The invention provides a new method of unequal error protection which is based on a particular parity matrix structure for LDPC-type codes - Figure 1.

Precise and reliable positioning is nowadays of paramount importance in several mass-market civil, industrial and transport applications, safety-critical receivers and a plethora of engineering fields. In general, Global Navigation Satellite Systems (GNSS) is the positioning technology of choice, but these systems were originally designed to operate under clear skies and its performance clearly degrades under non-nominal conditions. In general, the channel conditions and the main impairments at the receiver level are application dependent. Some harsh propagation conditions, and some relevant applications such as i) urban environments, where a clear impact for autonomous cars and vulnerable road users, the main impairments are multipath, Non-Line-of-Sight (NLOS), shadowing, and a possible lack of satellite visibility in deep urban canyons. ii) For space exploration applications, where a spacecraft is exiting the atmosphere, the main limitations are high receiver dynamics and very weak signal conditions. Such weak signal conditions are mainly due to the use of signals coming from satellites on the opposite side of the Earth (w.r.t. the standard GNSS use). In this talk, we consider the standalone GNSS robust navigation problem, and taking into account the GNSS system-level architecture (space segment, ground segment, user segment), we will talk about the following main signal design challenges: There exist different signals in space, ranging from the legacy GPS L1 C/A Gold codes and BPSK modulation to the Galileo AltBOC signals, each of them having different characteristics, which may have an impact on the achievable PVT performance. Besides the existing signals, and considering the non-nominal conditions of interest, some questions naturally arises: i) which is the best signal (waveform and coding) to improve the mitigation capabilities at the receiver level? ii) each type of impairment requires different signal characteristics or there exists an optimal solution for all of them?

The design of a new GNSS signal is always a trade-off between several figures of merit such as the position accuracy, the sensitivity or the Time To First Fix (TTFF). However, if the goal of the new signal design is to improve the acquisition process, the sensitivity and the TTFF have a higher relevance as figures of merit. Considering that, the main goal of this work is to present the joint design of a GNSS signal and the message structure to propose a new Galileo 2nd Generation (G2G) signal, which provides a higher sensitivity in the receiver and reduces the TTFF, in order to improve the acquisition process. Besides that, since this work has focused on the Galileo E1 Open Service (E1-OS), the signal must be compatible with those signals already presented in the same radio frequency spectrum. However, many of the concepts and methodologies can be easily extended to any GNSS signal. In order to present the join design of a GNSS signal and the message structure, several aspects such as the spreading modulation, the pseudorandom noise (PRN) codes, the channel coding or the signal multiplexing must be addressed.

This is a supplementary material associated with the article "Band-limited impulse response estimation performance" that can be found, in the online version, at doi: https://doi.org/10.1016/j.sigpro.2023.108998.

This is a supplementary material associated with the article "Untangling first and second order statistics contributions in multipath scenarios" that can be found, in the online version, at doi: https://doi.org/10.1016/j.sigpro.2022.108868.