MIMO Antenna Isolation via Spatial Filter Nulling
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Solution Overview
Problem
Modern wireless communication devices face intermodulation distortion due to limited isolation between transmission and reception paths, which degrades transceiver sensitivity and prevents distinction between desired signals and distortion.
Innovation Solution
A transceiver system employing a spatial filter with antenna weights to attenuate signals between transmit and receive antennas, dynamically adjusting to ensure high isolation by determining local communication channels and applying phase and amplitude shifts to achieve null angles, thereby reducing signal interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a duplexer is used to couple transmission and reception paths to a common antenna, then frequency separation is achieved, but isolation between paths is limited causing intermodulation distortion
Solution Approach 1:
A spatial filter is introduced as an intermediary component between the transmission and reception paths. This spatial filter processes the signals to provide additional isolation beyond what the duplexer alone can achieve, thereby reducing intermodulation distortion while maintaining frequency separation
Solution Approach 2:
The system combines multiple isolation mechanisms (duplexer frequency separation + spatial filter processing) to create a composite isolation solution that exceeds the capabilities of either component alone, achieving both frequency and spatial discrimination
2Power
If transmitted signal power is increased to improve communication range, then signal strength is improved, but leakage into reception path increases causing intermodulation distortion
Solution Approach 1:
The spatial filter acts as a mediator that allows high power transmission while blocking the leakage path to the receiver. It processes the transmitted signal to ensure that increased power does not result in proportional increases in harmful leakage into the reception path
3Productivity
If frequency bands for transmission and reception are made adjacent to enable full-duplex operation, then data rate is improved, but isolation between paths becomes more difficult achieving
Solution Approach 1:
The system transitions from relying solely on frequency domain separation to adding spatial domain separation through the spatial filter. This dimensional change allows adjacent frequency bands to be used while maintaining isolation through spatial processing
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively achieves high isolation between transmission and reception paths, even when frequencies overlap, enhancing transceiver performance and preventing signal distortion, while maintaining operational bandwidth.
Implementation Method 1
A mobile communication device is disclosed that utilizes a spatial filter to achieve a high degree of isolation between antennas of a MIMO antenna array
Implementation Method 2
A first data stream provided to a first antenna port connected to a plurality of wideband antennas is attenuated in a direction of a second antenna port connected to a wideband antenna by operating the plurality of wideband antennas to perform beamforming
Data Source
AI summary
The disclosed invention relates to a MIMO (multiple input, multiple output) wideband transceiver. In some cases, the MIMO wideband transceiver comprises a signal processor that outputs or receives a plurality of distinguishable data streams. A first data stream is provided to a first antenna port connected to a plurality of wideband antennas, while a second data stream is provided to a second antenna port connected to a wideband antenna. A spatial filter element configured to assign antenna weights to the plurality of wideband antennas, which cause the wideband antennas to operate in a manner that attenuates wireless signals, at a frequency range at which the wideband transmit wideband radiate, in the direction of the wideband antenna without attenuating the wireless signals in other directions. By attenuating signals extending between the plurality of wideband antennas and the wideband antenna, wideband decoupling between first and second antenna ports is achieved.