Adaptive PUCCH Format Selection for Carrier Aggregation Feedback
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Solution Overview
Problem
In LTE communication systems with carrier aggregation, the existing methods for cyclically feeding back channel state information (CSI) across multiple cells in a single subframe are inadequate, leading to inefficient bit allocation and prolonged feedback delays due to fixed bit number constraints in PUCCH formats 2/2a/2b.
Innovation Solution
The method involves configuring user equipment with multiple physical uplink control channel formats having different orthogonal sequences with varying expansion factors, allowing adaptive selection of channel formats based on feedback information load, thereby optimizing bit allocation and reducing feedback delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If cyclic CSI of multiple cells is fed back in one subframe using PUCCH Format 2/2a/2b, then feedback delay is reduced, but the number of feedback bits is limited to 1-11 bits
Solution Approach 1:
The patent introduces dynamic selection between two PUCCH formats (first format with expansion factor M1 and second format with expansion factor M2 where M2 is an integral multiple of M1). The UE adaptively chooses the appropriate format based on the number of CSI bits to be fed back, enabling the system to dynamically adjust the feedback capacity from 1-11 bits to support larger bit quantities while maintaining low feedback delay.
Solution Approach 2:
The patent changes the expansion factor parameter of the orthogonal sequence used in PUCCH formats. By configuring two different expansion factors (M1 and M2) where M2 is an integral multiple of M1, the system can adjust the spreading gain and thereby support different numbers of feedback bits. This parameter change allows the same PUCCH resource to flexibly accommodate varying CSI feedback volumes without increasing feedback delay.
2Adaptability or versatility
If the number of activated serving cells changes in carrier aggregation, then system adaptability is improved, but the feedback bit number becomes variable and cannot be met by fixed PUCCH formats
Solution Approach 1:
The patent makes the PUCCH resource universal by configuring two PUCCH formats with different expansion factors that can handle different feedback bit quantities. Instead of requiring separate PUCCH resources for different bit scenarios, the same PUCCH resource can adaptively support both small (1-11 bits) and large feedback volumes by switching between the first and second formats, reducing management complexity while maintaining high adaptability to cell activation changes.
3Ease of manufacture
If PUCCH Format 2/2a/2b is used for CSI feedback, then implementation simplicity is maintained, but feedback efficiency decreases due to long feedback delay and limited bit capacity
Solution Approach 1:
The patent enhances the simple PUCCH Format 2/2a/2b structure by introducing dynamic format selection capability. The UE can dynamically choose between the first PUCCH format (expansion factor M1) and the second PUCCH format (expansion factor M2) based on the actual feedback bit requirement, thereby improving feedback efficiency to handle both small and large CSI volumes efficiently while keeping the implementation relatively simple by building upon the existing format structure.
Data Source
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AI summary
The present invention provides a method and device for transmitting information, the method includes: configuring a first physical uplink control channel format and a second physical uplink control channel for a user equipment first, wherein, an orthogonal sequence of the first physical uplink control channel format and an orthogonal sequence of the second physical uplink control channel format correspond to different expansion factors; and then the user equipment select one of the physical uplink control channel format and the second physical uplink control channel format to transmit the feedback information.