Signal Generator Cyclic Prefix Generation
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Solution Overview
Problem
Existing signal generators require high computational power to create measuring signals with cyclic prefixes, resulting in degraded autocorrelation properties compared to classical signal generators.
Innovation Solution
A signal generator setup that includes a baseband signal generator, channel emulator, modulator, and cyclic prefix generating unit, which emulates a channel-modified cyclic prefix to achieve low computational complexity while maintaining ideal autocorrelation properties, by using windowing techniques on signals corresponding to symbol ends and beginnings, and optionally incorporating noise signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a classical signal generator generates a baseband signal, modulates it, then generates a cyclic prefix from the last part and adds it to the beginning, the resulting signal has ideal autocorrelation properties, but it requires a great deal of processing power
Solution Approach 1:
The channel emulator is applied to the baseband signal before modulation, pre-processing the signal to emulate channel effects in advance. This allows the cyclic prefix to be generated from the modulated signal without requiring additional complex processing, as the channel effects are already incorporated in the baseband domain
Solution Approach 2:
Instead of generating a cyclic prefix from the last part of the modulated signal (which requires copying and concatenation operations), the invention uses the channel emulator to create a virtual copy of the channel effects and applies them to the baseband signal before modulation. This copying approach reduces the computational burden while maintaining the desired autocorrelation properties
2Ease of operation
If the channel emulator is applied before cyclic prefix insertion, then the cyclic prefix corresponds exactly to the end of the symbol, but the autocorrelation peaks are shifted in time and degraded
Solution Approach 1:
The channel emulator is applied to the baseband signal before modulation, pre-emulating the channel effects. This ensures that when the cyclic prefix is generated from the modulated signal, it accurately represents the channel-modified signal structure, maintaining proper autocorrelation properties without time shifts
Solution Approach 2:
The invention replaces the mechanical operation of copying and concatenating signal parts to create a cyclic prefix with a mathematical approach using the channel emulator. By substituting the signal processing operations with channel emulation in the baseband domain, the system achieves both correct cyclic prefix correspondence and ideal autocorrelation properties
3Device complexity
If static or fading channel models are applied to the signal prior to signal modulation, then the signal generation is simplified, but the cyclic prefix creation becomes nonlinear and degrades autocorrelation properties
Solution Approach 1:
The channel emulator is applied to the baseband signal before modulation, pre-processing the signal to incorporate channel effects. This preliminary action simplifies the overall signal generation process by handling channel emulation in the baseband domain rather than after modulation, while maintaining linear signal processing operations that preserve autocorrelation properties
Solution Approach 2:
The invention changes the domain in which channel emulation is performed, moving it from the modulated signal domain to the baseband signal domain. This parameter change (domain transformation) allows the channel emulator to operate on simpler, unmodulated signals, reducing computational complexity while preserving the linearity needed for ideal autocorrelation properties
Data Source
AI summary
A signal generator for creating a measuring signal comprising a cyclic prefix comprises a baseband signal generator for generating a baseband measuring signal and a channel emulator for emulating a channel in the baseband measuring signal resulting in a channel modified signal. Moreover, it comprises a modulator for modulating the channel modified signal and a cyclic prefix generating unit for generating and inserting a cyclic prefix into the modulated signal. The cyclic prefix generating unit is set up for generating the cyclic prefix in such a manner that a channel modified cyclic prefix is emulated.