Dual Mode Terminal Cell Reselection Control
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Solution Overview
Problem
Dual mode terminals experience a ping-pong phenomenon during cell reselection between GSM and WCDMA cells due to failed location registration and inappropriate network selection, leading to unreliable voice and data services.
Innovation Solution
A method for controlling cell reselection in dual mode terminals that disconnects from the current cell, evaluates access conditions, checks for blocked frequencies and Primary Scrambling Codes, and verifies if the target cell is in a forbidden location area, preventing reselection into cells that do not provide adequate service.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a terminal performs cell reselection based on signal quality between GSM and WCDMA cells, then the terminal can maintain connection in diverse network environments, but the terminal experiences ping-pong phenomenon and service instability due to failed location registration
Solution Approach 1:
The patent applies preliminary action by performing location registration verification before completing cell reselection. When a terminal detects a WCDMA cell and attempts location registration, the network checks registration status beforehand. If registration fails (indicated by LA change without successful registration), the network prevents further reselection to the same WCDMA cell, avoiding the ping-pong effect while maintaining adaptability to network conditions.
2Productivity
If a terminal automatically reselects cells to retrieve different Location Areas, then the terminal can find suitable networks, but the terminal cannot perform appropriate call operations until GSM cell is obtained due to limited network mode
Solution Approach 1:
The patent implements feedback by using location registration results to control cell reselection behavior. When location registration fails in manual mode, the terminal receives feedback indicating the failure status. Based on this feedback, the terminal adjusts its reselection strategy - preventing automatic reselection attempts that would otherwise continue the ping-pong phenomenon, thereby maintaining both network retrieval capability and call operation functionality.
3Adaptability or versatility
If a terminal performs PLMN reselection regardless of cell reselection algorithm, then the terminal can retrieve different LAs with identical PLMN, but the same WCDMA network is obtained again causing repeated registration failures
Solution Approach 1:
The patent applies preliminary anti-action by implementing a mechanism that counteracts repeated failed registration attempts. When the terminal detects that location registration has failed and the LA has changed (indicating the same WCDMA network was reselected), the system preemptively blocks further reselection to WCDMA cells. This preliminary counter-action prevents the terminal from repeatedly attempting registration on the same problematic network, thereby improving registration success rate while preserving PLMN reselection capability for genuine network changes.
Data Source
AI summary
A method for controlling cell reselection of a dual mode terminal supporting Wideband Code Division Multiple Access (WCDMA) and Global System for Mobile communications (GSM), includes determining, when a signal strength of a first cell is less than a predetermined value, whether a condition for access to a second cell is satisfied; determining whether a frequency and a Primary Scrambling Code (PSC) for access to the second cell are blocked; and determining whether the second cell is included in a forbidden location area (LA) list. Then, if the frequency and PSC are not blocked, and if the second cell is not included in the forbidden LA list, the method includes connecting to the second cell. A dual mode terminal to perform the method includes a condition determination unit, a blocking determination unit, an LA determination unit, and a control determination unit.