2.4G Wireless Access Control System

With the continuous development of science and technology, a higher level ofsecurity management of modern office space and living accommodation is needed, thecommon door lock system is gradually replaced by intelligent access control systems,manual access control can not meet the actual needs of modern management.In this paper, based on the business project of Shenzhen Polytechnic“long-distance wireless access control system development and installation andmaintenance”, with theoretical analysis and engineering practice, a2.4G WirelessAccess Control System is developed. The main innovation of the paper includes:(1) The hardware system is designed by the demands of wireless access controlsystem. By transplantting μC/OS-II embedded systems to achieve8levels schedulingof the task. The performance of the2.4G transmission module and the CPU cardreader module are enhanced through the study of nRF24LE1and MF RC522circuit.(2) Aiming to the characteristics of wireless nodes do not need to move, wirelessnetwork is used as the static routing technology, consider the base node as center,using-64dBm signal strength as the transmission radius. At last, the OMNET are usedto simulate the wireless network which has30nodes. The simulation results can beanalysed the amount of base station node data, the amount of throughput data at alllevels of nodes, the packet transmission delay of node, the waiting queue depth ofdata in the node and so on. The communications protocol ensures the reliability of thesystem capacity and transmission time parameters.(3) In order to solve the tag collision problem in long distance RFID systems, anenhanced Q+Anti-collision algorithm is proposed. The new algorithm solved theproblem which a large number of electronic tags replyed a same reader will come outcollision, and reduced the average reader delay of cards. The algorithm’s reliabilityhas been proved by the simulation results.2.4G wireless access control had debugged the system hardware and software inthe laboratory environment. The reliability of2.4G wireless access control system hadproved by the experimental data, and it laid the foundation for further research anddevelopment of wireless access control system.