Full-Duplex Preamble Structure for Self-Interference Cancellation
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Solution Overview
Problem
In wireless communication networks, full duplex-capable devices face challenges in communicating effectively with non-full duplex-capable devices due to potential self-interference, especially when using the same frequency channel for simultaneous transmission and reception.
Innovation Solution
A network node transmits a downlink message with a preamble containing channel estimation information, allowing it to estimate and cancel self-interference, enabling simultaneous transmission and reception by including AFD information in the preamble, such as modified RL-SIG fields and AFD LTF fields, using different modulation for auto-detection, and employing Golay sequences for channel estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a full duplex-capable network node transmits and receives signals simultaneously on the same frequency channel, then communication efficiency is improved, but self-interference increases
Solution Approach 1:
The patent applies preliminary action by transmitting channel estimation information in the preamble before the actual data transmission. This allows the network node to estimate the self-interference channel characteristics in advance, enabling the interference cancellation mechanism to be prepared and applied during simultaneous transmit-receive operations.
Solution Approach 2:
The patent implements feedback through the interference cancellation mechanism that uses the estimated channel information to actively compensate for self-interference. The system continuously monitors and adjusts based on the channel estimation, creating a closed-loop system that reduces self-interference during full duplex operations.
2Reliability
If channel estimation information is included in the preamble, then self-interference cancellation capability is improved, but preamble length increases
Solution Approach 1:
The patent applies local quality by incorporating channel estimation information specifically in the preamble portion of the signal, rather than throughout the entire transmission. This localized approach ensures that the necessary estimation data is available at the critical initial stage for interference cancellation, while minimizing the overall time overhead.
Solution Approach 2:
The patent utilizes parameter changes by employing different modulation schemes for different parts of the preamble. Specifically, channel estimation information uses one modulation while other preamble fields use different modulation, allowing efficient encoding of estimation data without excessive time consumption.
3Measurement precision
If different modulation is used for auto-detection information, then detection accuracy is improved, but implementation complexity increases
Solution Approach 1:
The patent applies local quality by using different modulation schemes for different fields within the preamble structure. Auto-detection information is modulated differently from channel estimation information and other preamble fields, enabling the receiver to distinguish and process each type of information appropriately while maintaining clear signal characteristics.
Data Source
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AI summary
A method at a network node that is configured to simultaneously transmit and receive wireless RF signals, comprising: transmitting, from the network node, a downlink message, the downlink message having a preamble that includes channel estimation information for estimating a self-interference channel; monitoring at the network node, during an initial duration while transmitting the downlink message, for the channel estimation information, and estimating a self-interference channel based on received portions of the channel estimation information; and using the estimated self-interference channel to cancel self-interference while receiving an uplink message and simultaneously transmitting a remainder of the downlink message.