False Lock Probability in BOC Signals

Robust Unambiguous Estimation of High-Order BOC Signals: The DOME Approach

“…In this case, W 1 is such that three correlation samples are used in the fine estimation and the noise covariance matrix C is in practice not exploited, W 2 is defined as an identity matrix, and K = 10. As can be observed, the DOME is able to detect and correct the false lock successfully even at low C/No conditions (even if for low C/No conditions it might be in practice difficult to keep a relatively low probability of false lock for reasonable integration periods, as shown in [15]). Note that the time to detect and correct the false lock (i.e., the latency of the ambiguity resolution) depends on the P parameter used in the second optimization problem (defined in Equation (8)), selection of which is a design trade-off between the probability of false lock to be achieved (equivalent to the probability of false detection) and the latency to detect and correct eventual false locks.…”

“…This is shown in Figure , where the application of Equation with P = 10 shows a low probability of false lock for high C/No conditions for the configuration in Table in continuous tracking mode. Therefore, in this case, the application of Equation in the DOME would be desirable not only in terms of computational burden but also in terms of probability of false lock achieved (the ambiguity solution based on Equation is equivalent to the MLE when considering the application of a perfect match filter in the correlation and dump process, as shown in ).…”

“…5-Illustration of the sampling impact when processing a signal snapshot and no a priori information about the expected position of the main peak is considered. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com and www.ion.org] match filter in the correlation and dump process, as shown in [15]).…”

Collective Unambiguous Positioning With High-Order BOC Signals

“…In general, these techniques are well suited for mild propagation conditions typical of open-sky scenarios, but start having limitations or become unstable in urban scenarios where low C/No conditions (typically below around 30 dB-Hz) are experienced by the receiver [9]. Indeed, it is important to highlight that just additive white Gaussian noise (AWGN) channel conditions, without the need of additional multipath components, are enough to trigger the appearance of false locks given the structure of the high-order BOC signals [1], [10].…”

“…Longer coherent and non-coherent integration periods can be considered in order to increase the SNR observed by the estimators (reducing the probability of false lock) as proposed in techniques like the Double-Optimization Multi-correlator-based Estimator (DOME) [1], [12]. Nevertheless, the maximum integration periods that can be applied in practice are limited by receiver, user and environment constraints [13]- [15], such that for low C/No conditions the equivalent SNR observed by the estimator remains also low and the probability of false lock is still important [1], [10].…”