Random-Phase Multiple Access Interface for Collision-Tolerant Demodulation
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Solution Overview
Problem
Existing modulation and collision prevention techniques in communication systems, such as CDMA, TDMA, and FDMA, have limitations that restrict their capabilities and functionalities, particularly in managing multiple access scenarios and ensuring efficient data transmission without collisions.
Innovation Solution
A random phase multiple access communication interface system that uses spread spectrum modulation without orthogonal codes, employing a random selection of chip offsets for non-coordinated data transmission, allowing a PN array despreader to differentiate between signals and handle collisions by retransmitting with new offsets, and utilizing unique PN codes for security and signal filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If orthogonal codes (Walsh codes) are used in CDMA for multiple access, then different communication channels can be correlated and separated, but the system complexity increases and requires precise synchronization
Solution Approach 1:
The patent extracts and removes the orthogonal code component from the CDMA system, using only pseudo-random spreading codes without requiring orthogonal Walsh codes for channel separation. This simplifies the system by eliminating the need for precise orthogonal code management and synchronization while maintaining the core spread-spectrum multiple access functionality through random phase offsets.
Solution Approach 2:
The patent changes the fundamental parameter from using orthogonal codes with precise synchronization requirements to using pseudo-random codes with random phase offsets. This parameter change transforms the system from one requiring strict timing alignment to one that tolerates and utilizes random timing differences, thereby reducing system complexity.
2Reliability
If time slots are allocated in TDMA to coordinate multiple transmitters, then collisions are prevented, but the system requires centralized coordination and reduces flexibility
Solution Approach 1:
The patent implements a self-service mechanism where each transmitter independently selects random phase offsets and retransmission delays without requiring centralized time slot allocation or coordination. The system autonomously resolves collisions through randomization and exponential backoff, eliminating the need for external coordination while maintaining collision prevention.
Solution Approach 2:
The patent introduces dynamic random phase offsets and retransmission delays that change with each transmission attempt, replacing the static time slot allocation of TDMA. This dynamic approach allows transmitters to adapt their transmission timing independently, preventing collisions without requiring centralized coordination.
3Productivity
If frequency allocation is used in FDMA to separate users, then simultaneous transmission is enabled, but the available bandwidth is fragmented and efficiency is reduced
Solution Approach 1:
The patent merges all users onto a single frequency channel using spread-spectrum modulation with random phase offsets, eliminating the need for frequency division. This combining approach allows simultaneous transmission from multiple users on the same frequency without interference, maximizing bandwidth utilization while maintaining productivity.
4Reliability
If collision detection and exponential backoff are implemented, then collisions are handled, but transmission delay increases and throughput decreases
Solution Approach 1:
The patent applies preliminary action by pre-selecting random phase offsets and retransmission delays before collisions occur, rather than detecting and responding to collisions after they happen. This proactive randomization prevents collisions from occurring in the first place, significantly reducing transmission delays and improving throughput while maintaining reliable collision handling.
Data Source
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AI summary
A method for communicating through a multiple access communication interface includes receiving a first signal from a first tag, where the first signal is spread using a predetermined pseudo-noise (PN) code, and further where the first signal includes first payload data. A second signal is received from a second tag. The second signal is spread using the predetermined PN code, and the second signal includes second payload data. The first payload data from the first signal is identified at least in part with a PN array despreader. The second payload data from the second signal is also identified at least in part with the PN array despreader.