On Efficient and Low-Complexity Decoding of Binary LDPC-Coded CSK Signals for GNSS Links with Increased Data Rates

摘要

GNSS with high data rate links are of interest to accommodate new needs and applications (e.g. precise positioning, authentication, reduction of TTFFD). In this context, a binary LDPC-coded CSK signal is an attractive candidate to increase data rates with a high data recovery robustness. However, such a proposal requires an increase of receiver's computational complexity with respect to receivers for current coded DSSS/BPSK GNSS links. The computational complexity required for data recovery is analysed in this article and insights on crucial technical choices are given for the reception of binary LDPC-coded CSK signals. CSK demodulation is shown to dominate the overall computational cost and the use of digital chip-matched filtering prior to demodulation is proposed to reduce this cost. In addition, iterative demapping, which is crucial to optimize the power efficiency of binary LDPC-coded CSK links is also shown to have high computational complexity. Therefore, low-complexity iterative demapping strategies are studied and simple yet efficient solutions are proposed.