Shift Register Sequence Generation for Low-Correlation Signal Shaping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for generating multiple pseudorandom sequences with low mutual correlation are resource-intensive and complex, particularly when multiple sequences are needed for signal shaping applications, as they often require separate generation mechanisms for each sequence, which can introduce undesired spurs and spectral lines.
Innovation Solution
A single shift register structure is used to generate multiple sequences with low mutual correlation by reusing register elements and their states, where the first sequence has the same properties as a linear feedback shift register, and additional sequences are tapped from different positions to achieve low correlation without increasing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple separate shift register structures are used to generate multiple sequences, then sequence generation capability is improved, but device complexity and resource consumption increase
Solution Approach 1:
A single shift register structure is designed to perform multiple functions by generating multiple different sequences simultaneously through different output taps. The same register produces at least a first sequence from a first set of output taps and a second sequence from a second set of output taps, eliminating the need for separate register structures for each sequence generation task.
Solution Approach 2:
Multiple sequence generation functions are merged into one unified shift register structure. Instead of having separate registers for different sequences, the patent combines them by utilizing multiple output taps from a single register, thereby reducing the total number of register elements and simplifying the overall system architecture.
2Ease of manufacture
If traditional signal shaping methods are used, then implementation is straightforward, but spectral lines appear in the power spectral density limiting output power
Solution Approach 1:
The signal shaping process is segmented into multiple independent operations: generating a first sequence for complex conjugate multiplication, generating a second sequence for phase rotation, and applying both transformations to the basic baseband waveform. This segmentation allows each transformation to independently contribute to spectral flattening without creating harmful spectral lines.
Solution Approach 2:
The patent applies a composite signal shaping approach by combining two different signal transformations: complex conjugate multiplication (first signal shaping) and phase rotation (second signal shaping). This composite approach, where both transformations are applied to the basic baseband waveform, effectively flattens the power spectral density and eliminates spectral lines while maintaining implementation feasibility.
Data Source
AI summary
A structure for generating sequences. The structure includes a binary shift register; a feedback structure connected to the shift register arranged to define a linear feedback shift register according to a polynomial; a first output arranged to collect one or more state values from a first group of elements of the shift register, the one or more state values from the first group forming a value of a first sequence; and a second output arranged to collect one or more state values from a second group of elements of the shift register, the one or more state values from the second group forming a value of a second sequence. No element of the second group belongs to the first group.