Base Station Ghost SR Detection via UCI Power Prediction
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Solution Overview
Problem
In 5G communication systems supporting connected discontinuous reception (C-DRX) operation, ghost scheduling requests (SR) can lead to the base station continuously transmitting uplink grant messages, wasting resources and potentially cutting off the connection between the base station and the terminal, as the terminal cannot receive these messages when in a DRX-off state.
Innovation Solution
The base station receives periodic uplink control information (UCI) from the terminal, predicts and measures the reception power of SR messages, sets a maximum number of retransmissions for uplink grants based on the measured and predicted reception power, and determines if the SR message is not received by reaching the maximum number of retransmissions, thereby reducing resource wastage and maintaining connection integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base station continuously transmits UL grant messages in response to ghost SR, then the SR message detection reliability is improved, but the resource wastage increases and connection stability deteriorates
Solution Approach 1:
The base station implements a feedback mechanism by monitoring whether UL data is actually transmitted in response to SR messages. When UL data is not received despite multiple UL grant transmissions, the base station infers that the SR was a ghost message and adjusts its behavior accordingly, preventing continuous resource wastage while maintaining reliable detection of legitimate SR messages
Solution Approach 2:
The base station dynamically changes the maximum number of UL grant retransmissions parameter based on the measured SR reception power and predicted SR reception power. By setting this parameter adaptively rather than using a fixed value, the system can distinguish between ghost SR (low power) and legitimate SR (high power), reducing resource wastage while maintaining reliable message detection
2Reliability
If the base station increases the number of UL grant retransmissions to ensure terminal reception, then the connection reliability is improved, but the resource consumption increases
Solution Approach 1:
The base station applies partial action by limiting the number of UL grant retransmissions to a dynamically determined maximum value rather than continuously retransmitting. This partial action is sufficient to ensure reliable delivery to terminals with legitimate SR messages while avoiding excessive resource consumption that would result from unlimited retransmissions
Solution Approach 2:
The maximum number of UL grant retransmissions is made dynamic rather than static, changing based on the ratio of measured SR reception power to predicted SR reception power. This dynamic adjustment allows the system to adapt resource consumption to actual channel conditions, maintaining connection reliability while optimizing resource usage
3Measurement precision
If the base station uses predicted SR reception power to identify ghost SR, then the ghost SR detection accuracy is improved, but the measurement complexity increases
Solution Approach 1:
The base station performs preliminary action by predicting the SR reception power before actually receiving the SR message, using the measured power of periodic UCI messages from the terminal. This preliminary prediction enables the base station to prepare for ghost SR detection and set appropriate reception thresholds in advance, improving detection accuracy without adding complex real-time measurement mechanisms
Solution Approach 2:
The periodic UCI messages serve as an intermediary to indirectly measure terminal transmission characteristics. By measuring the power of these regular UCI messages, the base station can infer and predict the SR reception power without directly measuring the SR itself, simplifying the measurement process while maintaining detection accuracy
Data Source
AI summary
The disclosure relates to a method for operating a base station in a wireless communication system, and discloses a method and apparatus which: receive periodic uplink control information (UCI) from a terminal in a connected discontinuous reception (C-DRX) on state; predict reception power of a scheduling request (SR) message based on reception power of the periodic UCI; based on a base station receiving, in a C-DRX off state, the SR message from the terminal, measure the reception power of the SR message; based on the measured reception power of the SR message and the predicted reception power of the SR message, set a maximum number of retransmissions of an UL grant that may be transmitted by the base station; retransmit the UL grant by the base station in response to the received SR message; and based on identifying that the number of retransmissions of the UL grant reaching the maximum number of retransmissions of the UL grant, determine that the base station does not receive the SR message.