Antenna Virtualization via Signal Processing for Link Diversity
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Solution Overview
Problem
In wireless digital communications systems like WiMAX, the need arises to efficiently utilize multiple antennas to create a virtual antenna system that appears as fewer virtual antennas than physical antennas, enhancing link diversity and power amplifier efficiency while mitigating multipath propagation effects.
Innovation Solution
The implementation of antenna virtualization through signal processing operations such as cyclic delay diversity (CDD), amplitude shaping (AS1 and AS2), and null operations, which generate multiple transmit signals from a single input stream, allowing these signals to be transmitted by multiple antennas to form a radiation pattern resembling a single virtual antenna, thereby increasing link diversity and power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple physical antennas are used to increase link diversity, then communication reliability improves, but device complexity increases
Solution Approach 1:
The patent creates virtual copies of physical antennas through signal processing. Multiple transmit signals are generated from a single input stream by applying different signal transformations (delays, phase shifts, amplitude shaping) to simulate multiple physical antennas. This allows the system to achieve link diversity benefits without proportionally increasing physical antenna count, thus improving reliability while controlling device complexity.
Solution Approach 2:
The patent replaces physical antenna multiplication with signal processing operations. Instead of adding more physical antennas to increase link diversity, the system uses cyclic delay diversity, amplitude shaping, and null operations to create virtual antennas. This substitution of mechanical/physical solutions with signal processing achieves the same diversity benefit with reduced hardware complexity.
2Use of energy by moving object
If multiple physical antennas are used to create virtual antenna system, then power amplifier efficiency improves, but device complexity increases
Solution Approach 1:
The system generates multiple transmit signals from a single input stream by applying different signal transformations (delays, phase shifts, amplitude shaping) to simulate multiple physical antennas. This allows the system to achieve link diversity benefits without proportionally increasing physical antenna count, thus improving reliability while controlling device complexity.
Solution Approach 2:
The patent replaces physical antenna multiplication with signal processing operations. Instead of adding more physical antennas to increase link diversity, the system uses cyclic delay diversity, amplitude shaping, and null operations to create virtual antennas. This substitution of mechanical/physical solutions with signal processing achieves the same diversity benefit with reduced hardware complexity.
3Productivity
If conventional MIMO system uses multiple transmit antennas with equal number of streams, then spectral efficiency improves, but adaptability to different channel conditions deteriorates
Solution Approach 1:
The patent implements dynamic adaptation of signal transformations based on channel conditions. The system can adjust delays, phase shifts, and amplitude shaping parameters according to feedback information about the communication channel. This dynamic adjustment allows the virtual antenna system to adapt to varying channel conditions while maintaining spectral efficiency, resolving the contradiction between productivity and adaptability.
Solution Approach 2:
The system changes signal processing parameters (delay values, phase shift amounts, amplitude shaping functions) based on channel conditions. By dynamically modifying these parameters, the system can optimize performance for different channel scenarios while maintaining the virtual antenna configuration, thus achieving both spectral efficiency and adaptability.
Data Source
AI summary
Communication systems and methods are described in which multiple transmit signals are generated from an input stream or signal. The communication systems and methods, collectively referred to as antenna virtualization or virtual antenna systems, generate from each input stream multiple transmit signals that when driven into multiple antennas create a radiation pattern that effectively appears to originate from a single antenna. The communications operations include receiving at least one input stream. Multiple transmit signals are generated from the received input stream; the number of transmit signals generated is greater than the number of received input streams. Generation of the transmit signals involves transforming the input stream. The transforming includes applying one or more of a variable delay, a phase shift, and signal shaping to information of the input stream. The transmit signals are transmitted by a separate antenna of an antenna system.