Voice Group Call Service (VGCS) :
L Voice Broadcast Service (VBS)
L enhance much priority and forced demolition (enhanced Multi - Level Precedence and Preemption service, eMLPP) eMLPP
L Functional Addressing
L Location Dependent Addressing
Voice Group Call Service (VGCS) : One of the contents of advanced Voice Call Service.Voice group call service defines a mode of point-to-multipoint voice communication with multiple participants (mobile users and fixed users) in a certain area, some of whom can speak and many of whom can listen.Gsm-r network realizes VGCS via conference bridge.VGCS is identified by the group call area and group identity (group ID).The group call area is composed of one or more cells, which specifies the geographical scope of a group call action and is represented by the group call area.A group call area can be under one MSC area or across multiple MSC areas.A group call area can contain more than one group.A group ID is the number used to identify a group.The combined group call area ID and group ID Numbers are called group call references and can uniquely identify a VGCS.
Members who participate in group calls define two identities: the scheduling user and the business user.The dispatch user may be either a fixed user or a mobile user in the GSM-R network, using the corresponding ISDN number and mobile station ISDN (MSISDN).Scheduling users have a pair of dedicated channels in the group call, which can listen or speak.Each group call can define up to five scheduling users, each scheduling user can join more than one group.A business user is a mobile user that specifies a VGCS.Business users in each cell in the group call area share a group call downlink channel listening group call and fight for a group call uplink channel to get the right to speak.Each business user can join up to 50 groups.Both business users and scheduling users can initiate group calls, and their initiation and termination rights are defined by the network.VGCS allows only one business user to be the speaker at a time, while scheduling users can speak at any time.After releasing the uplink channel, the speaker becomes the listener, and other business users requesting to speak apply for the right to use the uplink channel on a first-come-first-served basis.If no one is speaking at the time specified by the network, the group call will automatically end.
Voice Broadcast Service (VBS) : One of the contents of advanced Voice calling Service.Voice broadcasting service defines a way of point-to-multipoint one-way voice communication within a certain area with multiple participants (mobile users and fixed users), one user speaking, and other users listening.Gsm-r network realizes VBS via conference bridge.VBS is identified by group call area and group ID.A group call area, or consisting of one or more cells, specifies the geographic scope of a group call effect and is identified by the group call area ID.A group call area can be under one MSC area or across multiple MSC areas.A group call area can contain more than one group.A group ID is the number used to identify a group.The group call area ID and the group ID together constitute a number called a group call reference that uniquely identifies a VBS.
Members participating in broadcast calls define two identities: scheduling user and business user.The dispatch user can be either a fixed user or a mobile user in the GSM-R network, using the corresponding ISDN number and MSISDN number.The dispatch user enjoys a pair of dedicated channels in the broadcast, which can listen or speak.Each broadcast call can define up to five scheduling users, and each scheduling user can join multiple groups.A business user is a mobile user with VBS specified.The business users of each cell in the group call area share a downlink channel to listen to the broadcast call.Each business user can join up to 50 groups.During the broadcast call, VBS only allows the business user authorized to initiate the broadcast call to use the uplinked channel to speak, while other business users can only listen, and scheduling users can speak and listen at any time.The rights of business users and scheduling users to initiate and terminate broadcast calls are defined by the network.
Enhanced much priority and forced demolition (enhanced Multi - Level Precedence and Preemption service, eMLPP) eMLPP: is the GSM - R senior voice calls (Advanced researched and Call the Item, the acsi) one of the content of the business.EMLPP's business consists of two parts: priority and forced demolition.Priority refers to assigning a priority level to a call in combination with fast call establishment.On the one hand, forced dismantling refers to the preemption of resources, that is, high-priority calls can preempt low-priority resources in the absence of idle resources, which mainly exists in the preemption of wireless interface resources when the call is established and the preemption of cells when the call is switched over.On the other hand, high-priority calls can interrupt ongoing low-priority calls, and users can automatically accept high-priority calls through the automatic response function of the mobile station.EMLPP services must be supported by both the network and the mobile station.
The eMLPP business specifies seven priorities, from highest to lowest, as follows: where A, B, 0,1,2,3,4.Priority A and B can only be used within the MSC area of ownership, and the network shall be reserved for internal use.The other five priorities can be used globally and defined by the user.If a user customizes the eMLPP service, the network defines a highest priority for each user to use, and users can use other priorities below this level.The caller defines any priority within the scope of each call as needed.If the user does not customize the eMLPP service, the network defines a default priority for each call the user makes.For high-priority calls, the call establishment time is required to be 1 ~ 2s, and the call establishment process does not require authentication and encryption.When connected to A network (such as integrated Services Digital Network) that does not support eMLPP services but does support multi-priority and MLPP services, priority A and B are automatically downgraded to priority 0 and other priorities remain unchanged.
Functional Addressing: Functional Addressing is a feature of the GSM-R network that allows the caller to call the called party by its function number instead of the mobile user ISDN number (MSISDN).Functional addressing ensures relative independence between addressing the GSM-R application subsystem or function and the MSISDN number of the physical terminal used by those applications or functions.
Location Dependent Addressing: This is a feature of the GSM-R network that routes calls initiated by a mobile user for a specific function to a destination address that is relevant to the user's current Location.For example, when a train driver calls a dispatcher or station attendant, the correct dispatcher or station attendant is determined by the location of the driver at that time.For example, in the "big Triangle" communication of wireless column, the dispatcher to be called by mobile station depends on the mobile user's current position.When the driver needs to call the current dispatcher while the train is running, he does not know the dispatcher's phone number, but he can use a short number, such as 1200, to make a call request to the network.The network identifies the short number and routes it to the correct dispatcher.
In railways, location-based addressing is mainly used to address mobile users calling fixed users.In the railway traffic command, the railway branch bureau has the direct command.Each railway branch has its own dispatching station and makes it the dispatching center of the railway under the jurisdiction of the railway branch.The dispatchers in the railway branch dispatch office include traffic dispatchers, power dispatchers and so on.The responsibility of traffic dispatcher is very important and its function is complex, which is directly related to traffic command.Depending on the traffic density of the route, each traffic dispatcher is responsible for a certain length of dispatch section, and all stations located in that section and all trains operating within that section are subject to his command.There is a watchman at each station, and all trains within the station area follow his instructions.The train has to go through some dispatching sections and some stations in the process of running. When the driver calls the traffic dispatcher or station watchman, he can only call the current traffic dispatcher or station watchman.However, the driver cannot know the phone number of the current traffic dispatcher or station watchman.Gsm-r solves this problem by using location-based addressing.The mobile station USES short code (1200) to call traffic dispatchers, and short code (1800) to call station watchmen, so as to facilitate the driver operation, there is no need to remember the mobile phone number of each traffic dispatcher and station watchmen.
