Radio Station Frequency Dispersion Time Delay
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Solution Overview
Problem
The termination of a point-to-multipoint MBMS service in UMTS networks often leads to network overload due to simultaneous frequency switching by multiple UEs, causing unnecessary signalling loads and potential reselection issues for subsequent services.
Innovation Solution
Implementing a configurable time delay for frequency dispersion based on the radio station's state or characteristics of the subsequent service, allowing for staggered frequency reselection and service transitions to mitigate network overload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UEs are forced to move to other frequencies immediately when an MBMS session ends, then the signalling load is spread over several frequencies, but a large number of UEs simultaneously selecting alternative frequencies causes further network signalling overload
Solution Approach 1:
The patent introduces periodic action by implementing a time-dispersed frequency reselection mechanism where UEs are distributed into different time groups (e.g., early dispersal group, normal dispersal group, late dispersal group) that reselect frequencies at different time intervals after MBMS session termination. This transforms the instantaneous frequency switching into a staggered, periodic process, reducing peak signalling load while maintaining network stability.
Solution Approach 2:
The patent applies segmentation by dividing the UE population into multiple dispersal groups with different time characteristics. Instead of treating all UEs uniformly, the system segments them based on their reselection timing preferences, allowing controlled distribution of signalling load across different time periods. This segmentation resolves the contradiction by preventing simultaneous frequency switching while still achieving load distribution.
2Reliability
If UEs perform frequency dispersion immediately after MBMS session termination, then network overload is reduced, but unnecessary dispersion occurs for UEs that will next receive a different MBMS service on the same frequency
Solution Approach 1:
The patent implements preliminary action by having UEs evaluate their next service requirements before executing frequency reselection. The network provides information about upcoming MBMS services, allowing UEs to anticipate whether they will need to return to the original frequency soon. This preliminary knowledge enables UEs to delay dispersion unnecessarily, avoiding wasteful reselections while still achieving load management for UEs that truly need to switch frequencies.
3Reliability
If a time delay is introduced for frequency dispersion, then simultaneous frequency switching is reduced, but service setup time for UEs is increased
Solution Approach 1:
The patent applies local quality by providing different time delay characteristics to different UE groups based on their specific service requirements. Instead of a uniform delay for all UEs, the system creates early, normal, and late dispersal groups with differentiated timing behaviors. This allows UEs with urgent service needs to switch sooner while others delay, optimizing both network stability and individual service setup times through localized quality differentiation.
Data Source
AI summary
When a radio station terminates a first service on a first radio frequency channel and selects a second radio frequency channel for engaging in a second service, a time delay is inserted after the termination of the first service and before selecting the second radio frequency channel or before engaging in the second service. The time delay is dependent on the state of the radio station and/or a characteristic of the second service.