LAA DRS and PDSCH Multiplexing in Unlicensed Spectrum

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Solution Overview

Problem

Current methods for multiplex transmission and reception of Discovery Reference Signal (DRS) and Physical Downlink Shared Channel (PDSCH) in LTE Licensed Assisted Access (LAA) systems face challenges in unlicensed spectrum, particularly in avoiding interference and ensuring accurate data reception due to the lack of effective solutions for multiplexing these signals during data transmission bursts.

Innovation Solution

A method for determining subframes within a data transmission burst for transmitting DRS and performing multiplex transmission with PDSCH, where the PDSCH is mapped to symbols or resource elements not occupied by DRS patterns, allowing for efficient multiplexing and reception, specifically utilizing subframes 0 and 5, and managing DRS patterns to ensure time domain continuity and occupied bandwidth requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If DRS and PDSCH are transmitted in the same subframe, then resource utilization is improved, but interference between signals increases and reception accuracy deteriorates

Engineering Contradiction:

Improveresource utilizationVSAvoidinterference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The subframe is segmented into different resource elements, with DRS occupying specific reference signal elements and PDSCH occupying remaining data elements. This segmentation allows both signals to coexist in the same subframe without overlapping, thereby improving resource utilization while avoiding interference.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different quality requirements are applied to different parts of the subframe. DRS requires high accuracy for channel estimation and synchronization, so its resource elements are protected from PDSCH mapping. PDSCH can utilize remaining resources with standard error protection. This local differentiation ensures DRS reception accuracy while maximizing overall resource usage.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If PDSCH rate matching is performed around DRS signals, then DRS reception accuracy is improved, but data transmission efficiency deteriorates

Engineering Contradiction:

ImproveDRS reception accuracyVSAvoiddata transmission efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The network pre-configures rate matching patterns that define which resource elements are occupied by DRS. The UE uses these pre-configured patterns to perform rate matching, avoiding the need for dynamic detection and reducing complexity. This preliminary configuration ensures accurate DRS reception while maintaining efficient data transmission by minimizing overhead.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If DRS is transmitted in multiple time positions within DMTC, then cell discovery reliability is improved, but time resource consumption increases

Engineering Contradiction:

Improvecell discovery reliabilityVSAvoidtime resource consumption

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

DRS is transmitted periodically within the DMTC window at multiple predetermined time positions. This periodic transmission ensures that at least one DRS instance will be successfully received despite potential failures at individual positions, improving cell discovery reliability. The periodic pattern is pre-configured to minimize time consumption while achieving sufficient coverage.

Inventive Principle:

Principle #19Periodic action

4Adaptability or versatility

If LAA DRS supports LBT and transmits at different time positions, then adaptability to unlicensed spectrum is improved, but transmission timing complexity increases

Engineering Contradiction:

Improveadaptability to unlicensed spectrumVSAvoidtransmission timing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The DRS transmission timing is made dynamic to adapt to LBT outcomes. After successful LBT, DRS can be transmitted at the initial DMTC position or deferred to subsequent positions within the window. This dynamic adjustment allows the system to adapt to unlicensed spectrum conditions while the network manages the complexity of timing coordination.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentEP3355635B1Multiplexing sending and receiving method and device for discovery signal and physical downlink shared channel

Publication Date: 2020.07.08 ZTE CORP

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AI summary

Disclosed are a multiplexing sending and receiving method and device for a discovery signal and a physical downlink shared channel. The method comprises: over a data sending time period, a base station determining a sub-frame that sends a DRS within the data sending time period; and performing multiplexing sending on a PDSCH on the sub-frame that sends the DRS within the data sending time period, or performing multiplexing sending on a PDSCH only on a sub-frame 0 and/or a sub-frame 5 that sends the DRS within the data sending time period. The present application solves the problem of how to perform multiplexing sending and receiving on an LAA DRS and the PDSCH within the data sending time period and a PDSCH rate matching problem.