Uplink Channel Quality Control Information Encoding in Carrier Aggregation
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Solution Overview
Problem
In a carrier aggregation environment, the existing LTE-A system faces challenges in efficiently encoding and transmitting uplink channel quality control information, particularly when channel quality indicator (CQI) and precoding matrix indicator (PMI) need to be transmitted using two or more transport blocks, and the number of resource elements (REs) allocated to these indicators is not accurately calculated, especially during HARQ retransmissions.
Innovation Solution
A method and apparatus for transmitting channel quality control information in a wireless access system that supports hybrid automatic retransmit request (HARQ), involving the calculation of the number of coded symbols required for CQI and PMI transmission using specific formulas and the inclusion of this information in the physical downlink control channel (PDCCH) signal, allowing efficient encoding and accurate allocation of REs on the physical uplink shared channel (PUSCH).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation is used to extend bandwidth, then system capacity and data rate are improved, but the complexity of encoding and transmitting uplink control information increases
Solution Approach 1:
The patent segments UCI into different types (HARQ-ACK, CQI, PMI, RI) and processes each type separately with specific encoding rules. For CA environments, it divides the calculation of resource elements into distinct steps: determining total UCI bits, calculating beta offset values for different UCI types, and allocating resources proportionally. This segmentation reduces encoding complexity by providing systematic handling of each UCI component.
Solution Approach 2:
The patent introduces dynamic adjustment mechanisms for resource element allocation in CA environments. The beta offset values (beta_ACK, beta_CQI, beta_PMI, beta_RI) are dynamically determined based on transport block size, modulation scheme, and UCI type. This dynamic approach allows the system to adapt resource allocation to current channel conditions and traffic patterns, improving efficiency while managing complexity.
2Reliability
If the number of transport blocks is increased for HARQ retransmission, then reliability is improved, but the accuracy of resource element calculation for CQI and PMI deteriorates
Solution Approach 1:
The patent performs preliminary determination of resource element requirements before actual UCI transmission. It calculates the number of resource elements needed for CQI and PMI based on pre-determined beta offset values and transport block parameters. This preliminary calculation ensures accurate resource allocation even when multiple transport blocks are involved in HARQ retransmission, as the method establishes a systematic framework that accounts for all transport blocks before resource assignment.
Solution Approach 2:
The patent incorporates feedback mechanisms where the base station determines beta offset values based on observed channel conditions and transmission performance. This feedback loop allows the system to refine resource element calculations for CQI and PMI across multiple HARQ retransmissions, improving measurement precision while maintaining reliability through adaptive resource allocation.
3Productivity
If resource elements are allocated dynamically for UCI, then spectral efficiency is improved, but the calculation complexity for determining RE allocation increases
Solution Approach 1:
The patent manages calculation complexity by parameterizing the resource element allocation process through beta offset values. Instead of complex real-time optimization, the system uses predefined beta parameters (beta_ACK, beta_CQI, beta_PMI, beta_RI) that can be adjusted semi-statically. This parameter change approach maintains spectral efficiency by allowing dynamic adaptation while reducing instantaneous calculation complexity to simple arithmetic operations based on these parameters.
4Productivity
If UCI is multiplexed on PUSCH with multiple layers, then transmission efficiency is improved, but the precision of determining coded symbols per layer deteriorates
Solution Approach 1:
The patent applies local quality by allocating different beta offset values to different UCI types and layers. Instead of uniform resource allocation, it tailors the resource element calculation to each specific UCI component (HARQ-ACK, CQI, PMI, RI) and its associated transport block and layer. This localized approach ensures precise coded symbol allocation for each layer while maintaining overall transmission efficiency through differentiated resource assignment.
Data Source
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AI summary
Provided is a method for transmitting channel quality control information using two transport blocks in a wireless access system that supports hybrid automatic retransmit request (HARQ). The method may include the steps of receiving a physical downlink control channel (PDCCH) signal including downlink control information (DCI); calculating the number of coded symbols, Q', required to transmit the channel quality control information using the DCI; and transmitting the channel quality control information through a physical uplink shared channel (PUSCH) on the basis of the number of coded symbols.