MIMO Transmission Delay Calibration Using Clock Phase Feedback

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Solution Overview

Problem

In MIMO transmission systems, the differences in delay between transmission systems can lead to misalignment of transmission timing, resulting in degraded reception accuracy due to the individual variations in analog circuits within digital-to-analog converters across multiple transmission radio processing units.

Innovation Solution

A control device and method that adjust delay differences by transmitting specific clock signals and acquiring phase values from a MIMO reception device to calculate correction values for delay adjustment units, ensuring synchronized timing across multiple transmission systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If analog circuits are used in transmission radio processing units, then device complexity is reduced and ease of manufacture is improved, but individual variations cause delay differences that degrade reception accuracy

Engineering Contradiction:

Improvereception accuracyVSAvoiddelay alignment complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by performing delay measurement and correction before actual MIMO transmission. The control device measures delay differences between transmission systems using test signals, calculates correction values, and adjusts delay adjustment units in advance. This preliminary calibration ensures that when actual transmission occurs, the timing is already aligned, preventing reception accuracy degradation without adding complexity to the manufacturing process.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If delay adjustment units are added to correct timing differences, then reception accuracy is improved, but device complexity increases

Engineering Contradiction:

Improvetiming alignment precisionVSAvoidsystem structure complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent introduces a control device as an intermediary that coordinates between transmission systems and reception devices. This control device manages the delay measurement, correction value calculation, and adjustment unit configuration. By placing the coordination function in a separate control device rather than embedding complex control logic in each transmission radio processing unit, the system achieves precise timing alignment while keeping individual component complexity manageable.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The delay adjustment units are designed to automatically apply correction values without requiring manual intervention. The control device sends correction values to the delay adjustment units, which then self-adjust their delay characteristics based on these values. This self-service mechanism eliminates the need for manual calibration and reduces operational complexity while maintaining high timing alignment precision.

Inventive Principle:

Principle #25Self-service

3Manufacturing precision

If multiple transmission systems operate independently, then ease of operation is improved, but delay misalignment occurs that degrades reception accuracy

Engineering Contradiction:

Improvetransmission timing precisionVSAvoidsystem coordination complexity

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent implements feedback by having the control device measure actual delay differences between independently operating transmission systems and use these measurements to calculate correction values. The delay adjustment units apply these corrections, and the system can perform repeated measurements to verify alignment. This feedback loop allows transmission systems to operate independently initially while still achieving synchronized timing through automated measurement and correction, maintaining both operational simplicity and timing precision.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11290154B2Control device, delay difference adjustment method, and non-transitory computer readable medium for storing delay difference adjustment program

Publication Date: 2022.03.29 NEC CORP

AI summary

A control device causes a first transmission system in a MIMO transmission device to transmit a first transmitting-end clock transmission signal (first transmission signal), causes a second transmission system to transmit a second transmission signal, and causes the first transmission system to transmit a third transmission signal. The control device acquires a first phase value and a second phase value. The first phase value is a phase value of the second transmission signal received in the second reception system operating based on a receiving-end clock signal synchronous with a transmitting-end clock signal by the first transmission signal. The second phase value is a phase value of the third transmission signal received in the second reception system in synchronous operation. The control device calculates a first correction value for correcting a first delay amount set value of a delay adjustment processing unit based on the first and second phase values.