A star-topology sensor network system for agriculture using 802.15.4k standard

This paper introduces a sensor network with star topology for agriculture applications in Japan. The system is based on Direct Sequence Spread Spectrum (DSSS) PHY of the IEEE 802.15.4k standard. It will operate It can operate in 920-928 MHz band with MHz bandwidth according to Japanase regulations. According to our analysis it has a range of 20 kms in line of sight and 5 kms in none-line-of-sight environment. In addition, we investigated the impact of co-channel interference (CCI) from a smart utility network transmitter with 200 kHz bandwidth based on IEEE 802.15.4g standard specifications to our system. Our results indicate that at desired to undesired signal (D/U) ratios more than 6.8 dB, our network can operate successfully at an E_b/N₀ of 5dB without the need of spreading. A spreading factor of 1024 protect 802.15.4 link up to D/U ratios of -55dB and sensor system can reduce the area that 802.15.4g effectively interfere by 10⁶ times compared with no spreading.