NB-IoT-u Baseband Phase Compensation for Waveform Alignment
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Solution Overview
Problem
The current NB-IoT-U baseband definition does not implement phase compensation, leading to misaligned waveforms across different frame structures, increasing device complexity and cost, as NB-IoT-U devices must adapt receiver algorithms based on geographical location and PRB number.
Innovation Solution
A method is introduced where a network node generates a time-continuous baseband signal with a phase compensation term that removes PRB-dependent phase rotation, aligning waveforms across all PRBs and regions, allowing for a unified receiver implementation and ultra-low device complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If phase compensation is not implemented in NB-IoT-U baseband definition, then different frame structures can be supported, but waveform misalignment occurs across different PRBs and regions, increasing device complexity
Solution Approach 1:
The patent introduces a phase compensation term θk,l that changes parameters (phase values) based on PRB index and OFDM symbol index. This parameter change approach allows the system to maintain waveform alignment across different frame structures and PRBs by dynamically adjusting the phase of subcarriers, thereby supporting frame structure versatility while keeping device complexity low through a unified receiver implementation.
Solution Approach 2:
The phase compensation is applied segment-wise across different PRBs and OFDM symbols. By dividing the baseband signal into segments (different PRBs and symbols) and applying appropriate phase compensation to each segment, the patent achieves waveform alignment across all segments without requiring complex receiver adaptations for each segment type.
2Adaptability or versatility
If PRB-dependent phase rotation is present, then different PRBs can be transmitted, but waveform alignment is lost across PRBs, requiring location-specific receiver adaptations
Solution Approach 1:
The patent applies parameter changes by introducing a phase compensation term θk,l that depends on the subcarrier index k and OFDM symbol index l. This parameter change compensates for the PRB-dependent phase rotation, ensuring that waveforms remain aligned across different PRBs. As a result, receivers can use a unified implementation without needing to adapt to location-specific phase characteristics.
3Device complexity
If unified receiver implementation is used across all markets, then device complexity is reduced, but waveform alignment must be maintained across all PRBs and regions
Solution Approach 1:
The patent uses parameter changes through the phase compensation term θk,l to maintain waveform alignment precision across all PRBs and regions. By dynamically adjusting phase parameters based on PRB index and OFDM symbol index, the system achieves consistent waveform alignment that enables unified receiver implementations without sacrificing alignment precision.
Solution Approach 2:
The phase compensation is applied in advance during baseband signal generation before transmission. This preliminary action ensures that waveform alignment is established at the transmitter side, allowing receivers to use simplified unified implementations without needing to perform complex alignment operations after receiving the signal.
Data Source
AI summary
A method performed by a network node in a wireless communications system is disclosed. The method comprises generating a time-continuous baseband signal by applying a phase compensation that removes a physical resource block (PRB)-dependent phase rotation on a subcarrier. The method comprises converting the generated time-continuous baseband signal into a radio frequency signal. The method comprises transmitting the radio frequency signal to a wireless device over a radio interface.