Research On Key Issues Of Low-power Mobile Data Collection Based On Semi-active RFID

With the rise of the Internet of Things,RFID devices are widely used in various commercial fields.For active RFID,as the number of deployed tags increases,the cost of replacing the battery of the tag equipment increases dramatically.Semi-active RFID adopts the working mechanism of low-frequency wake-up high-frequency communication,which can greatly reduce the power consumption of the system and save the cost of the project.Therefore,semi-active RFID begins to replace active RFID in many application scenarios.As a means of data collection,semi-active RFID devices face the following key problems:(1)Path planning problem for data collection by mobile readers:When a tag device is deployed,it is usually necessary to collect the information of the tag device through a mobile reader,and send the collected information to the data center.Shorter effective collection paths mean less cost.Therefore,a set of effective path planning algorithms is of great help to control the operating cost of the project.(2)Anti-collision problem during high concurrent reading:When performing high concurrent reading,the collision problem is inevitable.Due to the increasing number of deployed label devices,the power consumption caused by the collision problem cannot be ignored.A set of anti-collision algorithms with low power consumption is very important to prolong the service life of label devices.In summary,this paper mainly conducts research work on the above key issues of semi-active RFID data collection:(1)For the shortest effective path planning problem of mobile readers,based on the Group Steiner Tree theory,an effective mobile data collection algorithm based on inter-node accessibility is given,and it is proved that the approximate ratio of this algorithm to the theoretical shortest collection path does not exceed O(log2~nlog_tloglogn),n represents the number of static label nodes,t(t<n)is the maximum network cardinality.A large number of simulation results show that the proposed algorithm has better path length than the traditional algorithm.(2)Aiming at the collision problem in high concurrent reading,this paper proposes a dynamic frame adjustment algorithm based on the upper limit value of known tags.Based on the binomial distribution theory,the number of unrecognized tags in the area is estimated.Dynamically adjust the frame length through the estimated value to ensure a high system read rate and reduce system power consumption.We designed a semi-active RFID experimental system,and a large number of experimental results show that the algorithm in this paper reduces the power consumption of the tag device by 20%compared with the existing anti-collision algorithm when the average read loss rate is less than 5%.