Passive MIMO Channel Emulator for Low-Noise RF Testing

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Solution Overview

Problem

Existing multiple-input multiple-output (MIMO) channel emulators introduce noise and distortion, limiting the performance of devices under test and being costly, while also being limited to specific channel operations and requiring expensive components.

Innovation Solution

The development of multiple-input multiple-output passive channel emulators that emulate user-defined or measured static channel models using passive signal splitting and re-combining, eliminating the need for analog-to-digital or digital-to-analog conversion, and allowing for selective attenuation, delay, and phase shifting without software interfaces, thus avoiding noise floor limitations and costly components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If digital baseband channel modeling is used, then channel emulation flexibility is improved, but noise and distortion increase

Engineering Contradiction:

Improvechannel emulation flexibilityVSAvoidnoise and distortion

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the digital signal processing chain (analog-to-digital conversion, digital channel modeling, digital-to-analog conversion) with a purely passive RF-based channel emulator. The emulator uses passive components like attenuators, phase shifters, and delay elements to directly manipulate RF signals, eliminating the noise and distortion introduced by digital conversion processes while maintaining channel emulation flexibility through RF signal routing and parameter adjustment.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If known channel emulator components are used, then channel emulation capability is improved, but cost increases

Engineering Contradiction:

Improvechannel emulation capabilityVSAvoidcost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent employs inexpensive passive RF components such as attenuators, phase shifters, and delay elements that can be easily replaced or reconfigured, rather than relying on expensive digital signal processing hardware. The emulator's modularity allows individual components to be swapped without requiring costly replacements of the entire system, reducing overall system cost while maintaining full channel emulation capability.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Adaptability or versatility

If known channel emulator architecture is used, then channel modeling capability is improved, but device complexity increases

Engineering Contradiction:

Improvechannel modeling capabilityVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent divides the channel emulator into separate functional modules, each handling a specific channel characteristic (attenuation, phase shift, delay). This segmentation allows the system to achieve complex channel modeling capabilities through the combination of simple, well-defined modules rather than through complex integrated circuits or digital processing systems, thereby reducing overall device complexity while maintaining modeling capability.

Inventive Principle:

Principle #1Segmentation

4Adaptability or versatility

If known channel emulator components are used, then channel emulation functionality is improved, but reliability decreases

Engineering Contradiction:

Improvechannel emulation functionalityVSAvoidreliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces active digital processing components with passive RF components that operate directly at radio frequency. This substitution eliminates the noise floor limitations and signal degradation associated with analog-to-digital and digital-to-analog conversions, thereby improving the reliability of channel emulation while maintaining full functionality through passive signal manipulation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS7809404B2MIMO passive channel emulator

Publication Date: 2010.10.05 GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORP LTD

AI summary

Embodiments of methods and means for passively emulating channels in a multiple-input multiple output (MIMO) system are provided. Such embodiments include passively splitting a plurality of radio frequency signals into a greater plurality of such signals. Each of the greater plurality of radio frequency signals can then be selectively and passively attenuated, delayed and/or phase shifted. The resulting modified radio frequency signals are then recombined crossed over channels and coupled to a plurality of output nodes. Economical and versatile device and system testing is thus facilitated in a low-noise radio frequency environment without the need for complex up/down frequency or analog/digital conversions.