Idle-Mode User Positioning via Single-Occasion Group PRACH
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Solution Overview
Problem
Existing methods for determining user device positioning in mobile communications systems are inefficient and consume excessive power in idle or inactive modes, leading to reduced battery life and potential delays.
Innovation Solution
A user device transmits a group channel preamble message to a selected group of network nodes in a single random access channel occasion, utilizing a positioning module to receive and process location determining information from multiple nodes simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a user device in idle or inactive mode transmits positioning signals to multiple network nodes using existing methods, then positioning information can be obtained, but power consumption increases and battery life decreases
Solution Approach 1:
The network nodes are pre-configured with positioning reference signals and measurement configurations before the user device needs positioning. When positioning is required, the device can immediately transmit signals to pre-identified nodes, avoiding the energy cost of node selection and configuration during active positioning mode
Solution Approach 2:
Positioning operations are performed periodically or event-driven rather than continuously. The network triggers positioning only when necessary (e.g., handover preparation, location services requested), allowing the device to remain in low-power idle state otherwise
2Measurement precision
If a user device transitions from idle mode to connected mode for positioning determination, then accurate positioning can be achieved, but transmission delays increase
Solution Approach 1:
The network maintains configuration information and measurement capabilities at idle nodes, so when positioning is needed, the device can immediately engage in positioning measurements without transitioning through connected mode, eliminating the mode transition delay
Solution Approach 2:
Network nodes maintain dual functionality: they can serve as regular idle mode nodes and simultaneously be configured for positioning measurements. This allows the same node to handle both normal traffic and positioning functions, eliminating the need for mode switching
3Measurement precision
If the user device transmits channel preamble messages to multiple network nodes separately, then positioning information from multiple nodes can be obtained, but the number of random access channel occasions increases
Solution Approach 1:
The device transmits a single group channel preamble message that is simultaneously received by multiple network nodes. This combines multiple positioning measurement opportunities into one transmission event, reducing the number of random access channel occasions while still gathering positioning data from multiple nodes
Data Source
AI summary
An apparatus (e.g. a user device), method and computer program is described to perform steps including: receiving at a user device, while the user device in is an inactive, unconnected or idle mode, a paging message for positioning determination from one or more of a plurality of network nodes in a radio network; and transmitting, a same group channel preamble message dedicated for positioning determination, to a group of network nodes which are selected by the user device, wherein the same group channel preamble message which being a physical random access channel (PRACH) preamble message, is transmitted under a single random access channel occasion (RO).