Mobile Station Frequency Filtering for LTE Redirection
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Solution Overview
Problem
The existing Redirection method for switching between 3G and LTE systems does not ensure the mobile station's compatibility with the target frequency bands, leading to potential connection delays due to the core network mistakenly designating incompatible frequencies, causing the mobile station to search for and attempt connections on frequencies it cannot use.
Innovation Solution
The communication system includes a mobile station and a communication control device that transmit a switching instruction with multiple target frequencies, allowing the mobile station to search only for frequencies it can use, excluding unavailable frequencies, and if all targets are unavailable, it searches for cells within its capable frequency bands or returns to the original system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If switching to LTE is executed before the core network acquires the mobile station's capability information, then switching speed is improved, but connection delay increases due to searching incompatible frequencies
Solution Approach 1:
The mobile station performs capability information acquisition in advance before switching to LTE. The capability information includes frequency band support, which is used to filter and determine the target frequency for switching. This preliminary action ensures that the mobile station can quickly identify compatible frequencies without searching through incompatible ones, thus maintaining fast switching speed while avoiding connection delay.
2Adaptability or versatility
If the core network designates multiple switching target frequencies without capability acquisition, then frequency selection flexibility is improved, but search period increases due to incompatible frequencies
Solution Approach 1:
The mobile station applies local quality by filtering the multiple switching target frequencies based on its capability information. Specifically, it identifies which frequency bands it supports and selects only the compatible frequencies from the designated list. This localized filtering ensures that the mobile station maintains flexibility in frequency selection while avoiding time-wasting searches on incompatible frequencies.
3Ease of operation
If Redirection specifies multiple frequencies without capability verification, then network control flexibility is improved, but mobile station compatibility decreases
Solution Approach 1:
The mobile station uses feedback from its capability information to verify compatibility with the designated frequencies. After receiving the Redirection command with multiple frequencies, the mobile station checks its capability information to determine which frequencies it can actually use. This feedback mechanism ensures that network control flexibility is maintained while guaranteeing mobile station compatibility, as the mobile station will only attempt to connect to frequencies it is capable of using.
Data Source
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AI summary
A UE 300 is connectable to a first radio communication system and a second radio communication system which differs from the first radio communication system and uses multiple frequency bands. The UE 300 receives RRC CONNECTION REJECT which gives an instruction to switch from the first radio communication system to the second radio communication system and an indication on multiple switching target frequencies included in the frequency bands used by the second radio communication system, and, if the multiple switching target frequencies include an unavailable frequency at which the UE 300 is incapable of transmission/reception, searches for only a cell of a switching target frequency among the multiple switching target frequencies exclusive of the unavailable frequency.