Cell Portion Specific PRS for Indoor Positioning
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Solution Overview
Problem
Current LTE positioning techniques, particularly OTDOA, face challenges in indoor environments due to interference from neighboring cells, as they rely on cell-specific frequency shifts which are insufficient for accurate positioning in dense deployments, and cannot differentiate between co-located transmit points sharing the same Physical Cell Identity (PCI).
Innovation Solution
The solution involves transmitting cell portion-specific Positioning Reference Signals (PRSs) by multiple transmit points (TPs) sharing the same cell identity, using distinct PRS patterns and scheduling to avoid interference, and signaling Cell Portion IDs to enable independent PRS transmission, allowing for improved OTDOA-based positioning by differentiating between geographically separate TPs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If cell-specific frequency shifts are used for PRS transmission, then interference reduction between neighboring cells is achieved, but positioning accuracy in dense indoor deployments deteriorates due to inability to differentiate co-located TPs
Solution Approach 1:
The patent segments the cell-specific PRS into multiple TP-specific PRS instances by introducing a cell portion identifier. Each TP (transmit point) within a cell is assigned a unique cell portion identifier, allowing the PRS to be divided into distinct instances that can be differentiated by UEs. This segmentation enables precise identification of signal sources in dense indoor deployments while maintaining the interference reduction benefits of cell-specific frequency shifts.
2Device complexity
If multiple TPs share the same PCI to reduce complexity, then device complexity is reduced, but positioning accuracy deteriorates due to inability to differentiate between geographically separate TPs
Solution Approach 1:
The patent adds a new dimension for TP differentiation by introducing the cell portion identifier as an additional layer of identification. Instead of requiring unique PCIs for each TP, the system maintains the same PCI across multiple TPs but differentiates them through the cell portion identifier dimension. This allows TPs to share the same PCI while remaining distinguishable, resolving the contradiction between complexity reduction and positioning accuracy.
3Measurement precision
If cell portion-specific PRS transmission is implemented, then positioning accuracy in dense deployments is improved, but signaling complexity increases due to additional Cell Portion ID information
Solution Approach 1:
The patent merges the cell portion identifier information with existing PRS signaling structures. Rather than creating entirely separate signaling channels, the cell portion identifier is integrated into the existing PRS configuration and transmission framework. This merging approach enables accurate TP differentiation while minimizing additional signaling overhead by reusing existing protocol elements.
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AI summary
Systems and methods are disclosed herein that relate wireless device positioning based on cell portion specific Positioning Reference Signals (PRSs) by multiple Transmit Points (TPs) in a shared cell. In some embodiments, a method of operation of a TP in a cellular communications network is provided. The TP is one of multiple of non-co-located TPs of a shared cell that has a shared cell identifier. The method of operation of the TP comprises transmitting a PRS having at least one parameter that is a function of a cell portion identifier of the TP, where the at least one parameter comprises a frequency-shift of the PRS, a portion of a system bandwidth in which the PRS is transmitted, and/or a PRS sequence used for the PRS. By transmitting cell-portion-specific PRSs, the TPs in the shared cell enable wireless device positioning based on PRSs transmitted by the non-co-located TPs.