LTE Channel Sensing and Signal Transmission in Unlicensed Bands
Solution Overview
Problem
In LTE systems using unlicensed frequency bands, ensuring the quality of service (QoS) is challenging due to interference from other communication systems, and existing channel sensing mechanisms are inefficient in managing reference signals and data signals transmission.
Innovation Solution
A method for channel sensing and signal transmission that reserves specific time-frequency resources for reference signals, allowing for effective transmission while minimizing interference, by performing channel sensing before sending data or reference signals and using different time-frequency resources for CCA detection, thereby improving frequency domain multiplexing and coexistence with other access technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If channel sensing is performed before sending reference signals in unlicensed frequency bands, then interference with other systems is reduced, but transmission reliability of reference signals cannot be ensured due to uncertain channel availability
Solution Approach 1:
The base station performs channel sensing (CCA/LBT) in advance before the DMTC window to determine channel availability. Based on this preliminary channel status information, the base station proactively adjusts the reference signal transmission strategy, either transmitting normally or skipping transmission, ensuring reliable decision-making while respecting unlicensed band sharing requirements
Solution Approach 2:
The reference signal transmission mechanism is made dynamic by allowing the base station to adaptively adjust transmission parameters based on real-time channel sensing results. The system dynamically switches between different transmission modes (normal transmission, reduced power transmission, or skipped transmission) according to channel conditions and coexistence requirements with other systems
2Productivity
If the duration of discovery signal is shortened to increase transmission probability, then frequency domain multiplexing coefficient is improved, but measurement precision and synchronization accuracy are degraded
Solution Approach 1:
The patent introduces a new dimension of time-frequency resource allocation by reserving specific resources at the beginning of DMTC windows. This creates a structured framework where short-duration reference signals can be transmitted with guaranteed resources, while longer data transmissions are scheduled in remaining resources, achieving both high transmission probability and maintained signal quality
Solution Approach 2:
The DMTC window resources are segmented into distinct portions: reserved resources at the beginning for reference signals with guaranteed transmission, and remaining resources for data transmissions subject to LBT. This segmentation allows reference signals to maintain adequate duration for accurate measurement while increasing overall transmission probability through dedicated resource allocation
3Productivity
If multiple candidate locations for reference signals are increased in each DMTC window, then transmission probability is improved, but device complexity increases
Solution Approach 1:
The base station performs preliminary channel sensing before the DMTC window and determines the optimal reference signal transmission location in advance. This preliminary action eliminates the need for complex real-time decisions about multiple candidate locations, reducing device complexity while maintaining high transmission probability through pre-planned resource allocation
Data Source
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AI summary
A method for channel sensing and signal transmission is provided. The method includes that a signal transmission mode of a communication node in a predefined time window is different from a signal transmission mode of the communication node outside the predefined time window, which includes at least one of a channel sensing mode and a data transmission mode. By performing the method, a frequency domain multiplexing coefficient among nodes adopting the same access technology can be improved, and the coexistence of the access technology and others can be ensured.