WPCL 2BJ|x ` H   x|@  @8'@8' Recommendation Q.1002 A 9NETWORK FUNCTIONS A 1.HIntroduction 2.XHNetwork functions for basic service provision 3.HNetwork functions for supporting cellular operation 4.HAdditional network functions for call handling 5.HOperation and maintenance oriented network functions Recommendation Q.1002 9NETWORK FUNCTIONS 1.HIntroduction  X HThis Recommendation defines network functions which may be necessary to support services and facilities provided by PLMNs. A summary of the network functions is given in Table 1/Q.1002. The table also indicates whether or not a function requires internetwork signalling between PLMNs (i.e., use of Mobile Application Part, Recommendation Q.1051). HAll functions require signalling on the radio path either as subscriber line signalling or as mobile management signalling. 2.HNetwork functions for basic service provision 2.1HCall handling HThis set of functions enables the establishment of communications between a mobile subscriber and another network subscriber in one of the following types of networks: PSTN, ISDN, PSPDN, CSPDN and other PLMNs. 2.1.1HCall from MS registered in VLR HThis is the normal case where the call is routed according to the dialled number. After the call, the MSC shall send the charging information to the HLR, a billing entity and/or store the charging data on tapes or discs. 2.1.2HCall from MS not registered in VLR HWhen the VLR receives a request for call setup parameters from an MSC for an MS originating call, where the MS is not registered in the VLR, the VLR shall initiate a location updating procedure toward the HLR and in response parameters are given concerning category, services and restrictions. The call is then set up as in  2.1.1. 2.1.3HCall to a mobile subscriber HThe call is routed (rerouted or forwarded) according to location data obtained from the HLR to the actual MSC. 2.1.4HCall handling functions in HLR HThe HLR should accommodate call routing functions as described in 2.1.3. HThe HLR should also support control functions for handling of supplementary services. 2.1.5HCall handling functions in VLR HThe VLR should provide subscriber parameters to the MSC as required for call handling. HThe VLR should also support control functions for handling of supplementary services. 2.1.6HCall handling functions in MSC HThe MSC should perform normal call routing and call control functions. The MSC will obtain subscriber parameters from its associated VLR. HThe MSC should also be capable of performing handover as defined in 3.2. HIn some cases the MSC should be able to act as a gateway MSC. ITABLE 1/Q.1002 P BOverview of network functionsă P Class of net Network function Interworking work function (NF) with MAP   NF needed for basic  Call handling  x  service provision:      Subscriber authentication  x        Emergency calls         Supplementary services  x   Additional NF needed  Queuing  x  for call handling      Call duration limitation         OACSU         Mobile station with priority         Mobile station with preference         Security related services  x   NF needed for  Location registration  x  supporting cellular    operation  Handover     in the same BS     in the same MSC     in the same PLMN  x    between PLMNs  x        Power control         Dynamic channel allocation  (x)   Operation &  Test loops   maintenance oriented    NF:  Operation  x        Maintenance  x        Charging  x        Traffic survey  (x)        Malicious call identification         Tracing of mobile stations     2.2HSubscriber authentication HAuthentication procedures should be implemented in order to protect the network from access by nonregistered or fraudulent MSs. The authentication method is for further study. HA possible procedure could be as follows. HThe procedure is based upon a challenge/signed response method which goes as follows: H the fixed subsystem transmits a nonpredictable number RAND (the challenge) to the MS; H the MS calculates the signature SRES (the signed response) of RAND; H the MS transmits the signature SRES to the fixed subsystem; and H the fixed subsystem tests the signature for validity. HAuthentication may take place in the following cases: Hi)  at location registration, Hii)  at call setup, Hiii) when requesting operation of a supplementary service, or Hiv)  after handover. 2.3HEmergency call 2.3.1HGeneral HThe land mobile system should be capable of efficient handling of emergency calls from mobile stations. Signalling procedures on the radio path require further study. 2.3.2HThe call should be routed automatically to an appropriate emergency centre based on the geographical location of the mobile station. For this purpose the accuracy of geographical location determination may be the cell serving the MS. 2.3.3HCard operated stations HIt may be permissible to initiate emergency calls from card operated MSs also when the card is not inserted. This point is for further study. 2.4HSupplementary services HThe support of supplementary services may require control procedures in HLRs, VLRs and MSCs in addition to the control procedures in the fixed network. 3.HNetwork functions for supporting cellular operation 3.1HLocation registration 3.1.1HDefinitions HLocation registration means that the PLMNs keep track of where mobile stations are located in the system area. The location information is stored in functional units called location registers. Functionally there are two types of location registers: H the home location register where the current location and all subscriber parameters of a mobile station are permanently stored, and H the visitor location register where all relevant parameters concerning a mobile station are stored so long as the station is within the area controlled by that visited location register.  