BSC Signaling Flows

BSC CS Signal FlowAfter a CS call is established, the MS and the network communicate with each other. In this case, the signal flow is referred to as the CS signal flow. The method of processing the BSC CS signal flow varies with the transmission modes adopted on the Abis interface and the A interface, and also varies with the combination modes of BSC subracks. NOTE: For details on the transmission modes on the Abis interface, refer to Transmission and Networking on the Abis Interface. For details on the transmission modes on the A interface, refer to Transmission and Networking on the A Interface.

Abis over TDM + A over TDMIn BM/TC separated configuration mode, the TDM transmission is used on both the Abis interface and the A interface. For the BSC CS signal flow in this case, see Figure 1.

Figure 1 CS signal flow (1)

As shown in Figure 1, the CS signal flow in the uplink is as follows: 1. 2. 3. The uplink CS signals are sent from the BTS to the GEIUB/GOIUB in the GMPS/GEPS. The CS signals are demultiplexed in the GEIUB/GOIUB. One CS signal uses a 64 kbit/s timeslot and is transmitted to the GEIUT/GOIUT through the GTNU. The CS signals are multiplexed in the GEIUT/GOIUT. One full-rate CS signal uses a 16 kbit/s sub-timeslot, and one half-rate CS signal uses an 8 kbit/s sub-timeslot. The CS signals are then transmitted to the GEIUT/GOIUT in the GTCS over the Ater interface. The CS signals are de-multiplexed in the GEIUT/GOIUT of the GTCS. One CS signal uses a 64 kbit/s timeslot and is transmitted to the GDPUX/GDPUC through the GTNU. The GDPUX/GDPUC performs voice coding/decoding and rate matching on the CS signals, which are converted into 64 kbit/s PCM signals. The 64 kbit/s PCM signals are transmitted to the GEIUA/GOIUA through the GTNU, and then are transmitted to the MSC over the A interface.

4. 5.

In BM/TC combined configuration mode, the TDM transmission is used on both the Abis interface and the A interface. For the BSC CS signal flow in this case, see Figure 2.


As shown in Figure 2, the CS signal flow in the uplink is as follows: 1. The uplink CS signals are sent from the BTS to the GEIUB/GOIUB in the GMPS/GEPS.

2. 3.

The CS signals are de-multiplexed in the GEIUB/GOIUB. One CS signal uses a 64 kbit/s timeslot and is transmitted to the GDPUX through the GTNU. The GDPUX performs voice coding/decoding and rate matching on the CS signals, which are converted into 64 kbit/s PCM signals. The 64 kbit/s PCM signals are transmitted to the GEIUA/GOIUA through the GTNU, and then are transmitted to the MSC over the A interface.

Abis over HDLC/IP + A over TDMIn BM/TC separated configuration mode, the HDLC/IP transmission and TDM transmission are used on the Abis interface and A interface respectively. For the BSC CS signal flow in this case, see Figure 3.


As shown in Figure 3, the CS signal flow in the uplink is as follows: 1. 2. 3. 4. 5. 6. The uplink CS signals are sent from the BTS to the GFGUB/GOGUB/GEHUB in the GMPS/GEPS. The GFGUB/GOGUB/GEHUB transmits the CS signals to the GSCU, which then transmits the signals to the GDPUX. The GDPUX adjusts the frame order, eliminates jitter, and converts the PTRAU frames into TRAU frames, which are then transmitted to the GEIUT/GOIUT through the GTNU. The CS signals are multiplexed in the GEIUT/GOIUT of the GMPS/GEPS, and then are transmitted to the GEIUT/GOIUT in the GTCS. The CS signals are de-multiplexed in the GEIUT/GOIUT of the GTCS. One CS signal uses a 64 kbit/s timeslot and is transmitted to the GDPUX/GDPUC through the GTNU. The GDPUX/GDPUC performs voice coding/decoding and rate matching on the CS signals, which are converted into 64 kbit/s PCM signals. The 64 kbit/s PCM signals are transmitted to the GEIUA/GOIUA through the GTNU, and then are transmitted to the MSC over the A interface.

