Highly Detectable Pilot Structure for Near-Far Positioning
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Solution Overview
Problem
In wireless communication systems, particularly in urban and indoor areas where satellite measurements are unavailable, receivers face challenges in detecting pilots from multiple base stations due to the near-far effect, leading to inadequate location detection accuracy.
Innovation Solution
Implementing a highly detectable pilot (HDP) structure that utilizes OFDM symbols and a specific transmission pattern to enhance pilot detection, allowing receivers to identify a larger number of transmitters, even in the presence of dominant signals, by using a network-aware transmission strategy that allocates dedicated slots for HDPs and employs a hash function to determine transmission positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional pilot structures are used in wireless communication systems, then the system maintains standard operation, but receivers cannot adequately detect pilots from multiple base stations in urban and indoor areas due to the near-far effect
Solution Approach 1:
The patent segments the pilot transmission into dedicated HDP slots separated from data transmission. By dividing the transmission resources into distinct HDP slots where only HDP signals are transmitted and data slots where only data is transmitted, the system enables receivers to detect pilots from multiple base stations without interference from dominant signals during data transmission periods.
Solution Approach 2:
The patent implements periodic HDP transmission in dedicated slots throughout the transmission frame structure. HDP slots are periodically inserted at specific positions (e.g., every 10 subframes) allowing receivers to accumulate pilot measurements from multiple base stations over time, improving location detection accuracy while maintaining standard data transmission in between.
2Measurement precision
If dedicated slots are allocated for HDP transmission, then receivers can detect more base stations, but system resources and complexity increase
Solution Approach 1:
The patent makes HDP slots multi-functional by allowing them to serve both as pilot transmission carriers and as indicators for receiver behavior. During HDP slots, receivers are instructed to wake up from idle mode to detect pilots from multiple base stations, while in non-HDP slots they can remain in idle mode. This universal approach combines positioning functionality with power management, reducing overall system complexity.
Solution Approach 2:
The system uses the HDP slot structure to automatically manage receiver power states. By embedding power management instructions within the HDP transmission itself (through signaling in the HDP slots), the system enables receivers to self-regulate their wake-up and sleep cycles without requiring separate power management control channels, reducing complexity.
3Measurement precision
If receivers continuously monitor all base station signals, then location accuracy improves, but power consumption increases
Solution Approach 1:
The patent implements periodic wake-up behavior synchronized with HDP slot transmission. Receivers are instructed to wake up only during HDP slots to detect pilots from multiple base stations, and return to idle mode during non-HDP slots. This periodic monitoring pattern maintains location detection accuracy by capturing pilot signals when transmitted while dramatically reducing power consumption by keeping the receiver in low-power state during data slots.
Solution Approach 2:
The system performs preliminary power management configuration through signaling in HDP slots before receivers need to execute wake-up behavior. By providing advance instructions about when HDP slots will occur and what wake-up behavior is required, the system enables receivers to plan their power consumption in advance, waking up only when necessary for pilot detection and remaining in low-power mode otherwise.
Data Source
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AI summary
Aspects describe a Highly Detectable Pilot that allows a mobile device to detect more base stations and, thus, can provide more accuracy in location estimate. A highly detectable pilot can be transmitted in one or more data symbols that are not currently being utilized for transmission of data. Transmission of the highly detectable pilot in two data symbols provide a receiver with more convergence time, however, it can take the receiver a longer amount of time to acquire an adequate number of pilots for a location estimate.