Research And Implementation Of Key Technology Of The Physical Layer Of A Multi-node Broadband Wireless Personal Area Network

The wireless personal area network is a small wireless network around the area of the human body,which has a wide range of applications in the fields of military,medical,sports training and consumer electronics.In typical wireless personal area networks,such as Bluetooth,Zig Bee and other systems,users can interact with the main console with voice,video,image and other information through multiple electronic devices they wear.With the improvement of users'requirements for communication rate,wireless personal area network systems are also faced with the challenge of high-speed data transmission.Therefore,this paper designs and implements a physical layer scheme of the multi node high-speed wireless personal area network with 60MHz bandwidth.The main research contents of this paper are as follows:Firstly,the application scenarios and demand indicators of the wireless personal area network are analyzed in detail.The wireless channel is identified as the CM4 channel defined by IEEE 802.15.6,and the path loss model and the power delay distribution model are used to describe the channel characteristics.At the same time,various performance indicators that the physical layer baseband link needs to meet are given,and the requirements of transmitter transmitting power not less than-30d Bm and receiver resisting frequency offset above 3000Hz are put forward.Secondly,an uplink and downlink physical layer transmission scheme based on OFDM system is designed.The design of key technologies such as sub-carrier mapping,time-frequency synchronization,channel estimation,channel equalization and coding and decoding in the transceiver is completed.At the same time,the principle of multi-node uplink synchronization technology is analyzed and an uplink synchronization frame based on cyclic shift ZC sequence is designed.The whole process of uplink synchronization is described,and the processing flow of key modules in uplink synchronization is given.Thirdly,under the condition of 4000Hz frequency offset,the performance and analysis of the link in Gaussian channel,4-path Rice channel and 7-path Rice channel are completed.The results show that for the downlink,in the Gaussian channel,when the SNR is higher than 14d B,the bit error rate drops to10^-6,and the bit error rate performance under the two Rice channels is worse than that of the Gaussian channel by about 3d B and 5d B,respectively.For the uplink,because each user is affected differently by deep fading,its bit error rate is different.When the SNR is greater than 21d B,all users can communicate normally.The time synchronization algorithm selected by the link can achieve a capture probability of more than 99.9%under the condition that the false alarm probability is lower than 0.1%.The residual frequency offset of the frequency synchronization algorithm above the demodulation signal-to-noise ratio is less than100Hz.Fourthly,the hardware platform of Zync-XC7Z035 chip+AD9371 RF front-end is built,and the overall scheme of the uplink and downlink physical layer link implementation is given.The implementation methods of the downlink framing,downlink time synchronization,frequency synchronization and TA estimation are analyzed,and the performance and function of the physical layer are tested.The test results show that the indicators of the two-way transmission system can meet the design expectations.The downlink peak service rate is 80Mbps and the uplink single user peak service rate is 19.1Mbps.All users can successfully synchronize with the central node.This paper proposes a two-way link transmission scheme for multi node broadband wireless personal area network,which has a certain reference value for the engineering implementation of the physical layer of multi node,high-speed and broadband wireless personal area network.