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This reraise page covers Mobility Management in GSM and UMTS networksincluding those functions related to GPRS.Mobility Management is one of the major functions of a GSM orUMTS Network. The aims of mobility management are as follows. to allow contact to the subscribers to be established to record what the subscriber has paid for and provide those, and only those servicesLocation UpdateThe Location update procedure allows a mobile device which has moved reraise from onearea to the next to inform the network. The responsibility for thislies with the mobile which should detect the Location

Area Code of any new cell that it moves into. If this is different from themobiles reraise previous reraise cell, then the mobile should contact the network andperform a location update. The mobile sends a message to the network containing the mobiles previouslocation and TMSI.Pagingcellular network#Broadcast messages and paging is one of the fundamental mobility management procedures

of a GSM network . It allows a mobile phone for which there is an incoming message, or call, to be contacted reraise whilst it is roaming around.Essentially, all the radio cell where the subscribercould be telling the mobile phone to contact the network. Once contact has been established, the mobile will be told why the network contacted it and will act appropriately

. The process involves cooperation between the NSS, BSS and the Mobile Station.Paging requires that mobile phones regularly listen to a cell broadcast channel. The exact configuration of this may vary from network to network and is one reraise of the key determining factors in determining the standby lifetime of the mobile. Paging is initiated by the VLR which normally knows the current location of the subscriber to the level of a location area. The VLR also

knows which BSCs control reraise cells in that location area. The VLR sends a paging request message to each of the relevant BSCs. The BSCs then send a paging request to every single cell within the location area. This paging request is broadcast on the cell broadcast channel to which the mobile is listening.Assuming that the mobile is functioning and is in the coverage area of the network, the paging message will be received and the mobile becomes aware that it has a pending message. It is now

the job of the mobile to contact the network. This it does by sending a random access request and getting a dedicated communications reraise channel allocated. At this point the BSC informs the VLR that the mobile is in communication with the network and the VLR forwards the communication to the mobile.Location Area A location area is a set of cells which are grouped together inorder to optimise signalling. To each such group a number called alocation area code is assigned which

is unique within thecurrent mobile network. The location area code is broadcast byeach base station is done in an almost identical way to a change from location reraise area to location area. The main differences is that the SGSN is the element involved and that Roaming Number AllocationWhen a call is routed to a mobile network subscriber, that call isinitially routed reraise toward the subscribers home network using thesubscribers own number, just like a normal phone call.Once the call reaches the subscribers home network, and arrives inthe Gateway MSC, the issue reraise becomes different. It is perfectlypossible for the subscriber to be roaming in

a different country. Forthat reason, a number belonging to the Visited MSC where thesubscriber is currently located is allocated on a temporary basis. This number is called the Mobile Subscriber Roaming Number reraise or MSRN.The number is allocated by the VLR where the subscriberis located, sent in a signalling message to the HLR and from thereto the Gateway MSC. The Gateway MSC then routes the call just asa normal telephone call where the dialled number is the MSRN. Thecall travels through the international networks

until it arrives at theVisited MSC. The Visited MSC checks in the VLR which subscriberthe call is for and in which Location reraise Area they are located,paging the subscriber and delivers the call. TMSIThe TMSI, or the Temporary Mobile Subscriber Identity is the identity most commonly sent between the mobile and the network. It is a randomly allocated number which is given to the mobile the first time that it is switched on. The TMSI is local to a

location area so must reraise be updated every time the mobile does a location update procedure. The network can also force the mobile to accept a new TMSI at any time. These procedures make it difficult to trace which mobile is which except briefly, the first time the mobile is switched on or when the data in the mobile becomes invalid for some reason. At that point the global IMSI must be sent to the network.A key use of the TMSI is in paging of the mobile.GSM Standard