MIMO Base Station Antenna Signaling with Fewer Active Transmit Chains

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Solution Overview

Problem

Base stations in MIMO systems consume high power even when transmitting only common reference signals, as they operate with relatively inefficient power amplifiers, and reducing the number of transmit antennas dynamically is not supported by existing protocols.

Innovation Solution

The method involves disabling one or more transmit chains at the base station while continuing to advertise the original number of transmit antennas, allowing for reduced power consumption by using a fewer number of active transmit chains, and modifying channel estimation processing in user equipment to compensate for the reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If base stations operate with multiple transmit antennas in MIMO systems, then communication performance and throughput are improved, but power consumption increases due to inefficient power amplifiers

Engineering Contradiction:

Improvecommunication throughputVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The base station dynamically adjusts the number of active transmit chains based on traffic conditions. When traffic demand is low, the base station reduces the number of active transmit chains while maintaining the advertised antenna count, thereby reducing power consumption. When traffic demand increases, the base station activates additional transmit chains to improve throughput. This dynamic adjustment resolves the contradiction between maintaining high communication performance and reducing power consumption.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the operational parameter of the number of active transmit chains while keeping the advertised antenna configuration constant. By modifying this parameter based on traffic conditions, the system achieves optimal balance between power efficiency and communication performance without requiring changes to the overall MIMO system architecture or user equipment configurations.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If base stations reduce the number of active transmit chains to save power, then energy efficiency is improved, but communication performance may deteriorate

Engineering Contradiction:

Improvepower efficiencyVSAvoidcommunication performance

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The system dynamically adjusts the number of active transmit chains based on real-time traffic conditions. During low-traffic periods, fewer transmit chains are activated to improve power efficiency. During high-traffic periods, the system activates additional transmit chains to maintain communication performance. This dynamic behavior ensures that power efficiency is optimized without permanently sacrificing communication reliability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The base station periodically monitors traffic conditions and adjusts the number of active transmit chains accordingly. This periodic adjustment allows the system to maintain high power efficiency during low-traffic intervals while ensuring communication performance is restored when traffic demand increases, thus balancing energy loss and reliability over time.

Inventive Principle:

Principle #19Periodic action

3Use of energy by moving object

If base stations dynamically change the number of transmit antennas, then power consumption is reduced, but user equipment configurations may be affected

Engineering Contradiction:

Improvepower consumptionVSAvoidUE configuration compatibility

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The invention segments the antenna system into multiple independent transmit chains that can be individually activated or deactivated. This segmentation allows the base station to adjust the number of active transmit chains without changing the overall advertised antenna configuration. User equipment continues to operate with its existing configurations while the base station selectively activates only the necessary number of transmit chains, thus reducing power consumption without affecting UE adaptability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The base station acts as an intermediary by maintaining the advertised antenna configuration as a constant interface to user equipment, while internally adjusting the number of active transmit chains based on traffic conditions. This intermediary approach allows the system to reduce power consumption through dynamic transmit chain adjustment without requiring user equipment to change their configurations or be aware of the internal adjustments.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8548511B2Energy saving mode with maintained number of advertised transmit antennas

Publication Date: 2013.10.01 QUALCOMM INC

AI summary

Certain aspects of the present disclosure provide techniques for wireless communications, wherein first number of transit antennas is advertised, but a different number of transmit antennas are actually used for transmission.