w.ԌHSee also Recommendation Q.1001 where the network architecture is described. 3.1.2HProcedures HProcedures related to location registration are specified in Recommendation Q.1003. HThey comprise: Hi)h  location register updating which enables the MS to inform the network that its location has to be updated, i.e. the MS has received a location area identity which is different from that contained in its memory. In order to avoid unnecessary updating, the current location area identity should be stored in a non volatile memory in the MS; Hii)  location cancellation which is used to delete an MS from a previous VLR; HHX HHiii) periodic location updating which enables the location of silent and stationary MSs to be updated at a reasonable rate; and Hiv)  as a network option, IMSI detach/attach operation which will enable MSs to inform the network that they have entered a power down/power up state. HThe procedures also include mechanisms for restoration of location registers after failure. These procedures are defined in Recommendation Q.1004. 3.1.3HInformation stored in location registers HInformation to be stored in location registers is listed in Recommendation Q.1003. 3.2HHandover 3.2.1HDefinitions HThe following cases are considered:   HHi)h  handover between radio channels of the same base station;   HX Note: This capability could be used in the following situations:   HHX © when the radio channel carrying the call is subject to interference or other disturbances; and/or  `   8 HHX © when a radio channel or channel equipment carrying a call has to be taken out of service for maintenance or other reasons.  `    HHii)  handover between base stations of the same MSC in order to ensure continuity of the connection when an MS moves from one BS area to another;  `    HHX Hiii) handover between base stations of different MSCs of the same PLMN; and  `    HHiv)  handover between base stations of MSCs in difference PLMNs.  `  HFor cases iii) and iv) two procedures are defined:   HHa)h  basic handover procedure where the call is handed over from the controlling MSC (MSCA) to another MSC (MSCB); and  `   H HHb)h  subsequent handover procedure where the call is handed over from MSCB to MSCA or to a third MSC (MSCB').  `  3.2.2HProcedures HThe procedures are described in Recommendation Q.1005. 3.3HPower control HFor further study. 3.4HDynamic channel allocation HFor further study. 4.HAdditional network functions for call handling facilities 4.1HQueuing 4.1.1HGeneral  X HQueuing of calls from fixed and mobile subscribers may be offered as an optional facility. Calls should only be queued when there is congestion on the radio path when the call arrives. The queuing facility is accommodated in the MSC. 4.1.2HQueuing of MS originating calls HWhen an MS originated call is placed in a queue, a queuing indicator should be provided to the MS as display information. The maximum time that the call will be kept in the queue should also be indicated. This would enable timers to be set in the MS in accordance with the queuing arrangements of each PLMN. HThe MS should be marked as busy when the call is placed in the queue. HThe call is cancelled when: HH© the MSC receives a clearing message from the MS;  `  HH© there is timeout on the queuing time; or  8 HH© the VLR receives a location cancellation message from the HLR. Note It is for further study whether or not this is practicable.  `  4.1.3HQueuing of MS terminating calls  X HQueuing facilities for MS terminating calls may also be provided in the MSC. If so, general PSTN/ISDN specifications on abnormal release conditions and post dialling delays should be taken into account. Further study is required on interworking with the fixed network. HThe MS should be marked as busy when the call is placed in the queue. HMS terminating calls should be released if a location cancellation message is received while the call is being queued. Note It is for further study whether or not this is practicable. 4.1.4HQueuing conditions HNot more than one call should be queued for each MS.  w.ԌHCalls should be queued and serviced in the order they arrive at the MSC, except for calls subject to some priority condition, e.g. calls which are handed over should have priority over normal calls and emergency calls should have priority over any other call. HCalls arriving when all positions in the queue are occupied, should be rejected with a congestion indication provided to the calling party. HCalls which have been queued for a time longer than the maximum queuing time should be released from the queue. MS terminating calls should be cleared with a congestion indication provided to the calling party. 4.2HCall duration limitation 4.2.1HGeneral HThis is an optional facility. HPLMNs may support functions whereby the call duration is limited in order to increase the call handling capacity of the PLMN. Call duration limitation may apply independently to each cell depending on the current traffic load of the cell. If possible, an indication should be provided to the subscribers that a call is subject to call duration limitation. Procedures are for further study. 