Common and Dedicated Reference Symbols for Channel Estimation

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Solution Overview

Problem

Current data transmission methods in orthogonal frequency-division multiple access connections rely solely on either common or dedicated reference symbols for demodulation, limiting the flexibility and efficiency of channel estimation and precoding, especially in scenarios with multiple transmitter antennas.

Innovation Solution

A method that utilizes both common and dedicated reference symbols to construct and estimate effective channels, allowing for improved channel knowledge and precoding flexibility, enabling better data demodulation and link quality measurement in multi-antenna environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If only common reference symbols are used for demodulation, then the system complexity is reduced, but the channel estimation precision and precoding flexibility are limited

Engineering Contradiction:

Improvechannel estimation precisionVSAvoidreference symbol structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The reference symbol structure is segmented into two distinct types: common reference symbols (CRS) transmitted from common antenna ports and dedicated reference symbols (DRS) transmitted from dedicated antenna ports. This segmentation allows the system to separately estimate different channel components, improving overall channel estimation precision while maintaining manageable complexity through structured organization

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent merges the functionality of common and dedicated reference symbols into a unified demodulation process. The UE combines channel estimates from both CRS and DRS to reconstruct the effective channel, achieving enhanced measurement precision by leveraging the complementary strengths of both reference symbol types

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If dedicated reference symbols are added for each user, then the channel knowledge and precoding flexibility improve, but the pilot overhead increases

Engineering Contradiction:

Improveprecoding flexibilityVSAvoidpilot overhead

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

Dedicated reference symbols are introduced selectively for specific antenna ports and users rather than universally across all antenna ports. This local quality approach allows precoding flexibility to be enhanced where needed (for dedicated antenna ports serving specific UEs) while avoiding unnecessary pilot overhead in areas where common reference symbols suffice

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system implements partial dedicated reference symbol transmission, providing DRS only for dedicated antenna ports rather than all antenna ports. This partial action achieves the necessary precoding flexibility for multi-antenna scenarios without the excessive pilot overhead that would result from full dedicated reference symbol deployment across all ports

Inventive Principle:

Principle #16Partial or excessive action

3Productivity

If multiple antenna sets are used for transmission, then the data transmission performance improves, but the channel estimation complexity increases

Engineering Contradiction:

Improvedata transmission performanceVSAvoidchannel estimation complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The antenna system is segmented into common antenna sets and dedicated antenna sets, each associated with specific reference symbols. This segmentation allows the channel estimation process to be divided into separate stages: estimating common channel components from CRS and dedicated channel components from DRS, thereby managing complexity while supporting multiple antenna sets for improved transmission performance

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Reference symbols serve as intermediaries between the multiple antenna sets and the channel estimation process. By introducing CRS and DRS as intermediary signals, the system enables indirect channel estimation without requiring direct complex measurements, thus improving data transmission performance while keeping channel estimation complexity manageable through structured intermediary signaling

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8767843B2Employing cell-specific and user entity-specific reference symbols in an orthogonal frequency-division multiple access

Publication Date: 2014.07.01 GOOGLE TECHNOLOGY HOLDINGS LLC

AI summary

A method, a network base station, and a user communication device for transmitting data on an orthogonal frequency-division multiple access system are disclosed. A network base station may have a common antenna set to transmit on a subcarrier via a first effective channel able to be constructed based on at least one common reference symbol. The network base station may have a dedicated antenna set to transmit on a subcarrier via a second effective channel able to be estimated based on at least one dedicated reference symbol. The user equipment may demodulate a data transmission using the at least one common reference symbol and the at least one dedicated reference symbol.