为了解决射频识别（Radio Frequency IDentification，RFID）系统中的多标签防碰撞问题，在分析帧时隙ALOHA算法的基础上，提出一种基于分组自适应分配时隙的RFID防碰撞算法（GAAS）．首先让阅读器对标签随机所选的时隙进行扫描统计，并将其发送给每一个标签，标签再进行相应地时隙调整，使阅读器跳过空闲时隙和碰撞时隙，自适应地分配有效时隙，进而对标签进行快速识别．当未识别标签数比较大时，算法采用分组以及动态调整帧长等策略，以减少时隙处理的时间．仿真结果表明：GAAS算法提高了系统的识别效率和稳定性，降低了传输开销．特别是当标签数超过1000时，该算法的吞吐率仍保持在71％以上，比传统的帧时隙ALOHA-256算法和分组动态帧时隙ALO-HA算法的系统效率分别提高了300％和97．2％．%Based on frame slotted ALOHA algorithm,a grouped adaptive allocating slots (GAAS)anti-collision al-gorithm is presented to solve the problem of collision between the reader and multi-tag in radio frequency identification (RFID)system.First,the reader needs to obtain the time slots chosen randomly by tags and send the results to each tag;then the tags rectify the time according to the instruction;moreover,the reader skips free and collision time slots,and adap-tively distributes valid ones;finally,the tags are quickly recognized in GAAS.When the number of unidentified tags is ver-y large,the tags are grouped and the frame sizes are adjusted dynamically to reduce the processing time.The simulation re-sults show that GAAS has higher identification efficiency and stability,and lower cost of communication.Particularly, when the number of tags is over 1000,the throughput rate still maintains above 71%.Compared with the framed slotted ALOHA-256 algorithm and the grouped dynamic framed slotted ALOHA algorithm,the proposed algorithm enhances the system efficiency by 300% and 97.2% respectively.
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