PRACH Positioning Indication for Idle-State UE Localization

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Solution Overview

Problem

UEs in RRC idle or inactive states need to transition to the RRC connected state for positioning, leading to increased power consumption and latency.

Innovation Solution

A positioning method where a random access process is indicated for positioning purposes using specific preamble formats, root sequences, and PRACH settings, allowing UEs to perform positioning while remaining in idle or inactive states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If UE in RRC idle or inactive state transitions to RRC connected state for positioning, then positioning can be performed using conventional methods (DL-TDOA or DL-AoD), but power consumption increases and positioning latency increases

Engineering Contradiction:

Improvepositioning capabilityVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent segments the positioning process from the RRC state transition process. By introducing a positioning indication field in the random access response message, the system allows positioning to be performed as a separate function that does not require transitioning to RRC connected state. This segmentation enables idle/inactive UEs to receive positioning measurements from multiple base stations and calculate their position without the overhead of full connection establishment.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The random access procedure is given multi-functionality by enabling it to serve both access purposes and positioning purposes simultaneously. The positioning indication field in the random access response message allows the same random access channel to be used for both connection establishment and positioning measurements, eliminating the need for separate positioning procedures that would require RRC connected state.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If UE in RRC idle or inactive state transitions to RRC connected state for positioning, then positioning can be performed using conventional methods (DL-TDOA or DL-AoD), but positioning latency increases

Engineering Contradiction:

Improvepositioning capabilityVSAvoidpositioning latency

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs preliminary positioning measurements during the random access procedure itself. Base stations perform downlink measurements on the random access preamble before the UE even completes the access process. This preliminary action allows positioning calculations to begin in parallel with the access procedure, significantly reducing the total time required compared to waiting for RRC connection establishment.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent enables skipping of the intermediate RRC connected state by implementing a direct positioning mechanism. The positioning indication field triggers a streamlined positioning procedure that rushes through the essential measurement and calculation steps without requiring the UE to enter and exit the RRC connected state, thereby eliminating the time overhead associated with state transitions.

Inventive Principle:

Principle #21Skipping (Rushing through)

3Use of energy by moving object

If separate positioning procedures are implemented for idle/inactive UEs, then positioning can be performed without RRC connection, but system complexity increases

Engineering Contradiction:

Improvepower consumptionVSAvoidsystem complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent merges the positioning function with the existing random access procedure by introducing a positioning indication field in the random access response message. This merging approach reuses existing message structures and processing logic in both UE and base station, avoiding the need for entirely separate positioning protocols. The positioning measurements and calculations are integrated into the flow of the random access procedure, sharing common resources and reducing overall system complexity.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12538253B2Positioning method and apparatus indicating that a target random access process is a random access process for positioning by using information, terminal and base station

Publication Date: 2026.01.27 DATANG MOBILE COMM EQUIP CO LTD

AI summary

This disclosure provides a positioning method and apparatus, a terminal and a base station, wherein the positioning method includes: indicating that a target random access process is a random access process for positioning by means of at least one of following information: a preamble format, a type of a preamble root sequence, an index number of the preamble root sequence, a cyclic shift of the preamble root sequence, a physical random access channel (PRACH) set, a PRACH transmission time-frequency resource, first information in a message 3, second information in a message A or third information in a message 5.