Reference Signal for Wireless Position Location Accuracy
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Solution Overview
Problem
Current wireless communication systems face challenges in providing accurate and reliable time-of-arrival (TOA) measurements due to the susceptibility of pilot signals to errors, especially in poor channel conditions, which compromises the accuracy and reliability of position location services.
Innovation Solution
Implementing a reference transmission system where an access point (AP) sends a strong reference signal, either in a time-division-multiplexed or code-division-multiplexed format, to assist access terminals (ATs) in performing TOA and position-location measurements, by replacing normal data transmission or being sent on demand, thereby providing a robust signal for accurate location determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pilot signals are used for position location measurements in wireless communication systems, then position location services can be provided, but the accuracy and reliability of TOA measurements deteriorate due to susceptibility to errors in poor channel conditions
Solution Approach 1:
The patent introduces a reference signal as an intermediary between the pilot signal and the TOA measurement process. This reference signal, transmitted on a dedicated reference channel with known characteristics, serves as a mediator that provides a more reliable basis for TOA measurements compared to the pilot signal, thereby improving measurement accuracy and reliability in poor channel conditions
Solution Approach 2:
The patent changes the parameters of the measurement system by switching from relying solely on pilot signal characteristics to using reference signal characteristics. The reference signal has different parameters (known sequence, dedicated channel, controlled power) that make it less susceptible to errors, thereby improving TOA measurement accuracy and reliability
2Measurement precision
If reference transmission is implemented to improve TOA measurement accuracy, then measurement accuracy improves, but network complexity increases due to additional transmission infrastructure
Solution Approach 1:
The patent implements multi-functionality by enabling access points to transmit both pilot signals and reference signals, and by allowing the reference channel to serve multiple purposes including TOA measurements, channel estimation, and signal quality assessment. This universal approach improves measurement accuracy without requiring entirely separate infrastructure
Solution Approach 2:
The patent segments the transmission infrastructure by creating a dedicated reference channel separate from the pilot channel and data channels. This segmentation allows the reference signal to be transmitted independently with optimized characteristics, improving TOA measurement accuracy while maintaining clear functional separation that manages network complexity
Data Source
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AI summary
Embodiments disclosed herein relate to methods and systems for providing improved position-location (e.g., time-of-arrival) measurement and enhanced position location in wireless communication systems. In an embodiment, an access point may replace information (e.g., data) transmission by a "known" transmission (or "reference transmission") at a predetermined time known to access terminals in the corresponding sectors. The access terminals may use the received reference transmission to perform a position-location measurement, and report back the measured information. The access point may also send a reference transmission on demand, e.g., in response to a request from an access terminal in need for a location-based service.