Reference Signal Measurement for Distributed Antenna Systems

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Solution Overview

Problem

In LTE/LTE-A mobile communication systems with distributed antenna systems, the existing CRS measurement-based CQI generation method is inadequate, as it cannot accurately determine channel quality per transmission point and is limited to up to 4 antennas, failing to support systems with 8 antennas, and requires measurement of CSI-RS for accurate downlink channel assessment.

Innovation Solution

A method and apparatus that allow a UE to selectively measure either a Cell-specific Reference Signal (CRS) or a Channel Status Information Reference Signal (CSI-RS) for generating CQI in RI/PMI disabled mode, with explicit or implicit notification from the eNB, enabling accurate channel quality feedback to the eNB.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If CRS measurement-based CQI generation method is used, then the method is simple and compatible with legacy systems, but it cannot accurately determine channel quality per transmission point and is limited to up to 4 antennas

Engineering Contradiction:

Improvesimplicity of CQI generation methodVSAvoidaccuracy of channel quality determination

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent segments the reference signal measurement process by introducing CSI-RS as a separate, dedicated reference signal for channel state measurement, distinct from CRS which is used for other purposes. This segmentation allows accurate per-transmission-point channel quality determination while maintaining legacy CRS functionality, resolving the contradiction between measurement simplicity and accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces CSI-RS as an intermediary element that mediates between the need for accurate channel quality measurement and the existing CRS-based system. CSI-RS serves as a dedicated measurement reference that does not interfere with CRS operations, enabling precise channel quality determination per transmission point while preserving legacy system compatibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If CRS is used for channel measurement in distributed antenna systems, then legacy system compatibility is maintained, but accurate downlink channel assessment per transmission point cannot be achieved

Engineering Contradiction:

Improvecompatibility with legacy systemsVSAvoidaccuracy of downlink channel assessment

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent segments the reference signal functionality by dedicating CRS to legacy operations and introducing CSI-RS specifically for downlink channel state measurement. This segmentation enables accurate per-transmission-point channel assessment in distributed antenna systems while maintaining full compatibility with legacy CRS-based operations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

CSI-RS acts as an intermediary that bridges legacy system compatibility and modern distributed antenna system requirements. It provides the necessary measurement capability for accurate downlink channel assessment without disrupting existing CRS-based legacy operations, allowing seamless integration of new functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If only CRS measurement is supported, then implementation is straightforward, but systems with 8 antennas cannot be properly supported

Engineering Contradiction:

Improveimplementation complexityVSAvoidsupport for systems with 8 antennas

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent segments the antenna support capability by using CRS for legacy 4-antenna operations and CSI-RS for extended 8-antenna distributed antenna systems. This segmentation allows the system to support both configurations appropriately, with CSI-RS enabling accurate measurement across 8 antennas while CRS maintains straightforward implementation for legacy scenarios.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent creates a universal measurement framework where CSI-RS serves multiple functions: it supports both 4-antenna and 8-antenna configurations, works in both centralized and distributed antenna systems, and maintains compatibility with legacy operations. This multi-functionality resolves the contradiction between implementation simplicity and extended system support.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP2853040B1Reference signal measurement method and apparatus for use in wireless communication system including plural base stations with distributed antennas

Publication Date: 2020.02.26 SAMSUNG ELECTRONICS CO LTD

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AI summary

An apparatus and a method of measuring a reference signal for efficient downlink transmission in a mobile communication system are provided. The system includes plural base stations, each having a plurality of antennas distributed in the service area thereof based on a Distributed Antenna System (DAS). A method for a base station to notify a terminal of reference signal measurement information in a mobile communication system comprises determining whether the terminal is in a Rank Indicator/Precoding Matrix Indicator (RI/PMI) disabled mode, selecting, when the terminal is in the RI/PMI disabled mode, the reference signal to be measured by the terminal between a Cell-specific Reference Signal (CRS) and a Channel Status Information Reference Signal (CSI-RS), notifying the terminal of the reference signal measurement information with the selection result, and receiving channel information generated based on the reference signal measurement information from the terminal.