Uplink Transmitter Random Phase Access for Collision-Tolerant CDMA
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Solution Overview
Problem
Existing communication systems face limitations due to collisions and inefficiencies in modulation techniques, particularly in multiple access schemes, which affect the capabilities and functionalities of communication systems using CDMA, TDMA, and FDMA.
Innovation Solution
A random phase multiple access communication interface system that uses spread spectrum modulation without orthogonal codes, allowing non-coordinated data transmission with randomly selected chip offsets, and employs pseudo-noise codes for security and collision resolution through retransmission schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spread spectrum modulation with orthogonal codes (CDMA) is used, then multiple users can transmit simultaneously, but device complexity and code assignment overhead increase
Solution Approach 1:
The patent extracts and removes the orthogonal code requirement from the spread spectrum system. By using random phase offsets instead of orthogonal codes, the system eliminates the need for code assignment, code generation, and correlation processing, thereby reducing device complexity while maintaining multiple user simultaneous transmission capability
Solution Approach 2:
The patent changes the fundamental parameter from orthogonal codes to random phase offsets. Each user is assigned a random phase offset rather than a unique orthogonal code, which simplifies the system by removing the mathematical constraints of orthogonality while still enabling multiple access through phase diversity
2Reliability
If time slots are assigned for TDMA, then collisions are avoided, but transmission efficiency decreases due to time coordination overhead
Solution Approach 1:
The patent applies preliminary random phase assignment to users before transmission begins. This pre-established random phase relationship allows the receiver to separate signals without requiring time slot coordination or collision detection protocols, thereby maintaining reliability while improving transmission efficiency
Solution Approach 2:
The random phase offsets enable users to self-organize their transmissions without central coordination. Each user independently transmits with their assigned random phase, and the receiver automatically separates the signals through phase-based demodulation, eliminating the need for time slot management and collision avoidance protocols
3Productivity
If frequency allocation is used for FDMA, then simultaneous transmission is enabled, but bandwidth utilization decreases due to frequency guard bands
Solution Approach 1:
The patent merges multiple users' signals into the same frequency band by using random phase offsets instead of frequency separation. All users transmit simultaneously on the same carrier frequency, and the receiver separates them through phase-based processing, thereby achieving full bandwidth utilization without frequency guard bands
Data Source
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.