Phase Difference Signaling in MIMO Uplink
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Solution Overview
Problem
In MIMO wireless communication systems, maintaining relative transmit phase continuity between antennas is burdensome and expensive, especially for user equipment (UE) with limited resources, as it requires complex calibration and is sensitive to power variations and design differences in transmit chains.
Innovation Solution
A method where the UE transmits an indication of its ability to maintain relative transmit phase continuity to the base station, allowing the base station to adjust the uplink transmission format to accommodate the UE's capabilities, such as using precoders insensitive to phase differences or minimizing power variations, thereby optimizing communications without requiring constant phase maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE maintains relative transmit phase continuity between antennas, then the uplink transmission performance is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
Instead of requiring the UE to actively maintain phase continuity through complex calibration circuits, the patent inverts the approach by having the base station compensate for phase differences. The UE simply transmits with fixed phase relationships, and the base station's signal processing handles the phase alignment, eliminating the need for complex UE calibration hardware.
Solution Approach 2:
The patent introduces the base station as an intermediary that handles the phase alignment function. Rather than the UE directly maintaining phase continuity, the base station receives signals with potential phase differences and processes them accordingly, acting as a mediator that eliminates the need for complex UE phase control.
2Reliability
If the UE implements phase continuity maintenance, then spatial multiplexing performance is improved, but the ease of manufacture deteriorates
Solution Approach 1:
The patent inverts the traditional approach by not requiring the UE to actively maintain phase continuity through complex calibration. Instead, the UE transmits with simple fixed phase relationships, and the base station compensates for any phase differences in its signal processing, dramatically simplifying UE manufacturing.
Solution Approach 2:
The patent effectively replaces expensive, complex calibration hardware in the UE with a simpler approach where the UE can be manufactured with basic phase transmission capabilities, and the base station handles the complex phase compensation through software processing.
3Adaptability or versatility
If the UE uses transmit chains with different power levels, then communication flexibility is improved, but phase continuity is disrupted
Solution Approach 1:
The patent inverts the traditional approach by not requiring the UE to maintain phase continuity when using different power levels. Instead, the UE can freely switch between different power levels for different channels, and the base station compensates for the resulting phase differences through its signal processing capabilities.
Solution Approach 2:
The patent allows the UE to change power parameters freely between different transmit chains and channels. The base station then adjusts its processing parameters to compensate for the resulting phase differences, enabling flexible power management without sacrificing phase continuity requirements.
Data Source
AI summary
An uplink signaling method is described where the UE transmits an indication of its ability to maintain relative transmit phase continuity with respect to a plurality of transmit chains thereof in place of being required to actually maintain the phase difference between its transmitters. The signaling method utilizes straightforward signaling with very little overhead, because the indication may be provided by setting the value of a bit in an uplink transmission. In response, a base station adopts an uplink transmission format for communications by the UE based, at least in part, upon the received indication.