基于位图构建的RFID自适应N树防碰撞算法

Adaptive N Tree Anti-Collision Algorithm Based on Bitmap Construction

针对无线射频识别技术(RFID)共享信道多路访问导致的碰撞问题,提出两种基于位图构建的RFID自适应N树(N为子树个数)防碰撞算法——单帧位图跟踪N树算法(SFBTNA)和多帧位图跟踪N树算法(MFBTNA).利用极大似然位跟踪标签数估算法(MLBE)估算标签数量;在MLBE基础上提出了探针法构建位图,SFBTNA算法根据位图在单帧内自适应调整最优N值并构建N树,而MFBTNA算法则逐帧调整最优N值并构建多个N树.同时,对N树下的子树利用跟踪树算法(CT)识别,位图与跟踪树的结合使用极大降低了碰撞时隙的影响.理论分析和仿真实验表明,提出的两种算法的性能明显优于现有防碰撞算法.

Aimed at the RFID （radio frequency identification） collision problem caused by multiple access of shared channel, this paper proposed two RFID adaptive N tree anti-collision algorithms based on bitmap construction, single frame bitmap track N tree algorithm （SFBTNA） and multiframe bitmap track N tree algorithm（MFBTNA）. First of all, the two methods take advantage of the maximum likelihood tag numbers estimation method （MLBE） that can effectively estimate the number of tags. Secondly, based on the MLBE, it put forward the probe method construct bitmap. The SFBTNA adaptively adjusts the optimization value of N and builds N trees on one frame based on bitmap. The MFBTNA adaptively adjusts optimization value of N and builds N trees frame by frame. At the same time, the SFBTNA and MFBTNA identify the sub-trees using collision track tree algorithm （CT）. The combination of bitmap and CT greatly reduces the impact of collision time slot. Theoretical analysis and simulation experiments show that the performance of the two algorithms is higher than that of the other existing anti-collision algorithms.