# Intelligent MAP-D Multiplexer System

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Descriptions

When network operators extend their GSM networks to remote spots with satellite back haul, the data bandwidth between the local network and the public network is narrow and costly. The data link between the remote network and the public network becomes precious. Hence, the cost of local calls that don’t need to go through the expensive back haul is much cheaper than the public network calls. If the network operators can control the public network access privilege of the users then they may reduce the constraint of the traffic on the back haul bottleneck for a better utilization of their networks’ capacity.

Intelligent MAP-D Multiplexer enables GSM network operators to categorize their subscribers into three different groups with different network accessibility: “Public Users”, “Private Users” and “Hybrid Users”.

| Public User

User with subscription profile presents in HLR but do not have IMDX account in OPPS. Public user’s subscription profile may be present in public network’s HLR or local network’s HLR. Public user registers to the local network as a local GSM subscriber (with subscription profile in local HLR) or a roaming GSM subscriber (with subscription profile in public HLR). Public user can only call public users.

| Private User

User with subscription profile present in local network’s HLR and is being classified as “private user” in IMDX. Private users have two classes of privilege: ordinary and premium. Ordinary privilege can make calls among private users, but it is not allowed to make calls to public users (local or roaming GSM subscribers); Premium privilege is allowed to make calls to both private and public users. Please note that the private users are not accessible by public users.

There is an exception to this rule. If a private called party set call forward to a public user, then the private calling party can reach the forwarded public user.

| Hybrid User

User with two subscription profiles: one in the public network’s HLR and another in the local network’s HLR. Hybrid user has dual identities: public user and private user; and two MSISDNs: public phone number and private phone number. Hybrid user owns both the privileges of the public user and private user. He can access to and be accessible from both the public network and the local network. Hybrid user acts as a public user when being called by his public MSISDN or is calling a public MSISDN. He will act as a private user if he is being called by his local private MSISDN or calling the other private MSISDN.

| Registration

When a user tries to location update (register) to the local network, the VLR will check the user type of the user through the OPPS and then choose the proper registration process according to his user type.

Public users’ registration process is same as the standard GSM registration. If the public user is a local subscriber then the VLR collects his subscription profile from the local HLR. If the public user is a roaming subscriber then the VLR will collect his subscription profile from the HLR of his Home PLMN. VLR will store the profiles collected from the HLR in its database.

When private users try to register to the local network, VLR will replace the IMSI prefix (MCC+MNC) of the private user with the IMDX Pseudo Prefix to route the location update request to the local HLR. VLR then collect the subscription profile of the private user from the local HLR and save the profile in the VLR to complete the registration. Private user will get a private phone number (MSISDN), which is set by the network operator in the subscription profile in the local HLR.

Hybrid user has two subscription profiles, one in the public HLR and one in the local HLR. When a hybrid user registers to local network, VLR will perform twice Location Updates: one to the public HLR as a public user and the other to local HLR as a private user. The registration process is same as the public user and the private user respectively. VLR keeps the two subscription profiles for each hybrid user.

| Call Control

IMDX control the call traffic among the Private, Hybrid and Public users.

Private ordinary users can only call the private numbers defined in the Private Dialing Prefix table. The private number can be configured as short number format. Hence private ordinary users can only make calls among private users. They’re not allowed to make calls to public network and public users. Private numbers are not accessible by the public network; hence public users can’t call private users.

Private premium users have the premium privilege to make outgoing calls to both private and public users. Since private premium users are allowed to call public numbers, the operator may need to control the public call time of a private premium user. In this case the operator may set the private premium user as prepaid user. Then the private premium user’s public call time will be restricted by the tariff of the public calls and his budget.

Hybrid users have dual identities. They have the privileges of the private users and the public users. Hybrid users are allowed to call both the private users and the public users and they’re also reachable by the private users and the public users. When a hybrid user is being called or calling a private user then he is treated as a private user. If he is being called or calling a public user then he will be treated as a public user.

| Exclusive Access

The fundamental criterion of deploying the IMDX service is that the local network is not overlapping with the public network; a spot without overlapping radio coverage. Whenever a spot is covered by the public network then the roaming users and the hybrid users must register to their home network (public network). Hence IMDX must prohibit the roaming users and hybrid users from registering to the local network once the service spot is entering the public network regions, such as a cruise ship docking to a terminal. This requires the local network to prevent all the roaming users and public identity of hybrid users from roaming to the local network. The local network has to reject any location updates or MO attempts from roaming and hybrid users.

Sometimes due to the license issues, cruise ships operators are restricted to provide GSM service in marine areas. They must shut down their GSM services completely after the cruise ship has entered a port in order to prevent infringing the privileges of the terrestrial operators.

IMDX provides an “Exclusive Access” operation command line for the operator to alter the IMDX system status, which can be divided into four levels:

•Normal | Full IMDX functions.
•Exclusive Half | Prohibit the public (roaming) users from registration.
•Exclusive Full | Prohibit both public (roaming) and hybrid users from registration.
•Shutdown | Shutdown IMDX. Forbid all users from registration.

In the exclusive access mode, the network sends a "Location Area Updating Reject" message to user’s mobile to indicate the cause of rejection. The cause of rejection is configurable in the system. The operator may choose one of the following rejection cause value per his network requirement:

•PLMN not allowed | The PLMN is added to a "Forbidden PLMN List" stored in the SIM card to prevent mobile from any further attempt to register in the PLMN.
•LA not allowed | The mobile does not attempt registering in the PLMN, unless the user changes location area.
•Roaming not allowed in this LA | The selected location area does not accept visitors from another PLMN.

See Also

• Manage OPPS Subscriber

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