PRS Sequence Generation for PCI Ambiguity Resolution

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Solution Overview

Problem

In LTE wireless communication systems, the PCI ambiguity issue arises when multiple transmission points share the same physical cell identity, leading to inaccurate RSTD measurements and reduced positioning accuracy, especially in dense cellular networks.

Innovation Solution

Introducing an identifier, such as the ASID, to generate orthogonal PRS sequences for cells with the same PCI, allowing the UE to distinguish between cells and report accurate RSTD measurements, and supporting TP-specific PRS configurations to mitigate PCI ambiguity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If multiple transmission points share the same physical cell identity to reduce network complexity, then device complexity is reduced, but positioning accuracy deteriorates due to PCI ambiguity

Engineering Contradiction:

Improvenetwork complexityVSAvoidpositioning accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent segments the cell identity into two parts: the physical cell identity (PCI) shared by multiple transmission points, and a transmission point identifier (TP ID) that uniquely identifies each transmission point. This segmentation allows the network to maintain simplified PCI allocation while enabling precise identification of individual transmission points for accurate positioning measurements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a positioning reference signal (PRS) sequence initialization value as an intermediary element that combines the PCI and TP ID. This initialization value serves as a mediator that allows UEs to distinguish between different transmission points sharing the same PCI, thereby resolving the positioning ambiguity without increasing network complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If PRS sequences are generated based only on PCI for cells sharing the same identity, then configuration simplicity is improved, but measurement precision deteriorates due to inability to distinguish between cells

Engineering Contradiction:

Improveconfiguration simplicityVSAvoidRSTD measurement accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent merges the PCI and TP ID into a unified PRS sequence initialization value. This combination maintains configuration simplicity by using a single initialization parameter while enabling the UE to generate distinct PRS sequences for different transmission points, thereby achieving both simple configuration and precise measurement.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent changes the parameter used for PRS sequence generation from only PCI to a composite parameter that includes both PCI and TP ID. This parameter change enables the system to maintain simple PCI allocation while achieving precise RSTD measurements by incorporating the additional TP identification dimension.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If additional identifiers are introduced to distinguish cells with same PCI, then positioning accuracy is improved, but device complexity increases

Engineering Contradiction:

Improvepositioning accuracyVSAvoidconfiguration complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the TP ID a universal parameter that serves multiple functions: it identifies transmission points for positioning purposes, initializes PRS sequences to resolve ambiguity, and can be used in other network functions. This multi-functionality reduces the need for separate identification mechanisms, thereby limiting the increase in configuration complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP3456114B1Methods, user equipment, radio transmitter and network node for managing positioning reference signals

Publication Date: 2023.03.22 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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Figure 3a~3b

AI summary

A method and a user equipment (110) as well as a method and a radio transmitter (120) for managing positioning reference signals are disclosed. Moreover, a method and a network node (130) for configuring positioning reference signals are disclosed. The network node (130) sends (A050), to the user equipment (110), a reception configuration of positioning reference signals, wherein the reception configuration comprises a cell identity relating to the radio transmitter (120) and an identifier for determining of positioning reference signals. The network node (130) sends (A070), to the radio transmitter (120), a transmit configuration of positioning reference signals, wherein the transmit configuration comprises the cell identity and the identifier. The radio transmitter (120) determines (A090) the positioning reference signals based on the cell identity and the identifier. The radio transmitter (120) sends (A100) the positioning reference signals to the user equipment (110). The user equipment (110) estimates (A120), based on the positioning reference signals, signal characteristics relating to a position of the user equipment (110). The user equipment (110) sends (A130), to the network node (130), a report about the estimated signal characteristics. Corresponding computer programs and carriers therefor are also disclosed.