DMRS Insertion for Self-Interference Cancellation in Full-Duplex Uplink
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless communication systems, particularly in 5G New Radio (NR), face challenges with self-interference issues due to imperfect isolation of uplink transmission signals from downlink reception signals, leading to distortion and contamination of the receiver, which complicates full-duplex operation.
Innovation Solution
The method involves generating and transmitting Demodulation Reference Signals (DMRS) within the bandwidth of concurrent downlink reception, allowing for channel estimation and digital cancellation of self-interference, thereby enhancing the accuracy of channel estimation and reducing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the UE transmits uplink signals and receives downlink signals concurrently in the same bandwidth, then full-duplex operation capability is improved, but self-interference contamination of the receiver worsens
Solution Approach 1:
The patent introduces reference signals as intermediary elements that mediate between the uplink transmission and downlink reception. These reference signals are inserted into the uplink transmission and serve as known markers that enable the receiver to estimate the self-interference channel, thereby facilitating the cancellation process and resolving the contradiction between full-duplex operation and self-interference contamination
Solution Approach 2:
The patent implements a feedback mechanism where the receiver estimates the self-interference channel based on measured reference signals and uses this estimation to cancel self-interference from the downlink reception. This closed-loop feedback approach continuously adapts to the changing interference conditions, enabling full-duplex operation while mitigating self-interference contamination
2Measurement precision
If reference signals are inserted into uplink transmission for self-interference cancellation, then channel estimation accuracy is improved, but in-band emission limits may be exceeded
Solution Approach 1:
The patent employs parameter changes by adjusting the power level, density, and frequency positioning of reference signals to optimize channel estimation accuracy while maintaining compliance with in-band emission limits. By dynamically changing these parameters based on channel conditions and regulatory requirements, the system achieves precise self-interference cancellation without generating excessive emissions
Solution Approach 2:
The patent applies local quality by inserting reference signals selectively at specific frequency locations and time instances where they provide maximum channel estimation benefit while minimizing impact on in-band emissions. Rather than uniformly distributing reference signals across all resources, the system places them strategically in locations that optimize the trade-off between measurement precision and emission control
Data Source
AI summary
In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. In certain configurations, the UE transmits uplink data signals in a first bandwidth. The UE concurrently receives downlink data signals in a second bandwidth. The UE generates and transmits a reference signal in at least one of the second bandwidth and a bandwidth between the first bandwidth and the second bandwidth. The UE estimates a self-interference channel based on measurements of the reference signal. The UE cancels self-interference from the uplink transmission in the downlink data signals based on the estimated self-interference channel.