Dynamic TDD-FDD Duplexing for LTE Spectrum Utilization

Solution Overview

Problem

Long Term Evolution (LTE) wireless communication systems face inefficiencies in utilizing radio resources, particularly in Frequency Division Duplex (FDD) mode due to asymmetrical downlink (DL) and uplink (UL) traffic demands, leading to underutilization of valuable UL radio spectrum, while Time Division Duplex (TDD) systems are difficult to implement due to requirements for frequent switching between DL and UL modes.

Innovation Solution

A duplexing method that combines aspects of FDD and TDD in a single system, allowing radio spectrum to be more efficiently utilized by configuring existing FDD-LTE systems to carry full TDD radio frames on UL channels and adding an FDD DL-only channel, enabling dynamic adjustment of DL and UL sub-frame ratios based on traffic demand without requiring hardware changes to existing UEs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If FDD mode is used, then simultaneous DL and UL communications are enabled, but UL radio spectrum is underutilized due to asymmetrical traffic demands

Engineering Contradiction:

ImproveDL radio resource utilizationVSAvoidUL spectrum underutilization

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent implements dynamic TDD-FDD duplexing where the system can switch between FDD and TDD modes based on traffic conditions. Specifically, when UL traffic demand is low, the system uses FDD mode for simultaneous DL and UL communications. When UL traffic demand increases, the system dynamically switches to TDD mode to better utilize the UL spectrum by allocating more time resources to UL transmissions, thereby resolving the spectrum underutilization issue while maintaining high DL resource utilization

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the duplexing mode parameter from static FDD or TDD to dynamic TDD-FDD hybrid mode. This parameter change allows the system to adapt to varying traffic conditions by adjusting the duplexing mode, thereby optimizing both DL radio resource utilization and UL spectrum usage according to actual traffic demands

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If TDD mode is used, then UL and DL traffic asymmetry is better handled, but implementation becomes difficult due to frequent switching requirements

Engineering Contradiction:

Improvetraffic demand adaptationVSAvoidswitching complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements dynamic TDD-FDD duplexing where the system can switch between FDD and TDD modes based on traffic conditions. Specifically, when UL traffic demand is low, the system uses FDD mode for simultaneous DL and UL communications. When UL traffic demand increases, the system dynamically switches to TDD mode to better utilize the UL spectrum by allocating more time resources to UL transmissions, thereby resolving the spectrum underutilization issue while maintaining high DL resource utilization

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent makes the duplexing system universal by enabling it to operate in multiple modes (both FDD and TDD) within the same infrastructure. The eNodeB can dynamically select between FDD and TDD modes based on traffic conditions, making the system adaptable to different scenarios without requiring separate dedicated systems for each mode, thereby reducing overall complexity while maintaining versatility

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If dynamic TDD-FDD duplexing is implemented, then spectrum utilization is improved, but system complexity increases

Engineering Contradiction:

Improvespectrum utilization efficiencyVSAvoidduplexing system complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent implements dynamic TDD-FDD duplexing where the system can switch between FDD and TDD modes based on traffic conditions. Specifically, when UL traffic demand is low, the system uses FDD mode for simultaneous DL and UL communications. When UL traffic demand increases, the system dynamically switches to TDD mode to better utilize the UL spectrum by allocating more time resources to UL transmissions, thereby resolving the spectrum underutilization issue while maintaining high DL resource utilization

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system performs self-service by automatically monitoring traffic conditions and dynamically selecting between FDD and TDD modes without requiring manual intervention. The eNodeB autonomously adjusts the duplexing mode based on real-time traffic demands, which simplifies operation and reduces the complexity of manual configuration and management

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS9397800B2Duplexing in long term evolution (LTE) cellular networks

Publication Date: 2016.07.19 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

A duplexing method is provided that combines aspects of Frequency Division Duplex (FDD) and Time Division Duplex (TDD) methods in a network, such as a Long Term Evolution (LTE) network. The duplexing method may be implemented on an existing FDD network by replacing the FDD uplink (UL)-only radio frame with a full TDD radio frame having dynamically allocable UL and downlink (DL) sub-frames. Alternatively, the duplexing method may be implemented on an existing TDD network by adding a second frequency to pair with an existing frequency over which a FDD DL-only radio frame can be run.