MTC Long DRX Cycle Synchronization Under Clock Drift
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Solution Overview
Problem
Current wireless networks do not support long discontinuous reception (DRX) cycles or sleep lengths necessary for machine type communication (MTC) devices, leading to power inefficiencies and synchronization issues due to clock drift during extended sleep periods.
Innovation Solution
Implementing methods and apparatus to enable long DRX cycles and sleep periods for MTC devices, including mechanisms for device-network synchronization and clock drift adjustment, allowing MTC devices to operate with low power consumption and manage device waking times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If MTC devices use long DRX cycles or sleep periods to reduce power consumption, then energy efficiency is improved, but synchronization accuracy deteriorates due to clock drift during extended sleep periods
Solution Approach 1:
The network pre-calculates and provides clock drift compensation parameters to the MTC device before the device enters long DRX cycle. The device uses these pre-provided parameters to adjust its local clock during extended sleep periods, maintaining synchronization without needing to wake up frequently for network timing updates, thus reducing power consumption while preserving sync accuracy.
Solution Approach 2:
The system dynamically adjusts the DRX cycle length and clock drift compensation parameters based on network conditions and device state. By changing the DRX cycle parameter to allow longer sleep periods and simultaneously adjusting compensation parameters to account for expected clock drift, the system achieves both energy efficiency and synchronization accuracy.
2Measurement precision
If MTC devices monitor the network frequently to maintain synchronization, then synchronization accuracy is improved, but power consumption increases
Solution Approach 1:
Instead of continuous or frequent monitoring, the MTC device performs periodic synchronization checks at predetermined intervals during long DRX cycles. The device wakes up at specific intervals to receive timing information from the network and adjusts its local clock accordingly, then returns to sleep mode. This periodic approach maintains synchronization accuracy while significantly reducing power consumption compared to frequent monitoring.
Solution Approach 2:
The MTC device autonomously performs clock drift compensation using pre-configured parameters and local calculations. Rather than requiring the network to actively manage synchronization for each wake-up event, the device self-adjusts its timing based on stored compensation data and its own clock characteristics, reducing the need for frequent network contact and lowering power consumption.
3Adaptability or versatility
If current wireless networks use standard DRX cycles, then network compatibility is maintained, but MTC device battery life is limited
Solution Approach 1:
The system implements dynamic DRX cycle configuration where the DRX cycle length is not fixed but can be adjusted based on MTC device requirements and network conditions. The network can configure different DRX cycle lengths for different devices or time periods, allowing MTC devices to use extended sleep periods for improved battery life while maintaining the ability to switch to standard cycles when network compatibility or service requirements demand it.
Solution Approach 2:
The patent introduces configurable parameters for DRX cycle length and clock drift compensation that can be modified based on device type, service requirements, and network conditions. By changing these parameters to support longer DRX cycles for MTC devices specifically, the system extends battery life while maintaining backward compatibility with standard DRX operations for other device types or when needed.
Data Source
AI summary
Current wireless networks do not allow machine type communication (MTC) devices to have long discontinuous reception (DRX) cycles or sleep lengths. A long DRX cycle may allow MTC systems and devices to operate with much longer DRX/Sleep cycles/periods. This may facilitate the MTC operations for infrequent system access or infrequent system reaching (e.g. paged once in a week) with no or low mobility and may allow MTC devices to sleep for a long time with low power consumption.