LTE Network Node CRS Resource Element Scheduling

Solution Overview

Problem

The existing LTE communication systems face substantial overhead in downlink transmissions due to the use of Cell-specific Reference Signals (CRS), which does not provide increased performance for UE-specific RS-based transmission modes and results in additional overhead, especially in newer LTE releases.

Innovation Solution

Scheduling data transmission using resource elements reserved for CRS during subframes, allowing data to be transmitted on these elements, thereby reducing overhead and increasing spectral efficiency, while minimizing the impact on older UE releases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If CRS are transmitted on reserved resource elements to support legacy UEs and CRS-based transmission modes, then compatibility and reliability are maintained, but overhead increases and spectral efficiency decreases

Engineering Contradiction:

Improvecompatibility with legacy UEsVSAvoidoverhead

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies local quality by making CRS transmission selective rather than universal. Specifically, CRS are transmitted only in certain resource blocks (e.g., first set of RBs) and not in others (e.g., second set of RBs), allowing different parts of the spectrum to have different CRS presence. This enables legacy UE compatibility in regions where it's needed while reducing overall overhead in regions where it's not required.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the system bandwidth into multiple resource block sets (first set and second set of RBs) with different CRS transmission characteristics. This segmentation allows the network to independently control CRS transmission in each segment, thereby reducing overall CRS overhead while maintaining compatibility for UEs that require it in specific segments.

Inventive Principle:

Principle #1Segmentation

2Productivity

If CRS overhead is reduced by not transmitting CRS on all resource elements, then spectral efficiency increases, but impact on legacy UEs and CRS-based transmission modes increases

Engineering Contradiction:

Improvespectral efficiencyVSAvoidimpact on legacy UEs

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by making CRS transmission selective rather than universal. Specifically, CRS are transmitted only in certain resource blocks (e.g., first set of RBs) and not in others (e.g., second set of RBs), allowing different parts of the spectrum to have different CRS presence. This enables legacy UE compatibility in regions where it's needed while reducing overall overhead in regions where it's not required.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies partial action by transmitting CRS only partially (in some RBs but not others) rather than completely across the entire bandwidth. This partial CRS transmission is sufficient to support legacy UEs and CRS-based transmission modes in the regions where CRS are present, while avoiding the excessive overhead of transmitting CRS in all RBs.

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If CRS are transmitted across the entire system bandwidth, then legacy UEs can perform measurements and maintain connectivity, but resource utilization efficiency decreases

Engineering Contradiction:

ImproveUE connectivity and measurementsVSAvoidresource utilization efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies local quality by making CRS transmission selective rather than universal. Specifically, CRS are transmitted only in certain resource blocks (e.g., first set of RBs) and not in others (e.g., second set of RBs), allowing different parts of the spectrum to have different CRS presence. This enables legacy UE compatibility in regions where it's needed while reducing overall overhead in regions where it's not required.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the system bandwidth into multiple resource block sets (first set and second set of RBs) with different CRS transmission characteristics. This segmentation allows the network to independently control CRS transmission in each segment, thereby reducing overall CRS overhead while maintaining compatibility for UEs that require it in specific segments.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9736828B2Network node and a method therein for scheduling a downlink data transmission to a UE, and a UE and a method therein for receiving a downlink data transmission

Publication Date: 2017.08.15 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A network node, a UE and respective methods therein are provided for enabling transmission of data using a resource element reserved for CRS. The method in the network node for scheduling a downlink data transmission to the UE currently connected to the network node, comprises determining to schedule data transmission to the UE using at least one resource element reserved for transmitting CRSs during at least one subframe; and transmitting data to the UE using the at least one resource element reserved for transmitting the at least one CRS during the at least one subframe.