NTN Beam Reconfiguration Signaling for IoT and NR Link Combining
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Solution Overview
Problem
In non-terrestrial networks, low-cost IoT devices and advanced beamforming in New Radio (NR) face challenges in maintaining coherent waveforms and stable TCI states due to frequency reference drift, beam reconfiguration, and phase/amplitude discontinuities, which hinder efficient signal combining and beam selection.
Innovation Solution
Network nodes provide transmission property information to wireless devices, indicating times when coherent waveforms are unavailable or beam switches occur, allowing devices to adapt their receiver algorithms and optimize performance by avoiding combining during these times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time repetitions of radio blocks are used to improve coverage and reliability, then link reliability is improved, but waveform coherency and TCI state stability deteriorate due to frequency reference drift and beam reconfiguration
Solution Approach 1:
The network node provides transmission property information in advance to the wireless device, indicating times when coherent waveforms are unavailable or beam switches will occur. This allows the wireless device to prepare and adapt its receiver algorithms beforehand, avoiding attempts to combine signals during periods of waveform discontinuity, thus maintaining combining efficiency while accommodating necessary beam reconfigurations
Solution Approach 2:
The system dynamically adjusts receiver combining operations based on transmission property information. The wireless device can adaptively modify its combining strategy - performing combining when coherent waveforms are available and avoiding or adjusting combining when beam switches or waveform discontinuities are expected, optimizing performance under varying transmission conditions
2Productivity
If beam reconfiguration is performed to optimize beam selection, then beam performance is improved, but phase and amplitude discontinuities are introduced that hinder signal combining
Solution Approach 1:
The network node proactively provides transmission property information indicating when beam switches or TCI state changes will occur. This advance notice allows the wireless device to prepare its receiver algorithm, knowing in advance when to expect phase or amplitude discontinuities, and can adjust its combining operations accordingly to maintain accuracy despite beam reconfigurations
3Device complexity
If frequency reference drift is tolerated to simplify device requirements, then device complexity is reduced, but signal combining efficiency deteriorates
Solution Approach 1:
The network node takes responsibility for providing transmission property information to the wireless device, enabling the device to compensate for frequency reference drift effects without requiring complex internal frequency correction mechanisms. The device uses this information to adapt its receiver algorithm and combining operations, achieving efficient signal combining despite using simpler, lower-cost frequency references
Data Source
AI summary
A method, network node and wireless device for reliable link performance for cellular Internet of things (IoT) and New Radio (NR) in non-terrestrial networks. In some embodiments, a network node configured to operate in a cellular non-terrestrial network is provided. The network node includes processing circuitry configured to provide an indication of transmission property information associated with a reconfiguration of precoding weights where the indication of transmission property information provides information associated with decoding a physical downlink shared channel or physical downlink control channel.