High-Order QAM Modulation via RRC Signaling for LTE Small Cells
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Solution Overview
Problem
Existing mobile wireless communication standards, such as LTE, cannot meet the requirements for higher data transmission rates and spectral efficiency in heterogeneous networks, particularly in small-cell environments, due to limitations in modulation schemes and channel state adaptation.
Innovation Solution
The method involves a high-layer configuration signaling to indicate support for high-order Quadrature Amplitude Modulation (QAM) schemes, such as 256QAM, allowing for semi-static switching between different modulation and coding schemes based on channel state information, using separate CQI and TBS index tables to optimize modulation and coding for improved spectral efficiency and peak data rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-order modulation (64QAM or higher) is used to improve system throughput, then spectral efficiency increases, but reliability deteriorates in deep fading conditions
Solution Approach 1:
The patent implements dynamic switching between different CQI tables (legacy 64QAM table and new 256QAM table) based on channel conditions and configuration signaling. The network can semi-statically configure which CQI table to use via RRC signaling, allowing the system to adapt modulation and coding schemes dynamically to balance throughput and reliability according to actual channel quality.
2Reliability
If low-order modulation with high redundancy is used to ensure communication reliability, then reliability improves in deep fading, but system throughput is restricted
Solution Approach 1:
The patent introduces a new CQI table with higher code rates (up to 952/1024) and higher-order modulation (256QAM) to change the modulation and coding parameters. This allows the system to achieve higher spectral efficiency when channel conditions permit, while maintaining the ability to fall back to more robust schemes when needed, thus improving throughput without permanently sacrificing reliability.
3Productivity
If 256QAM is introduced to meet heterogeneous network requirements, then spectral efficiency improves, but device complexity increases
Solution Approach 1:
The patent segments the CQI reporting mechanism into multiple tables: the legacy 64QAM CQI table and the new 256QAM CQI table. Different CQI tables can be selected based on network configuration and channel conditions. This segmentation allows the system to introduce advanced modulation capabilities while maintaining compatibility with existing devices and protocols, thereby reducing the effective complexity burden on individual devices.
4Reliability
If adaptive coding and modulation is implemented to overcome channel time-varying characteristics, then communication quality improves, but system complexity increases
Solution Approach 1:
The patent utilizes CQI feedback mechanisms where the UE measures downlink channel quality and reports back to the network. The network uses this feedback to select appropriate CQI tables and configure MCS indices dynamically. This feedback-driven approach enables adaptive coding and modulation to maintain communication quality in time-varying channels while keeping the adaptation logic centralized in the network, reducing UE complexity.
Data Source
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AI summary
A modulation processing method, a UE and a base station are disclosed; wherein, the base station transmits a high-layer configuration signaling to the UE, wherein the high-layer configuration signaling is used to indicate whether to support a high-order Quadrature Amplitude Modulation (QAM) modulation scheme, wherein the high-order QAM modulation scheme is a modulation scheme of M QAM, wherein M is a number greater than 64. With a high-layer configuration signaling indicating whether to support the high-order QAM, the high-order QAM modulation scheme is supported on the basis of being compatible with existing wireless transmission networks, and the peak data rate and the spectral efficiency are improved.