30-05-2013, 03:32 PM
MOBILITY MANAGEMENT
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Mobility management is the essential technology that supports roaming users with mobile terminals to enjoy their services in progress through wireless networks.
Mobility management enables communication networks to:
- Locate roaming terminals in order to deliver data packets.
- Maintain connections with terminals moving into new areas.
Mobility management consist of:-
Location management
- locate a mobile node, track its movement, and update the location information
Handoff management
- controls the change of a mobile node’s access point during active data transmission.
REQUIREMENTS TO SELECT A MOBILITY MANAGEMENT SCHEME
Fast handoff:
The handoff operations should be quick enough in order to ensure that the mobile node can receive IP packets at its new location within a reasonable time interval.
Seamless handoff:
The handoff algorithm should minimize the packet loss rate into zero. It is referred to as smooth handoff.
Signalling traffic overhead:
The control data load should be lowered to within an acceptable range.
Hierarchical mobility management model
Hierarchical mobility management scheme localizes the management of mobility by introducing the concept of domain.
A domain can be defined as a collection of networks sharing a common network administration, which may include one or more foreign networks.
It helps to achieve the requirements on performance and flexibility especially for frequently moving hosts.
Two kinds of mobility:-
-Micro mobility, i.e. mobile node’s movements inside a domain.
-Macro mobility, i.e. mobile node’s movements between different domains.
working process:-
a. The mobility agents (HA and any FA) continuously send agent advertisement messages to the local link, to announce their existences.
b. The MN receives the advertisement messages, according to which it can determine whether its current attachment point is in the home network or any foreign network.
c. If the MN finds itself still in its home network , then it will not start the mobility management functions and the process is terminated.