Channel model-based sensing for indoor ultrasonic location systems

The Sensing in terms of precise ToF (time of flight) of the ranging signals is a general problem for indoor location systems. The ultrasonic indoor location systems are considered to be a promising approach for high accuracy and as well as low-cost. So far many indoor location systems based on broadband ultrasound and the DS-CDMA technique have been developed, which provide fine-grained position data for the multiple access channel (MAC) distance measurements. However, the design of optimal systems is strongly depending on the channel model and the signal structure. In this paper we will investigate the special structure of received signals in indoor ultrasonic MAC channel and formulate the appropriate general sensing approach, also including the compressed sensing (CS), for improving the distance error variance and reducing the complexity.