LTE Uplink MCS Table Selection via DCI Configuration

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Solution Overview

Problem

Wireless communication systems face challenges in efficiently adapting modulation and coding schemes (MCS) for uplink transmissions, particularly with the introduction of higher order modulations like 256 QAM, as existing MCS tables may not adequately support these advancements, leading to inefficiencies in resource allocation and interference management.

Innovation Solution

The method involves configuring downlink control information (DCI) to convey a reference to the appropriate MCS table for uplink transmissions, allowing user equipment (UE) to select between legacy and non-legacy MCS tables based on received DCI format and configuration, enabling support for higher order modulations such as 256 QAM while conserving control overhead resources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If additional MCS tables are developed to support higher order modulations like 256 QAM, then the system can support advanced modulation schemes, but the complexity of MCS table management increases and existing tables do not include data entries for these additional MCSs

Engineering Contradiction:

Improvesupport for higher order modulationsVSAvoidMCS table management complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements dynamic MCS table selection where the UE can be configured to use different MCS tables (legacy or non-legacy) based on received DCI configurations. The system transitions from static table assignment to dynamic table selection, allowing flexible adaptation between legacy MCS tables and new MCS tables supporting 256 QAM modulation based on channel conditions and network requirements.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of MCS table selection by introducing configuration parameters in DCI that indicate which MCS table the UE should use. This allows the system to switch between different MCS table configurations (legacy vs. non-legacy) by modifying the table selection parameter, enabling support for higher order modulations without fixed table assignments.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If multiple MCS tables are referenced, then more modulation schemes can be supported, but methods for referencing multiple MCS tables are required increasing signaling overhead

Engineering Contradiction:

Improvemodulation scheme optionsVSAvoidcontrol overhead

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent extracts the MCS table selection indication from the main DCI payload and implements it through CRC scrambling or specific DCI format configurations. By separating the table selection mechanism from the primary MCS indication, the system can reference multiple MCS tables without adding significant overhead to the control information, as the selection is conveyed through efficient signaling methods.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent creates a universal DCI structure that can reference both legacy and non-legacy MCS tables through a unified configuration mechanism. The same DCI format and signaling procedures can indicate different MCS tables based on configuration parameters, providing multi-functionality that reduces the need for separate signaling paths for different table types.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If MCS tables are expanded to include 256 QAM entries, then higher spectral efficiency can be achieved, but existing MCS tables may not include data entries that account for these additional MCSs

Engineering Contradiction:

Improvespectral efficiencyVSAvoidMCS table structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent performs preliminary configuration of MCS table associations through RRC signaling before actual data transmission. The network pre-configures the UE with indications of which DCI formats or search spaces are associated with non-legacy MCS tables, so that when uplink grants are received, the UE can immediately determine the appropriate MCS table without real-time negotiation, reducing latency and overhead.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP3134988B1Modulation coding scheme (MCS) tables indication in LTE uplink

Publication Date: 2021.08.11 QUALCOMM INC

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AI summary

Methods, systems, and devices for indicating a modulation coding scheme (MCS) in LTE are described. A user equipment (UE) may receive downlink control information (DCI) from an evolved Node B (eNB) that includes an uplink grant of resources. The DCI may be configured and have a format that conveys an MCS table reference. The UE may identify the MCS table reference and, based on the reference, identify a legacy MCS table or a non-legacy MCS table. The legacy MCS table may be associated with quadrature amplitude modulation (QAM) up to a first order, and the non-legacy MCS table may be associated with QAM up to a second order, the second order being higher than the first order. The UE may modulate and code information for uplink transmissions using the identified MCS table.