 200 micro seconds. In order to enhance both energy efficiency and to shorten end to end delay, we propose, in this report, a new MAC protocol allowing multi-channel allocation for 802.15.4a compliant devices.