Mobile Station SSAC for Priority Call Origination

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Solution Overview

Problem

In LTE mobile communication systems, the transmission of 'RA Preamble' during congestion can prevent priority and emergency calls from being processed successfully due to network resource depletion and congestion, especially when the mobile station is in the RRC_CONNECTED or DRX states.

Innovation Solution

A mobile station with an AS function unit and a NAS function unit is configured to receive and transmit Service Specific Access Control (SSAC) information, allowing the NAS function unit to perform access control processing on the transmission of 'RA Preamble' in intermittent reception states, thereby restricting or permitting the transmission based on SSAC information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If access control is applied to RA Preamble transmission in RRC_CONNECTED and DRX states, then network resource depletion is reduced, but origination processing for priority and emergency calls may be delayed or failed

Engineering Contradiction:
Improvenetwork resource depletionVSAvoidorigination processing success rate
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The patent applies different access control rules to different types of origination processing. Priority terminals and emergency calls are exempted from ACB restrictions on RA Preamble transmission, while ordinary terminals are subject to these restrictions. This local differentiation ensures that critical communications maintain high reliability while network resources are protected for general traffic.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent dynamically adjusts access control behavior based on terminal state and call type. In RRC_IDLE state, ACB is applied to all origination processing. In RRC_CONNECTED and DRX states, ACB is selectively applied only to non-priority/non-emergency calls. This dynamic adaptation resolves the contradiction by making access control flexible rather than static.

Inventive Principle:
Principle #15Dynamics

2Productivity

If ACB is applied during congestion to restrict RA Preamble transmission, then network congestion is reduced, but processing delays occur due to returning to DRX state

Engineering Contradiction:
Improvenetwork throughput during congestionVSAvoidorigination processing delay
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent performs preliminary classification of origination processing types before applying ACB. By identifying priority and emergency calls in advance (before congestion impact), these calls are exempted from ACB restrictions, ensuring they can proceed without delay even during network congestion. Ordinary calls are then subject to ACB to maintain overall network productivity.

Inventive Principle:
Principle #10Preliminary action

3Speed

If RA Preamble transmission is unrestricted in DRX state, then origination processing is faster, but network resources are depleted during congestion

Engineering Contradiction:
ImproveRA procedure completion speedVSAvoidnetwork resource consumption
Core Design Contradiction:
SpeedVSQuantity of substance

Solution Approach 1:

The patent applies selective access control based on call type and terminal state. In DRX state, priority and emergency calls are permitted to transmit RA Preamble without ACB restrictions, maintaining fast access speed. Ordinary calls in DRX state are subject to ACB restrictions, limiting their RA Preamble transmission to conserve network resources during congestion.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP2852241B1Mobile station
Publication Date: 2018.07.04 NTT DOCOMO INC
  • EP2852241B1 patent drawingFigure 1~2
  • EP2852241B1 patent drawingFigure 3

AI summary

To improve probability of successfully performing origination processing by a priority terminal and origination processing of an emergency call even during congestion. In a mobile station UE according to the present invention, an AS function unit 11 is configured to receive SSAC information from a radio base station eNB and transmit the SSAC information to the NAS function unit 12 at a predetermined timing, and a NAS function unit 12 is configured to perform SSAC on transmission of "RA Preamble" in a RA procedure for the mobile station UE in the DRX state to transmit an uplink signal, or on transmission of an uplink signal from the mobile station UE in the Non-DRX state.