Multi-Antenna Relay Self-Interference Suppression
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Solution Overview
Problem
Existing multi-antenna relays face significant self-interference issues due to poor isolation between their output and input, limiting their performance and capacity, with current solutions like half-duplex operation or orthogonal polarizations either reducing capacity or being impractical.
Innovation Solution
A method using a multi-antenna device with at least three antennas, employing filtering matrix arrangements to cancel specific eigenmodes of the self-interference channel by making the columns of the filtering matrices orthogonal to the eigenmodes to be cancelled, thereby reducing self-interference without capacity loss or requiring orthogonal polarizations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If half-duplex operation (TDD or FDD) is used to eliminate self-interference, then isolation between input and output is improved (infinite isolation), but capacity is reduced by 50%
Solution Approach 1:
The patent changes the parameter of isolation from infinite (half-duplex) to finite but sufficient (full-duplex with filtering), allowing simultaneous transmission and reception. The filtering matrix arrangements modify the signal processing parameters to achieve adequate isolation without capacity loss.
Solution Approach 2:
The patent introduces filtering matrix arrangements as intermediary components between the antennas and relay unit. These filters act as mediators that separate desired signals from self-interference, enabling full-duplex operation with acceptable isolation levels.
2Object-affected harmful factors
If orthogonal polarizations are used on receive and transmit sides to reduce self-interference, then isolation is improved, but capacity is reduced due to polarization mismatch when UE polarization is unknown
Solution Approach 1:
The patent changes the isolation mechanism from relying on polarization orthogonality to relying on spatial filtering. This allows the system to maintain adaptability to unknown UE polarizations while achieving sufficient isolation through the filtering matrix arrangements.
3Productivity
If full-duplex operation is used to maintain capacity, then productivity is improved (no 50% capacity loss), but self-interference increases due to poor isolation between output and input
Solution Approach 1:
The filtering matrix arrangements serve as intermediary signal processing components that enable full-duplex operation by separating transmitted and received signals in the signal space, allowing high capacity operation with controlled self-interference.
Solution Approach 2:
The patent applies different filtering characteristics to different signal components locally, allowing the system to pass desired signals while blocking self-interference components. This localized signal processing enables full-duplex operation with maintained capacity.
Data Source
AI summary
The invention provides a method for self-interference suppression in a multi-antenna device that is part of a communication channel between a transmitter and a receiver of a wireless communication system. The communication system uses the multi-antenna device, the multi-antenna device is located between the transmitter and the receiver and uses antennas and a relay unit forwarding signals from the transmitter to the receiver. The communication channel has a transmit channel, defined by a transmit channel matrix between the transmitter and the multi-antenna device, a receive channel defined by a receive channel matrix, between the multi-antenna device and the receiver and a self-interference channel between an output and an input side of the multi-antenna device. The self-interference channel is defined by a self-interference channel matrix wherein the method comprises the steps of: • quipping the multi-antenna device with at least three antennas and; • suppressing the self-interference channel by using at least one filtering matrix arrangement being inserted between the antennas and the relay unit. The invention also provides a node in a wireless communication system comprising the multi-antenna device for self-interference suppression in the multi-antenna device module that is part of a communication channel.