MIMO Antenna Isolation via Segmented Transmit Receive Paths
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Solution Overview
Problem
Current solutions for isolating uplink and downlink signals in wireless communication, such as duplexers and MIMO antenna arrays, become impractical due to increasing costs and complexity as frequency bands converge, especially in high-frequency broadband systems and distributed communication systems.
Innovation Solution
The proposed solution involves separating transmit and receive paths in a MIMO antenna array by operating on sufficiently different frequencies, physically interleaving downlink paths with uplink paths across different bands to minimize interference without increasing the antenna array's footprint, using a centralized radio access network with remote units that split signals across different remote units for physical separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a duplexer is used to isolate uplink and downlink signals, then signal isolation is improved, but cost increases significantly
Solution Approach 1:
The patent divides the antenna array into separate transmit and receive sub-arrays, physically segmenting the antenna elements to provide isolation without requiring expensive duplexers. This segmentation allows independent processing of uplink and downlink signals while reducing component costs.
Solution Approach 2:
The invention extracts the frequency separation function from the duplexer and implements it through digital signal processing in the baseband unit. By taking out the isolation function from the RF domain and moving it to the baseband domain, expensive hardware duplexers are replaced with less costly digital processing techniques.
2Reliability
If MIMO antenna arrays are used with interference cancellation, then signal isolation is improved, but device complexity increases
Solution Approach 1:
The patent segments the MIMO antenna array into dedicated transmit and receive sub-arrays, simplifying the interference cancellation process by reducing the number of antenna interactions that need to be managed. This segmentation reduces computational complexity while maintaining isolation performance.
Solution Approach 2:
The baseband unit acts as an intermediary that processes signals from the segmented antenna sub-arrays. By introducing this intermediate processing stage, the system achieves signal isolation through digital processing rather than complex RF circuitry, reducing overall device complexity.
3Reliability
If physical separation of antennas is increased to reduce interference, then signal isolation is improved, but area occupied by antenna array increases
Solution Approach 1:
The patent segments the antenna array into transmit and receive sub-arrays that can be closely spaced. By segmenting the array and using digital processing to handle the separated signals, the system achieves isolation without requiring large physical distances between antenna elements, thus maintaining a compact footprint.
Solution Approach 2:
The invention moves the isolation function from the spatial domain to the signal processing domain. Instead of relying on physical distance (spatial dimension) for isolation, the system uses digital signal processing techniques in the baseband unit to achieve separation, effectively transitioning the isolation mechanism to a different dimension.
Data Source
AI summary
Isolation for antennas in a wireless communication system is achieved between transmit and receive paths for a multiple input multiple output (MIMO) antenna array by separating a first transmit path from an associated receive path to be matched with a second transmit path and matching the first receive path with the second receive path. It is expected that the two transmit paths operate on sufficiently different frequencies that there is minimal interference there and the additional spacing from the transmit path to the receive path will reduce interference therebetween without increasing a footprint of the antenna array.