Abstract: In order to improve the identification efficiency of the Radio Frequency Identification（RFID）system, reduce the time of empty slot and collision slot, a new anti-collide algorithm is proposed. This algorithm detection of empty slots and collision slot is handled separately, it reduces the length of empty slot and collision slot. It dynamically adjusts the frame length according to the principle of time slot no equal long, maximally reduces the cost of invalid time slot to get the optimal identification efficiency. Algorithm analysis and simulation result show that the improved algorithm reduces the length of empty slot and collision slot, the succeed slot is increased and collision slot is reduced within a frame, and can reduce the times of frame length adjustment.

Key words: Radio Frequency Identification（RFID） system, anti-collision, invalid slot, length of slot, identification efficiency

摘要： 为了进一步提高射频识别系统的识别效率，降低空时隙和碰撞时隙时长，提出了一个降低无效时隙开销的防碰撞算法。该算法将空时隙和碰撞时隙的检测分开进行处理，降低了无效时隙的开销。并根据时隙不等长原理动态调整帧长，最大限度地降低无效时隙的开销，以获得最优的识别效率。算法分析和仿真实验结果表明该算法降低了空时隙和碰撞时隙的时长，识别速度明显增加，在一个识别周期内成功时隙数增多，碰撞时隙数减少，帧长的调整次数减少。

关键词: 射频识别系统, 防碰撞, 无效时隙, 时隙长度, 识别效率