13.20.5 Example

23.2053GPPBearer-independent circuit-switched core networkRelease 17Stage 2TS

Figure 13.20.5/1 shows a possible network model of an anchor MSC for a voice group call when the Talker is on the dedicated channel. At call setup Dispatchers, R-MSC and the talker can been seen as a multi party call. The listners are connected oneway in their context (bullet 1 and 2 in figure 13.20.5/2). In the example every kind of termination is shown in its own context.

Figure 13.20.5/1: VGCS call (termination overview for talker on dedicated channel)

If the talker is on a dedicated channel, the talker context contains two terminations which are connected bothway a termination overview is given in figure 13.20.5/1.

Figure 13.20.5/2 shows the message flow establishment of a VGCS call with two cells and the talker is located in cell1 when the Talker is on the dedicated channel. To connect the parties to the VGCS Multi Party Bridge the MSC server requests the MGW to establish internal Nb connections between the bearer terminations in the VGCS Multi Party bridge context and the call leg contexts, using the standard external bearer setup procedures. VGCS call acknowledge (bullet 3 in figure13.20.5/2) should be send after the ASCI broadcast channel is established in the cell where the talker is located (see 3GPP TS 43.068 [39], 3GPP TS 43.069 [40]).

Figure 13.20.5/2: Talker on dedicated channel (Message sequence chart)

Figure 13.20.5/3 shows a possible network model of an anchor MSC for a voice group call when the Talker is on one channel mode.

Figure 13.20.5/3: VGCS call (termination overview for Talker on one channel model)

Figure 13.20.5/4 shows the message flow establishment of a VGCS call with two cells and the talker is located in cell1 when the Talker is on one channel mode.

Figure 13.20.5/4: Talker on one channel mode (Message sequence chart)

Figure 13.20.5/5 shows the message flow of the talker move to uplink.

If the MSC server decides that the talker shall use the uplink of the cell. The MSC server adds a termination to the talker context which is connected to the Listener context and changes the topology of the talker context (bullet 1 and 2 in figure 13.20.5/5). Substract of the termination of the talker is only performed when the MSC server decides to move an active talker to the ASCI broadcast channel (bullet 3 in figure 13.20.5/5). The termination towards the cell where the talker is located is moved to the talker context. Further talker changes or cell changes of the current talker would be handled with move commands related to the termination towards the cell where the talker is located (bullet 4 in figure 13.20.5/5). Thus the talker’s speech to all the listeners in that cell is transmitted (broadcast channel). The termination overview after the talker is moved to the uplink is given in figure 13.20.5/3.

Figure 13.20.5/5: Information flow talker move to uplink (Message sequence chart)