Outline
- Addressing and routing to mobile users
- Mobile IP
- Handling mobility in cellular networks
- Phone numbers used to be Area code (214) the next 4 numbers being sub regions, say plano, and the last 4 were your designated phone.
- When you moved, you would need a new number because the first 6 digits were geographically fixed
- with the advent of mobile phones these geographical ties to number aren’t reliable.
- Mobile Switching center connects a wide area network to a wired public network
- The cell towers are covering a geographical region through air interface.
- The cell towers are typically wired directly to the MSCs but in more rural areas they may connect through satellites or relays
Cellular Standards
- 2G systems
- No data only voice systems
- 2.5G
- introduced data signals
- General packet radio service, evolved from GSM
- upped data rate to ~384Kb/s
- 3G / 4G
- both upped data rate and speeds
- can achieve up to 100 Mb/s in ideal conditions
- Let routing handle:
- Routers advertise permanent address of mobile nodes in residence via usual routing table exchange
- Not scalable to the millions of phones across the country because the amount of updates of routing tables would be unmanageable
- Let end systems handle it:
- Indirect routing:
- communication from correspondent to mobile goes through home agent, then forwarded to remote
- Direct routing:
- correspondent gets foreign address of mobile. sends directly to mobile
Definitions
- Home network, permanent home of mobile, some geographic place
- Home agent: entity that will perform mobility functions when phone is remote
- Visited network: network in which mobile currently resides
- Care-of-Address:
- You get a new temporary, second phone number when you are in a new location, that is mapped to your phone
- Home Location register:
- database in the home network containing permanent cell phone, profile information, and information about current location
- Visitor Location register
- database in foreign network containing your temporary cell phone number, and information about home network