Uplink Control Channel Latency Reduction via UE-Initiated CSI
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Solution Overview
Problem
In wireless communication systems, particularly in LTE, periodic and base station-initiated channel state information (CSI) reports can lead to dropped packets and delayed communications due to insufficient latency, especially in low latency scenarios.
Innovation Solution
User equipment (UE) initiates CSI reports using contention-based spectrum, a request-to-transmit indicator, or differential CSI, and combines these with scheduling requests (SRs) and hybrid automatic repeat request (HARQ) feedback, utilizing different time resources or cyclic shifts of predetermined sequences for uplink transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodic and base station-initiated CSI reports are used, then system complexity is reduced and resource allocation is simplified, but communication latency increases and packet delivery reliability deteriorates
Solution Approach 1:
The patent implements preliminary action by allowing UE to proactively send CSI reports before the base station would normally request them. The UE monitors channel conditions continuously and initiates CSI reporting when channel quality changes exceed a threshold, ensuring timely channel state information is available to the base station for rapid scheduling decisions, thus reducing communication latency while maintaining reliable packet delivery
Solution Approach 2:
The patent enhances feedback mechanisms by introducing UE-initiated CSI reports that provide real-time channel state information back to the base station. This continuous feedback loop allows the base station to adaptively adjust scheduling decisions based on current channel conditions, improving both packet delivery reliability and reducing latency through dynamic resource allocation
2Loss of time
If UE-initiated CSI reports are implemented, then communication latency is reduced and channel state accuracy is improved, but uplink resource consumption increases and system complexity increases
Solution Approach 1:
The patent applies parameter changes by introducing a threshold-based mechanism where UE only initiates CSI reports when channel quality changes exceed a predetermined threshold. This selective reporting approach reduces unnecessary uplink transmissions, optimizing the balance between maintaining current channel state accuracy and minimizing uplink resource consumption for CSI reporting
Solution Approach 2:
The patent implements partial action by having UE send differential CSI reports that only include changes from the previous reported state, rather than transmitting complete CSI information every time. This reduces the amount of data transmitted in uplink, thereby reducing resource consumption while still providing timely channel state updates to reduce latency
3Productivity
If multiple UEs share uplink resources for CSI and SR, then resource utilization efficiency is improved, but signal interference increases and detection reliability deteriorates
Solution Approach 1:
The patent applies segmentation by dividing uplink resources into dedicated portions for different UEs, including separate time slots, frequency resources, and orthogonal codes for CSI and SR transmissions. This resource segmentation allows multiple UEs to share the uplink channel simultaneously while maintaining sufficient signal separation, thereby improving resource utilization efficiency without significantly increasing interference and preserving signal detection reliability
Data Source
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AI summary
A method of wireless communication is described. The method comprises determining a set of resources reserved for uplink control information (UCI) the set of resources comprising a first resource block and a second resource block, wherein a group of users corresponding to a first symbol of the first resource block is a same group of users corresponding to a second symbol of the second resource block; and receiving at least one of a report with channel state information (CSI) a request for resources on which to send a CSI report, or signaling that indicates a change in CSI on resources of the set of reserved resources from a user equipment (UE) the receiving occurring during a first transmission time interval (TTI) duration in a system that supports operation with the first TTI duration and a second TTI duration that is greater than the first. Further, a corresponding apparatus and computer program are described.