OFDM Signal Generation With CP Phase Adjustment for NB-IoT
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Solution Overview
Problem
Current solutions for Narrowband IoT (NB IoT) systems face challenges in reducing sampling rates while maintaining compatibility with legacy LTE systems, leading to increased processing costs and power consumption, especially in low-cost Machine-Type Communication (MTC) devices.
Innovation Solution
A transmitter architecture that adjusts the sampling phase during cyclic prefixes, allowing for a lower sampling rate than the legacy LTE rate, using a digital-to-analog converter with non-uniform sampling and a control unit to manage the sampling phase, enabling efficient signal generation with reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a lower sampling rate is used in NB IoT systems, then power consumption and processing costs are reduced, but compatibility with legacy LTE systems and signal generation accuracy deteriorate
Solution Approach 1:
The patent changes the sampling rate parameter from the legacy LTE rate to a lower rate optimized for NB IoT, while adjusting related parameters such as cyclic prefix duration and subcarrier spacing to maintain system compatibility and signal integrity at the reduced sampling rate
Solution Approach 2:
The patent applies different sampling rates to different parts of the system - using a lower sampling rate specifically for NB IoT narrowband signals while maintaining the original LTE sampling rate structure for other components, allowing localized optimization without affecting overall system compatibility
2Device complexity
If a lower sampling rate is used in NB IoT systems, then processing complexity and cost are reduced, but signal generation accuracy and timing precision deteriorate
Solution Approach 1:
The patent adjusts multiple parameters including sampling rate, cyclic prefix duration, and subcarrier spacing in a coordinated manner to maintain signal generation accuracy at the lower sampling rate, ensuring that timing relationships and frequency precision meet NB IoT requirements
Solution Approach 2:
The patent introduces dynamic sampling phase adjustment during cyclic prefixes to compensate for the reduced sampling rate, allowing the system to adaptively maintain timing precision and signal accuracy despite operating at a lower fixed sampling rate
Data Source
AI summary
A method in a transmitter circuit of generating a signal comprising a first sequence of OFDM symbols, which are to be transmitted within a frequency sub band of a second sequence of OFDM symbols is disclosed. A first cyclic prefix (CP) of the second sequence of OFDM symbols has a first duration, and a second CP of the second sequence of OFDM symbols has a second duration. In order to generate both the first and the second cyclic prefix with an integer number of equidistant samples, a first sampling rate is required. The method comprises generating the signal comprising the first sequence of OFDM symbols at a second sampling rate, lower than the first sampling rate, and adjusting a sampling phase during CPs.