Full-Duplex Wireless Interference Mitigation for Timing Misalignment
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Solution Overview
Problem
In wireless communication systems, particularly in 5G NR, full-duplex communication experiences interference due to misalignment in the timing of uplink and downlink signals, leading to increased interference and reduced communication reliability.
Innovation Solution
Techniques such as modifying the cyclic prefix length, switching to a smaller subcarrier spacing, switching to a second beam pair, and increasing frequency domain separation are employed to mitigate interference by ensuring proper timing alignment and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If full-duplex communication is used to enable simultaneous uplink and downlink transmissions, then communication efficiency and throughput are improved, but interference between uplink and downlink signals increases due to timing misalignment
Solution Approach 1:
The patent modifies communication parameters including cyclic prefix length, subcarrier spacing, and timing advance values to align uplink and downlink signal timing. By adjusting these parameters, the system maintains full-duplex operation while reducing timing misalignment-induced interference between simultaneous transmissions.
Solution Approach 2:
The system dynamically adjusts timing advance values and cyclic prefix configurations based on real-time channel conditions and propagation delays. This dynamic adaptation allows the system to optimize the timing relationship between uplink and downlink signals, reducing interference while maintaining high communication efficiency.
2Reliability
If timing advance is increased to compensate for propagation delay, then timing alignment between uplink and downlink is improved, but the time difference between signal receptions exceeds cyclic prefix length causing inter-symbol interference
Solution Approach 1:
The patent extends the protection against inter-symbol interference by using an extended cyclic prefix that spans across the timing difference between uplink and downlink receptions. This additional time dimension provides sufficient guard interval to prevent interference even when timing advance values are large.
Solution Approach 2:
The system changes the cyclic prefix parameter from normal length to extended length specifically for full-duplex operations with large timing differences. This parameter modification ensures that the guard interval is sufficient to cover the extended timing misalignment between simultaneous uplink and downlink signals.
3Reliability
If normal cyclic prefix is used to maintain orthogonality between subcarriers, then frequency domain separation is maintained, but the cyclic prefix length is insufficient to cover large timing differences in full-duplex mode
Solution Approach 1:
The patent modifies the cyclic prefix parameter from normal to extended length specifically for full-duplex operations. This parameter change maintains the orthogonality properties of OFDM while providing sufficient time coverage for the extended timing differences between simultaneous uplink and downlink transmissions.
Solution Approach 2:
The system dynamically selects between normal and extended cyclic prefix configurations based on the timing difference magnitude and propagation delay conditions. This dynamic parameter selection ensures optimal performance by using extended prefix only when needed for full-duplex operations with large timing offsets.
Data Source
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AI summary
Aspects relate to techniques for mitigating wireless communication interference. For example, one or more of a cyclic prefix length, a subcarrier spacing, a beam pair, or a frequency domain separation may be changed to mitigate the effects of inter-symbol interference (ISI) at a UE or a base station. A UE may measure a received timing difference between a time at which the UE receives a downlink transmission and a time at which energy from an uplink transmission by the UE is received by the UE. If this received timing difference exceeds a specified duration of time (e.g., the length of a cyclic prefix), the ISI at the UE may increase. In some examples, the interference mitigation techniques described herein may be invoked if there is an increase in the measured received timing difference.