Design And Research Of Communication Protocol Based On BACnet

With the continuous development of information networks,traditional buildings can no longer meet the needs of humans nowadays.The development of smart buildings in China is very rapid,and BACnet is the only ISO standard in the field of smart building control.At present,the standard is mainly used in the wired market,and how to integrate it with the wireless network is the focus of intelligent building communication protocol research.Two wireless MAC protocols based on BACnet are designed.Firstly,the research status of intelligent building communication protocol at home and abroad is expounded.The development of BACnet standard and supported data transmission technology and the expansion from wired technology to wireless technology and the development status of wireless transmission protocol at home and abroad are intrduced.Secondly,the related technology of BACnet network and communication protocol are introduced.First,the BACnet,data transmission,the importance of wireless communication and the Zig Bee in the BACnet are introduced and the deficiencies of the IEEE 802.15.4 on which Zig Bee is based are pointed out.Then,the relevant technology of the wireless network of the intelligent building and the technical indicators of the MAC protocol design are analyzed.Finally,the CSMA/CA algorithm and the TDMA algorithm are introduced,and the network throughput of the two is compared and analyzed.Then,the design of MAC protocol system based on BACnet is proposed.Expanding the application of BACnet in wireless scenarios is considered,and two typical scenarios are introduced: intelligent building property management and integrated pipe corridor security monitoring.The two scenarios correspond to tree network topology and linear network topology,respectively.A general frame structure is designed based on IEEE 802.15.4.Next,the TrQ-MAC protocol based on the tree network of intelligent buildings is studied.The protocol effectively combines the CSMA and TDMA mechanisms,and the cluster routing node adjusts the MAC layer protocol scheme in real time according to the buffer queue status of the data packets to be sent by each data node,and dynamically allocates wireless resources to the data nodes in need.The simulation results show that,compared with the traditional Co Sen S protocol and RI-MAC-MC protocol based on the competition mechanism,the TrQMAC protocol provides better network performance under variable and burst traffic loads.Finally,the Lp CSMA-MAC protocol for a multi-patch topology network is designed.This protocol is suitable for LWN scenarios where only the source node generates data and LWSN scenarios where both the source node and the relay node generate data.According to the distance between the data node and the destination node,the protocol sets different priorities for the data node,and designs two time slot allocation schemes for different scenarios.The finite state transition diagram is used to derive the analytical expressions of the data transmission success rate and network throughput of the multi-hop network.The simulation results show that,compared with the traditional IEEE 802.15.4 protocol and the time slot ALOHA protocol,the Lp CSMA-MAC protocol provides better performance.