Base Station Dynamic Fallback Trigger Handling

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Solution Overview

Problem

In cellular wireless networks, the setup of enhanced circuit-switched fallback (eCSFB) calls can fail due to handover procedures interrupting critical signaling, making it inefficient or impossible to provide necessary information for establishing communication between LTE and CDMA networks.

Innovation Solution

A method where a base station detects both a fallback trigger and a handover trigger, determines if the handover trigger occurs before the fallback setup procedure, and accordingly forgoes the fallback setup procedure, instead directing the wireless communication device to establish direct communication with the second network, thereby avoiding call setup failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the base station follows the predetermined fallback setup procedure to provide carrier and traffic channel information to the WCD, then the WCD can be properly configured for CDMA communication, but the handover procedure interrupts the signaling and the call setup fails

Engineering Contradiction:

ImproveeCSFB call setup success rateVSAvoidfallback setup procedure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The base station performs preliminary actions by detecting the handover trigger and completing the handover procedure before initiating the fallback setup procedure. This ensures that the WCD is already handed over to the target base station before the fallback signaling begins, preventing interruption and ensuring call setup success.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the execution order of procedures based on detected triggers. When a handover trigger is detected, the base station modifies the standard fallback setup sequence by first completing handover, then initiating fallback setup. This dynamic adaptation resolves the contradiction between maintaining reliable call setup and managing procedure complexity.

Inventive Principle:

Principle #15Dynamics

2Reliability

If the base station detects and handles both fallback and handover triggers simultaneously, then call setup reliability improves, but the control logic and signaling complexity increases

Engineering Contradiction:

ImproveeCSFB call setup success rateVSAvoidbase station control logic complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The base station is configured to detect handover triggers preliminarily and act on them before proceeding with fallback setup. This preliminary detection and handling of handover triggers simplifies the control logic by establishing a clear priority rule: complete handover first, then execute fallback setup, thereby improving reliability without excessive complexity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the execution parameters of the fallback setup procedure based on the detection of handover triggers. Specifically, it modifies the timing and sequence parameters by delaying fallback setup until after handover completion, which resolves the contradiction between reliability and control logic complexity.

Inventive Principle:

Principle #35Parameter changes

3Loss of information

If the fallback setup procedure is executed before handover completion, then carrier information can be provided to the WCD, but the interrupting handover procedure makes it impossible or inefficient to provide necessary information

Engineering Contradiction:

Improvecarrier and traffic channel information deliveryVSAvoidcall setup time

Core Design Contradiction:

Loss of informationVSLoss of time

Solution Approach 1:

The base station performs the handover procedure as a preliminary action before executing the fallback setup procedure. This ensures that the WCD is already transferred to the target base station and the signaling path is established, so that carrier and traffic channel information can be delivered efficiently without interruption, preventing both information loss and time loss.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

By sequencing the procedures so that handover completes before fallback setup begins, the system ensures continuity of useful action. The signaling path remains continuous and uninterrupted, allowing carrier information to be provided to the WCD without loss, while the total time is optimized by avoiding retransmissions and retries.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS9629034B1Dynamic setup of fallback communications during handover

Publication Date: 2017.04.18 SPRINT SPECTRUM LLC

AI summary

A method and system to help avoid a failed eCSFB call setup in the presence of handover. While a WCD is being served by a base station of a first network, the base station may detect both a fallback trigger and a handover trigger. The fallback trigger may be a trigger to initiate a fallback setup procedure, where the fallback setup procedure involves execution of a sequence of steps including a particular step. The handover trigger may be a trigger to initiate a handover procedure. The base station determines that the handover trigger was detected before execution of the particular step of the fallback setup procedure. Responsive to determining that the handover trigger was detected before execution of the particular step, the base station (a) foregoes the fallback setup procedure and (b) transmits to the WCD a message directing the WCD to establish communication with the second network.