Base Station Inactivity Indicator for UE Power Saving
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Solution Overview
Problem
In packet-oriented mobile communication systems like LTE, user equipment must continuously monitor downlink signals for control messages, leading to significant power consumption and battery drain, especially when many transmission opportunities are unused, as they need to keep receiving and buffering radio signals until a control message is found.
Innovation Solution
A method where a base station transmits a downlink inactivity indicator, setting the Physical Control Format Indicator Channel to zero in subframes with no control or user data, allowing user equipment to disable its receiving circuitry and enter a power-saving mode when no activity is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal continuously monitors downlink signals and searches for control messages in the search space, then the reliability of receiving control information is improved, but the power consumption increases significantly
Solution Approach 1:
The terminal switches between active monitoring periods and sleep periods based on the DRX cycle. During active periods, the terminal monitors PDCCH for control information. During sleep periods, the terminal disables receiving circuitry to save power. This periodic on-off monitoring pattern resolves the contradiction by maintaining reliability during active periods while reducing power consumption during sleep periods.
Solution Approach 2:
The base station provides feedback through downlink indicators (such as PDCCH assignments or specific wake-up signals) that inform the terminal whether to remain active or enter sleep mode. This feedback mechanism allows the terminal to adjust its monitoring behavior dynamically, maintaining reliability when needed while saving power when no control information is expected.
2Speed
If the terminal keeps the RX front-end activated to search for control messages, then the speed of detecting control information is improved, but the power consumption increases
Solution Approach 1:
The terminal activates the RX front-end periodically according to the DRX cycle rather than continuously. During active subframes, the terminal quickly searches for control messages with high speed. During inactive subframes, the terminal turns off the RX front-end to save power. This periodic activation maintains detection speed when needed while dramatically reducing overall power consumption.
Solution Approach 2:
The terminal is pre-configured with DRX parameters and search space information before actual monitoring begins. This preliminary configuration allows the terminal to quickly activate and start monitoring at the beginning of each active period without requiring extensive setup, thus maintaining fast detection speed while enabling power savings during inactive periods.
3Reliability
If the terminal monitors all search spaces and decodes all control message candidates, then the completeness of control information reception is improved, but the processing power consumption increases
Solution Approach 1:
The terminal performs complete search space monitoring and control message decoding only during active DRX periods. During sleep periods, the terminal skips all monitoring and decoding operations entirely. This periodic complete monitoring maintains completeness of control information reception when needed while avoiding unnecessary processing power consumption during periods when no control information is expected.
Solution Approach 2:
The terminal performs partial monitoring by focusing on specific search spaces or control message formats that are most likely to contain relevant control information, rather than exhaustively monitoring all possible search spaces and formats. This partial action approach maintains sufficient completeness for practical purposes while significantly reducing processing power consumption.
Data Source
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AI summary
The invention relates to a method 10 in a base station 2 of a communication system 1 comprising one or more user equipment 4. The method 10 comprises the steps of: detecting 11 that no control transmission or data transmission is being prepared for the one or more user equipment 4; and transmitting 12 a downlink inactivity indicator to the one or more user equipment 4. The invention also encompasses methods in a user equipment, computer programs, and computer program products.