Random Phase Multiple Access Interface Using PN Code Offsets
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Solution Overview
Problem
Existing communication systems face challenges in efficiently managing multiple access scenarios without collisions, particularly in spread-spectrum technologies, where the use of orthogonal codes is required for demodulation, leading to complexity and power consumption issues.
Innovation Solution
A random phase multiple access communication interface that uses spread spectrum modulation methods without orthogonal codes, employing a pseudo-noise (PN) code with randomly selected chip offsets for non-coordinated data transmission, allowing for collision resolution through retransmission with new offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If orthogonal codes are used for demodulation in spread-spectrum technology, then reliable communication in multiple access scenarios is achieved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts the requirement for orthogonal codes from the demodulation process. Instead of using orthogonal codes for demodulation, the system uses correlation detection with locally generated pseudo-random sequences, eliminating the need for complex orthogonal code management while maintaining multiple access capability
Solution Approach 2:
Each transmitter copies the same pseudo-random sequence but with different time offsets. This copying approach with temporal differentiation allows multiple users to share the same frequency band without requiring unique orthogonal codes, reducing device complexity while maintaining communication reliability
2Productivity
If orthogonal codes are used for demodulation, then multiple users can transmit simultaneously, but power consumption increases
Solution Approach 1:
The patent changes the parameter used for user differentiation from orthogonal code selection to time offset positioning. By varying the temporal parameter (chip offset) rather than the spectral parameter (orthogonal code), the system achieves multiple access with lower computational complexity and reduced power consumption
3Reliability
If random chip offsets are used for non-coordinated transmission, then collision probability is reduced, but collision resolution requires retransmission protocols
Solution Approach 1:
The system performs preliminary random offset selection before transmission to avoid collisions proactively. By pre-randomizing the chip offsets, the system reduces the likelihood of collisions before they occur, though retransmission protocols remain necessary for handling cases where collisions do occur
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces power consumption and complexity by minimizing collisions during data transmission, enabling efficient communication in multiple access scenarios with simultaneous demodulation of numerous links using a PN array despreader.
Implementation Method 1
uses spread spectrum modulation methods without the use of orthogonal codes
Implementation Method 2
a PN array despreader at the access point can be used
Data Source
AI summary
Methods, systems and instructions stored on computer-readable media for generating a first data stream and a second data stream. The first data stream is spread using a first gold code unique to a first tag. The second data stream is spread using a second gold code unique to a second tag. The spread first data stream and the spread second data stream are combined into a combined data stream. The combined data stream is transmitted to the first tag and the second tag.