Punctured DMRS Resource Allocation for Relay Channel Estimation

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Solution Overview

Problem

In wireless communication systems, particularly in LTE and LTE-A networks, Type 2 relay nodes face challenges in decoding control information due to the inability to perform accurate channel estimation when relay nodes transmit data simultaneously with user equipment (UE), leading to system performance degradation.

Innovation Solution

The implementation of puncturing and orthogonal demodulation reference signals (DMRS) by relay nodes, where the UE and relay nodes transmit DMRS on different subsets or orthogonal patterns of resource elements, allowing the access node to perform separate channel estimation for data and control information, thereby improving decoding accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If relay nodes transmit data simultaneously with user equipment, then network coverage and capacity are improved, but channel estimation accuracy deteriorates leading to control information decoding failures

Engineering Contradiction:

Improvenetwork capacityVSAvoidchannel estimation accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The resource elements for DMRS transmission are segmented into different subsets for UE and relay nodes. UE transmits DMRS on one subset of resource elements while relay nodes transmit DMRS on a different subset, allowing the access node to separately estimate channels for each transmitter without interference

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different resource element subsets act as intermediaries to separate the DMRS transmissions from UE and relay nodes. This separation enables the access node to perform independent channel estimation for each transmitter, resolving the interference problem while maintaining simultaneous transmission capability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Area of stationary object

If relay nodes use full DMRS transmission, then channel estimation coverage is improved, but interference with UE DMRS increases reducing decoding accuracy

Engineering Contradiction:

ImproveDMRS coverage areaVSAvoidcontrol information decoding accuracy

Core Design Contradiction:

Area of stationary objectVSLoss of information

Solution Approach 1:

The DMRS resource elements are segmented into separate subsets for UE and relay nodes. This segmentation allows each transmitter to have sufficient DMRS coverage for accurate channel estimation while preventing interference between the two transmitters, as each uses a distinct subset of resource elements

Inventive Principle:

Principle #1Segmentation

3Measurement precision

If separate channel estimation is performed for UE and relay node, then decoding accuracy is improved, but signaling complexity increases

Engineering Contradiction:

Improvedecoding accuracyVSAvoidsignaling complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

By segmenting DMRS into separate resource element subsets, the system enables implicit separate channel estimation without requiring complex signaling. The access node can independently estimate channels for UE and relay nodes by processing the respective DMRS subsets, achieving high decoding accuracy with minimal additional signaling overhead

Inventive Principle:

Principle #1Segmentation

Data Source

PatentEP2465239B1Uplink transmissions using a type ii relay with a punctured dmrs

Publication Date: 2014.11.26 BLACKBERRY LTD

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AI summary

A method is provided for providing an access node with a demodulation reference signal (DMRS). The method includes, when the UE and at least one relay node are present in a cell, the relay node transmitting the DMRS on a subset of a set of resource elements in which the UE transmits the DMRS.