Cyclic Prefix Extension for Symbol Boundary Alignment
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Solution Overview
Problem
In slot-based communication systems, devices face a disadvantage when waiting for a timing reference to align with a symbol boundary during adaptivity procedures in shared unlicensed spectrum, leading to poor spectrum allocation and competition with other devices.
Innovation Solution
Extending the cyclic prefix (CP) of a symbol to align with a timing reference, allowing for efficient channel reservation and protection against competing devices by transmitting a useful signal instead of dummy payloads, and maintaining transmission gaps within specific time limits to prevent channel loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a device waits for a period of time before initiating an adaptivity procedure so that the end of the procedure aligns with a symbol boundary, then timing alignment with the reference is improved, but the device loses spectrum allocation opportunities to faster competitors
Solution Approach 1:
The device performs preliminary actions by extending the cyclic prefix of the initial symbol to span across the symbol boundary alignment point. This allows the adaptivity procedure to complete with precise timing alignment while the extended CP maintains continuous channel occupation, preventing other devices from acquiring the spectrum during the transition period.
Solution Approach 2:
The cyclic prefix duration is dynamically adjusted to extend beyond the normal symbol boundary, creating a flexible time structure that simultaneously achieves precise timing alignment and maintains channel reservation. The extended CP acts as a dynamic buffer that bridges the timing reference alignment requirement with continuous spectrum occupation.
2Productivity
If a device immediately initiates an adaptivity procedure when spectrum becomes available, then spectrum acquisition speed is improved, but timing alignment with the symbol boundary deteriorates
Solution Approach 1:
The device immediately initiates the adaptivity procedure without waiting, achieving fast spectrum acquisition. The preliminary extension of the cyclic prefix is configured in advance to ensure that despite the immediate start, the procedure concludes with proper symbol boundary alignment, thus maintaining both speed and precision.
Solution Approach 2:
The cyclic prefix length parameter is changed from its standard value to an extended value that compensates for the immediate initiation of the adaptivity procedure. This parameter adjustment ensures that the procedure completes at the correct symbol boundary timing, resolving the timing precision issue while maintaining rapid spectrum acquisition.
3Reliability
If the cyclic prefix is extended to align with the timing reference, then reception of the initial symbol is improved, but transmission duration increases
Solution Approach 1:
The extended cyclic prefix serves multiple functions simultaneously: it provides timing alignment with the symbol boundary, improves initial symbol reception reliability through extended guard interval, and maintains channel reservation to block competing devices. This multi-functionality justifies the increased transmission duration as it achieves multiple objectives in one structure.
Solution Approach 2:
The extended cyclic prefix is prepared in advance as part of the initial symbol structure, allowing the system to benefit from improved reception reliability and timing alignment from the very beginning of transmission. The preliminary extension ensures that all subsequent operations benefit from the enhanced timing reference without requiring additional transmission time for separate alignment procedures.
Data Source
AI summary
Examples pertaining to reserving channel by cyclic prefix (CP) extension for alignment with a symbol boundary in mobile communications are described. An apparatus extends a CP of a symbol to result in an extended symbol that aligns with a timing reference. The apparatus then transmits the extended symbol.