Unlicensed Spectrum Access Coordination via Timing Alignment
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Solution Overview
Problem
In wireless communication systems, the unlicensed radio frequency spectrum band is often underutilized due to contention protocols like LBT-LBE, where transmitters may prevent others from accessing the band, leading to inefficient operation and 'starvation' issues, especially when different transmitters generate different random integers for extended CCA procedures, causing asynchronous operation and loss of synchronization.
Innovation Solution
A method where a first transmitter identifies a contention access protocol timing and aligns a second timing with it, allowing coordinated access to the unlicensed band without interfering with other transmitters, by adjusting radio frame durations, skipping frames, and synchronizing random number generators to ensure synchronized and efficient access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transmitters use independent extended CCA procedures with different random integers, then each transmitter has a chance to access the unlicensed band, but the transmitters become asynchronous and lose synchronization
Solution Approach 1:
The patent merges the independent extended CCA procedures of multiple transmitters into a coordinated procedure. Transmitters share a common counter and random integer, combining their individual access attempts into a unified process that maintains synchronization while preserving access opportunities for all transmitters.
Solution Approach 2:
The patent implements feedback mechanisms where transmitters share information about their CCA procedure status and counter values. This feedback allows transmitters to adjust their behavior to maintain synchronization while still achieving coordinated access to the unlicensed band.
2Productivity
If transmitters perform extended CCA procedures independently, then access to the unlicensed band is attempted by all transmitters, but interference between transmitters increases
Solution Approach 1:
The patent applies preliminary action by having transmitters perform a first CCA procedure before the extended CCA procedure to identify potential conflicts. Transmitters also use a backoff mechanism with random integers to stagger their access attempts, reducing interference while maintaining productivity.
Solution Approach 2:
The patent makes the CCA procedure dynamic by allowing transmitters to adjust their behavior based on real-time conditions. The counter-based mechanism dynamically controls the number of CCA procedures performed, and transmitters can adapt their access timing to minimize interference while maintaining access opportunities.
3Device complexity
If a single CCA procedure is used, then the access process is simple, but transmitters may be starved of access to the unlicensed band
Solution Approach 1:
The patent segments the access process into multiple stages: a first CCA procedure for initial access determination, followed by optional extended CCA procedures with multiple counter-based attempts. This segmentation allows simple initial access while providing multiple opportunities for transmitters to gain access if the first attempt fails, preventing starvation.
Solution Approach 2:
The patent implements periodic action through the counter-based extended CCA procedure, where transmitters perform multiple CCA procedures in periodic cycles. The counter tracks the number of attempts and controls the timing of subsequent access attempts, ensuring that transmitters receive periodic opportunities to access the unlicensed band without creating excessive complexity.
Data Source
AI summary
Techniques are described for wireless communication. One method includes identifying, by a first transmitter, a first contention access protocol timing for accessing an unlicensed radio frequency spectrum band, and aligning a second contention access protocol timing with the first contention access protocol timing, the second contention access protocol timing being used by the first transmitter for accessing the unlicensed radio frequency spectrum band.