Analog Spatial Multiplexing for LoS Massive MIMO

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Solution Overview

Problem

Massive MIMO systems in wireless communications face high digital signal processing requirements, leading to increased cost, complexity, and energy consumption, particularly in 5G and mmWave communication systems.

Innovation Solution

The system performs spatial multiplexing purely in the analog domain between line-of-sight transmit and receive arrays, using an inverse steering matrix to process analog receive signals and recover analog transmit signals, thereby reducing digital signal processing needs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If digital MIMO processing is used in massive MIMO systems, then communication functionality is achieved, but digital signal processing complexity and energy consumption increase significantly

Engineering Contradiction:

Improvecommunication functionalityVSAvoiddigital signal processing complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces digital signal processing (electronic/computational system) with analog signal processing (physical field system). Specifically, it uses analog beamforming and spatial multiplexing techniques where the MIMO processing is performed in the analog domain using phase shifters and signal combining networks, thereby eliminating the need for complex digital baseband processing while maintaining communication functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If digital MIMO processing is used in massive MIMO systems, then communication functionality is achieved, but energy consumption increases

Engineering Contradiction:

Improvecommunication functionalityVSAvoidenergy consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent substitutes energy-intensive digital signal processing with energy-efficient analog signal processing. By performing beamforming and spatial multiplexing operations in the analog domain using passive components like phase shifters and hybrid couplers, the system dramatically reduces power consumption compared to digital baseband processing, while still achieving effective MIMO communication functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If digital MIMO processing is used in massive MIMO systems, then communication functionality is achieved, but system cost increases

Engineering Contradiction:

Improvecommunication functionalityVSAvoidsystem cost

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces expensive digital signal processing hardware with more cost-effective analog processing components. The analog MIMO system uses readily available components such as phase shifters, power dividers, and combiners that are generally less costly than the high-performance digital signal processors, FPGAs, or ASICs required for digital MIMO processing, thereby reducing overall system cost while maintaining communication functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10862551B2System and method for spatial multiplexing in LoS environments

Publication Date: 2020.12.08 CABLE TELEVISION LAB INC

AI summary

The present system and method provides a spatial multiplexing scenario that is performed purely in the analog domain when transmit and receive arrays are in Line of Sight (LoS) and hence significantly reduce the DSP requirements of massive MIMO systems.