Two-Tier RF Beamforming for mmWave Latency

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Solution Overview

Problem

Higher frequency access systems, such as millimeter wave (mmWave) systems, face challenges in maintaining and adapting beam directions due to user mobility and changing channel conditions, leading to high acquisition latency and overhead during initial access and potential interruptions in connections.

Innovation Solution

A two-tier RF beamforming architecture is implemented, where Tier-1 sectors provide broader coverage for low data-rate control channels and Tier-2 sectors offer narrower coverage for high data-rate channels, with periodic and triggered sector adaptation procedures using reference signals and control channels to dynamically select and adapt the best sectors based on channel conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If initial acquisition procedure is repeated after loss of beam direction, then beam direction can be re-established, but acquisition latency and overhead increase significantly

Engineering Contradiction:

Improvebeam connection reliabilityVSAvoidacquisition latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary beam direction tracking during connected mode by monitoring reference signals and channel conditions. This preliminary action detects beam direction degradation before complete loss occurs, enabling proactive beam refinement rather than reactive re-acquisition, thus reducing acquisition latency while maintaining connection reliability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms where the UE reports channel quality indicators (CQI) and beam measurement results to the eNB. This feedback enables the eNB to adaptively adjust beam directions and select appropriate beams based on real-time channel conditions, preventing beam direction loss and avoiding the need for repeated initial acquisition procedures

Inventive Principle:

Principle #23Feedback

2Reliability

If directional beamforming is used to achieve required SNR, then signal quality improves, but system complexity increases due to beam management procedures

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidbeam management complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The beam management process is segmented into distinct functional layers: Tier-1 sector-level beam management for broad coverage and initial access, and Tier-2 beam-level management for precise signal optimization. This segmentation allows independent optimization of each tier, reducing overall system complexity while maintaining the required SNR through coordinated operation of both tiers

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system employs universal reference signals (CSI-RS and SRS) that serve multiple functions simultaneously: channel estimation, beam measurement, beam selection, and channel quality indication. This multi-functionality reduces the need for separate dedicated signals for each beam management task, thereby reducing signaling overhead and system complexity while maintaining accurate SNR measurement

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Area of stationary object

If broader Tier-1 sectors are used for control channels, then coverage area increases, but beam precision for high data-rate channels decreases

Engineering Contradiction:

Improvesector coverage areaVSAvoidbeam direction precision

Core Design Contradiction:

Area of stationary objectVSMeasurement precision

Solution Approach 1:

The system segments the beam management function into two hierarchical tiers: Tier-1 sectors provide broad coverage for control channels with lower precision requirements, while Tier-2 beams provide narrow, high-precision coverage for data channels. This segmentation allows each tier to be optimized independently for its specific function, maintaining both broad coverage and high precision simultaneously

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The Tier-2 narrow beams are nested within the broader Tier-1 sector framework. Each Tier-1 sector contains multiple Tier-2 beams that inherit the sector's coverage area but provide finer angular resolution. This nested structure enables the system to use broad sectors for control channel coverage while deploying precise narrow beams within them for high data-rate transmissions

Inventive Principle:

Principle #7Nested doll (Nesting)

Data Source

PatentUS11711792B2Two-tier sector RF beamforming adaptation

Publication Date: 2023.07.25 INTEL CORP

AI summary

Briefly, in accordance with one or more embodiments, an apparatus of a user equipment (UE) comprises baseband circuitry including one or more processors to decode a secondary synchronization signal (SSS) or a beam reference signal (BRS) received from an evolved Node B (eNB) to select a Tier-1 sector for receiving downlink transmissions from the eNB, decode a downlink control channel message received from the eNB at one or more fixed time offsets after the UE decodes the SSS to obtain index information for the Tier-1 sector to identify the Tier-1 sector, and if the Tier-1 sector has changed initiate a random access procedure to select an updated Tier-1 sector, and generate an updated Tier-1 sector index message to report to the eNB.