Coherent Wireless Signal Processing for Urban Positioning
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Solution Overview
Problem
Current Global Navigation Satellite Systems (GNSS) face challenges in accuracy and availability, particularly in dense urban environments and indoors, where traditional satellite signals are unreliable, and there is a need for a positioning system that can utilize alternative signals to provide positioning information.
Innovation Solution
The method involves opportunistically receiving and coherently combining multiple wireless uplink signals with irregular and ad hoc frequency overlaps to estimate channel characteristics, such as time delay, for improved positioning and timing determinations, using a wide-band signal processing approach in wireless infrastructure networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional GNSS satellite signals are used for positioning, then positioning can be achieved in open environments, but positioning accuracy and availability deteriorate in dense urban environments and indoors
Solution Approach 1:
The patent uses terrestrial communication signals (LTE, WiFi, Bluetooth) as intermediary signals to enable positioning when direct satellite signals are blocked. These signals propagate through urban canyons and indoor environments where GNSS signals cannot reach, serving as mediators that carry positioning information through otherwise impassable electromagnetic barriers
Solution Approach 2:
The patent makes positioning systems universal by enabling them to function across multiple environments (outdoor, urban, indoor) using diverse signal sources. The system can switch between or combine GNSS signals, LTE signals, WiFi signals, and Bluetooth signals depending on environmental conditions, making the positioning capability universally applicable regardless of location
2Measurement precision
If multiple wireless signals with irregular frequency overlaps are combined for positioning, then positioning accuracy is improved, but signal processing complexity increases
Solution Approach 1:
The patent segments the complex task of processing multiple wireless signals by handling each signal type (LTE, WiFi, Bluetooth) through separate processing modules. Each module extracts timing information from its specific signal format, and the results are then combined. This segmentation reduces the complexity of any single processing module while maintaining the benefits of multi-signal integration
Solution Approach 2:
The patent introduces intermediary processing steps that convert diverse signal formats into a common time-of-arrival representation. Rather than directly comparing raw signals with different modulations and protocols, the system uses intermediate timing extraction modules that translate each signal type into standardized timing measurements that can be easily combined and processed
Data Source
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AI summary
Methods and apparatus for estimating one or more characteristics of the communications channel. The method comprises receiving (230) a first wireless signal transmitted by a transmitter (122p) at a first set of frequencies in a first time slot; and receiving (232) a second wireless signal transmitted by the transmitter (122p) at a second set of frequencies in a second time slot. The second set of frequencies partially overlaps with the first set of frequencies and the second time slot is different from the first time slot. The method further comprises jointly processing (240) the first wireless signal and the second wireless signal to estimate the one or more characteristics of the communications channel. A corresponding apparatus is configured to implement the method. Also disclosed is a transmitter device (122p). The transmitter device is configured to: transmit a first wireless signal at a first set of frequencies in a first time slot; and transmit a second wireless signal at a second set of frequencies in a second time slot. The second set of frequencies partially overlaps with the first set of frequencies and the second time slot is different from the first time slot. The first and second wireless signals are transmitted coherently.