Mumbai university > Comp > SEM 8 > Mobile Communication

Marks: 10M

Year: Revised 2012

• Mobility Management Service manages network roaming and tracks the location of each CDPDsubscriber, as well as keep the serving MD-IS informed of that location down to the specificcell site.

• In a traditional data network, the endpoints of the data connections remain in the samephysical location, and routing of data between these system-endpoints is not a problem. However,in a wireless mobile data network, the endpoints of the data connections can be located anywherein the network coverage area, and the location of these endpoints can change over time thus mobility management is important.

• Like voice cellular networks, CDPD supports roaming. CDPD devices have a home sub-domain usually the home city of the subscriber. One may travel from a sub-domain registered as one’s home area to a new serving area. The CDPDnetwork’s Mobility Management Service handles the routing of packets for all visiting M-ESs in its serving area. If one has pre-arranged the service provider, he can obtain service inanother area served by that carrier, or even in an area supported by another service provider soCDPD modem can roam outside its home sub-domain anywhere that CDPD service isavailable.

• The home area is that in which the CDPD subscriber has registered their device with a CDPD service provider. If the subscriber travels to another area, the mobility management servicesmaintain information about their current serving area. If data is destined for that subscriber intheir new location, the mobility management services at the home area forward the data to thesubscriber in their new location.

• Mobility management services in the new serving area regularly notify the subscriber’s home-areaCDPD network of the subscriber’s new location. Therefore, a CDPD subscriber can travelthroughout the country and still obtain CDPD network services. The subscriber in the CDPDnetwork appears to have a seamless data connection as they change their location within thenetwork coverage area. The mobility management services that provide this seamless coverageare transparent to the CDPD subscriber. See section 5.2.1 for more detail on mobilitymanagement.

• CDPD mobility management is based on principles similar to mobile-IP. The MD-IS is the central element in the process.

• An MD-IS is logically separated into a home MD-IS and serving MD-IS. A home MD-IS contains a subscription database for its geographic area. Each subscriber is registered in his home. MD-IS associated with his home area. The IP address of a subscriber points to his home MD-IS. At the home MD-IS, MHF maintains information about the current location of MHS associated with that home MD-IS.

• The MHS also encapsulates any packet that is addressed to an M-ES homes with it directing it to an MSF associated with the serving MD-IS, whose serving area the M-ES is currently visiting. A serving MD-IS manages one serving MD-IS, whose MSF contains information about all subscribers currently visiting the area and registered with it.

• The MSF employs the mobile network location protocol (MNLP) to notify the MHF about the presence of the M-ES in its service area. The channel stream in which a subscriber is active is also indicated. The MSF decapsulates forwarded packets and routes them to the correct channel stream in the cell.