| Summary: | 碩士 === 元智大學 === 通訊工程學系 === 98 === Radio frequency identification (RFID) is a short-distance, low-complexity wireless communication system. The two major components of an RFID system are the reader and the tags, and the tag-reading speed is a major performance index of the RFID system. When multiple tags replied simultaneously within the range of a reader, collisions occurred, preventing the reader from recognizing tag signals. The current approach for collision prevention is based on ALOHA.
In this research, the use of Mutually Orthogonal Golay Complementary Sequence Sets (MOGCS) for RFID systems is explored to resolve the collisions of asynchronous tag signals using the technique of Code-Division Multiple Access (CDMA). Liu and Kuo have used a Huffman sequence and its cyclic shifted version as the CDMA sequences for RFID, but the asynchronous correlation of these sequences can be large, which affects their performance. In our work, Mutually Orthogonal Golay Complementary Ssequence Sets (MOGCS) are used as the spreading sequences of RFID tag signals. If two tags use different sequence sets, there will be no mutual interference whether or not tag signals are synchronized. Even if two tags use the same sequence sets for spreading, as long as the spreading sequences are not aligned at the reader, the tag signals can still be read without any mutual interference. Simulation shows that the performance of MOGCS is better than that of the Huffman sequence. A simulation on throughput comparing RFID EPC Generation-2 and the CDMA approach for the transmission of the RN16 signals using MOGCS is conducted. The result shows that the throughput can be significantly increased with the use of the MOGCS.
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