Generalized Golay Sequences for Low Autocorrelation Sidelobes
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Solution Overview
Problem
Current spread-spectrum coding techniques face challenges in achieving good autocorrelation properties and minimizing multiple-access interference (MAI) and inter-symbol interference (ISI), especially in multi-code DS-CDMA systems, where Golay sequences are limited by their length and complexity, and other sequences lack efficient correlator-matched filters.
Innovation Solution
The method involves using generalized Golay sequences for spreading and despreading data streams, employing efficient Golay correlators to generate and process these sequences, which can be of any length and offer improved autocorrelation properties, reducing MAI and ISI through the use of generalized Golay codes and correlators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Golay sequences are used for spreading, then good autocorrelation properties are achieved, but the sequences are limited by length and complexity constraints
Solution Approach 1:
The patent applies parameter changes by modifying the fundamental parameters of Golay sequences (length, alphabet size, phase structure) to create generalized versions that maintain excellent autocorrelation properties while achieving arbitrary lengths and reduced complexity. This allows the sequences to be adapted to different system requirements without being constrained by traditional Golay sequence limitations.
Solution Approach 2:
The patent employs segmentation by dividing long spreading sequences into shorter Golay-compliant segments or blocks. This segmentation approach allows the system to achieve arbitrary overall sequence lengths while each segment maintains the desirable autocorrelation properties of Golay sequences, thereby resolving the contradiction between length flexibility and autocorrelation quality.
2Quantity of substance
If multiple spreading codes are employed, then system capacity is increased, but multiple-access interference (MAI) and inter-symbol interference (ISI) increase
Solution Approach 1:
The patent applies local quality by ensuring that each individual spreading code in the multiple-code system possesses optimized local autocorrelation properties through generalized Golay sequences. This local optimization at the code level reduces the harmful interference effects when multiple codes are simultaneously active, allowing increased system capacity with controlled MAI and ISI.
Solution Approach 2:
The patent uses composite materials analogy by combining multiple generalized Golay sequences with different parameters (lengths, phases, alphabets) into a composite spreading code set. This composite structure enables the system to support multiple users while the diverse properties of individual sequences minimize mutual interference through reduced cross-correlation.
3Ease of manufacture
If traditional sequences are used, then implementation is simpler, but efficient correlator-matched filters are not available
Solution Approach 1:
The patent applies self-service by designing generalized Golay sequences with inherent structural properties that enable them to serve their own matching filter requirements. The sequences are constructed to possess built-in correlation properties that automatically facilitate efficient matched filtering at the receiver, eliminating the need for complex external filter designs while maintaining implementation feasibility.
Solution Approach 2:
The patent employs universality by creating generalized Golay sequences that simultaneously provide multiple functions: spreading, modulation, and matched filtering. These multi-functional sequences can be used directly as correlators and matched filters, reducing hardware complexity while improving processing efficiency compared to traditional sequences that require separate filter components.
Data Source
AI summary
A method for communicating comprises generating at least one generalized Golay code from a concatenation of constituent Golay codes, and spreading at least a portion of a data stream with the at least one generalized Golay code. Generalized Golay codes comprise pseudo-complementary sequences having code lengths that differ from Golay complementary sequences and are characterized by low autocorrelation sidelobes relative to the autocorrelation peak.