eDRX Synchronization via MIB-NB Timing Drift Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wireless communication devices using extended discontinuous reception (eDRX) cycles in NB-IoT systems face synchronization challenges due to time and frequency drift during inactivity periods, leading to battery drainage and loss of synchronization with network nodes.
Innovation Solution
A method for a wireless communication device to calculate the earliest and latest points in time to receive and decode the narrowband master information block (MIB-NB) during a single NPBCH transmission interval, allowing for minimal energy consumption and synchronization with the network node upon activation, by estimating the time until eDRX On and checking for significant time drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If extended DRX cycles are used to reduce power consumption, then battery operation time is improved, but synchronization accuracy deteriorates due to time and frequency drift
Solution Approach 1:
The patent performs synchronization procedures in advance during the DRX On period before entering the extended DRX Off period. By calculating timing drift compensation values and adjusting the device's time reference beforehand, the system prepares for the expected drift that will occur during the long inactive period, thereby maintaining synchronization accuracy without requiring continuous power consumption.
Solution Approach 2:
The patent implements periodic synchronization adjustments at the boundaries of eDRX cycles (during DRX On periods) rather than continuous synchronization. This periodic approach allows the device to maintain synchronization over extended periods by making discrete corrections at intervals, balancing power consumption with synchronization accuracy requirements.
2Reliability
If complete synchronization procedures are performed during eDRX activation, then synchronization reliability is improved, but energy consumption increases
Solution Approach 1:
The patent performs a reduced set of synchronization procedures during eDRX activation compared to a complete synchronization. Specifically, it relies on pre-calculated timing drift compensation values and performs only essential synchronization checks rather than full re-synchronization. This partial action approach maintains adequate synchronization reliability while significantly reducing the energy consumption associated with extensive synchronization activities.
Solution Approach 2:
The patent changes the synchronization parameters by using pre-calculated timing drift compensation values instead of performing measurements from scratch. By adjusting the time reference using these pre-determined parameters, the system achieves reliable synchronization with minimal processing and energy expenditure during activation.
3Measurement precision
If timing drift compensation is performed continuously, then synchronization accuracy is improved, but computational overhead and power consumption increase
Solution Approach 1:
The patent calculates timing drift compensation values in advance during DRX On periods and stores them for use during the extended DRX Off period. This preliminary calculation eliminates the need for continuous computational adjustments, as the pre-computed values are simply applied during activation, thereby maintaining timing synchronization accuracy while minimizing computational power consumption.
Data Source
AI summary
A wireless communication device in a 3GPP NB-IoT wireless communication network operates during an inactivity period of an eDRX cycle. An activation procedure comprises calculating, in a time reference frame inherent to the wireless communication device, an earliest and a latest point in time for obtaining a narrowband master information block (MIB-NB) transmitted by a network node in a narrowband physical broadcast channel (NPBCH) during a single NPBCH transmission time interval. Between the calculated earliest point in time and latest point in time, radio receiver circuitry is activated in the wireless communication device and at least one radio subframe comprising the NPBCH is received and decoded. By this decoding, the MIB-NB is obtained, from which a system frame number (SFN) is read. A communication procedure then comprises activating the wireless communication device according to the eDRX cycle, and communicating, in a designated time interval as determined by the SFN, with the network node.