A study on the design of large-scale mobile recording and tracking systems

A mobile inventory control system involves a large number of highly mobile and dispersed databases in the form of RFID (radio frequency ID) tag devices. Radio tags have limited communication range, bandwidth, computing power and storage. We examine some critical impacts of these characteristics on design of facilities and techniques required for supporting integrated mobile distributed databases and computing environments. We analyze the performance of RF tag protocols and database mechanisms using process oriented discrete event simulation tools. We present the results of experiments on three simulation models for RF tag protocols: slotted ALOHA/TDMA, Id arbitration and CDMA. The performance results show that packet direct sequence (DS) CDMA gives superior performance compared to slotted ALOHA/TDMA and ID Arbitration. The main performance result of experiments on mobile databases shows that optimistic concurrency control performs better for situations where tag transaction probability and write percentage is high. This scenario is found in many active in-transit visibility recording and tracking systems.