Access Point Training Weight Storage for MIMO Channel Estimation

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Solution Overview

Problem

Conventional wireless communication methods require an equal number of training signals equal to the number of transmit antennas, leading to increased time for channel information estimation and feedback, which degrades throughput as the number of antennas increases.

Innovation Solution

A wireless communication method where an access point communicates with stations using training weights to reduce the number of training signals needed for channel estimation, involving a training weight reading, weight training symbol transmission, channel information estimation, feedback, transmission weight calculation, and storage of new training weights.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the number of transmit antennas is increased to achieve higher transmission speeds, then the transmission capacity is improved, but the number of training signals required increases proportionally, leading to increased time for channel information estimation and feedback

Engineering Contradiction:
Improvetransmission speedVSAvoidtime for channel information estimation and feedback
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The access point stores training weights in advance for each station, which are pre-calculated optimal weight values for channel estimation. When channel estimation is needed, these pre-stored weights are directly utilized rather than calculating them in real-time, significantly reducing the time required for channel information acquisition while supporting multiple antennas

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Instead of using separate training signals for each transmit antenna, the system uses a single training symbol that is processed with stored training weights to generate weight training symbols. This copying approach allows the same training signal to serve multiple antennas through weight multiplication, reducing the total number of training signals needed while maintaining estimation accuracy

Inventive Principle:
Principle #26Copying

2Measurement precision

If the number of training signals is increased to match the number of transmit antennas, then the channel information estimation accuracy is improved, but the throughput is degraded due to increased overhead

Engineering Contradiction:
Improvechannel information estimation accuracyVSAvoidthroughput
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The system changes the parameter representation from using multiple independent training signals (one per antenna) to using a single training symbol combined with stored weight parameters. This parameter transformation maintains the information content needed for accurate channel estimation while reducing the signal overhead, thereby improving throughput without sacrificing estimation accuracy

Inventive Principle:
Principle #35Parameter changes

3Loss of information

If conventional training signals are used for channel estimation, then the channel information can be obtained, but the computational load increases and channel estimation errors increase due to time consumption

Engineering Contradiction:
Improvechannel information acquisitionVSAvoidcomputational load
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

Training weights are pre-calculated and stored in the access point's storage unit before actual communication occurs. This preliminary preparation eliminates the need for complex real-time calculations during channel estimation, reducing computational load and allowing the system to focus on acquiring channel information efficiently

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The stored training weights act as an intermediary between the training symbol and the channel information estimation process. Instead of directly processing multiple training signals from multiple antennas, the system uses these weights as a mediator to transform a single training symbol into weight training symbols that capture the essential channel characteristics, simplifying the overall computation

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2725731B1Wireless communication method and base-station device
Publication Date: 2018.07.18 NIPPON TELEGRAPH & TELEPHONE CORP
  • EP2725731B1 patent drawingFigure 1
  • EP2725731B1 patent drawingFigure 2
  • EP2725731B1 patent drawingFigure 3

AI summary

The number of training signals for channel estimation is reduced. A wireless communication method includes: a step of reading, by an access point apparatus, stored training weights for a station which performs channel estimation; a step of generating, by the access point apparatus, a weight training symbol by multiplying the training weights by a training symbol and transmitting the generated weight training symbol; a step of estimating, by a station apparatus, weight channel information from the received weight training symbol; a step of transmitting, by the station apparatus, the weight channel information to the access point apparatus; a step of calculating, by the access point apparatus, transmission weights using the received weight channel information and the stored training weights; a step of transmitting, by the access point apparatus, a data signal in accordance with the transmission weights; and a step of calculating and storing, by the access point apparatus, new training weights using the weight channel information and the stored training weights.