Research And Theoretical Analysis Of Orthogonal Accessing Control Without Spectrum Spreading For Massive RFOD Network

In a sensor-based radio frequency identification(RFID)system,each sensor contains a unique tag.Before the sensor sends data,each tag needs to send its ID for channel reservation.During this process,IDs collision always happens and causes considerable delays.In this paper,we propose orthogonal coset identification(OCSID).The proposed scheme can recover tags in collision slots,and greatly improve the efficiency at channel reservation stage.The research of this paper is given as follow:(1)Prove the theorem of the division of orthogonal subsets.By group theory,we first prove that the binary vector set{-1,+1}~B and the Hadamard product°form a group{{-1,+1}~B}.The group can be evenly decomposed into 2~BB subsets,and each subset containsmutually orthogonal binary vectors,where=2~k,is a positive integer.Then we generalize the proof todimensional-ary vector set,and design the corresponding orthogonal subset generation algorithm.(2)Propose orthogonal coset identification(OCSID).According to the proof of orthogonal division of binary vector set and-ary vector set,we propose binary phase shift keying(2PSK)OCSID and-ary phase shift keying(MPSK)OCSID,respectively.In addition,we also design the corresponding orthogonal decoding scheme.Finally,we apply the proposed protocol to the existing EPC global C1 Gen2 protocol.(3)Aiming at the problem that the OCSID requiring ID length to be an integer power of 2,this paper proposes a combination scheme of QT and OCSID:QT-OCSID.Aiming at the problem that the out-of-sync scene will destroy the orthogonality of OCSID,this paper proposes a combination scheme of OCSID and Aloha:OCSID-Aloha.Code division multiple access(CDMA)can also recover multiple tags from collision,but the CDMA realizes orthogonal access by spreading spectrum,while OCSID utilizes the orthogonal structure of ID itself.Therefore,OCSID based schemes are more suitable for devices with limited hardware.In addition,the numerical and simulation results show that the proposed schemes have better performance in some cases,especially in massive RFID network.