Composite Spreading Codes for Variable Chipping Rates

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Solution Overview

Problem

Spread spectrum systems face challenges in accommodating heterogeneous terminals with varying power availability and capabilities, leading to limited system performance due to the need for all terminals to operate with the same spreading codes and rates, which can waste higher potential throughput.

Innovation Solution

A direct sequence spread spectrum system using multiple predefined component codes with relatively prime nominal lengths, including prime number multiplicands, to form composite spreading codes for various chipping rates, allowing terminals to operate at different rates and adapt communication parameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If all terminals operate using the same spreading codes and spreading rates, then system synchronization and detection are simplified, but heterogeneous terminals with varying power availability cannot be accommodated efficiently

Engineering Contradiction:

Improveaccommodation of heterogeneous terminalsVSAvoidsystem synchronization and detection complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The spreading code is segmented into multiple component codes with different nominal lengths. Each terminal can select and combine appropriate component codes based on its capabilities, allowing heterogeneous terminals to operate at different effective spreading rates while maintaining system-wide synchronization through the common component code structure

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A set of universal component codes is defined that can be used by all terminals in the system. Each terminal universally uses these component codes but combines them differently based on its specific capabilities, allowing the same code library to serve multiple functions and terminal types

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If spread spectrum processing is implemented, then covertness and anti-jam capability are improved, but hardware cost and power consumption increase due to higher clock rates

Engineering Contradiction:

Improveanti-jam capabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Terminals can change the effective spreading rate parameter based on their power availability and communication needs. By selecting different combinations of component codes, terminals can operate at lower spreading rates when power is constrained, reducing the clock rates required for digital circuitry while maintaining spread spectrum anti-jam capabilities when needed

Inventive Principle:

Principle #35Parameter changes

3Productivity

If higher chipping rates are used, then data throughput is increased, but hardware cost and power consumption increase

Engineering Contradiction:

Improvedata throughputVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The system enables dynamic adjustment of the effective chipping rate by allowing terminals to selectively combine component codes. Terminals can dynamically adapt their spreading rate based on power availability, channel conditions, and throughput requirements, optimizing the balance between data rate and power consumption rather than operating at a fixed high rate

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8102897B1Direct sequence spread spectrum system and method with plural chipping rates

Publication Date: 2012.01.24 L3 TECHNOLOGIES INC

AI summary

Direct sequence spread spectrum communications can use composite codes and can operate at a plurality of different chipping rates. The composite codes can be formed using a plurality of component codes, wherein the component codes can be relatively prime and at least one of the nominal lengths of the component codes can include a plurality of prime number multiplicands. The chipping rate and code length can be reduced by dividing a master rate by one or more of the prime number multiplicands. Symbol timing and time division multiple access timing can be tied to epochs of the component codes.