In Band Full Duplex Node Self-Interference Cancellation
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Solution Overview
Problem
In Band Full Duplex (IBFD) wireless communication systems face challenges in managing self-interference and adjacent channel interference due to the high power difference between received and transmitted signals, which complicates data detection and reduces spectral efficiency, especially in 5G wireless networks with tight channel resource usage and close frequency operations.
Innovation Solution
The system employs an IBFD node that transmits and receives signals simultaneously over the same channel, using orthogonal resources in time, frequency, space, or code, and determines optimal power allocation based on interference and channel parameters to mitigate self-interference and adjacent channel interference, allowing for efficient data transmission and reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If IBFD systems transmit and receive data simultaneously using the same channel, then spectral efficiency is improved, but self-interference makes data detection difficult
Solution Approach 1:
The patent segments the received signal into self-interference component and desired signal component. The self-interference cancellation unit separately identifies and removes the self-interference portion from the received signal, allowing clean detection of the desired signal. This segmentation approach resolves the contradiction by isolating the harmful self-interference from the useful signal.
Solution Approach 2:
The patent converts the harmful self-interference into a detectable pattern that can be cancelled. By modeling the self-interference as a function of the transmitted signal and channel response, the system transforms the harmful interference into a known component that can be subtracted, thereby enabling successful data detection despite simultaneous transmission and reception.
2Object-affected harmful factors
If RF filters are used to reduce adjacent channel interference, then interference mitigation is improved, but spectral leakage cannot be practically eliminated
Solution Approach 1:
The patent introduces an intermediary processing stage between signal reception and detection. The adjacent channel interference mitigation unit acts as an intermediary that processes the received signal to remove interference components from adjacent channels before the desired signal is detected, thereby protecting signal reception reliability without requiring perfect RF filtering.
Solution Approach 2:
The patent changes the processing domain from purely RF filtering to baseband signal processing. By applying interference mitigation algorithms in the baseband domain, the system can more effectively remove adjacent channel interference that cannot be eliminated by RF filters alone, thereby improving signal reception reliability.
3Difficulty of detecting and measuring
If power difference between received and transmitted signals is reduced, then data detection becomes easier, but self-interference power increases
Solution Approach 1:
The patent employs feedback mechanisms where the transmitted signal is fed back through the channel model to predict the self-interference component. This predicted self-interference is then subtracted from the received signal. The feedback loop continuously adapts to channel conditions, maintaining effective self-interference cancellation even when power differences vary, thereby enabling data detection without excessively reducing transmitted power.
Data Source
AI summary
The embodiments herein provide a method for In Band Full Duplex (IBFD) communication in a radio network including at least one IBFD node, at least one first non-IBFD User Equipment (UE) and at least one second non-IBFD UE. The method includes transmitting by the at least one IBFD node a first signal to the at least one first non-IBFD UE over a forward channel, and receiving by the at least one IBFD node a second signal from the at least one second non-IBFD UE over the same forward channel simultaneously, where the second signal includes at least one of a pilot signal, Channel State Information (CSI), and control information, where the forward channel is orthogonal to a reverse channel in at least one of time, frequency, space, and code.