QoS-Based Power Control for Carrier Aggregation Uplink
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Solution Overview
Problem
The existing PUCCH formats in LTE Rel-8 do not adequately support the increased number of HARQ ACK/NAK bits required in carrier aggregation systems and fail to properly account for the different quality of service requirements of various uplink control information types, leading to inefficient power control and potential errors in decoding.
Innovation Solution
New PUCCH formats and power control parameters are defined to accommodate the higher number of HARQ ACK/NAK bits, with open-loop and closed-loop power control parameters that differentiate between the relative importance of HARQ and CQI bits, ensuring appropriate transmit power levels based on the information types and their reliability requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing PUCCH formats and power control algorithms are used in carrier aggregation systems, then the system can support basic uplink control signaling, but the algorithms cannot properly account for the increased number of HARQ ACK/NAK bits and different QoS requirements, leading to inadequate power control and decoding errors
Solution Approach 1:
The patent introduces dynamic power control parameters (ΔF_PUCCH and h(n)) that adapt to the specific carrier aggregation configuration and information type being transmitted. The power control algorithm dynamically adjusts based on the number of component carriers, the type of control information (HARQ ACK/NAK, CQI, SR), and the relative importance weights assigned to different information types, rather than using static power control settings.
Solution Approach 2:
The patent applies different power control parameters and importance weights to different types of control information (HARQ ACK/NAK, CQI, SR) and different component carriers. Each information type can be assigned a specific weight reflecting its relative importance, allowing the system to allocate power locally based on the specific requirements of each information type rather than treating all control information uniformly.
2Reliability
If power control algorithms treat all control information bits equally, then the implementation is simple, but HARQ ACK/NAK bits are outweighed by CQI bits despite their higher reliability requirements
Solution Approach 1:
The patent assigns different importance weights to different types of control information bits. HARQ ACK/NAK bits can be assigned a higher weight than CQI bits, ensuring that the power control algorithm prioritizes the reliable transmission of HARQ feedback. This differential weighting allows the system to treat different information types with their respective quality requirements rather than uniformly.
Solution Approach 2:
The patent modifies the power control parameters (specifically the closed-loop parameter h(n)) to reflect the relative importance of different information types. By changing the parameter values based on information type and carrier aggregation configuration, the system achieves differentiated power control without requiring a completely new algorithm structure.
3Productivity
If the number of component carriers is increased to support wider bandwidths, then system throughput is improved, but the number of HARQ ACK/NAK bits increases significantly requiring more robust power control
Solution Approach 1:
The patent makes the power control parameters dynamic with respect to the number of component carriers. As carriers are aggregated, the system automatically adjusts the power control parameters and importance weights to maintain appropriate power levels for the increased number of HARQ bits. This dynamic adaptation allows throughput to scale with carrier aggregation while maintaining control information reliability.
Data Source
AI summary
A user equipment (UE) is configured for carrier aggregation in a wireless communication system. The UE selects control information to be transmitted in an uplink control channel format in a component carrier of two or more component carriers, where the control information includes information types associated with different information reliability requirements. The UE generates an open-loop power control parameter and/or a closed-loop power control parameter based on the information types. The UE transmits the control information in the uplink control channel format at a power level determined by the open-loop power control parameter and/or the closed-loop power control parameter.