Wireless Communications and Networking - Vijay Garg - Capitulo 12.pptx

Wireless Communications and Networking - Vijay Garg

1. Wireless Communications and Networking - Vijay Garg Chapter 12 : Mobility Management in Wireless Networks

2. Wireless PLMN

3. Cell global identification .

4. Mobility Model

5. Example 12.1

6. Solution

7. Transactions at Peak Hour The results show that, under heavy traffic conditions, the impact of LUs can be significant . In terms of radio channels used, we find that between 0.25 to 1.25 GSM RF carriers can be used for LA boundary crossings. Although this load cannot directly cause call blocking on the radio interface (in a GSM1800 network with 4 3 reuse cluster, the average number of RF carriers per cell with 3 operators is about 10), it is nevertheless not a negligible impact on traffi c channel (TCH ), consumption . In terms of processing at the MSC/VLR side, with a processing load of about 16.85 106 transactions per hour, it is obvious that blocking can rapidly occur with the given scenario. The MSC/VLR resources dedicated to LU processing cannot be used to provide other services. A major concern of operators , where objectives are to provide users with rich and sophisticated services, is to have more processing resources at the MSC/VLR.

8. 12.4 Mobile Registration Registration may be initiated by the MS or the network, or may be implied during MS access. Upon receiving the registration request from the MS, the radio system (base station) constructs the Registration Update Request message and sends it to the network (MSC). The Registration Update Request message contains the MS’s identification and location information and may contain authorization parameters. The network (MSC) may respond with a request for authorization (optional) and finally with a Registration Update Response message. The network (MSC) sends a Registration Update Response message to the BS when a registration procedure has been successfully completed. This message indicates whether the MS’s registration has been accepted or rejected. The message may contain additional parameters to be sent to the MS. Upon receipt of this message, the BS sends an appropriate response to the MS. The three possible results in registration requests are: successful registration, unsuccessful registration, and cancellation of registration . A mobile station registering on an access channel may perform any one of the following registration types :

9. Distance-based registration: when the distance between the current cell and the cell where the mobile last registered exceeds a threshold. Geographic-based registration: whenever a mobile enters a new area of the same system. A service area may be segmented into smaller regions, known as location areas, which are groups of one or more cells. The MS identifies the current location area via parameters transmitted by the MS on the forward control channel. Location-based registration reduces the paging load of the system by allowing the network to page only in the location area(s) where a mobile station is registered. Parameter change registration: when specific operating parameters in the mobile are changed . Periodic registration: when the system sets parameters on the forward control channel to indicate that all or some of the mobile stations must register. The registration can be directed to a specific mobile or a class of mobile stations . Power-down registration: when the mobile is switched off. This allows the network to deregister a mobile immediately upon its power-down. Power-up registration: when power is applied to the mobile, and used to notify the network that the mobile is now active and ready to place or receive calls . Timer-based registration: when a timer expires in the mobile. This procedure allows the database in the network to be cleared if a registered MS does not register after a fixed time interval. The time interval can be varied by setting parameters on the control channel.

10. It should be noted that all registration types are not supported in a network. The following are the call flows for the registration (ANSI-41 standard) of all MSs listening to a control channel (see Figure 12.3): 1. The MS determines that it must register with the system. 2. The MS listens on the control channel for the global challenge, random n umber (RAND). 3. The MS sends a message to the BS with IMSI, RAND, and other parameters, as needed, in the MS Registration Request. 4. The BS validates RAND. 5. The BS sends a REGISTER message to the new MSC/VLR. 6. If the MS is not currently registered to the serving VLR, the VLR sends a REGistration NOTification (REGNOT) message to the user’s HLR containing the IMSI and other data as needed.

11. 7. The MS’s HLR receives the REGNOT message and updates its database accordingly (stores the location of the VLR that sent the REGNOT message ). 8. The MS’s HLR sends an IS-41 REGistration CANCel (REGCANC) message to the old VLR where the MS was previously registered so that the old VLR can cancel the MS’s previous registration. 9. The old VLR returns a Confi rmation message that includes the current value of the call count (CHCNT). 10. The user’s HLR then returns a REGNOT Response message to the new VLR and passes along information that the VLR needs (e.g., user’s profile, interexchange carrier ID, shared secret key for authentication, and current value of CHCNT). If the registration is a failure (due to invalid IMSI, service not permitted, nonpayment of bill, or other reason), then the REGNOT message will include a failure indication. 11. Upon receiving the successful REGNOT message from the user’s HLR, the VLR assigns a TMSI. The MSC receives the message, retrieves the data and sends a REGISTER message to the BS. 12. The BS receives the REGISTER message and forwards it to the MS to Confirm Registration . Note: For details of various messages refer to the ANSI-41 standard

12. References 1. Akyildiz , I. F., et al. Mobility Management in Current and Future Communication Networks. IEEE Networks , July/August, 1998. 2. Bhagwat, P., Perkins, C., and Tripathi , S. Network Layer Mobility: An Architecture and Survey . IEEE Personal Communications, vol. 3, no. 3, June 1996, pp. 54–64 . 3. Brown, T. X., and Mohan, S. Mobility Management for Personal Communications Systems. IEEE Transactions Vehicular Technology , vol. 46, no. 2, May 1997, pp. 269–278. 4. 3GPP, http://www.3gpp.org. 5. 3GPP2, http://www.3gpp2.org. 6. GSM Specifi cation Series 8.01–8.60, “BSS-MSC Interface, BSC-BTS Interface.” 7. GSM Specifi cation Series 9.01–9.11, “Network Interworking, MAP.” 8. Kaaranen , H., et al. UMTS Networks: Architecture, Mobility and Services. John Wiley & Sons , 2001. 9. Lam, D., Cox, D. C., and Widom , J. Teletraffi c Modeling for Personal Communications Services . IEEE Communications Magazine , February 1997, pp. 79–87. 10. Lin, Y-B., and Chlamtac , I. Wireless and Mobile Network Architecture. John Wiley & Sons , 2001. 11. Markoulidakis , G., et al. Mobility Modeling in Third-Generation Mobile Telecommunications Systems . IEEE Personal Communications , vol. 4, August 1997, pp. 41–56. 12. McNair , J., Akyildiz , I. F., and Bender , M. An Intersystem Handoff Technique for IMT- 2000 System. Tel Aviv , Israel: Infocom00. March 2000. 13. Mouly , M., and Pautet , M. The GSM System for Mobile Communications . Palaiseau , France , 1992.