NEPS: ''Narrowband Efficient Positioning System'' for Delivering Resource Efficient GNSS Receivers

Abstract : We present a new architecture to perform localization (position estimation) in GNSS systems, termed NEPS (Narrowband Efficient Positioning System). The NEPS archi- tecture is composed of three components: a low powered cheap receiver; a communication system which trans- mits the measurements; and a processing unit which receives the distorted observations (due to quantisation and imperfect transmission medium) and performs the position estimation algorithm. The NEPS is a stand-alone system which is designed to incorporate the quantised measurements as well as the imperfect communication channels between receiver and the backend in order to perform inference on the user's position. Compared with a conventional system, the NEPS consumes less band- width, requires lower power consumption and provides faster reporting rates. We derive the joint Maximum Likelihood (ML) for the position and the receiver's clock offset. We then develop an efficient algorithm to solve the resulting non-convex optimisation problem. Further- more, we derive a theoretical performance lower bound on the achievable accuracy via Crame ́r-Rao lower bound (CRLB). Simulate results show that the performance of the NEPS ML position estimator is close to the theoretical performance bound.