LBT Contingent UL Grants for LTE-U Carrier Sensing
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Solution Overview
Problem
In LTE-based wireless communications over unlicensed carriers, existing technologies face challenges in ensuring efficient coexistence with other LTE-U service providers and multiple radio access technologies, particularly in managing uplink transmissions to avoid channel occupancy conflicts and optimize resource utilization.
Innovation Solution
The implementation of dedicated listen-before-talk (LBT) procedures for user equipment (UE) to determine the availability of unlicensed carriers before transmitting, using clear channel assessments (CCAs) and enhanced CCAs (eCCAs) to ensure the carrier is idle, allowing for optimized uplink transmissions and minimizing resource wastage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LTE-based transmissions are performed over unlicensed carriers without LBT procedures, then transmission efficiency and resource utilization improve, but coexistence with other service providers and radio access technologies deteriorates due to channel occupancy conflicts
Solution Approach 1:
The patent applies preliminary action by requiring the UE to perform LBT procedures (clear channel assessments) before initiating uplink transmissions on unlicensed carriers. This advance checking ensures the channel is idle before transmission, preventing conflicts with other service providers and radio access technologies while maintaining efficient resource utilization
2Reliability
If LBT procedures are implemented for uplink transmissions, then coexistence and fairness among service providers improve, but transmission delay and complexity increase due to additional sensing requirements
Solution Approach 1:
The patent extracts the LBT procedure as a separate, standardized component that can be independently implemented and configured. By defining specific LBT types (Type 1, Type 2a, Type 2b) with predetermined parameters, the complexity is managed through modular design rather than ad-hoc implementation, reducing overall system complexity while maintaining coexistence capabilities
3Reliability
If LBT procedures are implemented for uplink transmissions, then coexistence and fairness among service providers improve, but transmission delay increases due to additional sensing requirements
Solution Approach 1:
The patent applies dynamics by configuring different LBT procedure types and parameters dynamically based on traffic conditions, channel state, and service requirements. The network can adaptively select between Type 1, Type 2a, and Type 2b LBT procedures, adjusting sensing durations and retry mechanisms to minimize transmission delay while maintaining coexistence capability under varying operational conditions
Data Source
AI summary
Carrier-sensing techniques for LTE-based transmissions over unlicensed carriers are described. In one embodiment, for example, an apparatus may comprise at least one memory and logic for user equipment (UE), at least a portion of the logic comprised in circuitry coupled to the at least one memory, the logic to cause the UE to receive an uplink (UL) grant indicating a transmit subframe, the transmit subframe to comprise a subframe during which the UE is authorized to perform UL transmission via an unlicensed carrier, the logic to cause the UE to determine whether the UL grant comprises a listen-before-talk (LBT)-contingent UL grant and in response to a determination that the UL grant comprises an LBT-contingent UL grant, identify an LBT interval for the transmit subframe and perform an LBT procedure during the LBT interval to determine whether the unlicensed carrier is idle. Other embodiments are described and claimed.