Reference Signal Enhancement for Shared Cell Identification

Solution Overview

Problem

In cellular radio networks, especially in CoMP scenarios where transmit stations have identical physical cell identifiers, reference signals from different cells become indistinguishable, making it difficult for user equipment to measure reference signal time differences, which are crucial for accurate location determination using OTDOA techniques.

Innovation Solution

Implementing a muting pattern, time offset, or virtual cell identifier to differentiate reference signals from each cell, allowing user equipment to identify the source of each signal and measure accurate reference signal time differences, which are then reported to calculate the physical location.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If transmit stations use identical physical cell identifiers in CoMP networks, then network coordination and resource allocation are simplified, but reference signals from different cells become indistinguishable and measurement precision deteriorates

Engineering Contradiction:

Improvenetwork coordination complexityVSAvoidreference signal time difference measurement

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent segments the identification function by introducing virtual cell identifiers (VCIDs) that are separate from physical cell identifiers (PCIDs). Each transmit station is assigned a unique VCID for reference signal identification purposes, while maintaining the same PCID for network coordination. This segmentation allows reference signals to be distinguished by VCID even when PCIDs are identical, resolving the contradiction between simplified coordination and measurement precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces virtual cell identifiers as an intermediary element between the physical cell identifier system and the reference signal measurement system. The VCID acts as a mediator that provides unique identification for reference signals without affecting the underlying PCID-based coordination mechanism. This intermediary layer enables both identical PCIDs for coordination simplicity and distinguishable reference signals for accurate measurement.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If reference signals are transmitted on identical resource elements, then resource allocation efficiency is improved, but the ability to distinguish signals from different cells is lost

Engineering Contradiction:

Improveresource allocation efficiencyVSAvoidsignal source identification

Core Design Contradiction:

ProductivityVSLoss of information

Solution Approach 1:

The patent segments the identification function by introducing virtual cell identifiers (VCIDs) that are separate from physical cell identifiers (PCIDs). Each transmit station is assigned a unique VCID for reference signal identification purposes, while maintaining the same PCID for network coordination. This segmentation allows reference signals to be distinguished by VCID even when PCIDs are identical, resolving the contradiction between simplified coordination and measurement precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the identification parameter from physical cell identifier (PCID) to virtual cell identifier (VCID) specifically for reference signal generation and transmission. By modifying which parameter is used for signal identification while keeping the resource element allocation structure intact, the system maintains resource allocation efficiency while enabling signal distinction through VCID-based differentiation.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If discovery reference signals are used for location determination, then positioning capability is enhanced, but signal distinguishability deteriorates when cells share the same PCID

Engineering Contradiction:

Improvelocation determination accuracyVSAvoidsignal source identification

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent segments the identification function by introducing virtual cell identifiers (VCIDs) that are separate from physical cell identifiers (PCIDs). Each transmit station is assigned a unique VCID for reference signal identification purposes, while maintaining the same PCID for network coordination. This segmentation allows reference signals to be distinguished by VCID even when PCIDs are identical, resolving the contradiction between simplified coordination and measurement precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements a feedback mechanism where the user equipment measures reference signal time differences based on VCID identification and reports these measurements back to the network. The network uses these VCID-associated measurements to determine the user's location. This feedback loop enables accurate location determination by linking measurements to specific transmit stations through VCIDs, overcoming the signal indistinguishability problem.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP3893423A1Reference signal enhancement for shared cell

Publication Date: 2021.10.13 APPLE INC

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AI summary

In embodiments, apparatuses, methods, and storage media may be described for distinguishing, by a user equipment (UE), a reference signal (RS) transmitted by a cell that may have a same identifier (ID) as another cell in a network. In embodiments, a muting pattern, a time offset, or a virtual cell identifier (VCID) may be used to generate an RS sequence or RS resource allocation.