In BM/TC combined configuration mode, the HDLC/IP transmission and TDM transmission are used on the Abis interface and A interface respectively. For the BSC CS signal flow in this case, see Figure 4.


As shown in Figure 4, the CS signal flow in the uplink is as follows: 1. 2. 3. The uplink CS signals are sent from the BTS to the GEHUB/GFGUB/GOGUB in the GMPS/GEPS. The CS signals are transmitted to the GDPUX through the GSCU. The GDPUX adjusts the frame order, eliminates jitter, and performs voice coding/decoding and rate matching. The PTRAU frames are then converted into 64 kbit/s PCM frames.

4.

The PCM frames are transmitted to the GEIUA/GOIUA through the GTNU, and then are transmitted to the MSC over the A interface.

Abis over TDM + A over IPThe TDM transmission and IP transmission are used on the Abis interface and A interface respectively. For the BSC CS signal flow in this case, see Figure 5.


As shown in Figure 5, the CS signal flow in the uplink is as follows: 1. 2. 3. 4. The uplink CS signals are sent from the BTS to the GEIUB/GOIUB in the GMPS/GEPS. The CS signals are de-multiplexed in the GEIUB/GOIUB. One CS signal uses a 64 kbit/s timeslot and is transmitted to the GDPUX through the GTNU. The GDPUX converts the TRAU frames into RTP frames, adjusts the frame order, and eliminates jitter. The GSCU transmits the CS signals to the GFGUA/GOGUA, which are then transmitted to the MGW over the A interface.

Abis over HDLC/IP + A over IPThe HDLC/IP transmission and IP transmission are used on the Abis interface and A interface respectively. For the BSC CS signal flow in this case, see Figure 6.


As shown in Figure 6, the CS signal flow in the uplink is as follows: 1. 2. 3. 4. The uplink CS signals are sent from the BTS to the GFGUB/GOGUB in the GMPS/GEPS. The CS signals are transmitted to the GDPUX through the GSCU. The GDPUX converts the PTRAU frames into RTP frames, adjusts the frame order, and eliminates jitter. The GSCU transmits the CS signals to the GFGUA/GOGUA, which are then transmitted to the MGW over the A interface.

Parent topic: BSC Signal Flow

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BSC PS Signal FlowAfter a PS communication is established, the MS and the network communicate with each other. In this case, the signal flow is referred to as the PS signal flow. The method of processing the BSC PS signal flow varies with the types of PCU and with the transmission modes on the Abis interface. NOTE: For details on the transmission modes on the Abis interface, refer to Transmission and Networking on the Abis Interface.

BSC PS Signal Flow (Built-in PCU)When the built-in PCU is used, three transmission modes can be used over the Abis interface: Abis over TDM, Abis over HDLC, and Abis over IP. The BSC PS signal flow varies with the transmission modes on the Abis interface. The built-in PCU is used and the TDM transmission is used on the Abis interface. For the BSC PS signal flow in this case, see Figure 1.

Figure 1 PS signal flow (Abis over TDM)

When the built-in PCU is used, the PS signal flow on the uplink is as follows: 1. The packet data is sent from the BTS to the GEIUB in the GMPS/GEPS. The packet data uses one to four 16 kbit/s sub-timeslots on the Abis interface, depending on the modulation and coding scheme, such as CS1-CS9 or MCS1MCS9. The GEIUB transmits the packet data to the GTNU. After receiving the data, the GTNU transmits the signals to the GDPUP. The GDPUP performs format conversion, and then transmits the data to the GEPUG/GFGUG through the GSCU. The GEPUG/GFGUG processes the packet data at layer 1 and at a part of the NS layer on the Gb interface. Then, the packet data is transmitted to the SGSN over the Gb interface.

2. 3. 4.

When the built-in PCU is used, the BSC PS signal flow in Abis over HDLC transmission mode is the same as that in Abis over IP transmission mode. See Figure 2.

Figure 2 PS signal flow (Abis over IP)

The BSC PS signal flow in the uplink is as follows: 1. 2. 3. The PS signals are sent from the BTS to the GEHUB/GFGUB/GOGUB in the GMPS/GEPS. The GSCU transmits the PS signals to the GDPUP. The GDPUP performs format conversion, and then transmits the data to the GEPUG/GFGUG through the GSCU.

