Abstract: Combining time slot mechanism with Manchester encoding, a new algorithm is proposed based on binary search algorithm and ALOHA algorithm. Tags, whose identifiers（TID） accordance with the principle of “x-dimensional code distance equals to x”, can be accessed in one slot. At least three TIDs can be recognized at the same time based on regulation of code distance inversion. Time slot reservation method is recommended to restrain empty slot’s generation, then access speed and efficiency can be improved. Simulation results show that the new algorithm and time slot reservation method can not only increase the access rates, but also improve tag’s accessing efficiency.

Key words: Radio-Frequency Identification（RFID）, anti-collision, x-dimensional code distance, slot reservation

摘要： 对二进制搜索算法的“单比特碰撞”和ALOHA算法中的时隙机制做了研究，设计出一种基于码距反演的RFID防碰撞算法。不同于传统防碰撞手段中尽量避免多个标签同时接入，新算法通过促进符合“x维码距等于x”原则的ID按位发生碰撞来对标签进行识别，阅读器至少能同时识别三个标签。针对ALOHA算法中普遍存在的空白时隙现象，设计出时隙预定方法，提高了标签接入速度和系统效率。仿真实验表明，新算法及时隙预订方法不仅能加速标签的接入，更能大大优化标签的接入效率。

关键词: 射频识别, 防碰撞, x维码距, 时隙预定