MIMO Antenna Leakage Canceller Using Active Signal Subtraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems for isolating receiver portions from transmitter portions in MIMO devices face challenges such as high cost, bulkiness, and increased power consumption, particularly in space-constrained applications like LTE small-cell devices, due to limited antenna isolation leading to transmitter interference with receivers.
Innovation Solution
The implementation of a system that combines passive and active cancellation methods using a duplexer to sample and filter transmit signals, adjusting them based on determined phase, amplitude, and delay of leakage, and using a coupler to subtract the leakage cancellation signal from received signals, thereby reducing power consumption and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If passive ceramic or air cavity duplexer is used to provide high isolation between transmit and receive portions, then interference reduction is improved, but device size and cost increase
Solution Approach 1:
The patent replaces the mechanical/passive isolation system (ceramic or air cavity duplexer) with an electronic active cancellation system. The system uses signal processing to generate an inverted copy of the transmit signal and subtract it from the receive signal, eliminating the need for bulky passive isolation structures while maintaining interference reduction effectiveness.
Solution Approach 2:
The patent introduces an active canceller as an intermediary component between the transmit and receive portions. This canceller samples the transmit signal, processes it through phase/amplitude/delay adjustment, and injects the inverted signal into the receive path to cancel interference, providing a compact alternative to large passive duplexers.
2Object-affected harmful factors
If passive ceramic or air cavity duplexer is used to provide high isolation between transmit and receive portions, then interference reduction is improved, but device cost increases
Solution Approach 1:
The patent replaces expensive passive ceramic or air cavity duplexers with a cost-effective active cancellation system implemented using standard RF components and digital signal processing, significantly reducing manufacturing costs while maintaining performance.
Solution Approach 2:
The active canceller creates a copy of the transmit signal, processes it to match the leakage characteristics (phase, amplitude, delay), and inverts it to cancel the interference. This copying approach using standard components is more economical than manufacturing expensive passive isolation structures.
3Productivity
If multiple antennas are used in MIMO arrangement to increase data rate, then productivity is improved, but antenna coupling and interference increase
Solution Approach 1:
The patent implements a feedback mechanism where the transmit signal is sampled and fed back through the active canceller to generate the cancellation signal. This feedback loop continuously adapts to cancel the coupling between antennas in the MIMO system, enabling higher data rates without suffering from antenna interference.
Solution Approach 2:
The patent converts the harmful transmit signal that causes coupling interference into a beneficial cancellation signal. By sampling the transmit signal and processing it through the active canceller, the system transforms the source of interference into the means of eliminating it, allowing MIMO operation with closely-spaced antennas.
Data Source
AI summary
A system includes a first duplexer that receives samples of a signal transmitted from a first transmit portion of a communication device and outputs a filtered signal based on sampled transmitted signal. A first modulator adjusts the filtered signal based on at least one of a phase, amplitude, and delay of leakage associated with the transmitted signal. The leakage corresponds to leakage from the first transmit portion of the communication device to a first receive portion of the communication device. The first modulator provides a leakage cancellation signal based on the adjusted filtered signal. A first coupler subtracts the leakage cancellation signal from a signal received by the first receive portion of the communication device.