4.3HOffaircallsetup (OACSU) 4.3.1HGeneral HOACSU may be implemented in PLMNs in order to increase the call handling capacity of the PLMN. HOACSU may be implemented in PLMNs on an optional basis subject to the following conditions:   HHi)h  OACSU should not be used for calls to an international number;  `    HHii)  OACSU should not be used for incoming international calls;  `   HHX Hiii) foreign MSs not supporting the OACSU procedure should be allowed to access the PLMNs where OACSU is used;  `   ( HHiv)  MSs supporting OACSU should be capable of operating in PLMNs where OACSU is not implemented;  `   8 HHv)h  OACSU must not be used for calls involving an ISDN or a PDN or for nonvoice services in the PSTN.  `  4.3.2HSignalling procedures   HInterworking requirements for supporting OACSU are described in Recommendation Q.1031 4.4HMobile stations with priority HThis is an optional facility. HIt may be possible to offer priority for certain subscribers for: H incoming calls; H outgoing calls; or H all calls.   HPriority could comprise priority in queuing systems, preemption of outgoing calls in order to service a call with priority, etc. HProcedures for handling MSs with priority are for further study. 4.5HMobile stations with preference HThis is an optional facility.  X HPreference means that in certain circumstances only MSs with preference are allowed to access the network. The condition may be controlled by the BS by inserting a preference indication in the messages sent on the common signalling channel on the radio interface. HProcedures for handling of MSs with preference is for further study. HIt should be possible to set the preference condition individually in each cell. 4.6HSecurity related supplementary services HPLMNs may offer encryption of information sent on the radio path. Procedures for encryption and key distribution are for further study. 4.7HDiscontinuous reception HDiscontinuous reception is a technique used to reduce the average battery consumption of mobile stations. The operation of this function is for further study. 4.8HDiscontinuous transmission HDiscontinuous transmission is a technique used to reduce the battery consumption of mobile stations. The operation of this function is for further study. 5.HOperation and maintenance oriented network functions 5.1HTest facilities HThe public land mobile systems may contain test facilities which can perform tests similar to those defined for the ISDN subscriber line. HFurther study is required. 5.2HOperation 5.2.1HGeneral HIn PLMNs tasks related to system operation are divided among several functional units: H home location registers, H visitor location registers, H MSCs, H BSs, H national operation and maintenance centres,  w.ԌH encryption key distribution centres, and H centres for management of equipment identities. HIt should be noted that several of these functional units may be co located or even be accommodated in the same physical equipment. HIn addition, other aspects concerning system operation will be the responsibility of subscribers, MS manufacturers, sales agents, etc. HTasks allocated to each of the functional units are described below. 5.2.2HResponsibilities of HLRs HThe main responsibilities of the HLRs are:  ( HHi)h  subscriber administration, i.e. management of all subscriber parameters of MSs registered in the HLR. Subscriber administration also includes the possibility of making changes to subscription conditions and subscriber parameters. It may also include additional administrative functions related to CUGs and MSs with preference;  `   8 HHii)  charging administration, e.g. relaying of charging information from a foreign PLMN to the charging point in the home PLMN; and  `  HHX Hiii) updating of VLRs. 5.2.3HResponsibilities of VLRs HThe main responsibilities of the VLRs are: Hi)  management of mobile station roaming numbers; Hii)  management of temporary mobile station identities, if implemented; Hiii) subscriber administration of visiting MSs; Hiv)  updating of HLRs;   Hv)  management of MSC areas, location areas and BS areas; and   HHvi)  radio channel management (e.g. channel allocation tables, dynamic channel allocation management, channel blocking status).  `    Note Some or all of the functions in vi) may be in the MSC or the BS. This is for further study. 5.2.4HResponsibilities of MSCs HThe main responsibilities of the MSCs are: Hi)  routing administration; Hii)  charging and tariff administration; Hiii) traffic administration, e.g. traffic monitoring; and   HHiv)  sending of relevant traffic and charging information to the HLR (see  5.4).  `  5.2.5HResponsibilities of national 0 & M centres  8 HThe operational responsibilities of national O & M centres could be remote control and monitoring of the operation of functional units, e.g. remote management of subscriber parameters. 5.2.6HResponsibilities of BSs HFor further study. 5.2.7HResponsibilities of encryption key distribution centres HFor further study. 5.2.8HResponsibilities of centres for management of equipment identities HFor further study. 5.3HMaintenance 5.3.1HGeneral HMaintenance of PLMNs may require activities in several functional units. Some maintenance activities are autonomous, i.e. within one functional unit, and others require cooperation between several functional units. Functional units which may be involved in cooperative maintenance activities are: H mobile stations, H base stations, H MSCs, H visitor location registers, H home location registers, and H national operation and maintenance centres. HIn some cases maintenance activities may require international cooperation. In such cases the maintenance responsibilities, the information exchanges and the activities required for restoration of service should be in accordance with rules set down for the PSTN/ISDN (MSeries of Recommendations). 