11-08-2012, 03:13 PM
HAND-OFFS
handoff.pptx (Size: 239.77 KB / Downloads: 30)
DEFINITION
It is a process of changing the channel
associated with current connection while a call
is in progress.
HANDOFF STRATEGIES
Network-controlled handoff (NCHO):-The handoff process is handle by the network(BSs).
Mobile-assisted handoff(MAHO):-The handoff process is handle by mobile host itself(MS).
HAND OFF MANAGEMENT PROCESS
Decision to perform hand-off is taken and hand-off is initiated.
Mobile registers with the new VDB via a handoff announcement message.
VDB contacts HDB to authenticate the mobile.
HDB responds to VDB with the authentication and profile info.
HDB send a msg to the old VDB to flush the mobile entry from its DB.
Old VDB drops or redirects packets to the new visiting DB.
USER WITH DIFFERENT SPEEDS
For pedestrians carrying MSs, the handoffs do not take place very frequently .so, the cell size in the network can be kept smaller (micro cell approach).
For fast moving users ,the cell size is to be large (macro cell approach) to ensure efficient handling of handoff .