Random Phase Tag Ranging for Collision-Resistant Location Tracking
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Solution Overview
Problem
Existing communication systems in random phase multiple access networks lack the ability to determine the location of elements and face limitations in capacity and security due to collisions and the need for orthogonal codes.
Innovation Solution
A random phase multiple access communication interface system using spread spectrum modulation without orthogonal codes, where tags transmit with a shared pseudo-noise code and random chip offsets, and the access point uses a PN array despreader to handle multiple signals, incorporating retransmission schemes and unique PN codes for security and location determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If orthogonal codes (Walsh codes) are used for CDMA, then communication channels can be correlated and separated, but device complexity increases and system capacity is limited
Solution Approach 1:
The patent extracts and removes the orthogonal code requirement from the CDMA system. By using random phase codes instead of Walsh codes, the system eliminates the need for complex code assignment and correlation mechanisms while maintaining channel separation capability through randomization and processing gain.
Solution Approach 2:
The patent changes the fundamental parameter of code structure from orthogonal (deterministic) to random phase (stochastic). This parameter change transforms the system from requiring precise code alignment and correlation to utilizing statistical properties of random signals, thereby reducing complexity while maintaining reliability.
2Quantity of substance
If time slots are assigned for TDMA, then multiple transmitters can share the same channel, but loss of time occurs due to coordination and synchronization requirements
Solution Approach 1:
The patent implements periodic retransmission attempts with random phase adjustments. Instead of strict time slot coordination, transmitters periodically retry with different random phases, allowing the system to achieve multiple simultaneous transmissions without synchronization overhead or time loss.
Solution Approach 2:
The patent introduces dynamic random phase selection that changes with each transmission attempt. This dynamic behavior allows transmitters to adapt their timing independently without coordination, eliminating the need for static time slot assignments and synchronization protocols.
3Quantity of substance
If frequency allocation is used for FDMA, then different users can transmit simultaneously on different frequencies, but loss of frequency spectrum efficiency occurs and device complexity increases
Solution Approach 1:
The patent makes the single random phase code serve multiple functions that previously required separate mechanisms: it provides both spreading code and frequency-like separation, enables simultaneous transmissions, and eliminates the need for frequency allocation management. One universal mechanism replaces multiple specialized functions.
4Adaptability or versatility
If location determination methods are added to random phase multiple access system, then location tracking capability is enabled, but device complexity and processing requirements increase
Solution Approach 1:
The patent enables the random phase code and timing offset mechanism to serve dual purposes: both data transmission and location determination. The same random parameters used for collision avoidance also provide unique identifiers for location tracking, eliminating the need for separate location determination hardware or protocols.
Data Source
AI summary
A method of determining the location of a communication tag in a random phase multiple access communication network is disclosed. A ranging request signal that is spread using a first pseudo-noise code and offset with a first random timing offset is transmitted at a first time. A ranging response signal that is spread using a second pseudo-noise code and offset with a second random timing offset is received at a second time. A propagation delay that is dependent on the first time and the second time is calculated.