| Summary: | 碩士 === 國立海洋大學 === 導航與通訊系碩士班 === 91 === In the VHF Digital Link, STDMA (Self-Organized Time Division Multiple Access) employs the GNSS (Global Navigation Satellite System) to fix the position and obtain the precision time simultaneously, and then utilizes the self-organization algorithm to allocate the time slot for data transmission. Without reliance on a master station, the mobile stations can communicate with each other more easily.
Estimation of synchronization and STDMA Algorithm are the key issues for the STDMA based AIS (Automatic Identification System). In case of losing the primary time source, timing estimation has to be performed to maintain the system operation. We assume that all the stations in the network would function as a secondary time source to the failed station. Measuring the time of arrival of a transmitted signal from other station can be treated as a measurement of sensor with observation noise. On the other hand, the sync state of the station, reporting rate and the signal to noise ratio related to the distance between two stations determine the precision and resolution of the measurement. Accordingly, we label the available stations with the multiresolution status. Utilizing the concept of multisensor data fusion and multiresolution technique, we obtain a more accurate time estimate.
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