Research On Application Of Intra-body Communication In Multi-nodes Physiological Signal Acquisition And Transmission System

With the increasing applications of wearable/implantable information service, the techniques of Wireless Body Area Network are widely applied in near-field communication between medical sensors. The intelligent sensors which attached on body or implanted in body continuously monitor critical physical and physiological parameters such as glucose level, blood pressure and electrocardiogram (ECG) signal. Low power, low-radiation and high transmission efficiency are required in the communication method in WBAN. Because of the high power consumption, high electromagnetic interference and low security, the radio frequency (RF) techniques such as blue tooth and Zigbee are not the optimal choice in the application of WBAN. Intra-body Communication (IBC) utilizes the human body as a data channel to share information between the medical device. Due to the extremely low frequency and its implementation process is not affected by the surrounding environment, the IBC technology conquered the defects of RF above and has more extensive application circumstance in the Wireless Area Body Networks.In this paper, a method to investigate the application of Intra-body Communication in WBAN was provided. Based on the existing MAC protocols, the propagation properties of human body channel and the hardware characteristics of the node was studied to constitute a multi-nodes physiological signal acquisition and transmission system. The performance of the system under the given application scenario was analyzed. The main work in this paper can be described as follows:First of all, the key technologies of the WBAN including applications, topological structure, physical and MAC layer was analyzed as a research foundation of multi-nodes physiological signal acquisition and transmission system. The working module of the standard IEEE802.15.6 was also studied.Secondly, in vivo experiments with forearm in frequency range from 10 kHz to 500 kHz were carried out in order to attain the attenuation properties and equalization. A simulation model of intra-body communication system was constituted. The BER versus SNR and constellations of PSK under different modulation method were analyzed in the model. Meanwhile, the optimum modulation method was selected.Thirdly, combine with the results of the simulation mode and the characteristics of the equalizer, the transceiver device of the IBC system was improved and a node of the system was designed. The functions of node are including the transmission of the data, the collection, storage and displaying the physiological signal. In order to suppress the power line interference and common-grounded, battery was used to supply the system.At last, a multi-nodes physiological signal acquisition and transmission system was set up. Combine with the parameter of IBC channel and hardware studied above the MAC performance of the system under the given application was investigated.In conclusion above, a reference of selection of modulation methods and frequency band was provided by the channel characteristic of IBC system, relevant equalization scheme and the parameter of hardware of the node. Low power, low radiation and High security reflected a great advantage of IBC in WBAN. A beneficial investigation and attempt was provided to promote the application of IBC in multi-node physiological signal acquisition and transmission system.