GNSS Receiver Joint Channel Time Estimation Indoor
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Solution Overview
Problem
Global navigation satellite systems (GNSS) face challenges in providing accurate time synchronization and positioning in indoor conditions due to strong fading and non-line-of-sight multipath components, which degrade performance beyond the requirements for 5G telecom networks.
Innovation Solution
A receiver is designed to perform a joint estimation of clock bias and composite channel using cross-correlation functions from multiple GNSS signals, mitigating the effects of indoor propagation channels by combining signals from multiple antennas and using a multi-hypothesis estimation approach to refine clock bias estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If GNSS signals are used for time synchronization in indoor conditions, then positioning and timing applications can be enabled, but performance degrades due to strong fading and non-line-of-sight multipath components
Solution Approach 1:
The patent combines signals from multiple antennas and integrates multipath components into a unified signal processing approach. By merging the direct line-of-sight signal with reflected multipath signals and processing them jointly through joint channel and time estimation, the system achieves accurate timing synchronization indoors without requiring signal separation or rejection of multipath components.
Solution Approach 2:
The patent converts the harmful multipath components into beneficial information sources. Instead of treating multipath signals as noise to be rejected, the system uses joint channel estimation to characterize the indoor propagation environment and leverages the multipath components to improve timing accuracy, transforming the previously detrimental effect into a useful resource for enhancement.
2Measurement precision
If conventional cross-correlation methods are used for code-phase alignment, then positioning can be determined, but timing accuracy is degraded due to bias from non-line-of-sight components
Solution Approach 1:
The patent implements an iterative joint estimation process where the channel characteristics are continuously refined based on the received signal structure. The algorithm uses feedback from the cross-correlation function analysis to update the channel estimation, which in turn improves the time delay estimation, creating a feedback loop that progressively reduces timing bias and enhances measurement precision.
Solution Approach 2:
The patent performs preliminary channel estimation and characterization before final time synchronization. By first estimating the composite channel response and its delay profile, the system prepares the necessary information to correct for multipath effects in subsequent timing calculations, preventing bias rather than correcting it after occurrence.
3Adaptability or versatility
If multiple antennas are used to receive GNSS signals, then signal diversity and indoor coverage are improved, but system complexity increases
Solution Approach 1:
The patent designs a unified signal processing framework that handles multiple antennas and multipath components through a single joint estimation algorithm. Rather than processing each antenna signal separately or requiring separate processing paths, the system uses a universal approach that simultaneously estimates channel characteristics and time delays across all antennas, reducing overall system complexity while maintaining the benefits of multi-antenna diversity.
Data Source
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AI summary
A receiver is provided for use with a global navigation satellite system (GNSS) comprising multiple satellites. Each satellite transmits a respective navigation signal containing a spreading code. The GNSS maintains a time reference which is encoded into the navigation signals. The receiver comprises a receiver clock and at least one antenna for receiving multiple signals over multiple respective channels, each channel being defined by a transmitting satellite and a receiving antenna at opposing ends of the channel. The receiver further comprises at least one correlator for calculating cross-correlation functions between (i) the signals received over the multiple channels and (ii) reference versions of the navigation signals provided by the receiver. The receiver is configured to use the calculated cross-correlation functions to perform a joint estimate of (i) a clock bias of the receiver clock relative to the time reference maintained by the GNSS, and (ii) a composite channel comprising the combined contribution of the multiple channels as a function of time-delay.