5.3.2HMaintenance responsibilities of MSs   HTo some degree the MS should be capable of detecting faulty operation. When faults are detected, the MS should initiate internal testing and prevent accidental transmission. 5.3.3HMaintenance responsibilities of the BSs HThe BS should monitor the radio path. If faulty operation is detected, information should be sent to the MSC and/or to a national operation and maintenance centre. HThe BS may also have facilities for blocking and unblocking of radio channels and BSMSC circuits. 5.3.4HMaintenance responsibilities of MSCs HThe MSC should include maintenance facilities and support maintenance w. functions as for exchanges of the PSTN/ISDN. These functions include: Hi)h  maintenance of the MSCBS circuits and signalling links, including: H  test, observation and measurement of MSCBS (MSCMS) protocols; and H  blocking and unblocking of MSCBS circuits and radio channels. Hii)  maintenance of circuits to exchanges of the PSTN/ISDN, Hiii) maintenance of signalling links to a signalling network, Hiv)  fault reporting to operation and maintenance centres, and Hv)  maintenance of their own equipment. 5.3.5HMaintenance responsibilities of location registers HThe location registers will be responsible for: Hi)  maintenance of signalling links; and  8 HHii)  restoration after restarts including information exchange with other location registers.  `    5.3.6HMaintenance responsibilities of operation and maintenance centres HFor further study. 5.4HCharging HThe MSC and the BS must be capable of obtaining all information required for determining call charges for MS originating calls. HFor charging of MS originating calls information as follows may be required: H address of called party, H IMSI, H time of the call, H charging rate for the called destination,   HH© call duration and possibly also parameters such as traffic volume and radio channel resources used,  `    HH© additional charges, e.g. for use of supplementary services,  `    HH© charging conditions, e.g. normal charging, debit card, credit card, and  `  HH© location of MS (e.g. cell, location area, MSC area).  ( HFor calls within the same PLMN the information is directed to the relevant billing entity. How this is achieved is a national concern, however, examples could be: Hi)  by use of the Mobile Application Part; Hii)  by use of a public data network; Hiii) by use of dedicated links;  ( HHiv)  by use of physical transfer of magnetic tapes containing the billing information; or  `  Hv)  a combination of the above. HCase i) above is specified in Recommendation Q.1051.  ( HThe need for Recommendations covering the other alternatives is a matter for further study. They may be required to permit different manufacturers equipment to interwork. HIt should be noted that the use of the Mobile Application Part will only allow charging data on a per call basis to be transferred, though not necessarily immediately after the call has been terminated. For instance if the Mobile Application Part signalling or network processing load is such that the transfer of billing information would compromise normal call set up procedures, then the transfer of billing information should be delayed until the signalling load decreases (e.g. overnight transmission of stored billing data). HIn the longer term it is not clear, even if overnight transfer of billing information is used, whether the Mobile Application Part will have sufficient capacity, therefore a move to another technique will be necessary. HFor calls involving a roaming mobile in a visited PLMN, the same techniques as above can be applied by bilateral agreement. For instance the situation could be imagined where a roaming service is opened between two networks, but the level of roaming traffic does not justify either the use of   a public data network, or physical transfer of magnetic tapes, therefore the Mobile Application Part is used initially. HThe destination for international billing information should be the relevant billing entity of the home network, however, when using the Mobile Application Part, addressing difficulties may mean that only the HLR can be addressed. HThe MSC may support facilities for debit card calls. The signalling procedure on the radio path should support this type of operation. HThe MSC may also support facilities for credit card calls. This involves facilities and procedures for authentication of the credit card number and transfer of the required information to the billing authority. The procedures will not be specified for the Mobile Application Part. On a national basis Signalling System No. 7, public data networks or other networks convenient for the administration may be used for these purposes. HFor MS terminating calls where part of or the whole charge is to be paid by the MS, the information to be stored would be similar to that of MS originating calls. Further study is required. 5.5HTraffic survey HFor further study. 5.6HMalicious call identification HIf required and regulatory and technical constraints permit, the MSC may support the malicious call identification (MCI) facility for MS originating w. and MS terminating calls. The exact implementation of this facility will depend upon national variations of the signalling system being used. 5.7HTracing of mobile stations HFor further study.