Adaptive Wireless Transceiver Feedback Reduction

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Solution Overview

Problem

In wireless communication systems using frequency division duplexing, conventional adaptive transmission methods are ineffective due to the large amount of feedback information required, especially in multi-carrier systems with fast mobile speeds, leading to degraded system performance.

Innovation Solution

The use of received log likelihood ratio distribution as feedback information to determine antenna, modulation, and encoding methods, with a modulation and encoding method and transmit power determining unit that adjusts transmit power based on pre-defined tables and parameters, allowing adaptive transmission with a reduced amount of feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If per-carrier SNR feedback is used for adaptive transmission in multi-carrier systems, then transmission performance can be optimized, but the amount of feedback information becomes very large

Engineering Contradiction:

Improvetransmission performanceVSAvoidfeedback information amount

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent segments the multi-carrier channel into frequency regions and groups carriers within each region. Instead of providing per-carrier SNR feedback for all carriers, the system provides feedback only for representative carriers in each frequency region, significantly reducing feedback overhead while maintaining adaptive transmission performance through frequency-selective modulation and coding.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extracts only the essential feedback information needed for adaptive transmission by selecting representative carriers from each frequency region. The system identifies and feeds back SNR information only for these representative carriers, eliminating the need to transmit feedback for every single carrier while still enabling effective channel adaptation.

Inventive Principle:

Principle #2Taking out (Extraction)

2Loss of information

If carrier groups are formed to reduce feedback information, then feedback amount decreases, but system performance degrades in frequency selective fading channels

Engineering Contradiction:

Improvefeedback information amountVSAvoidsystem performance

Core Design Contradiction:

Loss of informationVSReliability

Solution Approach 1:

The patent applies local quality by treating different frequency regions differently. Each frequency region is analyzed separately and representative carriers are selected based on local channel characteristics. This allows the system to adapt to frequency-selective fading locally in each region rather than applying a uniform grouping approach, thereby maintaining performance while reducing feedback.

Inventive Principle:

Principle #3Local quality

3Loss of information

If the number of carriers in carrier groups is increased, then feedback information amount is reduced, but channel gain variations within groups increase and performance degrades

Engineering Contradiction:

Improvefeedback information amountVSAvoidchannel gain uniformity

Core Design Contradiction:

Loss of informationVSManufacturing precision

Solution Approach 1:

The patent introduces dynamic adaptation by allowing the system to flexibly determine the number of representative carriers and their selection based on actual channel conditions. The representative carrier selection is not fixed but adapts to the frequency selective fading characteristics, enabling the system to optimize between feedback reduction and channel gain uniformity dynamically.

Inventive Principle:

Principle #15Dynamics

4Manufacturing precision

If the number of carriers in carrier groups is decreased, then channel gain uniformity is improved, but feedback information amount remains large

Engineering Contradiction:

Improvechannel gain uniformityVSAvoidfeedback information amount

Core Design Contradiction:

Manufacturing precisionVSLoss of information

Solution Approach 1:

The patent merges multiple carriers into frequency regions and selects representative carriers from each region. By combining the benefits of carrier grouping with intelligent representative selection, the system achieves both reduced feedback overhead and maintained channel gain uniformity, resolving the contradiction between these two objectives.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS7627050B2Adaptive transmitting and receiving device and method in wireless communication system using frequency division duplexing

Publication Date: 2009.12.01 ELECTRONICS & TELECOMM RES INST

AI summary

Disclosed is an adaptive transmitting and receiving device and method using frequency division duplexing. A transmitter transmits a preamble or a pilot to a receiver. The receiver estimates a received SNR from the preamble or pilot, determines parameters (received log likelihood ratio parameters) of determining the distribution of the received log likelihood ratio, and feeds them back to the transmitter. The transmitter adaptively determines an antenna method, a modulation method, and a transmit power according to the parameters, and adaptively transmits traffic data to the receiver according to the determined antenna method, the modulation method, and the transmit power.