Slotted Wake-Up Timing for Low-Power Network Synchronization
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Solution Overview
Problem
Existing communication systems face challenges in power conservation and efficient data transmission in slot-based communication networks, particularly in managing collisions and synchronizing multiple users with different timing offsets in spread-spectrum technologies.
Innovation Solution
A random phase multiple access communication interface system that uses spread spectrum modulation without orthogonal codes, allowing non-coordinated data transmission with pseudo-noise codes and randomly selected chip offsets, enabling efficient demodulation and minimizing collisions through retransmission schemes and unique PN codes for security and collision resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple users transmit in the same time slot using spread spectrum modulation, then channel sharing efficiency is improved, but collision probability increases making demodulation impossible
Solution Approach 1:
The system dynamically adjusts the random chip offset for each transmission attempt. When a collision is detected, the tag selects a new random chip offset for retransmission, transforming the static transmission parameter into a dynamic one that adapts to collision conditions, thereby resolving the contradiction between channel sharing and demodulation reliability
Solution Approach 2:
The invention changes the chip offset parameter randomly for each transmission attempt. By varying this critical parameter, the system allows multiple users to share the channel while ensuring that colliding transmissions use different chip offsets, enabling successful demodulation through the PN array despreader
2Measurement precision
If tags remain in awake state to maintain timing synchronization, then synchronization accuracy is improved, but power consumption increases
Solution Approach 1:
The system performs timing acquisition in advance during slot boundaries, allowing tags to enter sleep mode for the duration of the slot while maintaining synchronization. This preliminary timing capture enables tags to conserve power without sacrificing synchronization accuracy, as they only need to be awake briefly at slot boundaries
Solution Approach 2:
The invention implements periodic timing acquisition at slot boundaries rather than continuous synchronization. Tags wake up periodically at slot boundaries to perform rapid timing acquisition, then return to sleep mode, achieving both power conservation and timing accuracy through this periodic rather than continuous approach
3Reliability
If orthogonal codes are used for multiple access, then collision resolution is improved, but device complexity increases due to code assignment requirements
Solution Approach 1:
The invention extracts the collision resolution capability from the orthogonal code structure itself and replaces it with random chip offsets combined with PN array despreading. This removes the need for complex orthogonal code assignment while maintaining collision resolution through the mathematical properties of the PN sequence and random offset mechanism
Solution Approach 2:
Instead of assigning unique orthogonal codes to each user, the system uses the same PN code for all users but applies different random chip offsets. This copying approach with parameter variation achieves collision resolution without the complexity of unique code assignment, simplifying the device architecture
Data Source
AI summary
A method for conserving resources in a communication system includes entering an awake state from a sleep state at a first time, where the first time occurs a predetermined period prior to a communication event. The predetermined period is greater than or equal to a worst-case determination period for determining a timing offset relative to an access point. An initial timing offset relative to the access point is determined during the predetermined period. The sleep state is entered for a remainder of the predetermined period upon determination of the initial timing offset. The awake state is entered for the communication event. The timing offset relative to the access point is determined based at least in part on the initial timing offset.