Heterogeneous Reference Signal Merging for Indoor OTDOA Positioning
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Solution Overview
Problem
Indoor user equipment (UE) in LTE networks face reduced detectable cells and lower Signal to Interference-plus-Noise Ratio (SINR) due to signal penetration through buildings, affecting OTDOA positioning accuracy, as existing techniques are optimized for outdoor environments.
Innovation Solution
The use of heterogeneous reference signals, such as Positioning Reference Signals (PRS), Cell-Specific Reference Signals (CRS), and Channel State Information Reference Signals (CSI-RS), combined coherently or non-coherently, to enhance RSTD measurement accuracy, along with interference cancellation techniques, to improve positioning in indoor environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional OTDOA techniques using only PRS are used, then outdoor positioning performance is adequate, but indoor positioning accuracy deteriorates due to signal penetration loss
Solution Approach 1:
The patent combines multiple types of reference signals (PRS, CRS, and CSI-RS) into a unified RSTD measurement process. By merging these different signal types, the system compensates for signal penetration loss in indoor environments, as the combined energy from multiple signal sources improves measurement reliability when individual signals are weakened by building structures.
Solution Approach 2:
The patent creates a composite measurement approach by integrating measurements from heterogeneous reference signals with different characteristics. PRS provides positioning-optimized signals, CRS offers cell-specific coverage, and CSI-RS adds channel state information - together forming a composite measurement strategy that overcomes the limitations of any single signal type in penetrating building structures.
2Measurement precision
If multiple heterogeneous reference signals are combined, then RSTD measurement energy increases and positioning accuracy improves, but measurement complexity increases
Solution Approach 1:
The patent develops a universal measurement framework that handles multiple reference signal types (PRS, CRS, CSI-RS) through a common RSTD measurement process. This multi-functional approach allows the same measurement methodology to process different signal types, reducing the need for separate processing chains and thereby managing complexity while maintaining improved accuracy.
Solution Approach 2:
The patent modifies measurement parameters to accommodate heterogeneous signals by introducing signal-type-specific configuration parameters while maintaining a unified measurement framework. This allows flexible adaptation to different signal characteristics without fundamentally changing the core measurement process, thus managing complexity through parameterization rather than structural complexity.
3Quantity of substance
If PRS-only measurements are used, then measurement process is simple, but detectable cell count reduces in indoor environments due to lower SINR
Solution Approach 1:
By merging measurements from multiple reference signal types, the system effectively increases the total signal energy available for detection. This combination allows the UE to detect additional cells that would be below the SINR threshold when using only PRS, thereby increasing the number of detectable cells while maintaining measurement reliability through the aggregated signal energy.
Data Source
AI summary
Techniques for observed time difference of arrival (OTDOA) positioning based on heterogeneous reference signals (RSs) are discussed. One example apparatus configured to be employed within a user equipment (UE) comprises receiver circuitry, a processor, and transmitter circuitry. The receiver circuitry can receive, from each of a plurality of evolved Node Bs (eNBs), one or more RSs of each of a plurality of distinct types of RSs. The processor can determine, for each of the eNBs, a time of arrival (TOA) of the one or more RSs of each of the plurality of distinct types of RSs; and compute, for each of the eNBs, a reference signal time difference (RSTD) based at least in part on the TOAs of the one or more RSs of each of the plurality of distinct types of RSs. The transmitter circuitry can transmit the RSTD computed for each of the eNBs.