Chapter 4 North American Intersystem Operations 2018/9/22 Peter Yeh
Architecture TIA IS-41 (Telecommunications Industry Association Interim Standard 41)- an open communications interface between a pair of AMPS systems IS-41.1-B: Functional Overview IS-41.2-B: Intersystem Handoff IS-41.3-B: Automatic Roaming IS-41.4-B: Operations, Administration and Maintenance IS-41.5-B: Data Communications 2018/9/22 Peter Yeh
2018/9/22 Peter Yeh
2018/9/22 Peter Yeh
2018/9/22 Peter Yeh
Automatic Roaming Mobility Management Authentication Call Management Mobility management procedures begin when a system detects the presence of a visiting terminal (refer to Figure 4.4). Authentication Authentication begins with a Qualification Request Invoke message initiated by the serving VLR (refer to Figure 4.4). Call Management Call management begins when someone dials the cellular phone number of the roaming subscriber (refer to Figure 4.5). 2018/9/22 Peter Yeh
2018/9/22 Peter Yeh
2018/9/22 Peter Yeh
Call Management The other conditions covered in Figure 4.6 are: Delivery of call waiting service to a busy subscriber Forwarding a call when the subscriber does not respond to an incoming call Transmitting an announcement to the calling party when the subscriber does not respond Unconditional call forwarding to another telephone number 2018/9/22 Peter Yeh
2018/9/22 Peter Yeh
Intersystem Handoff The status of MSCs Handoff Categories Anchor MSC Serving MSC Candidate MAC Target MAC Handoff Categories Handoff Forward Handoff Back Handoff to third 2018/9/22 Peter Yeh
2018/9/22 Peter Yeh
2018/9/22 Peter Yeh
2018/9/22 Peter Yeh
2018/9/22 Peter Yeh
Handoff Forward The serving MSC sends Facilities Directive Invoke message to the target MSC. If the target MSC accepts the handoff, it selects a channel to handle the call in the new cell and then sends Facilities Directive Result message to the serving MSC. 2018/9/22 Peter Yeh
2018/9/22 Peter Yeh
Handoff Back If the location phase results in a determination by the serving MSC that the call would best be handled in the system previously occupied by the terminal, the serving MSC initiates a handoff back procedure. 2018/9/22 Peter Yeh
2018/9/22 Peter Yeh
Handoff to Third Handoff to third is an example of a path minimization procedure, in which the system reduces the number of voice trunks carrying a call through three or more systems 2018/9/22 Peter Yeh
2018/9/22 Peter Yeh
Status of IS-41 IS-41B (since 1991) IS-41C (since 1997) IS-136 (TDMA) Is in wide-spread use in the USA and Canada. IS-41C (since 1997) For roaming calls to use the network operations defined in the TDMA and CDMA. IS-136 (TDMA) IS-95 (CDMA) 2018/9/22 Peter Yeh
Review Exercises Why is a cellular phone capable of operating with more than one telephone number? During a phone call, explain the conditions that cause a mobile switching center to perform each of the following functions: Anchor MSC, Serving MSC, Candidate MAC and Target MSC Why does IS-41 specify three different handoff procedures? 2018/9/22 Peter Yeh