UE Power Limit Determination for Carrier Aggregation with Shortened TTIs
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Solution Overview
Problem
In wireless communication systems, determining appropriate maximum transmit power limits for uplink signals across multiple carriers with different transmission time intervals (TTIs) is challenging, leading to potential distortion and reduced throughput due to varying power usage.
Innovation Solution
A method where user equipment (UE) identifies a reference component carrier and determines a maximum transmit power limit based on overlapping shortened TTIs, ensuring compliance with initial power limits and maintaining constant power across carriers by adjusting bounds at TTI boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the UE transmits uplink signals on different carriers during TTIs with different durations, then the system supports carrier aggregation and flexible scheduling, but it becomes challenging to identify appropriate bounds for the maximum transmit power limit
Solution Approach 1:
The patent applies local quality by selecting one component carrier as a reference carrier with specific TTI duration properties, while other carriers are adjusted relative to this reference. This allows different carriers to have different TTI durations (maintaining adaptability) while establishing a local reference framework that simplifies power limit determination (reducing complexity).
Solution Approach 2:
The patent uses preliminary action by pre-determining the maximum transmit power limit based on the reference carrier's TTI boundaries before actual transmissions occur. This advance determination ensures that power limits are established prior to overlapping TTI scenarios, making the power control mechanism more manageable despite the complexity of multi-carrier aggregation.
2Ease of operation
If the UE determines maximum transmit power limit for each TTI independently, then the power control is simple, but transmissions may exceed the maximum power limit when TTIs overlap across carriers
Solution Approach 1:
The patent merges the power limit determination across multiple carriers by establishing a unified maximum power limit that applies to overlapping TTIs on different carriers. Instead of treating each carrier independently, the reference carrier framework combines power considerations across carriers, ensuring the total transmit power remains within limits while maintaining relatively simple control mechanisms.
Solution Approach 2:
The patent implements feedback by continuously monitoring TTI overlaps across carriers and adjusting the maximum transmit power limit accordingly. When TTIs overlap, the system feedback ensures the power limit is recalculated to prevent exceeding maximum power, while when no overlaps occur, the simpler independent determination applies, thus balancing reliability and ease of operation.
3Reliability
If the maximum transmit power limit is updated frequently to account for overlapping sTTIs, then power compliance is ensured, but the processing complexity and signaling overhead increase
Solution Approach 1:
The patent segments the power limit update process by triggering updates only at specific TTI boundaries rather than continuously. This segmentation reduces the frequency of power limit recalculations while ensuring compliance is maintained at critical transition points, thereby reducing processing complexity while preserving reliability.
Solution Approach 2:
The patent applies dynamics by making the power limit update mechanism adaptive - updates occur dynamically only when TTI overlaps are detected or at relevant TTI boundaries, rather than following a fixed rigid schedule. This dynamic approach ensures power compliance is maintained when needed while avoiding unnecessary updates that would increase complexity and overhead.
Data Source
AI summary
Methods, systems, and devices for wireless communication are described. Some wireless communications systems may support communication between a user equipment (UE) and a base station on multiple carriers (i.e., carrier aggregation). In some cases, the UE may be scheduled to transmit uplink signals on the different component carriers during transmission time intervals (TTIs) that have different durations. In such cases, it may be appropriate for the UE to determine a maximum transmit power limit relating to the amount of power used for the uplink transmissions on the multiple carriers. As described herein, the UE may identify one of the component carriers as a reference component carrier, and the UE may determine the maximum transmit power limit for a duration of a TTI associated with the reference component carrier. The UE may then transmit on the multiple carriers in compliance with the maximum transmit power limit.