Vehicle MIMO Antenna Switching for Signal Correlation
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Solution Overview
Problem
Current MIMO systems for vehicles face performance degradation in 'less path' or 'line of sight' environments due to insufficient antenna spacing, leading to decreased data throughput, and require larger antenna modules to maintain efficiency.
Innovation Solution
A MIMO system with external and internal antennas, an RF transceiver, and an antenna selecting device that adjusts antenna connections based on signal strength and signal-to-noise ratio thresholds, using switches to connect external or internal antennas to the RF transceiver to optimize data throughput by decorrelating signals and utilizing multipath signals within the vehicle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If antenna spacing between MIMO antennas is increased to improve system performance, then spatial correlation decreases and system performance improves, but the size of the antenna module must be increased
Solution Approach 1:
The patent divides the antenna system into two separate modules: an external antenna module mounted on the vehicle exterior and an internal antenna module mounted inside the vehicle. This segmentation allows each module to be compact in size while collectively providing sufficient antenna spacing for MIMO performance. The external antennas are positioned on the vehicle roof or body, while internal antennas are positioned inside the vehicle cabin, creating effective spatial separation without requiring a single large antenna module.
Solution Approach 2:
The patent transitions from a two-dimensional planar arrangement of antennas within a single module to a three-dimensional distributed arrangement across different spatial locations. By placing antennas both outside and inside the vehicle, the system utilizes the third dimension (vehicle interior space) to achieve adequate antenna spacing and reduce spatial correlation, thereby improving MIMO performance without increasing the footprint of any single antenna module.
2Reliability
If external antennas are used in rich scattering environments, then antenna efficiency increases, but performance degrades in line of sight environments with insufficient multipath signals
Solution Approach 1:
The patent combines both external and internal antennas into a single MIMO system that works together. The external antennas are optimized for rich scattering environments where they can efficiently capture multipath signals, while the internal antennas are optimized for line of sight environments where they can effectively receive direct signals. By merging these two antenna types, the system achieves both high antenna efficiency in scattering environments and good performance in line of sight environments.
Solution Approach 2:
The patent implements dynamic antenna selection and switching capabilities that allow the system to adapt to different environmental conditions in real-time. The controller monitors signal conditions and dynamically switches between using external antennas, internal antennas, or combinations thereof, based on whether the environment is a rich scattering environment or a line of sight environment. This dynamic adaptation ensures optimal performance across varying driving conditions.
3Productivity
If MIMO antennas are integrated into shark-fin antenna modules on the vehicle roof, then data throughput is improved in rich scattering environments, but the module size must be increased relative to non-MIMO modules
Solution Approach 1:
The patent segments the MIMO antenna system into two separate modules: an external antenna module and an internal antenna module. This segmentation allows each module to maintain a compact size suitable for its specific mounting location, while collectively providing the antenna diversity and spacing needed for high data throughput MIMO operation. The external module is mounted on the vehicle exterior where space is available, and the internal module is mounted inside the vehicle where it can be compact.
Data Source
AI summary
A MIMO system is provided for a vehicle having an exterior structure and an enclosure. The system includes external antennas attached to the exterior structure and internal antennas positioned within the enclosure. The system further includes an RF transceiver and an antenna selecting device. The selecting device is disposable between a first state where the selecting device is configured to operably connect at least two of the external antennas to the RF transceiver and a second state where the selecting device is configured to operably connect one or more of the external antennas and one or more of the internal antennas to the RF transceiver. A controller is configured to actuate the selecting device to move to the second state, in response to the signal strength being above an upper strength threshold, and in further response to the ratio being above an upper ratio threshold.