MU-COMP Channel State Normalization Measure Quantization

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Solution Overview

Problem

In Multi-User Coordinated Multipoint Transmission/Reception (MU-COMP) networks, existing techniques face challenges with excessive uplink overhead due to the need for full channel state information feedback, which reduces available resources and is impractical, especially since channel elements between geographically distributed antennas are not identically distributed, leading to inefficient interference management.

Innovation Solution

The solution involves each User Equipment (UE) calculating a quantized normalization measure of channel elements as a ratio of complex Gaussian variables, which is then quantized in phase and amplitude, reducing the number of bits required for feedback, allowing the network to set transmitter weights efficiently, thereby reducing uplink overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If full channel state information is fed back from UE to network, then accurate channel knowledge is available for transmitter, but uplink overhead becomes excessive and resources for other traffic are reduced

Engineering Contradiction:
Improvechannel state information accuracyVSAvoiduplink overhead
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent extracts only the essential normalization measure information from the complete channel state information. Instead of feeding back all channel elements, the UE calculates a single normalization measure that captures the key characteristics needed for interference management, significantly reducing feedback overhead while maintaining sufficient accuracy for transmitter optimization

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent transforms the channel state information from a high-dimensional complex matrix into a simplified scalar normalization measure. This parameter transformation reduces the feedback dimensionality while preserving the critical information needed for adjusting transmitter weights and managing interference in MU-COMP systems

Inventive Principle:
Principle #35Parameter changes

2Reliability

If traditional MU-MIMO techniques are applied to MU-COMP, then interference management is improved, but the non-identically distributed channel characteristics are not fully exploited leading to inefficiency

Engineering Contradiction:
Improveinterference managementVSAvoidsystem efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies different processing approaches to different channel characteristics. It recognizes that channel elements in MU-COMP are not identically distributed and tailors the normalization measure calculation to exploit the specific statistical properties of each channel element, optimizing interference management for the local channel conditions rather than applying a uniform approach

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent performs preliminary calculation of the normalization measure at the UE side before transmission. By pre-processing the channel state information and extracting only the essential normalization characteristics, the system prepares the data in an optimized format that enables efficient transmitter weight adjustment without requiring complex real-time processing at the network side

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2351242B1MU-COMP channel state normalization measure quantization and transmission
Publication Date: 2014.03.05 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP2351242B1 patent drawingFigure 1
  • EP2351242B1 patent drawingFigure 2
  • EP2351242B1 patent drawingFigure 3

AI summary

Uplink overhead is significantly reduced in a MU-COMP wireless communication network (10) by exploiting the dissimilarity of received signal strength in signals transmitted by geographically distributed transmit antennas (14, 16), as seen by receiving UEs (18, 20). Each UE (18, 20) calculates a quantized normalization measure of channel elements for a channel weakly received from a first transmitter (14, 16) to that for a channel strongly received from a second transmitter (14, 16). The quantized normalization measure may be modeled as a ratio of complex Gaussian variables, and quantized in phase and amplitude by making simplifying assumptions. The ratios are quantized, and transmitted to the network (10) using far fewer bits than would be required to transmit the full channel state information. The network (10) uses the quantized normalization measures to set the transmitter (14, 16) weights.