Performance simulation of 915MHz direct sequence spread spectrum system in maize fields

In terms of wireless sensor networks (WSN) for agricultural applications, whether the transceiver using direct sequence spread spectrum (DSSS) technology can meet the requirements of cropland environments needs further investigation. Using Simulink, the 915MHz DSSS system with the wireless channel in cropland environments was simulated. The clustered Rayleigh model was adopted for multipath fading, which was modified from the Saleh-Valenzuela model, and large-scale path loss model was obtained from the field test data in the cropland with maize in mature growth stage. It is found that the small-scale multipath fading affects the system performance greatly, and the DSSS system could compensate the effect of multipath fading to a certain extent. However, in the cropland with severe multipath fading phenomena, the compensation capacity was limited, and the system performance was only good (bit error rate <5%) within short transmission range (<80 m). It was very hard to meet the requirements of wireless sensor networks for agricultural information acquisition in wide-area croplands. Although spread spectrum technology has been widely employed in the design of WSN nodes, it is not an optimal solution for the agricultural applications in croplands with worse transmission environments.