70% Energy Saving in Wireless Positioning Systems: Non-Data-Bearing OFDM Transmission Replaces Non-Pulse-Shaping PN Transmission

This paper investigates the green characteristic of the non-data-bearing orthogonal frequency-division multiplexing (NDB OFDM) transmission in wireless localization, relative to being widely used non-pulse-shaping pseudorandom noise (NPS PN) transmission in current satellite- and ground-based positioning systems. For obtaining a fixed ranging accuracy, the required NDB OFDM transmit energy is proven in this paper to be equal to 30% of the required NPS PN transmit energy, spending less nonrenewable resource, emitting smaller CO₂ and indicating a “green” activity. Furthermore, the localization performance and the optimal network topology for obtaining the best accuracy are mathematically derived. By assuming a positioning system with the proposed optimal network topology, the positioning accuracy is derived, and the total energy saving is reported when using NDB OFDM transmission instead of NPS PN transmission. Numerical results and experimental measurements both show a consistency with our proposed theory.