Hybrid Frequency Time Duplexing for Channel Reciprocity
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Solution Overview
Problem
Current wireless communication systems, particularly FDD, face challenges in achieving accurate beamforming and efficient spectrum management due to the lack of channel reciprocity, leading to sub-optimal CSI feedback and potential spectrum waste due to unequal UL and DL traffic volumes.
Innovation Solution
Implementing a hybrid frequency and time duplexing method that allows for per-band duplexing cadences, enabling flexible distribution of spectral resources and reciprocity-based beamforming by systematically switching UL and DL across time slots in each frequency band, thereby optimizing both UL and DL throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FDD is used for wireless communication, then uplink and downlink can operate simultaneously on different frequency bands, but channel reciprocity cannot be achieved leading to sub-optimal CSI feedback
Solution Approach 1:
The patent applies dynamic time slot allocation within frequency bands, switching between uplink and downlink directions based on traffic demands. This dynamic configuration allows the system to achieve channel reciprocity in TDD mode when needed for accurate CSI feedback, while maintaining FDD-like simultaneous operation capabilities, thus resolving the contradiction between reliability and information loss.
Solution Approach 2:
The patent changes the operational parameters by introducing flexible duplexing modes that can switch between FDD and TDD configurations. By adjusting the duplexing mode parameter based on channel conditions and traffic requirements, the system can achieve channel reciprocity when TDD mode is activated, thereby improving CSI feedback accuracy while maintaining the benefits of FDD operation.
2Productivity
If traditional FDD with equal bandwidth allocation is used, then spectrum bands are efficiently managed, but spectrum waste occurs due to unequal UL and DL traffic volumes
Solution Approach 1:
The patent implements dynamic resource allocation that adjusts the proportion of uplink and downlink resources within frequency bands based on real-time traffic demands. This allows the system to allocate more spectrum resources to the direction with higher traffic volume, thereby improving overall spectrum utilization efficiency and reducing waste while maintaining efficient spectrum management.
Solution Approach 2:
The patent introduces flexible parameter configuration for resource allocation ratios between uplink and downlink. By dynamically adjusting these parameters based on traffic conditions, the system can optimize spectrum utilization to match actual demand patterns, preventing spectrum waste while maintaining efficient band management.
3Measurement precision
If TDD is used for wireless communication, then channel reciprocity can be achieved for beamforming, but flexible spectrum resource distribution between UL and DL is limited
Solution Approach 1:
The patent merges the advantages of both FDD and TDD by creating a hybrid flexible duplexing system. This combined approach allows the system to achieve channel reciprocity for accurate beamforming when TDD mode is used, while simultaneously maintaining the spectrum resource flexibility and simultaneous operation capabilities of FDD, thus resolving the contradiction between measurement precision and adaptability.
Solution Approach 2:
The patent creates a universal duplexing framework that can operate in multiple modes (FDD, TDD, and flexible configurations) within the same system. This multi-functional capability allows the system to achieve channel reciprocity for precise measurements when needed, while also providing flexible spectrum resource distribution, making the system adaptable to various operational requirements.
4Quantity of substance
If quantized or compression CSI feedback schemes are used in FDD, then uplink resources are conserved, but beamforming performance deteriorates
Solution Approach 1:
The patent applies dynamic mode switching that can transition between FDD and TDD configurations based on system requirements. When accurate beamforming is needed, the system switches to TDD mode where channel reciprocity provides full CSI feedback without quantization loss, while maintaining reasonable uplink resource consumption through efficient feedback mechanisms, thus resolving the contradiction between resource consumption and beamforming precision.
Data Source
AI summary
A method, network node and wireless device configured for allocating resources for reverse link transmissions from a second network node to a first network node and forward link transmissions from the first network node to the second network node in a wireless communication system are disclosed. According to one aspect, the method includes selecting a per-band duplexing cadence for each of at least two frequency bands, a duplexing cadence defining a forward link/reverse link pattern of adjacent successive time slots. The method also includes allocating each of the at least two frequency bands to one of forward link and reverse link transmission in each of adjacent successive time slots according to the per-band duplexing cadence for the frequency band.