Master-Slave AAS Calibration via RF Cable

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Solution Overview

Problem

Radio communication systems face challenges in compensating for variations in amplitudes and phases of transceivers, especially when multiple Active Antenna Systems (AAS) are connected, which affects beamforming accuracy and transmission/reception performance.

Innovation Solution

A radio communication system where one AAS acts as a master and the others as slave, connected via RF and Ethernet cables, with calibration signals transmitted between them to compensate for variations in transceivers, enabling collective DL and UL calibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If multiple AAS are connected in cascade to extend transmission distance and coverage, then the transmission distance and spatial multiplexing capability are improved, but the complexity of compensating for variations in amplitudes and phases of transceivers increases significantly

Engineering Contradiction:

Improvetransmission distanceVSAvoidcalibration complexity

Core Design Contradiction:

Length of moving objectVSDevice complexity

Solution Approach 1:

The system divides the calibration process into two distinct phases: intra-AAS calibration (within each AAS) and inter-AAS calibration (between AASs). This segmentation allows each calibration stage to be handled independently, reducing the overall complexity by breaking down the large-scale calibration problem into manageable segments.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each AAS performs preliminary calibration with its own transceivers before being connected to the cascade system. This preliminary intra-AAS calibration ensures that each unit is individually calibrated, simplifying the subsequent inter-AAS calibration process and reducing the complexity of compensating for variations across the entire system.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If multiple AAS are connected to improve beamforming accuracy and extend coverage, then the degree of freedom for generating Null is improved, but the number of transceivers requiring calibration increases

Engineering Contradiction:

Improvebeamforming accuracyVSAvoidnumber of transceivers

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The calibration process is segmented into intra-AAS and inter-AAS stages. This allows the system to handle calibration of individual AASs separately before integrating them into the cascade, making the calibration of a large number of transceivers manageable through divided phases.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each AAS undergoes preliminary calibration with its transceivers before being added to the cascade system. This preliminary action ensures that individual transceiver variations are compensated early, reducing the burden on the subsequent inter-AAS calibration process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 3:

The system uses reference signals as intermediaries to facilitate calibration between AASs. These reference signals enable the measurement and compensation of amplitude and phase variations across multiple AASs without requiring direct complex interactions between all transceivers.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If more transceivers are incorporated to extend spatial multiplexing order, then the transmission performance is improved, but the variations in amplitudes and phases among transceivers increase

Engineering Contradiction:

Improvespatial multiplexing orderVSAvoidtransceiver consistency

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system employs feedback mechanisms where each AAS measures the amplitude and phase variations of its transceivers using reference signals from other AASs. This feedback information is then used to adjust and compensate for the variations, ensuring consistent performance across all transceivers even as the spatial multiplexing order increases.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

Reference signals act as intermediaries that enable the measurement and compensation of transceiver variations. These signals facilitate the comparison and alignment of amplitude and phase characteristics across multiple transceivers, maintaining reliability as the system scales.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11581956B2Radio communication system, radio communication apparatus, radio communication method, and non-transitory computer readable medium

Publication Date: 2023.02.14 NEC CORP

AI summary

One of a plurality of radio communication apparatuses (100) becomes a master apparatus (100-M), and a rest of them become slave apparatuses (100-S). The master apparatus and each of the slave apparatus includes a plurality of transceivers (31) each composed of a transmitter and a receiver and first ports (55 and 56). The master apparatus further includes a calibration transceiver (51). The first port of the master apparatus is connected to the first port of the slave apparatus via an RF cable. When transmission calibration is performed, each transmitter of the slave apparatus transmits a transmission calibration signal to the calibration transceiver of the master apparatus via the RF cable. When reception calibration is performed, the calibration transceiver of the master apparatus transmits a reception calibration signal to each receiver of the slave apparatus via the RF cable.