Downlink Phase Noise Cancellation in FDM and SDM Multiplexing
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Solution Overview
Problem
As network node transmit (TX) phase noise level increases, the separation level of multiplexed users in frequency and space domains degrades, leading to significant inter-user leakage that limits system performance in FDM and SDM operations.
Innovation Solution
A network node transmits a frequency domain allocation map or modulation order information to a UE, enabling the UE to cancel inter-UE interference associated with phase noise, thereby improving system performance at higher carrier frequencies and modulation orders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If FDM or SDM operations are used to multiplex multiple users, then system capacity and spectral efficiency are improved, but inter-UE interference due to phase noise increases
Solution Approach 1:
The network node performs preliminary actions by transmitting downlink control information that includes frequency domain allocation map and modulation order information to the UE before the actual data transmission. This enables the UE to prepare interference cancellation parameters in advance, allowing for effective inter-UE interference cancellation during the data reception phase without requiring additional real-time signaling.
Solution Approach 2:
The patent introduces an intermediary information transmission mechanism where the network node sends control information containing frequency domain allocation map and modulation order information as intermediaries. This intermediary data enables the UE to construct interference cancellation models without direct interaction with other UEs, resolving the interference problem through information mediation rather than direct interference management.
2Reliability
If phase noise compensation is implemented at the UE, then inter-UE interference is canceled, but device complexity increases
Solution Approach 1:
The patent applies local quality by tailoring the interference cancellation parameters specifically for each UE based on its frequency domain allocation and modulation order. Instead of using a universal compensation method, the system adapts the cancellation parameters locally for each UE's specific transmission characteristics, reducing unnecessary processing complexity for UEs that do not experience significant inter-UE interference.
Solution Approach 2:
The system changes parameters dynamically by adjusting the frequency domain allocation map and modulation order information based on channel conditions and interference levels. The UE modifies its interference cancellation parameters according to the received control information, allowing for flexible adaptation to varying interference scenarios without requiring complex fixed-structure compensation algorithms.
Data Source
AI summary
A network node may transmit a frequency domain allocation map associated with one or more first UEs or first modulation order information associated with the one or more first UEs to a UE. The UE and the one or more first UEs may be associated with an FDM operation or an SDM operation. The UE may cancel inter-UE interference associated with the one or more first UEs and the FDM operation or the SDM operation based on the frequency domain allocation map or the first modulation order information. The inter-UE interference may be associated with a phase noise associated with the network node. The phase noise associated with the network node may be associated with an oscillator at the network node. The UE may cancel the inter-UE interference based on one or more ICI estimates.