Research And Design Of SoC For Wireless Sensor Networks

Wireless sensor network(WSN) is a combination of the computing ,communications and sensor technology.It is also a new type of information acquisition and processing based on micro-electromechanical systems (MEMS),System on Chip (SoC) and wireless communication technologies.The traditional sensor node has high power consumption,big size and costs more.So we decide to design a SoC for WSNs which has good performance in power consumption,size and cost.The existing Spruce is chosen as the radio frequency chip which has low power consumption . And a low-power microprocessor called MSP430F1161 is also uesd.Spruce has very low power consumption,but its baseband processing capacity is weak,so the paper focuses on the function improvement of RF chip baseband.In order to improve the reliability of data transmission,the paper brings the use of RS code to correct errors in the channel.In order to effectively resist interference,the paper adds spread spectrum to the baseband.After detailed analysis and comparison,the direct-sequence spread-spectrum(DSSS) approach is selected and Gold sequence is chosen as the PN code.There is GFSK modulation in the Spruce,which has high modulation rate and good spectral characteristics.However,in the low SNR,GFSK cannot work well.And QPSK has good performance in the low SNR.So the paper adds QPSK modulation to the baseband working with GFSK.The system will determine one kind between GFSK and QPSK based on the actual transmission environment. So that the SoC can be configured to achieve a multi-mode modulation.In the paper,we also design a detailed implementation program for each module and achieve that with FPGA to verify the correction of the function and timing.