LTE Network Return via Signal Ranking

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Solution Overview

Problem

Existing methods for mobile user equipment to return to an LTE network after a circuit-switched fallback (CSFB) procedure are either slow due to Cell Reselection or require expensive upgrades for Fast Return, which may not be supported by all 2G/3G network architectures.

Innovation Solution

A method and multi-mode mobile user equipment that initiate a packet-switched network return procedure by measuring signal strength of LTE access points and selecting a preferred cell for reconnection based on received lists, without requiring redirection instructions from the CSN, thereby implementing a connection to the LTE network.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If Cell Reselection is used for returning to LTE network after CSFB, then the method is universally compatible with existing network architectures, but the return speed is slow

Engineering Contradiction:
Improvereturn speed to LTE networkVSAvoidtransition delay
Core Design Contradiction:
SpeedVSLoss of time

Solution Approach 1:

The mobile terminal performs measurements of LTE access point signal strengths while still connected to the CSN and generates a ranked list of potential target cells before disconnecting. This preliminary preparation allows the terminal to immediately initiate connection to the preferred LTE access point upon disconnection, eliminating the need for measurements and selection procedures after leaving the CSN, thereby significantly reducing return time.

Inventive Principle:
Principle #10Preliminary action

2Speed

If Fast Return mechanism is implemented, then the return speed to LTE network is improved, but expensive network architecture upgrades are required

Engineering Contradiction:
Improvereturn speed to LTE networkVSAvoidnetwork upgrade cost
Core Design Contradiction:
SpeedVSEase of manufacture

Solution Approach 1:

The mobile terminal autonomously performs the complete return procedure to LTE network without requiring any special network infrastructure or redirection instructions from the CSN. The terminal independently measures signal strengths, ranks LTE access points, initiates disconnection from CSN, and connects to the selected LTE access point using only standard procedures already supported by existing network architectures, thereby achieving fast return without expensive upgrades.

Inventive Principle:
Principle #25Self-service

3Loss of time

If the mobile terminal autonomously initiates packet-switched network return procedure with pre-generated ranking, then transition delays are reduced, but the device complexity increases

Engineering Contradiction:
Improvetransition delayVSAvoidterminal processing complexity
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The terminal generates the ranked list of LTE access points and stores it while connected to the CSN, before the actual return procedure begins. This preliminary generation of the ranking eliminates the need for complex real-time measurements and decision-making during the transition, simplifying the execution phase to merely initiating disconnection and connecting to the pre-selected target, thereby reducing overall transition delay without requiring excessively complex device processing during the critical return window.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2750454B1Packet-switched network return
Publication Date: 2015.05.27 SPREADTRUM COMMUNICATION (SHANGHAI) CO LTD
  • EP2750454B1 patent drawingFigure 1
  • EP2750454B1 patent drawingFigure 2
  • EP2750454B1 patent drawingFigure 3

AI summary

Systems and methods for generating a Long Term Evolution network return procedure. A mobile terminal may generate, in absence of redirection instruction from a circuit-switched network, a Long Term Evolution network return procedure that when instantiated by the mobile terminal implements connection of the mobile terminal to a Long Term Evolution network based on a ranking of measured Long Term Evolution network access points.