4.

The GEPUG/GFGUG processes the packet data at layer 1 and at a part of the NS layer on the Gb interface. Then, the packet data is transmitted to the SGSN over the Gb interface.

BSC PS Signal Flow (External PCU)The external PCU is used. For the BSC PS signal flow in this case, see Figure 3.

Figure 3 BSC PS signal flow (external PCU )

When the external PCU is used, the BSC PS signal flow on the uplink is as follows: 1. The packet data is sent from the BTS to the GEIUB in the GMPS/GEPS. The packet data uses one to four 16 kbit/s sub-timeslots on the Abis interface, depending on the modulation and coding scheme, such as CS1-CS9 or MCS1MCS9. The GTNU transmits the PS signals to the GEIUP/GOIUP. The PS signals are transmitted to the PCU over the Pb interface, and then to the SGSN over the Gb interface.

2. 3.

Parent topic: BSC Signal Flow


Signaling Flow on the Abis InterfaceThe protocol stack and signaling flow on the Abis interface vary with the transmission modes on the Abis interface. NOTE: The GXPUM originates and terminates all the signaling flows of the BSC.

Signaling Flow on the Abis Interface (Abis over TDM)The TDM transmission is used on the Abis interface. For the signaling flow on the Abis interface in this case, see Figure 1.

Figure 1 Protocol stack on the Abis interface (Abis over TDM)

Figure 2 shows the signaling flow on the Abis interface.

Figure 2 Signaling Flow on the Abis Interface (Abis over TDM)

The signaling flow on the Abis interface is as follows: 1. 2. 3. The signaling is transmitted to the GEIUB/GOIUB in the GMPS/GEPS over the Abis interface. Then, the signaling is transmitted to the GSCU. The GSCU transmits the signaling to the GXPUT/GXPUM. The GXPUT/GXPUM processes the signaling according to the LAPD and RR protocols. The GXPUM processes the signaling according to the BTSM protocol.

Signaling Flow on the Abis Interface (Abis over HDLC)The HDLC transmission is used on the Abis interface. For the signaling flow on the Abis interface in this case, see Figure 3.

Figure 3 Protocol stack on the Abis interface (Abis over HDLC)


Figure 4 Signaling Flow on the Abis Interface (Abis over HDLC)

The signaling flow on the Abis interface is as follows: 1. 2. 3. The signaling is transmitted to the GEHUB in the GMPS/GEPS over the Abis interface. Then, the GEHUB transmits the signaling to the GSCU. The GSCU transmits the signaling to the GXPUT/GXPUM. The GXPUT/GXPUM processes the signaling according to the LAPD and RR protocols. The GXPUM processes the signaling according to the BTSM protocol.

Signaling Flow on the Abis Interface (Abis over IP)The IP transmission is used on the Abis interface. For the signaling flow on the Abis interface in this case, see Figure 5.

Figure 5 Protocol stack on the Abis interface (Abis over IP)


Figure 6 Signaling Flow on the Abis Interface (Abis over IP)

The signaling flow on the Abis interface is as follows: 1. 2. 3. The signaling is transmitted to the GFGUB/GOGUB in the GMPS/GEPS over the Abis interface. The GFGUB/GOGUB processes the signaling according to the MAC, IP, and UDP protocols, and then transmits the signaling to the GXPUT/GXPUM through the GSCU. The GXPUT/GXPUM processes the signaling according to the LAPD and RR protocols. The GXPUM processes the signaling according to the BTSM protocol.

Parent topic: BSC Signaling Flow


Signaling Flow on the A InterfaceThe protocol stack and signaling flow on the A interface vary with the transmission modes on the A interface.

Signaling Flow on the A Interface (A over TDM)The A interface is the logical interface between the BSC and the MSC. The BSC internal signaling flow from the A interface varies, depending on the signaling protocols used on the A interface. When TDM transmission is used on the A interface, the E1/T1 or STM-1 transmission is used on the physical layer. The transmission on the data link layer complies with the SS7 MTP2 protocol. The transmission on the network layer complies with the MTP3 and SCCP protocols. The transmission on the application layer complies with the BSSAP protocol and the layer-3 protocols on the Um interface. Figure 1 shows the protocol stack on the A interface.

