Study Of Bit Error Characteristics In The Physical Layer Of IEEE 802.15.4 Protocol

Wireless sensor network(WSN) is widely used in industrial field, automotive devices,environment monitoring and many other fields for its low cost, multi-hop and easy deployment. Since the WSN devices based on IEEE 802.15.4 mainly work in 2.4GHz ISM band, the broadcast characteristic of radio channel makes it coexist with lots of wireless signal which works in the same band, and be vulnerable to all kinds of signal. Furthermore, low power consumption of WSN makes it easy to get influences of shadow fading and multipath fading during transmition. These interfrences and fadings will directly affect the performance of WSN, and result in failure of data transmission. This thesis will take transmission characteristics of PHY layer in consideration, study bit error characteristics under different environments.The research idea of this thesis can be summarized as follows, based on test data, we investigate the effects of different environments on the transmission performance. The mainly work of this thesis includes following four parts: First, we analyze the factors which cause the data frame error of the signal during transmission, and compare effects of interference or fading in different environments, which provides a theoretical basis for the post-test design. Next, we set up experimental platform, design performance metrics and select the experimental scenarios for different factors on the basis of theoretical analysis. And then, we design the test program for sending and receiving nodes by studying IEEE 802.15.4 frame filtering mechanism. Finally, we analyze the error features of different scenarios during the data transmission based on the error data frames in our experiments, the error features include bit error patterns in a packet, bit error characters between the plurality of packet continuly, etc.Our research can provide a smaller granularity reference for the designing of upper layer protocol and underlying coding, contribute new ideas to improve the network transmission performances of WSN.