OFDM Duplex Carrier Phase Synchronization
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Solution Overview
Problem
In OFDM systems, the echo signal from a near-end device is not completely synchronous with the far-end OFDM signal due to channel delay, causing severe interference and limiting spectrum efficiency in overlapped spectrum duplex transmission.
Innovation Solution
A method and system that adjust the carrier phase of the near-end OFDM signal by obtaining and synchronizing the carrier phase difference between the near-end echo and far-end OFDM signals, either by local adjustment or through a notification message to the far-end device, ensuring synchronization and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If overlapped spectrum duplex transmission is implemented in OFDM system, then spectrum efficiency is improved, but carrier phase synchronization between echo signal and far-end signal deteriorates
Solution Approach 1:
The patent applies parameter changes by adjusting the carrier phase of the echo signal based on the calculated phase difference. The near-end device modifies the carrier phase parameter of the echo signal to match the far-end signal's phase, thereby resolving the synchronization issue while maintaining overlapped spectrum duplex transmission
Solution Approach 2:
The patent implements feedback by calculating the carrier phase difference between the echo signal and far-end signal, then using this difference information to adjust the echo signal's carrier phase. The phase difference notification message carries this feedback information to enable continuous synchronization
2Object-affected harmful factors
If carrier phase adjustment is performed on near-end echo signal, then interference is reduced, but system complexity increases
Solution Approach 1:
The patent introduces an intermediary approach by using phase difference notification messages to convey carrier phase difference information between devices. This intermediary mechanism enables coordination without requiring complex real-time processing at both ends, thus reducing overall system complexity while still achieving interference reduction
Solution Approach 2:
The patent segments the synchronization problem into two independent approaches: the near-end device can independently adjust its echo signal phase, or the far-end device can adjust based on received notification messages. This segmentation allows flexible implementation and reduces the complexity burden on any single device
Data Source
AI summary
Embodiments of the present invention provide a method, an apparatus, and a system for multi-carrier OFDM duplex transmission, and relate to the communications field, so as to solve the problem where spectrum duplex transmission cannot be normally performed due to interference that is generated by an echo signal transmitted by using an OFDM technology. The method for multi-carrier OFDM duplex transmission includes: performing, on at least one OFDM subcarrier channel, sending and receiving of a near-end OFDM signal; obtaining a carrier phase difference between a near-end echo OFDM signal and a far-end OFDM signal; and performing a phase adjustment for the near-end OFDM signal according to the carrier phase difference.