SFN Positioning Signals for OTDOA Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current OTDOA techniques in wireless communication networks face challenges due to interference from non-orthogonal Positioning Reference Signals (PRS) from different base stations, which degrades the Signal-to-Interference plus Noise Ratio (SINR) and reduces positioning accuracy, especially when reuse factors are high, and require significant overhead for PRS transmission.
Innovation Solution
Implementing a Single Frequency Network (SFN) approach where multiple base stations transmit the same PRS or positioning signal synchronously, allowing the signals to add constructively at the user equipment (UE), reducing noise-like interference and enabling better detection of Line-of-Sight (LOS) impulses, and using cyclic shifts in the time domain to differentiate between variations of the PRS signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If different base stations transmit orthogonal PRS using different resource elements, then interference between PRS is reduced, but latency and overhead increase
Solution Approach 1:
The patent merges PRS transmissions from multiple base stations into a Single Frequency Network where all base stations transmit the same PRS on the same resource elements simultaneously. This combining approach allows signals to add constructively at the UE, reducing interference while maintaining low latency and overhead by reusing the same time-frequency resources across the network.
Solution Approach 2:
The patent changes the transmission parameter strategy from orthogonal resource element allocation to synchronized same-resource transmission. By modifying the transmission parameters (time, frequency, code) to be identical across base stations rather than orthogonal, the system achieves better signal combining at the receiver while reducing the overhead associated with orthogonal resource allocation.
2Object-affected harmful factors
If different base stations transmit orthogonal PRS using different resource elements, then interference between PRS is reduced, but overhead increases
Solution Approach 1:
The patent merges PRS transmissions from multiple base stations into a Single Frequency Network where all base stations transmit the same PRS on the same resource elements simultaneously. This combining approach allows signals to add constructively at the UE, reducing interference while maintaining low overhead by reusing the same time-frequency resources across the network instead of allocating separate orthogonal resources.
Solution Approach 2:
The patent makes the PRS transmission universal across all base stations by having them transmit the same signal on the same resources. This multi-functional approach allows the same time-frequency resources to serve multiple base stations simultaneously, reducing overhead while maintaining interference reduction through constructive signal combining at the UE.
3Loss of time
If base stations reuse the same resource elements for PRS transmission, then latency and overhead are reduced, but interference increases
Solution Approach 1:
The patent converts the potentially harmful effect of signal overlap into a beneficial effect by having all base stations transmit PRS on the same resources simultaneously. The interference is transformed into constructive signal combining at the UE, where multiple copies of the same PRS add up to improve signal strength and detection accuracy, turning what would normally be interference into a useful signal enhancement.
4Quantity of substance
If non-orthogonal PRS are used to reduce overhead, then positioning accuracy degrades due to noise-like interference
Solution Approach 1:
The patent changes the fundamental parameter of PRS transmission from orthogonal resource allocation to synchronized identical transmission. By modifying the transmission parameters (time, frequency, code) to be the same across base stations rather than orthogonal, the system achieves both low overhead and high positioning accuracy through constructive signal combining, eliminating the noise-like interference effect.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enhances positioning accuracy by reducing interference, allowing for more accurate detection of LOS components and improving the SINR, while minimizing the overhead required for PRS transmission.
Implementation Method 1
two or more variations of a positioning signal being transmitted synchronously by respective ones of the two or more base stations as an SFN signal to effect one or more time shifts at the receiving terminal
Implementation Method 2
allowing the signals to add constructively at the user equipment (UE), reducing noise-like interference
Implementation Method 3
The OTDOA of the positioning signals is determined by pairwise comparison of the channel impulse responses (CIRs) associated with the positioning signals
Implementation Method 4
The CIRs are obtained by correlating the received positioning signals with the known positioning signals
Implementation Method 5
using cyclic shifts in the time domain to differentiate between variations of the PRS signals
Data Source
AI summary
The disclosure relates to an OTDOA positioning technique wherein different base stations transmit different variations of the same basic PRS or other positioning signal synchronously as an SFN signal to effect an observed time shift at the UE between the different variations of the basic PRS signal or positioning signal. This added time shift resulting from the transmission of different variations by different base stations effectively spreads the corresponding channel impulses in the CIR of the SFN signal in the time domain so that the UE is better able to detect and discriminate between different instances of the positioning signal transmitted from different base stations.