Multi-Antenna LO Phase Control for Leakage Mitigation
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Solution Overview
Problem
Local oscillator signal leakage in multi-antenna transceivers leads to performance degradation, including error vector magnitude (EVM) degradation, decreased signal-to-interference ratio (SIR), and decreased throughput, especially in beam-forming scenarios where the spatial direction of communication varies quickly and widely.
Innovation Solution
A multi-antenna transceiver apparatus with a controller that dynamically adjusts the phase-locked loop to generate a local oscillator signal with a phase offset, steering or broadening the local oscillator leakage emission to avoid the communication beam, thereby mitigating leakage without requiring centered signal tracking and avoiding mismatch issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If local oscillator signal leakage is suppressed by tracking and cancellation, then EVM degradation is reduced, but tracking complexity increases and mismatch problems arise
Solution Approach 1:
The patent changes the phase parameter of the local oscillator signal to redirect the leakage emission spatially. By adjusting the phase of individual LO signals in different transceiver chains, the leakage is steered away from the communication beam direction, mitigating EVM degradation without requiring complex tracking of the centered signal component.
Solution Approach 2:
The patent moves the mitigation approach from the temporal/signal processing domain to the spatial domain. Instead of tracking and canceling leakage in the time domain, the solution uses phase control to steer leakage in different spatial directions, effectively separating leakage from the desired signal in space rather than time.
2Reliability
If local oscillator leakage is mitigated by tracking centered signal component, then performance degradation is reduced, but the approach is not suitable when information is carried by centered signal
Solution Approach 1:
The patent extracts the local oscillator leakage component from the centered signal component. By using phase control to steer leakage away from the communication beam direction, the solution separates leakage mitigation from centered signal processing, allowing information carried by centered signals to be preserved without adverse suppression effects.
3Object-generated harmful factors
If static phase adjustment is used for LO leakage mitigation, then leakage is reduced in fixed direction, but it is not suitable for beam-forming scenarios with varying spatial directions
Solution Approach 1:
The patent makes the phase adjustment dynamic by linking it to the beam-forming control. The phase offsets applied to individual LO signals are adjusted in real-time according to the current beam direction, allowing the leakage mitigation to adapt automatically as the communication beam steers to different spatial directions.
Solution Approach 2:
The patent makes the phase control mechanism serve dual purposes: it controls both the communication beam direction and the LO leakage direction. The same phase offsets applied to antenna elements for beam forming are also applied to the LO signals, making the system universally effective for both communication and leakage mitigation across all beam directions.
Data Source
AI summary
An apparatus for a multi-antenna transceiver is disclosed. The multi-antenna transceiver has a plurality of antenna elements connected to respective transceiver chains. Each transceiver chain includes a frequency converter operated using a respective local oscillator signal provided by a respective phase-locked loop. The apparatus includes a controller configured to cause control of the respective phase-locked loop of one or more transceiver chain to generate the respective local oscillator signal with a respective phase offset for mitigation of local oscillator leakage through the frequency converter. In some embodiments, the controller is further configured to cause, for each transceiver chain with a non-zero respective phase offset, a corresponding phase adjustment of a signal for frequency conversion. Corresponding multi-antenna transceivers, wireless communication devices and methods are also disclosed.