Multi-RAT PLMN Search Frequency Profiling
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Solution Overview
Problem
Current mobile communication devices with multiple Subscriber Identity Module (SIM) cards conduct full scans of the frequency space for each radio access technology (RAT) during a Public Land Mobile Network (PLMN) search, which is time-consuming, as they cannot determine which frequency bands are already in use by other RATs, leading to redundant searches.
Innovation Solution
The device profiles the frequency space to identify frequency bands used by each RAT, creates exclude lists based on priority ordering and neighbor cell information, and conducts PLMN searches while excluding frequencies already in use by other RATs, thereby reducing the search time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full scans of the frequency space are conducted for each RAT during PLMN search, then comprehensive network coverage is ensured, but the search time increases significantly
Solution Approach 1:
The patent applies preliminary action by profiling the frequency space before conducting PLMN searches for multiple RATs. The device identifies and stores frequency bands that are already in use by other RATs in advance, creating exclude lists that prevent redundant scanning. This preliminary profiling action resolves the contradiction by ensuring comprehensive coverage (through initial full scanning) while reducing subsequent search time (by excluding known frequencies).
Solution Approach 2:
The patent segments the frequency space scanning process by dividing it into initial profiling phase and subsequent search phases. During profiling, the entire frequency space is scanned once to identify all active frequency bands. Then, the search process is segmented into RAT-specific searches that exclude already-identified frequencies. This segmentation resolves the contradiction by performing comprehensive scanning once rather than repeatedly for each RAT.
2Measurement precision
If separate PLMN searches are conducted for each RAT, then each RAT can find its available frequency bands, but redundant searches occur on frequencies already in use by other RATs
Solution Approach 1:
The patent implements feedback by using information obtained from one RAT's frequency identification to improve subsequent searches for other RATs. After profiling identifies frequency bands used by any RAT, this information is fed back into the exclude lists for other RAT searches. This feedback mechanism resolves the contradiction by maintaining precise RAT-specific frequency identification while eliminating redundant searches through accumulated knowledge from previous scans.
Solution Approach 2:
The patent merges the frequency identification process across multiple RATs by conducting a unified profiling scan that identifies all active frequency bands regardless of which RAT uses them. This merged approach consolidates redundant identification efforts into a single comprehensive scan, then distributes the results to all RAT searches. This resolves the contradiction by achieving precise frequency identification for each RAT while improving overall productivity through combined scanning efforts.
3Loss of time
If the device profiles the frequency space and creates exclude lists, then the PLMN search time is reduced, but the initial profiling process adds complexity
Solution Approach 1:
The patent applies self-service by enabling the mobile device to automatically profile its own frequency space and generate exclude lists without external intervention. The device uses its existing scanning capabilities to identify active frequency bands and autonomously creates the exclude lists for optimized searching. This self-service approach resolves the contradiction by reducing PLMN search time through automated profiling while avoiding the need for complex external systems or manual configuration.
Solution Approach 2:
The patent achieves universality by designing the frequency profiling mechanism to serve multiple purposes: it identifies frequency bands for all RATs simultaneously, creates exclude lists for all subsequent searches, and provides a foundation for future network selection decisions. This multi-functional approach resolves the contradiction by reducing search time across all RATs through a single profiling operation, making the added complexity worthwhile through broad applicability.
Data Source
AI summary
Various embodiments for conducting a public land mobile network (PLMN) search for a plurality of radio access technologies (RATs) on a mobile communication device may include profiling a frequency space to identify one or more frequency bands that may be utilized by one of the plurality of RATs and determining, according to a priority ordering of the plurality of RATs, a RAT that utilizes each identified frequency band. The mobile communication device may add, for each RAT in the plurality of RATs, the identified frequency bands utilized by each RAT to exclude lists associated with other RATs in the plurality of RATs. The mobile communication device may then conduct a PLMN search for each RAT in the plurality of RATs utilizing the exclude lists associated with each RAT.