Contention-Free Access Resource Assignment for CSFB Call Fallback
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Solution Overview
Problem
In cellular wireless networks, the transition between different air interface protocols for fallback communications, such as CSFB calls, often results in delays due to the use of non-contention-free access resources, which can cause contention and collisions, especially when a user rejects the call and needs to quickly return to the original network.
Innovation Solution
Assigning a contention-free access resource to the user equipment (UE) upon detecting an attempt to set up a fallback communication, allowing for a contention-free access request and seamless transition back to the original network, thereby avoiding access-resource contention and collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If non-contention-free access resources are used for fallback communication, then the system supports protocol transition, but access delays and collisions occur when users reject calls and need to return to the original network
Solution Approach 1:
The network assigns a dedicated contention-free access resource to the UE before the UE actually needs to access the network again. This preliminary assignment ensures that when the UE needs to return to the original network (e.g., after rejecting a fallback call), it can immediately use the pre-assigned resource without waiting or contending, thus eliminating access delay while maintaining protocol transition capability
Solution Approach 2:
The UE is given autonomous control over a specific contention-free access resource, allowing it to independently and immediately access the network without competing with other UEs. This self-service mechanism enables the UE to autonomously manage its own access timing and resource usage, eliminating both delay and collision issues
2Device complexity
If non-contention-free access resources are used, then resource allocation is simple, but contention and collisions occur during network access
Solution Approach 1:
The access resources are segmented into dedicated contention-free resources assigned to specific UEs and shared contention-based resources. By segmenting the resource pool and assigning exclusive rights to particular UEs for specific purposes (fallback communication and quick return), the system eliminates contention and collisions for those UEs while maintaining overall system manageability
Solution Approach 2:
Different access resources have different qualities assigned to them - some are designated as contention-free with exclusive access rights for specific UEs, while others remain contention-based for general use. This local differentiation in resource quality allows critical operations (quick network return) to use high-reliability resources while maintaining overall system simplicity
Data Source
AI summary
A method and system to assign a contention-free access resource is disclosed. A first network may be configured to serve user equipment devices (UEs) according to a first protocol and a second network may be configured to serve UEs according to a second protocol. The method involves the first network detecting an attempt to set up a circuit-switched-fallback (CSFB) call between (i) a UE served by the first network and (ii) a remote party, where the CSFB call is to be served by the second network to which the UE would transition to be served with the CSFB call. The method further involves, in response to detecting the attempt to set up the CSFB call, the first network assigning a contention-free access resource to the UE, so as to allow a contention-free access request by the UE to the first network.