Coordinated Multi-Point Phase Rotation for Downlink Frame Alignment
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Solution Overview
Problem
In coordinated multi-point transmission/reception (COMP) systems, downlink radio frame misalignment leads to performance degradation due to time misalignment of signals from different transmission and reception points, causing destructive interference and inter-symbol interference, which degrades channel estimation and beamforming.
Innovation Solution
Implementing a phase rotation mechanism to align phases of signals from different cells by estimating time offsets and applying phase adjustments, effectively negating the impact of time misalignment without requiring time realignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If time realignment is applied to synchronize downlink transmissions from multiple cells, then signal alignment is improved, but system complexity and processing overhead increase
Solution Approach 1:
The patent replaces the mechanical/time-domain realignment operation with a phase rotation operation in the frequency domain. Instead of physically adjusting transmission timing to achieve synchronization, the system applies phase rotations to compensate for time misalignment, substituting a simpler mathematical operation for a more complex temporal coordination mechanism.
Solution Approach 2:
The patent changes the parameter domain from time-domain alignment to phase-domain adjustment. By estimating time offsets and converting them into corresponding phase rotation values, the system adjusts signal phases rather than attempting to realign transmissions in time, thereby reducing system complexity while maintaining alignment precision.
2Object-affected harmful factors
If phase rotation is applied to correct time misalignment, then signal interference is reduced, but computational processing is required
Solution Approach 1:
The patent applies phase rotation compensation in advance, before the actual signal transmission occurs. By pre-calculating the required phase adjustments based on estimated time offsets, the system prepares corrected signals ahead of time, reducing interference during transmission without requiring complex real-time processing during the actual communication.
3Adaptability or versatility
If multiple cells use the same scattering sequence for COMP, then UE perceives cells as one cell, but downlink frame misalignment still occurs
Solution Approach 1:
The patent introduces phase rotation as an intermediary mechanism between the coordinated multi-point transmission system and the UE. This phase rotation component acts as a mediator that compensates for the frame misalignment caused by different propagation paths, allowing the UE to perceive coherent signals from multiple cells without requiring perfect temporal synchronization.
Data Source
AI summary
Correction of downlink radio frame misalignment for coordinated multi-point transmission/reception (COMP) by phase rotation is described herein. A method as described herein can include estimating a time offset between a first time, at which a first transmission is received by a user equipment (UE) from a first cell, and a second time, at which a second transmission is received by the UE from a second cell; determining a phase rotation value based on the time offset; and adjusting a first phase of a third transmission, to be transmitted by the first cell to the UE, relative to the first transmission based on the phase rotation value, resulting in the first phase of the third transmission being aligned with a second phase of a fourth transmission, to be transmitted by the second cell to the UE and offset in time relative to the third transmission by the time offset.