ACK/NACK Resource Allocation in LTE Control Channels
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Solution Overview
Problem
In LTE mobile communication systems, the simultaneous transmission of ACK/NACK and CQI control information can lead to increased Peak-to-Average Power Ratio (PAPR) and performance degradation due to overlapping transmission times and interference between signals from multiple users, especially in fast-moving environments where channel changes are significant.
Innovation Solution
A resource allocation method that prioritizes ACK/NACK transmission by using resources initially allocated for CQI transmission, ensuring orthogonality between signals and reducing interference, and employing joint coding to prevent detection errors, while also allowing repeated transmission of ACK/NACK over multiple subframes to enhance reception reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ACK/NACK and CQI are transmitted simultaneously using separate resources, then both control information types can be transmitted, but PAPR increases and performance degradation occurs
Solution Approach 1:
The patent merges ACK/NACK and CQI transmissions by allowing ACK/NACK to use CQI resources when they overlap in time. This combines the resource allocation mechanisms, enabling the system to transmit both control information types without requiring completely separate resources, thereby reducing PAPR while maintaining transmission capability.
Solution Approach 2:
The patent changes the resource allocation parameters dynamically based on transmission timing. When ACK/NACK and CQI transmission times overlap, the system changes the resource assignment by allocating ACK/NACK to use CQI resources instead of dedicated ACK/NACK resources. This parameter change resolves the PAPR issue while preserving both transmission functions.
2Device complexity
If ACK/NACK uses dedicated resources separate from CQI, then resource allocation is simple, but interference occurs when transmission times overlap
Solution Approach 1:
The patent introduces dynamic resource allocation where ACK/NACK resources are not fixed but can change based on transmission timing conditions. When overlap is detected, the system dynamically reassigns ACK/NACK to use CQI resources. This dynamic approach maintains simple base allocation while adapting to prevent interference when needed.
Solution Approach 2:
The patent uses transmission timing information as an intermediary condition to mediate resource allocation. This intermediary parameter determines whether ACK/NACK uses dedicated resources or CQI resources, providing a simple decision mechanism that prevents interference without complex allocation rules.
3Object-affected harmful factors
If CQI transmission resources are used for ACK/NACK when times overlap, then interference is reduced, but CQI transmission is blocked
Solution Approach 1:
The patent extracts the critical control information (ACK/NACK) from the general control information category and gives it priority access to CQI resources when needed. By taking out ACK/NACK as a special case with higher priority, the system can block CQI transmission in specific overlapping scenarios without compromising overall system performance, since ACK/NACK is essential for HARQ operations.
4Reliability
If frequency hopping is applied to PUCCH, then frequency diversity is improved, but resource allocation complexity increases
Solution Approach 1:
The patent segments the resource allocation process into two independent parts: base resource allocation (which remains simple) and frequency hopping pattern application (which provides diversity). By segmenting these functions, the system maintains simple base allocation while adding frequency hopping as a separate layer that improves reliability without significantly increasing overall complexity.
Data Source
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AI summary
A method for allocating resources in a mobile communication system is provided. The resource allocation method includes determining whether a transmission time of response information indicating presence/absence of an error in received data overlaps a transmission time of channel state information; and when the transmission times overlap each other, allocating, to the response information, a resource block for the channel state information, cyclic shift values in a frequency domain, and orthogonal sequences having orthogonality in a time domain.