Clear Channel Assessment Technique for LTE Unlicensed Spectrum
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Solution Overview
Problem
In wireless communication systems, especially in LTE-LAA and LTE-U, there is a challenge in efficiently performing clear channel assessments (CCA) in unlicensed radio frequency spectra to avoid collisions with other radio access technologies like WLAN, due to the lack of optimization for unscheduled coexistence measures in transceivers adapted for scheduled operations.
Innovation Solution
A method and device that switch between two operating states for signal processing, where the first state introduces a greater delay optimized for data reception and the second state is less time-consuming, allowing for rapid CCA and equitable contention for the unlicensed spectrum, thereby minimizing collisions and optimizing usage for both LTE and WLAN.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If signal processing is performed in the first operating state with complete processing chain, then data reception quality is improved, but CCA delay increases causing unfair contention with WLAN
Solution Approach 1:
The patent applies dynamics by making the signal processing chain configurable and switchable between different operating states. The processing chain adapts its complexity based on the current operation mode (data reception vs. CCA), allowing the system to optimize between processing quality and speed as needed.
Solution Approach 2:
The patent changes processing parameters by selectively enabling or disabling processing stages based on the operating state. During CCA operations, the system uses a second operating state with reduced processing (bypassing certain stages) to minimize delay, while switching to the first operating state with complete processing for data reception to ensure quality.
2Productivity
If LTE transceiver uses rigid frame structure for scheduled operations, then spectral efficiency is improved, but adaptability to unscheduled coexistence measures deteriorates
Solution Approach 1:
The patent makes the transceiver dynamic by introducing configurable processing chains that can switch between different operating states. This allows the rigid LTE frame structure to coexist with unscheduled WLAN operations by adapting the processing behavior based on whether data reception or CCA is the current priority.
Solution Approach 2:
The patent creates a universal processing framework that handles both scheduled LTE operations and unscheduled CCA operations. The same transceiver infrastructure supports multiple functions by switching between first and second operating states, making it versatile enough to handle both transmission modes effectively.
3Reliability
If signal processing chain is optimized for data reception, then reception performance is improved, but CCA contention performance with WLAN deteriorates
Solution Approach 1:
The patent applies dynamics by switching between two distinct operating states: the first operating state with complete signal processing for reliable data reception, and the second operating state with reduced processing for fast CCA contention. This dynamic switching allows the system to optimize for the current task rather than being constrained by a fixed processing chain.
Data Source
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AI summary
A technique for performing a clear channel assessment (CCA) in an unlicensed radio frequency (RF) spectrum is described. The CCA is performed for transmitting data (420) according to a first radio access technology (RAT) in coexistence with a second RAT. As to a method aspect of the technique, signals (411) are received in the unlicensed RF spectrum. The received signals (411) are processed according to an operating state. The processing in a first operating state (402) causes a first delay that is greater than a second delay caused by the processing in a second operating state (404). The operating state depends on the presence of data (420) to be transmitted according to the first RAT in the unlicensed RF spectrum. The CCA is performed based on the processed signals.