Almanac Message Coherence Indication for AoD Estimation
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Solution Overview
Problem
In wireless communication systems, particularly in 5G networks operating at high frequencies like mmW bands, propagation loss and multipath propagation complicate precise timing measurements due to varying signal paths, leading to suboptimal beamforming for data communication and position estimation.
Innovation Solution
A system where a network entity provides an almanac message to a node indicating a set of collocated transmission points that transmit coherent signals, allowing the node to determine phase differences of arrival (PDoAs) among these signals, which are used to estimate angle of departure (AoD) and improve position estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If beamforming is used to extend RF signal coverage and increase data transfer speeds, then propagation loss is mitigated and throughput is improved, but measurement precision for timing and position estimation deteriorates due to multipath propagation and phase inconsistencies
Solution Approach 1:
The network entity performs preliminary actions by determining coherence relationships between transmission points before actual positioning measurements. The almanac message is prepared in advance with coherence indicators, allowing the wireless device to properly interpret phase differences without requiring real-time coherence assessment, thus resolving the contradiction between beamforming gains and measurement precision
Solution Approach 2:
The almanac message serves as an intermediary that carries coherence information from the network entity to the wireless device. This intermediary structure enables the device to distinguish between coherent and non-coherent transmission points, allowing accurate position estimation even in the presence of beamforming and multipath propagation effects
2Reliability
If multiple transmission points transmit signals for position estimation, then coverage and reliability are improved, but device complexity increases due to the need to process and differentiate signals from multiple sources
Solution Approach 1:
The network entity performs the complex task of determining coherence relationships between transmission points and encoding this information in the almanac message. This self-service approach transfers the computational burden from the wireless device to the network entity, allowing the device to simply read the coherence indicators and perform straightforward position calculations, thus improving reliability without significantly increasing device complexity
Solution Approach 2:
The invention changes the parameter representation by introducing coherence indicators in the almanac message that transform the complex multi-point signal processing problem into a simpler parameter-based solution. Instead of requiring the device to analyze phase relationships directly, the coherence state is represented as discrete parameters that guide the position estimation process
Data Source
AI summary
Disclosed are techniques to determine angle of departure (AoD) of signals transmitted from a set of transmission points associated with a transmitter (e.g., a base station, a user equipment (UE)). In an aspect, the set of transmission points are collocated and transmit coherent signals. A receiver (e.g., UE, network entity) determines phase difference of arrivals (PDoAs) of the signals. Based on the PDoAs and locations of the set of transmission points, the AoD can be calculated. When the UE is the receiver, the network entity can send a base station almanac (BSA) message to the UE indicating the set of transmission points and their locations.