LTE Channel Detection in Unlicensed Bands
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Solution Overview
Problem
LTE systems operating in unlicensed frequency bands face significant time delays in data traffic transmission due to fixed channel detection periods, leading to inefficiencies and interference with other systems like Wi-Fi, as they lack a Listen Before Talk (LBT) mechanism to prevent collisions.
Innovation Solution
A novel channel detection method based on load, where data traffic transmission is initiated immediately upon detecting an idle channel state, regardless of sub-frame type, with the option to set channel detection times within the current or adjacent sub-frames, allowing for flexible and variable detection periods to reduce time delays and enhance coexistence with other systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If LTE system transmits data traffic without channel detection in unlicensed frequency band, then transmission speed is improved, but interference to other systems increases
Solution Approach 1:
The patent applies preliminary action by performing channel detection before data transmission in unlicensed frequency bands. The base station detects channel occupancy status prior to transmitting data traffic, and the terminal performs similar detection before uplink transmission. This preliminary detection mechanism prevents interference to other systems while maintaining efficient transmission.
2Device complexity
If fixed channel detection period is used, then system simplicity is improved, but time delay increases
Solution Approach 1:
The patent implements dynamics by making the channel detection period variable rather than fixed. The detection period adapts based on channel occupancy status: when the channel is idle, detection occurs at standard intervals; when occupied, the terminal delays detection until the channel becomes idle. This dynamic adjustment reduces unnecessary time delays while maintaining system manageability.
3Stability of the object's composition
If channel detection is performed at fixed periods, then detection regularity is improved, but transmission efficiency deteriorates
Solution Approach 1:
The patent applies preliminary action by performing channel detection immediately before data transmission attempts. The terminal determines whether to perform channel detection based on whether data needs to be sent, rather than adhering to a rigid fixed schedule. This approach maintains detection regularity when needed while eliminating unnecessary detections, thereby improving transmission efficiency.
4Adaptability or versatility
If LTE uses unlicensed frequency band without LBT mechanism, then frequency band utilization is improved, but coexistence with Wi-Fi deteriorates
Solution Approach 1:
The patent applies preliminary action by implementing Listen Before Talk (LBT) mechanism where both base station and terminal perform channel detection before transmitting in unlicensed frequency bands. The terminal specifically checks channel occupancy status before uplink transmission, ensuring LTE and Wi-Fi systems can coexist harmoniously while utilizing unlicensed bands effectively.
Data Source
AI summary
In one aspect of the disclosure, a channel detection method applied when an LTE system works in an unlicensed frequency band comprises determining a current sub-frame and a channel detection time when a data traffic arrives, wherein the channel detection time is set in at least one of the current sub-frame and a next adjacent sub-frame to perform channel state detection, and judging whether the terminal or base station that performs the channel state detection and other terminals or base stations belong to a same telecommunication operator in order to perform the channel state detection in a corresponding way; and performing data traffic transmission when it is detected that the channel is in an idle state. Other aspects of the disclosure relates to a terminal and a base station using the channel detection method.