Figure 1 Protocol stack on the A interface (A over TDM)

The BSC internal signaling flow from the A interface varies with the configuration modes of the BSC subracks.

Figure 2 shows the BSC internal signaling flow in the BM/TC separated configuration mode. Figure 3 shows the BSC internal signaling flow in the BM/TC combined configuration mode..

Figure 2 Signaling flow on the A interface (A over TDM) (BM/TC separated)

As shown in Figure 2, the BSC internal signaling flow from the A interface is as follows: 1. 2. In the GMPS/GEPS, the GXPUM/GXPUT processes the signaling according to the MTP3, SCCP, and BSSAP protocols. The GEIUT processes the signaling according to the MTP2 protocol. The signaling is transparently transmitted in the GTCS, and then is transmitted to the MSC over the A interface.

Figure 3 Signaling flow on the A interface (A over TDM) (BM/TC combined)

As shown in Figure 3, the BSC internal signaling flow from the A interface is as follows: 1. 2. In the GMPS/GEPS, the GXPUM/GXPUT processes the signaling according to the MTP3, SCCP, and BSSAP protocols. The GEIUA/GOIUA processes the signaling according to the MTP2 protocol. Then, the signaling is transmitted to the MSC over the A interface.

Signaling Flow on the A Interface (A over IP)If IP transmission is used on the A interface, the E1/T1 or STM-1 transmission is used on the physical layer. The transmission on the data link layer complies with the SigTRAN M3UA/SCTP/IP protocols. The transmission on the network layer complies with the SS7 SCCP protocol. The transmission on the application layer complies with the DATP and BSSAP protocols. Figure 4 shows the protocol stack on the A interface.

Figure 4 Protocol stack on the A interface (A over IP)

Figure 5 shows the signaling flow on the A interface.

Figure 5 Signaling flow on the A interface (A over IP)

The BSC internal signaling flow from the A interface is as follows: 1. 2. In the GMPS/GEPS, the GXPUM/GXPUT processes the signaling according to the BSSAP, SCCP, SCTP, and M3UA protocols. Then, the signaling is transmitted to the GFGUA/GOGUA through the GSCU. The GFGUA/GOGUA processes the signaling according to the IP protocol. Then, the signaling is transmitted to the MSC through the A interface.



Signaling flow on the Pb interfaceThis describes the protocol stack and signaling flow on the Pb interface. When the external PCU is used, the BSC provides the Pb interface to enable the communication between the BSC and the PCU. The Pb interface, defined by Huawei, is a non-standard logical interface between BSC and PCU. Figure 1 shows the protocol stack on the Pb interface.

Figure 1 Protocol stack on the Pb interface

Figure 2 shows the signaling flow on the Pb interface.

Figure 2 Signaling flow on the Pb interface

The BSC internal signaling flow from the Pb interface is as follows: 1. 2. 3. The signaling is transmitted to the GEIUP/GOIUP in the GMPS/GEPS over the Pb interface. The GEIUP/GOIUP processes the signaling according to the LAPD protocol. On receiving the signaling from the GSCU, the GXPUT/GXPUM processes the signaling based on the PbIP and RR protocols.



Signaling Flow on the Gb InterfaceThis describes the protocol stack and signaling flow on the Gb interface. The Gb interface is the logical interface between the BSC and the SGSN. The E1/T1 or FE/GE transmission is used on the physical layer. The transmission on the data link layer complies with the NS protocol, and the sub NS layer of the NS protocol complies with the FR or IP protocol. The transmission on the application layer complies with the BSSGP protocol.Figure 1 shows the protocol stack on the Gb interface.

Figure 1 Protocol stack on the Gb interface

Figure 2 shows the signaling flow on the Gb interface.

Figure 2 Signaling flow on the Gb interface

The BSC internal signaling flow from the Gb interface is as follows: 1. The signaling is transmitted to the GMPS/GEPS over the Gb interface. If the sub NS layer of the NS protocol complies with the FR protocol, the Gb interface board is the GEPUG. If the sub NS layer of the NS protocol complies with the IP protocol, the Gb interface board is the GFGUG. 2. 3. The GSCU transmits the signaling to the GXPUM. The GXPUM processes the signaling according to the NS and BSSGP protocols.



