Location Estimation Method Based on Viterbi Algorithm

I have developed a novel location estimation method that is based on the Viterbi algorithm. Using this method enables us to estimate the most likely location at several 10 nsec by using past location transition and signal detection. In addition, the system implementing this method can be composed of a single LSI. Since the Viterbi algorithm has two functions, signal detection from noisy received signal and finding a maximum likelihood sequence path, this method can be applied to location estimation. The level of the received signal is proportional to the distance between the move terminal and the fixed node. The trellis of Viterbi decoder/encoder is similar to the track of move terminal. The Viterbi algorithm has no backward search function like the Fano algorithm, so the time needed for detection is fixed and short. The scale of the execution circuit is reduced with the truncation path memory because of the survivor path selection. When the location for the 16 × 16 array was located, there were 256 states. The required number of elements was 10 k, and the required memory was 68 kbit. This shows that using the proposed method can achieve a highly effective medium-scale FPGA. In a field test, when the 3D location (8 × 8 × 8 array) was estimated with the proposed Viterbi algorithm, accuracy was 70% higher than when using the conventional method due to pattern matching the received signal strength to detect location.