Variable Coherence Integration for Weak Signal Location
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Solution Overview
Problem
Network-based wireless location systems face challenges in detecting weak signals due to decreasing radio power levels and the introduction of advanced spread spectrum coding schemes, which reduce their ability to detect signals at neighboring receivers, and they struggle with latency and processing load when using parallel computations for correlation processing.
Innovation Solution
The system employs a variable coherence integration process that uses historical and real-time data to determine the number of partial coherence processing paths and sample segmentation, optimizing signal detection by maximizing coherence and reducing latency through the use of multiple processing paths with different subdivision sizes, allowing for precise time of arrival determination of wireless devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parallel processing is used in correlation processing to maximize coherence for matched replica signal samples, then signal detection capability is improved, but processing load and system latency increase
Solution Approach 1:
The patent segments the received signal into multiple blocks and processes them through different numbers of parallel correlation processing paths. By dynamically adjusting the number of parallel paths based on signal characteristics and using historical/real-time radio environment information, the system maximizes coherence for weak signal detection while avoiding excessive processing load and latency that would result from always using maximum parallel processing.
2Use of energy by moving object
If stricter power control schemes and advanced spread spectrum coding schemes are introduced, then power efficiency is improved, but the ability to detect radio signals at neighboring receivers is reduced
Solution Approach 1:
The patent uses historical radio environment information and preliminary analysis of received signal characteristics to pre-determine the optimal number of parallel correlation processing paths before actual signal detection. This preliminary action allows the system to be prepared to detect weak signals from neighboring receivers even when power control schemes reduce transmitted power, as the processing configuration is optimized in advance based on environmental conditions.
Solution Approach 2:
The system dynamically adjusts the number of parallel correlation processing paths based on real-time radio environment information and signal characteristics. This dynamic adaptation allows the system to maintain high signal detection capability for weak signals from neighboring receivers while accommodating the reduced power levels imposed by strict power control schemes and advanced spread spectrum coding.
3Measurement precision
If longer integration lengths are used to increase accuracy of TDOA and AoA, then location accuracy is improved, but processing time increases
Solution Approach 1:
The patent segments the integration period into multiple blocks and processes them through variable numbers of parallel correlation paths. This segmentation allows the system to achieve long integration lengths for high location accuracy while maintaining reduced processing time by using parallel processing paths that can be dynamically adjusted based on signal strength and coherence requirements.
Data Source
AI summary
In a network-based Wireless Location System (WLS), geographically distributed Location Measurement Units (LMUs) must be able to detect and use reverse channel (mobile to network) signals across multiple BTS coverage areas. By using Matched Replica correlation processing with the local and reference signals subdivided into discrete segments prior to correlation, the effects of mobile clock drift and Doppler shifts can be mitigated allowing for increased processing gain. By using historical network and real-time data about the radio signal and/or radio channel, the segmentation and computation scheme may be optimized to reduce latency and enhance capacity while maximizing location accuracy.