FDD Channel Estimation Through TDD Fusion and IDFT
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Solution Overview
Problem
In frequency division duplex (FDD) systems, network devices struggle to accurately estimate downlink channels due to the lack of uplink-downlink reciprocity, leading to inaccurate precoding and reduced system throughput.
Innovation Solution
A method involving the combination of FDD downlink and time division duplex (TDD) channels, followed by inverse discrete Fourier transform (IDFT) to enhance channel estimation precision, utilizing energy and phase information from the transformed channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional FDD downlink channel estimation is used, then the network device can obtain downlink channel information, but the channel estimation precision is insufficient leading to inaccurate precoding
Solution Approach 1:
The patent combines FDD downlink channel and TDD channel to form a joint channel representation. By merging channel information from both FDD and TDD systems, the method leverages the advantages of both: FDD provides downlink channel information while TDD provides accurate channel state through reciprocity, thereby improving overall channel estimation precision and precoding accuracy
Solution Approach 2:
The patent introduces an intermediary transformation process (IDFT) that converts the frequency-domain combined channel information into time-domain channel impulse response. This intermediary step enables the network device to extract precise channel characteristics including delay spread and multipath components, which directly improves channel estimation precision
2Measurement precision
If FDD downlink channel estimation is performed independently, then the estimation process is simple, but the precision is insufficient particularly in large bandwidths
Solution Approach 1:
The patent merges FDD downlink channel H_COMUE,f with TDD channel H_COMBS,f to create a joint channel representation. This combination enables the system to achieve high precision channel estimation in large bandwidths by leveraging TDD's accurate channel state information while maintaining FDD's operational benefits
Solution Approach 2:
The patent replaces traditional mechanical channel estimation methods with signal processing transformations (IDFT). By substituting the direct frequency-domain estimation approach with an intermediary time-domain transformation, the system achieves superior precision without proportionally increasing hardware complexity
3Measurement precision
If the network device uses only FDD channel information, then the system operation is straightforward, but the channel state information accuracy is reduced
Solution Approach 1:
The patent combines channel information from both FDD and TDD systems into a unified channel representation H_COMUE,f. This merging enables the network device to achieve accurate channel state information by leveraging TDD's precise channel measurements while maintaining the operational simplicity of FDD systems
Solution Approach 2:
The patent creates a multi-functional channel estimation approach that works across both FDD and TDD systems. The joint channel processing methodology provides universal applicability, enabling accurate channel state information acquisition regardless of the duplexing mode, thereby improving ease of operation across different system configurations
Data Source
AI summary
Embodiments of this application provide a channel information obtaining method and an apparatus. The method includes: obtaining a frequency division duplex FDD downlink channel and a time division duplex TDD channel; determining a first channel expression (I) based on the FDD downlink channel and the TDD channel; performing inverse discrete Fourier transform IDFT on the first channel expression (I) to obtain a second channel expression (II); and sending first information based on the second channel expression (II). According to the foregoing method, channel estimation quality can be improved.