Here is the list of system areas from largest to smallest. UMTS network domains interconnection visually effects on UE states and is necessary for keeping in mind before making planning in any NW element. Figure 2. A "Location Area" is a set of base stations that are grouped together to optimize signaling.
RNC handles allocation of radio channels, receives measurements from the mobile phones, and controls handovers from base station to base station, included to LA. The cells are typically adjacent between each others. For CS services, the whole network is divided into location areas.
For example, location area is used at CN initiated paging related to CS services. A CS service related temporary identity might be assigned to the UE. This temporary identity is then unique within a LA. A location area consists at minimum of one cell and at maximum of the entire VLR area. The optimal size of a location area in terms of cells is limited by the LA update load on one side and on the paging load on the other side.
This leads to a typical optimization problem. The Routing Area is the PS domain equivalent of the location area. A "routing area" is normally a subdivision of a "location area".
Routing areas are used by mobiles which are GPRS-attached. The bursty nature of packet traffic means that more paging messages are expected per mobile, and so it is worth knowing the location of the mobile more accurately than it would be with traditional circuit-switched traffic.
A change from routing area to routing area called a "Routing Area Update" is done in an almost identical way to a change from location area to location area. The routing area is used at CN initiated paging related to PS services. A PS service related temporary identity might be allocated to the UE.
This temporary identity is then unique within a RA. The cells are typically adjacent because the target is to maximize the dwelling time within one routing area which implicitly prevents a large number of routing area updates.
Routing areas are used for the packet switched part of the network to localize the subscriber. Routing area consists of at minimum one cell and at maximum of the entire location area. More than one routing area can be defined per location area. Minimum and maximum values in terms of number of cells are limited by paging results in signaling load on RNC and SGSN on the one side.
On the other side the routing area update load of the SGSN limits the number of cells, i. In the last case only a subset of the routing area update procedure will be executed to update the HLR.
There are some differences, which results from the Iu interface and from the used handover strategy in UMTS. This is valid especially for a change between cells of two BSS. The SGSN takes care of undelivered or duplicated user packets. If no suitable cell is found in the cell reselection procedure, the UE eventually enters idle mode.
When an Initial cell reselection is triggered, the UE shall use the Initial cell reselection procedure to find a suitable cell. One example where this procedure is triggered is at radio link failure, where the UE may trigger an initial cell reselection in order to request re-establishment of the RRC connection. If the UE is unable to find a suitable cell, the UE eventually enters idle mode. The URAs can be overlapping or even hierarchical.
This arrangement is done to further reduce the amount of location update signaling because now the UEs moving back and forth in the boundary area of two URAs do not have to update their URA location information if the boundary cells do belong to both URAs. One cell can belong to several URAs.
URA may overlap geographically and for that purpose up to 8 URA identities can be broadcasted in one cell. URA can be defined to overlap with one another to avoid ping-pong scenarios for UE. A single cell can belong to a maximum of 8 URA. If the network wants to initiate any downlink activity, it needs to make a paging request in all cells on the PCCH logical channel within the URA where the location of the UE is known.
The routing area identity RAI , defined by an operator, identifies one or several cells. RAI is broadcast as system information and is used by the UE to determine, when changing cell, if an RA border was crossed. If that is the case, the UE initiates the RA update procedure. Instead of this, the concept of Service Area SA has been introduced.
A cell is allowed to belong to more than one service area. Release 99 requires that for the broadcast BC domain the service area matches one cell.
For the CS and PS domain, the service area can consist of This system feature specification defines upper layer coordination for the Service Area Broadcast. Since cells are not known by the CN, service area definition is used instead. The new terminology has not changed the functionality of the service. As in 2G based documents the term "Cell Broadcast" is still widely used, the terms "Service Area Broadcast" and "Cell Broadcast" can be understood as synonyms so far.
These messages could be used for informing of, for example, PLMN news, emergencies, traffic reports, road accidents, delayed trains, weather reports, theatre programs, telephone numbers or tariffs.
CBS permits a number of unacknowledged general CBS messages to be broadcast to all receivers within a particular region. CBS messages are broadcast to defined geographical areas known as Service Area. Service Area will consist of one cell. Architecture for the Cell Broadcast Service is given in Figure 2. The distribution of broadcast information relates on the mapping between service area and cell will be controlled by the RNC.
Three areas definitions picture is shown below in hierarchical area concept figure. Paging 3GPP definition In computer operating systems there are various ways in which the operating system can store and retrieve data from secondary storage for use in main memory.
One such memory management scheme is referred to as paging. In Mobile Telecommunication, the thermion paging means indication to the user about the need for transaction. Paging procedure is always initiated by the network and is made in order to find out the actual location of the user.
This procedure is used to transmit paging information to selected UE in idle mode using the paging control channel PCCH. A normal paging message to the RNC contains information on the area in which the paging message shall be broadcast.
This is indicated with the Paging Area ID parameter. Important is that paging is processing completely independently for CS and PS services. When a mobile finds that the location area code is different from its last update, it performs another update by sending to the network,.
Routing Area Update :. The routing area is the PS domain equivalent of the location area. You also have the option to opt-out of these cookies. But opting out of some of these cookies may affect your browsing experience. Necessary Necessary. Non-necessary Non-necessary. And it normally does so, in order to avoid the subscriber from being identified, and tracked by eavesdroppers on the radio interface.
This makes it difficult to trace which mobile is which, except briefly, when the mobile is just switched on, or when the data in the mobile becomes invalid for one reason or another. At that point, the global "international mobile subscriber identity" IMSI must be sent to the network.
The number is stored in the SIM card. The IMSI is sent as rarely as possible, to avoid it being identified and tracked. A key use of the TMSI is in paging a mobile. The most important use of broadcast information is to set up. Every cellular system has a broadcast mechanism to distribute such information to a plurality of mobiles.
Size of TMSI is 4 octet with full hex digits and can't be all ones. Roaming is defined[1] as the ability for a cellular customer to automatically make and receive voice calls, send and receive data, or access other services, including home data services, when travelling outside the geographical coverage area of the home network, by means of using a visited network.
This can be done by using a communication terminal or else just by using the subscriber identity in the visited network.
Roaming is technically supported by mobility management, authentication, authorization and billing procedures. The BSC handles allocation of radio channels, receives measurements from the mobile phones, controls handovers from base station to base station.
To each location area, a unique number called a "location area code" is assigned. If the location areas are very large, there will be many mobiles operating simultaneously, resulting in very high paging traffic, as every paging request has to be broadcast to every base station in the location area. This wastes bandwidth and power on the mobile, by requiring it to listen for broadcast messages too much of the time.
If on the other hand, there are too many small location areas, the mobile must contact the network very often for changes of location, which will also drain the mobile's battery. A balance has therefore to be struck[citation needed]. A "routing area" is normally a subdivision of a "location area". Routing areas are used by mobiles which are GPRS-attached. The bursty nature of packet traffic means that more paging messages are expected per mobile,.
A change from routing area to routing area called a "Routing Area Update" is done in an almost identical way to a change from location area to location area.
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