Two-Stage Channel Estimation for SUDAC Relay Distortions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional relay networks face challenges in channel estimation and synchronization, particularly in frequency conversion scenarios, leading to magnified effects like Doppler shift and channel distortions due to the assumption of similar channel characteristics within the same frequency band, which are not adequately addressed by existing methods.
Innovation Solution
A transceiver system with a two-stage approach for channel estimation and equalization, utilizing frontend and backend channel estimators and equalizers to compensate for distortions caused by extremely-high and ultra-high frequencies, respectively, and employing a method to remotely control signal processing in a SUDAC to enhance synchronization and signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single-stage channel estimation is used in relay networks, then device complexity is reduced, but measurement precision of channel characteristics deteriorates due to inability to distinguish frontend and backend channel effects
Solution Approach 1:
The patent divides the relay communication channel into two separate segments: frontend channel (base station to relay) and backend channel (relay to user equipment). Two independent channel estimators are employed - one for each segment. This segmentation allows precise estimation of each channel's characteristics without interference, resolving the contradiction by improving measurement precision through structural division while keeping each estimator's complexity manageable.
Solution Approach 2:
The relay node acts as an intermediary that not only forwards signals but also performs independent channel estimation for both frontend and backend channels. This intermediary function enables separate characterization of each transmission segment, improving overall channel estimation precision without requiring the user equipment to handle the entire complex channel directly.
2Measurement precision
If frequency division multiplexing is used to separate control and data channels, then channel estimation accuracy is improved, but loss of time for synchronization increases due to separate estimation processes
Solution Approach 1:
The patent employs preliminary synchronization actions where the relay node performs frontend channel estimation and synchronization before backend transmission. By pre-establishing channel knowledge at the relay, the system avoids time-consuming synchronization procedures at the user equipment, thus reducing overall synchronization time while maintaining high estimation accuracy through the two-stage approach.
Solution Approach 2:
The system maintains continuous channel estimation and synchronization processes at the relay node for both frontend and backend channels. This continuous operation ensures that channel knowledge is always current, enabling rapid data transmission without repeated full synchronization procedures, thereby reducing time loss while preserving accuracy.
3Reliability
If pilot data is transmitted in every OFDM symbol for channel tracking, then reliability of channel estimation is improved, but use of energy increases due to continuous pilot transmission
Solution Approach 1:
The patent applies partial pilot transmission strategy where pilots are transmitted only in critical OFDM symbols rather than every symbol. The two-stage channel estimation at the relay node allows reliable channel tracking with reduced pilot density, as the relay can interpolate and track channel variations between pilot symbols more effectively than a single-stage system, thus maintaining reliability while reducing energy consumption.
Solution Approach 2:
The relay node uses feedback from frontend channel estimation results to optimize backend pilot transmission requirements. By continuously monitoring frontend channel conditions and updating backend channel knowledge, the system can reduce pilot transmission frequency while maintaining estimation reliability, thereby lowering energy consumption.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A transceiver of a user equipment comprises a receiving stage, a frontend channel estimator, a frontend channel equalizer, a backend channel estimator, and a backend channel equalizer. The receiving stage is configured to receive an inbound signal from a SUDAC, which enables a relay communication comprising a frontend communication using extremely-high frequencies and a backend communication using ultra-high frequencies. The inbound signal comprises a data portion, a backend control portion and a frontend control portion, the frontend control portion comprising a frontend evaluation signal and a configuration signal. The frontend channel estimator is configured to perform a channel estimation based on the frontend evaluation signal wherein the frontend channel equalizer is configured to equalize distortions, caused by using the extremely-high frequencies, based on the channel estimation of the frontend channel estimator. The backend channel estimator is configured to perform a channel estimation based on the backend control portion wherein the backend channel equalizer is configured to equalize distortions, caused by using the ultra-high frequencies, based on the channel estimation of the backend channel estimator.