FDR Self-Interference Estimation via Pilot Cross-Correlation
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Solution Overview
Problem
Full duplex radio (FDR) systems face significant performance deterioration due to intra-device self-interference, which needs to be efficiently cancelled to operate effectively.
Innovation Solution
A method for estimating self-interference signals using a communication device that transmits a pilot signal with a selected sequence, receives the self-interference signal, and estimates the channel of non-linear self-interference components using cross-correlation properties, allowing for efficient cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If full duplex radio (FDR) mode is used to double system capacity, then productivity is improved, but self-interference signal strength increases causing performance deterioration
Solution Approach 1:
The patent applies preliminary action by transmitting a pilot signal before actual data transmission to pre-estimate the self-interference channel characteristics. The communication device uses this pilot signal to calculate channel coefficients and generate compensation signals that will be used to cancel self-interference during subsequent data transmission, thereby preparing the system in advance to handle the harmful self-interference effect.
Solution Approach 2:
The patent converts the harmful self-interference signal into a useful estimation target. By deliberately receiving and analyzing the self-interference signal that carries channel information, the system extracts beneficial channel coefficients that enable accurate self-interference cancellation. The harmful interference becomes the source of information needed to eliminate interference in future transmissions.
2Reliability
If self-interference cancellation is performed to improve performance, then reliability is improved, but device complexity increases due to additional processing requirements
Solution Approach 1:
The patent segments the self-interference cancellation process into distinct functional modules: pilot signal transmission, channel estimation, compensation signal generation, and interference cancellation. By dividing the complex cancellation task into separate processing stages, each handled by dedicated functional blocks, the system manages complexity through modular organization while maintaining reliable interference cancellation performance.
Solution Approach 2:
The patent introduces an intermediary compensation signal that mediates between the transmitted signal and the received signal. This compensation signal, generated based on estimated channel coefficients, acts as a bridge to cancel self-interference before the received signal is processed further. The intermediary element simplifies the overall processing by removing interference early in the signal chain.
3Measurement precision
If pilot signal with selected sequence is transmitted to estimate self-interference channel, then measurement precision is improved, but loss of time increases due to additional pilot transmission
Solution Approach 1:
The patent makes the pilot signal multi-functional by designing it to serve both as a channel estimation reference and as a carrier of selected sequences for identifying different communication devices. The pilot signal simultaneously enables self-interference channel estimation and device identification, thereby achieving multiple objectives in a single transmission and reducing the need for separate signaling overhead.
Solution Approach 2:
The patent applies partial action by transmitting pilot signals only when FDR mode is activated and self-interference cancellation is required, rather than continuously. The system selectively performs channel estimation using pilot signals based on operational conditions, thereby minimizing time loss while maintaining measurement precision when needed. The pilot transmission is performed partially rather than excessively.
Data Source
AI summary
A method by which a communication device using an FDR method estimates a self-interference signal can comprise the steps of: transmitting, in a transmitting end, a pilot signal to which a selected sequence is applied; receiving, in a reception end, a self-interference signal relating to the pilot signal; and estimating a channel of a nonlinear self-interference signal component in a self-interference channel by using a cross correlation characteristic of the selected sequence.