Subcarrier Ambiguity Resolution Techniques for HOBOC signals under Harsh Realistic Scenarios

Currently, a main challenge in HOBOC (High Order Binary Offset Carrier) modulations is the presence of ambiguities caused by multi-peaked autocorrelation functions. In harsh environments, such as urban and suburban, distinguishing multipath and BOC (Binary Offset Carrier) side peaks is key to performant acquisition and tracking stages. This problem originates in the notches of the multi-peaked autocorrelation function resulting in increased difficulties in acquisition process and locking on the wrong peak for tracking. To overcome this issue at acquisition level, it requires the use of a finer time step with full BOC processing which in turn slows down the process, whilst for tracking, the use of complex techniques (with respect to the standard PLL/DLL) will ultimately bring a trade-off between complexity, robustness, accuracy and convergence time.

This work addresses the lack of a thorough comparison of techniques specifically applied to the use with high order BOC modulations such as BOCcos(15,2.5) and BOCcos(10,5). This study presents an assessment of this specific problem from two different perspectives based on different classes of techniques: open and closed loop. The state of the art for both types of techniques is investigated through experimentation in a bit true simulator, representative of real receivers and capable of processing SW simulated signals, in a thorough test campaign to create a solid baseline of test data to be used in the analysis of the techniques performance in order to highlight its features and provide a thorough insight aiming its application in real-world receivers.