*3.1. System Architeture*

Figure 1 is the implementation platform of Texas Instruments CC430F6137. The network architecture is a simple star scheme, as shown in Figure 2, and the frequency-shift keying (FSK)/Gaussian frequency-shift keying (GFSK) was selected as the radio modulation method. The network consisted of multiple sensing nodes and a central bridge. The bridge was supplied by grid power and the sensor nodes were supplied by the battery. The placements of the bridge and nodes are shown in Figure 3. The bridge received packet from the nodes, and it was connected by cable to a gateway. The exact position is shown in Section 6.1. The TDMA protocol was proposed in this system, and the data rate and transmission power control algorithms were used to reduce the power consumption of the node to extend the battery life.
