Enhanced Slow Link Adaptation for Wireless CSI Selection

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Solution Overview

Problem

Current link adaptation methods in wireless communication systems, such as those in LTE and LTE-A, face limitations in fast link adaptation due to impairment in SINR estimation and inaccurate mapping, leading to inefficient data transmission rates, especially when channel conditions change rapidly or when UE velocity increases, resulting in high block error rates and degraded throughput.

Innovation Solution

The implementation of an enhanced slow link adaptation (ESLA) technique with multiple stages and a BLER target tracking algorithm, which adjusts CSI based on historical data and filter parameters to optimize link throughput and adapt to changing channel conditions, including a first stage that refines CQI selection and a second stage that filters CSI when RBIR correlation is below a threshold, and a BLER target adjustment mechanism to optimize data transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If fast link adaptation (FLA) is used to quickly react to channel changes, then response speed to channel conditions improves, but SINR estimation accuracy deteriorates leading to high block error rates

Engineering Contradiction:

Improveresponse speed to channel changesVSAvoidblock error rate

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The link adaptation process is segmented into two distinct loops: Fast Link Adaptation (FLA) for rapid response to channel changes and Slow Link Adaptation (SLA) for accurate SINR estimation and CQI selection. This segmentation allows each loop to specialize - FLA handles speed while SLA handles accuracy, resolving the contradiction between response speed and reliability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The SINR estimation acts as an intermediary between channel measurement and CQI selection. The FLA uses SINR estimation to quickly adapt to channel changes, while the SLA refines this estimation to improve accuracy. This intermediary mechanism allows the system to balance between rapid response and reliable throughput

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If SINR to CQI mapping is used for fast link adaptation, then adaptation speed improves, but mapping accuracy deteriorates leading to inefficient data transmission rates

Engineering Contradiction:

Improvelink adaptation speedVSAvoidSINR to CQI mapping accuracy

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The CQI selection process is divided into two stages: FLA-based CQI selection for speed and SLA-based CQI selection for accuracy. The SLA refines the FLA CQI selection by using historical BLER information and adaptive BLER targets, improving mapping accuracy without sacrificing the initial rapid adaptation capability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system implements feedback mechanisms where BLER measurements from previous transmissions are fed back into the SLA to adjust the CQI selection. This feedback loop allows the system to learn from past performance and improve the SINR to CQI mapping accuracy over time, resolving the accuracy deficiency of pure FLA approaches

Inventive Principle:

Principle #23Feedback

3Device complexity

If pre-defined BLER target is used in slow link adaptation, then system complexity is reduced, but adaptability to specific channel conditions deteriorates

Engineering Contradiction:

Improvelink adaptation algorithm complexityVSAvoidadaptability to channel conditions

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The BLER target is made dynamic rather than static. The SLA adapts the BLER target based on historical BLER measurements and current channel conditions. This dynamic adjustment allows the system to maintain low complexity while improving adaptability - the system automatically tunes the BLER target to match specific channel conditions without requiring complex algorithms

Inventive Principle:

Principle #15Dynamics

4Device complexity

If CQI feedback delay increases with UE velocity, then system simplicity is maintained, but link adaptation efficiency deteriorates

Engineering Contradiction:

Improvesystem complexityVSAvoiddata transmission rate

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The SLA performs preliminary CQI refinement before actual transmission based on historical BLER information and adaptive BLER targets. This preliminary action compensates for the CQI feedback delay caused by high UE velocity, allowing the system to maintain simplicity while improving link adaptation efficiency by proactively adjusting CQI selections

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP2959620B1Method and apparatus for enhanced slow link adaptation in a wireless communication system

Publication Date: 2018.08.29 HUAWEI TECH CO LTD

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AI summary

A transceiver operable for selecting channel state information (CSI) of a communication link includes a radio frequency (RF) unit configured to receive a communication signal from the communication link and produce a received data signal, a processing apparatus coupled to the RF unit and configured to receive the data signal, and a memory coupled to the processing apparatus. The processing apparatus is configured to select the CSI with a fast link adaptation (FLA) stage, a first stage of enhanced slow link adaptation (ESLA), a second stage of ESLA, and a BLER tracking process.