Baseband SIM File Caching for Cellular Bootup Delay
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Solution Overview
Problem
Wireless devices experience significant delays during cellular bootup due to the time-consuming process of reading SIM files from the SIM card, which can take up to 10-15 seconds of the total 10-15 seconds required for cellular connectivity.
Innovation Solution
Caching SIM files and files with SIM dependencies on the baseband processor of a wireless device, along with associating SIM identification information and generating indicator information for version comparison, allows the device to determine if cached files are valid and use them instead of re-reading from the SIM card during subsequent initializations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SIM files are read from the SIM card during cellular bootup, then the device obtains necessary subscriber identity and configuration information, but the bootup process experiences significant delays (10-15 seconds)
Solution Approach 1:
The baseband processor performs preliminary action by caching SIM files during normal operation and then utilizing these cached files during subsequent bootup sequences. The system pre-loads and stores SIM file information in the baseband processor's memory before the actual bootup event, so that when bootup occurs, the files are already available for immediate use, eliminating the need to read from the SIM card during the critical bootup window and reducing bootup time.
Solution Approach 2:
The invention creates a copy of the SIM files in the baseband processor's local memory. Instead of reading SIM files directly from the SIM card during bootup, the system uses a cached copy that was previously obtained and stored in the baseband processor. This copying approach allows the bootup process to access data from the faster baseband memory rather than the slower SIM card interface, significantly reducing bootup time while maintaining the same functional outcome.
2Loss of time
If the device caches SIM files in the baseband processor, then bootup time is reduced by avoiding SIM card reads, but the device complexity increases due to caching mechanism requirements
Solution Approach 1:
The baseband processor is designed to serve multiple functions: it not only processes cellular communication signals but also serves as a caching storage location for SIM files. By making the baseband processor multi-functional (both signal processing and file caching), the system avoids adding a separate dedicated caching device. The baseband processor's existing memory resources are utilized for caching, which reduces overall device complexity compared to adding a separate caching subsystem.
3Loss of time
If the baseband processor stores locally cached versions of SIM files, then subsequent bootups are faster, but the reliability may be compromised if cached files become invalid or outdated
Solution Approach 1:
The system implements a feedback mechanism where the baseband processor checks the validity of cached SIM files before using them during bootup. The processor compares cached file information with current SIM card information or uses validity indicators stored with the cached files to determine whether the cache is still valid. This feedback loop allows the system to detect when cached files are outdated or invalid and switch to reading from the SIM card, thus maintaining reliability while benefiting from faster bootup when the cache is valid.
Data Source
AI summary
This disclosure relates to caching SIM files at a baseband processor to reduce cellular bootup time. According to one embodiment, a wireless device may read SIM files from a SIM and store a local copy of each file in a cache of the baseband processor of the wireless device. SIM identification information for the SIM from which the cached files were read may be associated with the cache. Indicator information usable for comparing file versions may also be generated and stored in the cache for each file. Upon a subsequent SIM initialization, the wireless device may read SIM files from the cache instead of from the initialized SIM if the cached version is identical to the SIM version, which may be determined based at least in part on the SIM identification information and the indicator information for such files.