Uplink Control Format Selection for Carrier Aggregation
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Solution Overview
Problem
In wireless communication systems, especially those employing enhanced carrier aggregation, the reporting of channel state information (CSI) faces challenges due to increased uplink control information sizes, leading to resource constraints and potential collisions, particularly when multiple component carriers are used, which existing techniques struggle to efficiently manage.
Innovation Solution
The solution involves a user equipment (UE) selecting appropriate physical uplink control channel (PUCCH) formats based on the relative importance of CSI reporting, applying prioritization rules to manage multiple CSI reports, and multiplexing CSI with HARQ ACK/NACK to optimize resource usage and reduce collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of component carriers is increased for enhanced carrier aggregation, then the system capacity and data rate are improved, but the uplink control information size increases causing resource constraints and transmission collisions
Solution Approach 1:
The patent segments the uplink control information by introducing separate physical channels: PUCCH for HARQ-ACK feedback and PUSCH for CSI reporting. This segmentation allows different types of control information to be transmitted through different channels, preventing resource constraints and collisions that occur when all control information is transmitted through a single channel.
2Loss of information
If multiple P-CSI reports are scheduled for transmission in the same subframe, then the channel state information coverage is improved, but the uplink control channel resources are insufficient for simultaneous transmission
Solution Approach 1:
The patent uses the PUSCH as an intermediary channel specifically for CSI report transmission. When multiple P-CSI reports are scheduled, they are transmitted through PUSCH rather than competing for PUCCH resources. This intermediary channel provides additional capacity for CSI reporting without interfering with HARQ-ACK feedback transmission on PUCCH.
3Productivity
If P-CSI reports are transmitted together with HARQ feedback on the same channel, then the resource usage efficiency is improved, but transmission collisions and information loss occur
Solution Approach 1:
The patent segments the transmission paths by assigning HARQ-ACK feedback to PUCCH and CSI reports to PUSCH. This segmentation ensures that each channel type has dedicated resources, eliminating transmission collisions while maintaining high resource usage efficiency through optimized channel selection based on traffic conditions.
Data Source
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AI summary
Methods, systems, and devices for wireless communication are described. A user equipment (UE) may detect the size of a payload for reporting hybrid automatic repeat request (HARQ) feedback for transmissions on a set of component carriers (CCs) and may determine whether a scheduling request (SR) and/or a periodic channel state information (P-CSI) report is present. The UE may compare a size of an uplink control message, which may include a HARQ payload size and a payload for the SR or P-CSI report, with a threshold to select an uplink control format. The selected uplink control format maybe associated with a large number of CCs if the uplink control message has a payload size above a threshold. The UE may also use a configuration for transmitting two or more P-CSI reports during a subframe for CCs of a carrier aggregation (CA) configuration. P-CSI reports due for transmission during a given subframe.