Abstract—Assigning neighboring RFID readers with nonoverlapping interrogation time slots is one approach to solve the reader collision problem. In which, Distributed Color Selection (DCS) and Colorwave algorithm have been developed, and simulated annealing (SA) technique have been applied. Some of them (we call them non-progresive algorithms), like DCS, require the user to pre-deﬁned the number of time slots. While some of them (we call them progressive), like Colorwave, determine the number automatically. In this paper, a comparative analysis on both non-progressive and progressive algorithms to solve such a problem in a random RFID reader network is presented. By extensive simulations on a dense network consisting of 250 readers whose transmission rates are 100%, a number of useful results have been found. For those non-progressive type algorithms, it is found that DCS is unlikely to generate a collision-free solution, even the number of time slots is set to 20. On the other hand, heuristic and SAbased algorithms can produce collision-free solutions whenever the number of time slots is set to 16. For the cases when the number of time slots is not speciﬁed, heuristic-based, SAbased and Colorwave algorithms are all able to determine the number automatically and thus generate collision-free solution. However, SA-based algorithms require much longer time than the heuristic-based and Colorwave algorithms. In terms of distribution uniformity, it is found that SA-based algorithms can generate almost evenly distributed time slot allocations. That is to say, the number of readers assigned and hence the volume of data sending to the host computer in each time slot will almost be equal. No special transmission protocol is needed to handle the communication between readers and the host computer. Keywords : Colorwave,...

# Solving Reader Collision Problem in Large Scale Rfid Systems

Abstract—Assigning neighboring RFID readers with nonoverlapping interrogation time slots is one approach to solve the reader collision problem. In which, Distributed Color Selection (DCS) and Colorwave algorithm have been developed, and simulated annealing (SA) technique have been applied. Some of them (we call them non-progresive algorithms), like DCS, require the user to pre-deﬁned the number of time slots. While some of them (we call them progressive), like Colorwave, determine the number automatically. In this paper, a comparative analysis on both non-progressive and progressive algorithms to solve such a problem in a random RFID reader network is presented. By extensive simulations on a dense network consisting of 250 readers whose transmission rates are 100%, a number of useful results have been found. For those non-progressive type algorithms, it is found that DCS is unlikely to generate a collision-free solution, even the number of time slots is set to 20. On the other hand, heuristic and SAbased algorithms can produce collision-free solutions whenever the number of time slots is set to 16. For the cases when the number of time slots is not speciﬁed, heuristic-based, SAbased and Colorwave algorithms are all able to determine the number automatically and thus generate collision-free solution. However, SA-based algorithms require much longer time than the heuristic-based and Colorwave algorithms. In terms of distribution uniformity, it is found that SA-based algorithms can generate almost evenly distributed time slot allocations. That is to say, the number of readers assigned and hence the volume of data sending to the host computer in each time slot will almost be equal. No special transmission protocol is needed to handle the communication between readers and the host computer. Keywords : Colorwave,...

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