An innovative multipath mitigation method using coupled amplitude delay lock loops in GNSS receivers

In this paper a novel multipath mitigation architecture for satellite navigation receiver, named Coupled Amplitude Delay Lock Loops (CADLL) is presented. This architecture exploits the “turbo principle” to separately track the Line Of Sight (LOS) signal and multipath signals in order to mitigate the effects of the multiple reflections. The Delay Lock Loop (DLL) and the Amplitude Lock Loop (ALL) are two basic elements in the structure. DLL is in charge of estimating and tracking the code delay of a specific ray in the incoming signal while ALL is in charge of estimating the corresponding amplitude. A pair of DLL and ALL makes a Unit, devoted to track LOS or a multipath signal. Several Units are incorporated in the CADLL structure, that is then able to track the different component rays from the overall incoming signal, and wiping them off from the received signal. The feedback architecture of the CADLL boosts the performance of the estimation and wipe-off process. CADLL is shown to have good performance in terms of accuracy of estimating and tracking LOS and multipath as well as the robustness to cope with severe multipath scenario.