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Lecture 5 Intersystem Operation. Basic AMPS. Gives air interface between tower and mobile phone Does not provide capability to deliver roaming between different service providers Why? Business arrangement between providers Validate the user. Initial solutions. Clearing house database - PowerPoint PPT Presentation
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Lecture 5 Intersystem Operation
Basic AMPS
• Gives air interface between tower and mobile phone
• Does not provide capability to deliver roaming between different service providers– Why?
• Business arrangement between providers
• Validate the user
Initial solutions
• Clearing house database
• Special number (two numbers) system
• Call forwarding by forcing the user to punch special numbers whenever the user moves to new locations
IS-41
• Telecommunications Industry Association (TIA) produced a Interim Standard 41.
• IS-41 is open air communications interface between a pair of service (AMPS) providers
• IS-41 is a seven layer protocol conforming to the OSI model– Layer 7 and layers 1 thro’ 4 are used
IS-41 reference model
MSC
PSTN
VLRVLR
ACHLR
ISDN
EIR
BS
MSC
CSS
AC – Authentication centerBS – Base StationCSS - User
EIR – Equipment identity registerHLR – Home location registerISDN – integ. services digital net
MSC – mobile switching centerPSTN – public switched tele. NetVLR – visitor location register
Elements of the model
• Two databases (VLR and HLR)
• Though we have functionally different elements, they may be in the same location
• Connection between two systems (or MSC) is established by two separate lines called– Voice trunks (transport of user info)– Data link (signaling)
PriorMSC
PriorVLR
HLR VLR MSC Base
Registration of a user while visiting a new Base
Reg. info
storeReg. notification
storeReg. notification
Reg. Notification ack
Reg. Notification ack
Reg. cancellation
Reg. Cancellation ack
Remove user
PriorMSC
PriorVLR
HLR VLR MSC Base
Registration of a user while visiting a new Base
Reg. cancellation
Reg. Cancellation ack.
Authenticate user
Authentication info
Remove user
User profile?
User profile info
Store profile
HomeMSC
HLR VLR MSC Base
Call Setup to a roaming subscriber
User
Receive Call
AMPS call setup protocol
Location requestRoute request
Route request
Route info
Route info
Location info
Call setup request (use temp. phone #)Page command
PAGEDetect MIN
