1. January 6, 20161 Mobile Computing COE 446 Network Operation Tarek Sheltami KFUPM CCSE COE http://faculty.kfupm.edu.sa/coe/tarek/coe446.htm Principles of Wireless Networks K. Pahlavan and P. Krishnamurth

2. January 6, 20162  Handoff Management  Architectural Issues in Handoff  Handoff Decision Time Algorithms  Types of Handoffs Outline

3. January 6, 20163 Handoff Management 1. Architectural Issues in Handoff  Set of protocols to notify all related entities of a particular connection that a handoff has been executed and the connection has to be redefined  In voice network, MT selects the BS that is serving its location  When an MT moves from one point of attachment to another, the old serving point of attachment has to be informed about the change (dissociation)  Other network components involved in routing mechanism have to be aware of the handoff in order to seamlessly continue the ongoing connection of the call Mobile Management

4. January 6, 20164  Handoff are classified according to the connection creation  Seamless handoff and hard handoff  Handoffs are classified into: 1. Network Controlled Handoff (NCHO) 2. Mobile Controlled Handoff (MCHO) 3. Mobile Assisted Handoff (MAHO) Mobile Management

5. January 6, 20165 (Cellular Digital Packet Data)

6. January 6, 20166 Handoff Management 2. Handoff Decision Time Algorithms  Traditional handoff algorithms are based on the RSS. Some of them are as follows: 1. RSS 2. RSS plus Threshold 3. RSS plus Hysteresis 4. RSS, Hysteresis and Threshold 5. Algorithms plus Dwell Timer Mobile Management

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9. 9 Handoff Management 2. Handoff Decision Time Algorithms  The performance of handoff algorithms measures have been considered such as call blocking probability, handoff blocking probability, delay between handoff request and execution, and call dropping probability  Handoff rate is related to the ping-pong effect and algorithms are designed to minimize the number of unnecessary handoffs Mobile Management

10. January 6, 201610 Generic Handoff Management Process 1. Handoff decision is made and initiated 2. MT register with new visiting database via handoff messages 3. New visiting database communicates with the home database to get the subscriber profile and for authentication 4. Home database responds to the new visiting database with authentication of the MT 5. Home database sends messages to the old visiting database to cancel registration 6. The old visiting database flushes or redirects to the new visiting database and removes the MT from its list Mobile Management

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12. January 6, 201612 Handoff Management  Types of Handoffs: 1. Intracell, two channels 2. Intercell intradomain handoff, between two BSs associated with the same database 3. Intercell interdomain handoff, between two BSs with different database Mobile Management