Terminal Device PDCCH Monitoring Timer Alignment in NB-IoT
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Solution Overview
Problem
In NB-IoT networks, the inconsistency in repetition numbers of message transmissions between terminal devices and base stations leads to misaligned timer starts, resulting in partial or non-overlapping time windows for data transmission, which can cause random access failures, resource wastage, and increased power consumption.
Innovation Solution
The terminal device transmits first information based on a first repetition number, which is less than or equal to a second repetition number, and starts or restarts a timer at the actual transmission end moment of the first information. The terminal device then monitors the PDCCH search space before the timer expires or stops, ensuring consistent timing with the base station.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the base station determines the repetition number through blind detection, then the base station can obtain the repetition number without additional signaling, but the determined repetition number may be inconsistent with the actual transmission repetition number, leading to timer misalignment
Solution Approach 1:
The terminal device feeds back the actual repetition number to the base station after completing message 3 transmissions. This feedback mechanism enables the base station to accurately determine the repetition number without blind detection, ensuring both timer start moments align while avoiding complex additional signaling for repetition number indication.
2Ease of operation
If the terminal device and base station start timers at different moments due to repetition number inconsistency, then each side operates independently, but the time windows for message 4 transmission and monitoring may not overlap, causing random access failure
Solution Approach 1:
The terminal device feeds back the actual repetition number to the base station, enabling both sides to synchronize their timer start moments. This ensures the time windows for message 4 transmission and monitoring overlap properly, preventing random access failure while maintaining independent operation of each device.
3Adaptability or versatility
If the terminal device retransmits random access due to failed DCI detection, then the terminal device can attempt recovery, but resources are wasted and power consumption increases
Solution Approach 1:
The terminal device feeds back the actual repetition number to the base station, ensuring accurate timer alignment and successful DCI detection on the first attempt. This eliminates the need for random access retransmission, thereby reducing power consumption while maintaining the ability to recover from transmission errors through proper synchronization.
Data Source
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AI summary
A monitoring method and an apparatus are provided. The method includes: transmitting, by a terminal device, first information based on a first repetition number, where the first repetition number is less than or equal to a second repetition number, and the second repetition number is a maximum repeat transmission number of the first information; determining, by the terminal device, a scheduling end moment of the first information based on the second repetition number, where the scheduling end moment of the first information is a transmission end moment of the first information when the first information is transmitted based on the second repetition number; and starting or restarting, by the terminal device, a timer at the scheduling end moment of the first information, and monitoring physical downlink control channel PDCCH search space before the timer expires or stops.