Diseño de esquemas de modulación para un sistema de posicionamiento local ultrasónico codificado con secuencias Zadoff-Chu

Many Ultrasonic Local Positioning Systems (U-LPS), consists of multiple fixed beacons that simultaneously emit ultrasonic signals whose times of arrival (ToA) are estimated at a mobile receiver. The ultrasonic signals can be encoded to allow separation of the signals at the receiver, identification of the transmitters, and mitigation of signal impairments such as multipath, the near-far efect, multiple access interference, and Doppler shift. Therefore,waveform design (coding and modulation) constitutes a key factor in determining the performance of such a system. This paper compares by simulation the performance of three modulation techniques (specifically QPSK, OFDM and FHSS) transmitting Zadoff-Chu (ZC) sequences in an U-LPS. Simulation results indicate that ZC coded QPSK modulation with non-coherent detection, ofers greater accuracy under realistic conditions than the other modulation schemes.