TDD–FDD Spectrum Sharing With Out-of-Band Interference Control
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Solution Overview
Problem
Existing LTE FDD networks face inefficiencies due to asymmetric data traffic patterns, with downlink (DL) spectrum heavily utilized while uplink (UL) spectrum remains underutilized, leading to wasteful and inefficient use of limited mobile spectrum.
Innovation Solution
Concurrently operating user devices in TDD mode within the same spectrum as currently used UL or DL FDD spectrum, coordinated to avoid conflicts, and implementing Distributed-Input Distributed-Output (DIDO) technology to optimize spectrum usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If FDD spectrum is allocated for both UL and DL, then spectrum coverage is provided, but spectral efficiency deteriorates due to asymmetric data traffic patterns causing UL underutilization
Solution Approach 1:
The patent merges TDD and FDD operations by allowing TDD devices to operate concurrently with FDD networks in the same spectrum. TDD user devices utilize the underutilized UL spectrum resources by switching to TDD mode, effectively combining the resource pools of both technologies to improve overall spectral efficiency and reduce spectrum waste.
Solution Approach 2:
The system dynamically allows user devices to switch between FDD and TDD modes based on traffic conditions. When UL traffic demand exceeds available FDD UL resources, devices can dynamically transition to TDD mode to access additional spectrum resources, enabling adaptive resource utilization that responds to changing traffic patterns.
2Productivity
If TDD devices operate in FDD spectrum, then spectral efficiency improves, but interference increases between TDD and FDD systems
Solution Approach 1:
The patent applies local quality by allowing TDD operation only in specific geographic locations where FDD UL underutilization is detected. Rather than blanket TDD deployment, the system enables TDD devices to operate locally in areas where it provides benefit, thereby improving spectral efficiency locally while minimizing overall interference through spatially selective deployment.
Solution Approach 2:
The system employs an intermediary coordination mechanism that manages spectrum sharing between TDD and FDD systems. This intermediary layer coordinates resource allocation, manages interference through power control and resource scheduling, and enables seamless operation of both technologies in the same spectrum by mediating their interactions.
3Productivity
If TDD mode is used to utilize underutilized UL spectrum, then spectrum usage is optimized, but device complexity increases due to mode switching requirements
Solution Approach 1:
The system implements self-service by enabling user devices to autonomously determine when to switch between FDD and TDD modes based on local traffic conditions and network signals. Devices can self-manage their operational mode without requiring complex centralized control, thereby optimizing spectrum usage while keeping device complexity manageable through decentralized decision-making.
Data Source
AI summary
Systems and methods are described to mitigate interference to out of band receivers using out of band training signals.