Concurrent FDD-TDD Spectrum Sharing for Asymmetric Traffic
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Solution Overview
Problem
Existing LTE FDD networks face inefficiencies due to asymmetric data usage, where downlink channels are congested while uplink channels are underutilized, leading to wasteful spectrum allocation and limited capacity.
Innovation Solution
Implementing concurrent spectrum usage by allowing user devices to operate in TDD mode within the same spectrum as existing FDD networks, coordinating TDD usage to avoid conflicts with FDD usage, and utilizing Distributed-Input Distributed-Output (DIDO) technology to enhance spectral efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If FDD networks use symmetric spectrum allocation for uplink and downlink, then network compatibility and simplicity are maintained, but spectral efficiency decreases due to asymmetric data usage patterns
Solution Approach 1:
The patent applies asymmetry by allowing TDD mode operation within FDD spectrum allocation, enabling asymmetric uplink-downlink resource allocation that matches actual traffic patterns. This resolves the contradiction by making the spectrum utilization asymmetric (improving adaptability) while maintaining efficient use of available resources (improving spectral efficiency).
Solution Approach 2:
The patent introduces dynamic spectrum sharing between FDD and TDD modes, allowing the network to adaptively allocate resources based on real-time traffic conditions. This dynamic approach enables the system to switch between symmetric and asymmetric allocation as needed, resolving the contradiction between maintaining simplicity and improving spectral efficiency.
2Productivity
If downlink spectrum capacity is increased to handle congested traffic, then network capacity improves, but uplink spectrum remains underutilized causing waste
Solution Approach 1:
The patent makes the spectrum resource universal by enabling it to serve both FDD and TDD modes within the same frequency allocation. The same spectrum can be dynamically shared between symmetric FDD operation and asymmetric TDD operation, allowing the resource to fulfill multiple functions and resolve the waste problem while maintaining high network capacity.
Solution Approach 2:
The patent adds a time dimension to spectrum utilization by introducing TDD's time-division approach within FDD's frequency-division framework. This allows the system to exploit both frequency and time dimensions simultaneously, enabling asymmetric allocation in the time domain while maintaining frequency efficiency, thus eliminating waste without sacrificing capacity.
3Loss of energy
If TDD mode is introduced within FDD spectrum, then spectral efficiency increases through asymmetric allocation, but interference management complexity increases
Solution Approach 1:
The patent introduces coordination mechanisms as intermediaries between FDD and TDD operations. These intermediaries manage the interface between the two modes, handling interference coordination and resource allocation decisions. This resolves the contradiction by adding controlled complexity only where needed for interference management, while maintaining the spectral efficiency benefits of TDD operation.
Data Source
AI summary
Systems and methods are described to mitigate interference to out of band receivers using out of band training signals.