Phase Rotation for In-Band Narrowband Signal Demodulation
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Solution Overview
Problem
In narrowband wireless communication systems like NB-IoT, transmitting data is limited due to restricted resources, and phase differences between narrowband and wideband signals complicate the use of wideband reference signals for demodulation, hindering efficient data reception.
Innovation Solution
A method where a base station determines and applies a phase offset to narrowband signals based on a reference point in time, allowing User Equipment (UE) to use wideband reference signals for demodulation by rotating symbols of the wideband signal to undo the phase rotation applied by the base station, enabling joint processing of narrowband and wideband reference signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If narrowband signals are transmitted using wideband resources, then resource utilization is improved, but phase differences between narrowband and wideband signals cause demodulation difficulties
Solution Approach 1:
The patent applies parameter changes by introducing a phase offset parameter that adjusts the phase relationship between narrowband and wideband signals. The base station determines a phase offset value and applies it to rotate the narrowband signal, transforming the signal phase to match the wideband reference signal phase, thereby enabling accurate demodulation while maintaining resource utilization benefits
Solution Approach 2:
The patent uses phase offset as an intermediary parameter that mediates between the narrowband signal and wideband reference signal. By introducing this intermediate phase adjustment mechanism, the system allows the UE to use wideband reference signals for demodulating narrowband signals despite the inherent phase differences, thus resolving the contradiction between resource utilization and demodulation accuracy
2Ease of operation
If phase rotation is applied to narrowband signals, then wideband reference signals can be used for demodulation, but signal processing complexity increases
Solution Approach 1:
The patent applies preliminary action by having the base station pre-calculate and apply the phase offset to the narrowband signal before transmission. The base station determines the phase offset value in advance based on the relationship between narrowband and wideband signals, and applies the rotation beforehand, so that the UE can directly use wideband reference signals for demodulation without needing to perform complex phase correction operations
Solution Approach 2:
The patent extracts the phase correction function from the UE side and relocates it to the base station side. Instead of requiring the UE to perform complex phase alignment operations, the base station extracts and applies the phase offset independently, thereby simplifying the UE's demodulation process while maintaining the ability to use wideband reference signals
Data Source
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AI summary
In order to enable a UE receiving a narrowband signal transmitted using in-band resources to use the LTE reference signals to assist the UE in receiving the narrowband signal using an in-band deployment, a phase rotation employed by the base station may be fixed relative to a known reference position in time. An apparatus for wireless communication at a base station may determine a phase offset for a narrowband signal for transmission using wideband resources, the phase offset having a relationship to a reference point in time and transmit the narrowband signal using the determined phase offset. An apparatus for wireless communication at a UE may receive a narrowband signal having a frequency location within a wideband signal and rotate a symbol of the wideband signal by a per symbol phase offset having a relationship of the phase offset to a reference point in time.