Uplink Transmission Start Position Determination in Unlicensed Spectrum
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems, particularly in LTE, there is a time delay between uplink data transmission and grant transmission due to uncertain channel availability in unlicensed bands, leading to potential insufficiency in downlink subframes for uplink grants, which affects resource utilization and reliability.
Innovation Solution
A method and apparatus for determining and utilizing partial subframe positions for uplink transmission and receiving, allowing for flexible start and end positions within a subframe based on clear channel detection, thereby improving resource utilization and reducing time delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Listen-Before-Talk (LBT) is used for unlicensed band transmission, then channel availability is improved, but time delay and uncertainty in transmission scheduling worsen
Solution Approach 1:
The patent applies preliminary action by performing LBT channel detection before the actual uplink transmission to determine channel availability in advance. The UE detects the channel status and prepares transmission resources beforehand, allowing the system to anticipate channel availability and reduce scheduling delays. This is implemented through the LBT procedure that checks channel clear status before granting uplink resources.
Solution Approach 2:
The patent implements dynamics by making the uplink transmission timing flexible and adaptive based on real-time channel conditions. Instead of fixed scheduling, the UE can dynamically adjust transmission start positions within a subframe based on LBT results. The system transitions from static grant-based scheduling to dynamic channel-condition-dependent transmission timing.
2Device complexity
If fixed downlink subframe scheduling is used for UL grants, then scheduling simplicity is improved, but resource utilization worsens due to insufficient DL subframes
Solution Approach 1:
The patent applies segmentation by dividing the downlink subframe into multiple potential grant transmission positions rather than using a single fixed position. The eNB can select from multiple candidate positions (e.g., different symbol indices) within the subframe to transmit UL grants, increasing flexibility in resource allocation while maintaining subframe-based scheduling structure.
Solution Approach 2:
The patent implements parameter changes by allowing the grant transmission position parameter to vary within a subframe. Instead of a fixed time offset, the system can adjust the grant position parameter based on channel conditions and traffic requirements, enabling more efficient use of downlink resources for grant transmission.
3Stability of the object's composition
If uplink transmission starts from fixed subframe positions, then scheduling predictability is improved, but channel usage efficiency worsens
Solution Approach 1:
The patent implements dynamics by enabling flexible transmission start positions within a subframe based on LBT channel detection results. The UE can determine its transmission start position dynamically within the subframe structure, allowing the system to adapt to channel availability while maintaining subframe-based scheduling predictability. This creates a hierarchy of predictability at the subframe level with flexibility at the symbol level.
Data Source
AI summary
Embodiments of the present disclosure relate to a method and apparatus of performing the uplink (UL) transmission and receiving. In one embodiment of the present disclosure, a method of performing the UL transmission comprises: determining a transmission start position for the UL transmission from a plurality of potential start positions in a subframe in response to detecting of a clear channel on an unlicensed carrier; and performing the UL transmission from the determined transmission start position.