MIMO Antenna Isolation-Dependent Coexistence in Wireless Systems
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Solution Overview
Problem
In wireless communication systems with multiple air interfaces and MIMO antennas, achieving sufficient antenna isolation is challenging due to spatial constraints and interference between different air interfaces, leading to issues like data drop-outs and degraded performance in devices such as smartphones and laptops.
Innovation Solution
A method and apparatus that determine asymmetric isolation between antenna pairs and selectively operate antenna elements to mitigate interference, allowing simultaneous operation of multiple air interfaces without significant degradation, using a software algorithm to evaluate operational status and select between MIMO or SISO modes based on isolation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple antenna elements are used for MIMO operation, then data transmission rate is improved, but antenna isolation becomes insufficient leading to interference
Solution Approach 1:
The system dynamically selects between MIMO and SISO operating modes based on real-time isolation measurements between antenna pairs. When isolation is sufficient, MIMO mode is used to maximize data transmission rate. When isolation deteriorates below threshold, the system transitions to SISO mode to eliminate interference, thus adaptively optimizing performance based on actual antenna coupling conditions.
Solution Approach 2:
The invention changes the operational parameter of the antenna system by switching between different operating modes (MIMO/SISO) based on measured isolation characteristics. This parameter change allows the system to adapt to varying antenna isolation conditions and prevent interference-induced performance degradation.
2Volume of moving object
If antenna elements are placed closer together to meet form factor constraints, then device compactness is improved, but antenna isolation deteriorates causing data drop-outs
Solution Approach 1:
The system incorporates dynamic mode selection that responds to isolation measurements between closely-spaced antenna elements. By continuously monitoring isolation and switching between MIMO and SISO modes, the system maintains reliable data transmission even when antennas must be placed close together to meet compact form factor requirements.
Solution Approach 2:
The invention performs preliminary isolation measurements between antenna pairs before initiating data transmission. This preliminary assessment allows the system to pre-select the appropriate operating mode (MIMO or SISO) to ensure reliable transmission, preventing data drop-outs that would occur with insufficient isolation.
3Productivity
If all antenna elements are activated simultaneously, then MIMO performance is maximized, but power consumption increases
Solution Approach 1:
The system dynamically activates or deactivates antenna elements based on measured isolation characteristics. When isolation is sufficient, all antenna elements are activated to maximize MIMO performance. When isolation is insufficient, the system selectively deactivates problematic antenna elements and operates in SISO mode, thereby reducing power consumption while maintaining acceptable performance.
Solution Approach 2:
The invention applies different operational states to different antenna elements based on their individual isolation characteristics. Rather than uniformly activating all antennas, the system selectively activates only those antenna elements that meet isolation requirements, optimizing the local quality of each antenna's operation to balance performance and power consumption.
4Reliability
If antenna isolation is increased to reduce interference, then signal quality is improved, but device complexity increases
Solution Approach 1:
The system incorporates feedback through isolation measurement between antenna pairs. By measuring actual isolation characteristics and using this feedback to dynamically select operating modes, the system achieves high signal quality without requiring complex predetermined antenna placement designs. The feedback loop allows the system to adapt to the actual antenna coupling conditions present in the device.
Data Source
AI summary
Methods and apparatus for selectively switching one or more antennas in a multiple-input, multiple-output (MIMO) antenna array so as to mitigate interference with another RF interface within the same space-constrained device, based on radio frequency isolation. In one embodiment, the MIMO interface comprises a WLAN interface having a 2×2 or 3×3 array of antennae which are placed in a wireless device in an asymmetric fashion with respect to the antenna of the second interface, and the other interface comprises a PAN (e.g., Bluetooth) interface operating in an overlapping frequency band (e.g., ISM band). When both interfaces are operating, interference is mitigated through selectively switching off one or more of the MIMO antennae, and using the remaining antenna(e) having the best isolation from the Bluetooth antennae. This approach allows simultaneous operation of both interferences without significant degradation to user experience or the operation of either interface, and may also provide power savings critical to mobile device battery longevity.