Uplink Power Control via Subframe Set Accumulators
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Solution Overview
Problem
In time division duplex (TDD) systems, the interference between uplink (UL) and downlink (DL) transmissions due to differing UL/DL configurations in neighboring cells affects the quality of UL and DL transmissions, necessitating improved power control mechanisms to mitigate interference.
Innovation Solution
A wireless transmit/receive unit (WTRU) receives UL subframe sets configurations and maintains transmit power control (TPC) command accumulator values, adjusting TPC commands to determine the power for UL transmissions based on the specific UL subframe set, ensuring optimal power control across varying subframe configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If TDD systems use different UL/DL configurations in neighboring cells to increase flexibility and capacity, then system adaptability and resource utilization improve, but interference between UL and DL transmissions increases
Solution Approach 1:
The patent segments the TPC command accumulation process into separate accumulators for different UL subframe sets. Instead of using a single TPC accumulator for all UL transmissions, the system maintains multiple accumulators (e.g., one for each UL subframe set), allowing independent power control adjustments for transmissions in different subframe configurations. This segmentation enables precise interference management while preserving the flexibility of dynamic TDD configurations.
Solution Approach 2:
The patent applies local quality by making TPC command accumulation behavior specific to each UL subframe set rather than uniform across all UL transmissions. Each UL subframe set can have its own TPC accumulator with independent accumulation rules, allowing the system to optimize power control parameters locally for each subframe configuration pattern. This enables differentiated power control strategies tailored to specific interference conditions in different subframe sets.
2Device complexity
If a single TPC accumulator is used for all UL transmissions, then device complexity is reduced, but power control precision deteriorates in dynamic TDD configurations
Solution Approach 1:
The patent introduces dynamics by making the TPC accumulator selection adaptive based on the current UL subframe set. The system dynamically determines which TPC accumulator to use based on the configured UL subframe sets and the current transmission subframe. This dynamic approach allows the power control mechanism to adapt to changing TDD configurations while maintaining reasonable device complexity through systematic selection rules.
Solution Approach 2:
The patent changes the parameter of TPC accumulator state by maintaining multiple accumulators with different accumulated values corresponding to different UL subframe sets. Instead of using a single TPC state for all transmissions, the system maintains separate TPC states (parameters) for different subframe configurations, allowing precise power control adjustments tailored to each configuration's specific interference characteristics and transmission requirements.
Data Source
AI summary
A method and apparatus are described for controlling uplink (UL) transmission power. A wireless transmit/receive unit (WTRU) may receive a configuration of UL subframe sets and maintain a plurality of transmit power control (TPC) command accumulator values that correspond to respective ones of the UL subframe sets. The WTRU may receive a TPC command in a subframe n of a downlink (DL) transmission, determine a subframe n+k of a UL transmission that the received TPC command corresponds to, determine which of the UL subframe sets the UL transmission subframe n+k belongs to, and adjust a TPC command accumulator value that corresponds to the determined UL subframe set to determine power of the UL transmission when transmitting in the UL transmission subframe, where n is an integer, and k is an integer greater than zero.