BSC OM Signal Flow (BM/TC Separated)The BSC OM signal flow (BM/TC separated) refers to the signal flow that is generated when OM is performed on the BSC and when the BM and TC are configured in different subracks. The BSC internal OM signal flow varies with the installation position of the GTCS.

GTCS Configured on the BSC SideThe GTCS is configured on the BSC side. For the OM signal flow in the BSC in this case, see Figure 1.

Figure 1 OM signal flow (GTCS configured on the BSC side)

As shown in Figure 1, the OM signal flow in the BSC is as follows:

OM signal flow in the GMPS 1. 2. The OM signal is transmitted from the LMT/M2000 to the GBAM/GOMU. After being processed by the GBAM/GOMU, the OM signal is transmitted to the GSCU in the GMPS. The GSCU then transmits the OM signal to the service boards that require maintenance.

OM signal flow in the GEPS 1. 2. 3. The OM signal is transmitted from the LMT/M2000 to the GBAM/GOMU. After being processed by the GBAM/GOMU, the OM signal is transmitted to the GSCU in the GMPS. The GSCU then transmits the OM signal to the GSCU in the GEPS. In the GEPS, the GSCU transmits the OM signal to the service boards that require maintenance.

OM signal flow in the GTCS 1. 2. 3. The OM signal is transmitted from the LMT/M2000 to the GBAM/GOMU. After being processed by the GBAM/GOMU, the OM signal is transmitted to the GSCU in the GMPS. The GSCU then transmits the OM signal to the GSCU in the main GTCS. In the main GTCS, the GSCU transmits the OM signal to the service boards that require maintenance. Alternatively, the GSCU in the main GTCS transmits the OM signal to the GSCU in an extension GTCS. Then, in the extension GTCS, the GSCU transmits the OM signal to the service boards that require maintenance.

GTCS Configured on the MSC SideThe GTCS is configured on the MSC side. For the OM signal flow in the BSC in this case, see Figure 2.

Figure 2 OM signal flow (GTCS configured on the MSC side)




OM signal flow in the GTCS 1. 2. The OM signal is transmitted from the LMT/M2000 to the GBAM/GOMU. After being processed by the GBAM/GOMU, the OM signal is transmitted to the GEIUT/GOIUT in the GMPS. Then, the GEIUT/GOIUT in the GMPS transmits the OM signal to the GEIUT/GOIUT in the main GTCS through the Ater interface. In the main GTCS, the GSCU transmits the OM signal to the service boards that require maintenance. Alternatively, the GSCU in the main GTCS transmits the OM signal to the GSCU in an extension GTCS. Then, in the extension GTCS, the GSCU transmits the OM signal to the service boards that require maintenance.

3.

Parent topic: BSC OM Signal Flow


BSC OM Signal Flow (BM/TC Combined)The BSC OM signal flow (BM/TC combined) refers to the signal flow that is generated when OM is performed on the BSC and when the BM and TC are configured in the same subrack. Figure 1 shows the OM signal flow in the BSC in BM/TC combined configuration mode.

Figure 1 BSC OM signal flow (BM/TC combined)






BSC OM Signal Flow (A over IP)The BSC OM signal flow (A over IP) refers to the signal flow that is generated when OM is performed on the BSC and when the IP transmission is used on the A interface. Figure 1 shows the OM signal flow in the BSC in A over IP configuration mode.

Figure 1 BSC OM signal flow (A over IP)






Transmission and Networking on the Abis InterfaceThis describes the networking between the BSC and the BTS.

Transmission Modes on the Abis InterfaceThe following transmission modes can be used on the Abis interface:

Abis over TDM Abis over TDM indicates that the TDM transmission is used on the Abis interface. In this case, the Abis interface board is the GEIUB/GOIUB, and the transmission network between the BSC and the BTS is the SDH/PDH network.

Abis over HDLC Abis over HDLC indicates that layer 2 of the Abis interface protocol stack uses the HDLC protocol. In this case, the Abis interface board is the GEHUB, and the transmission network between the BSC and the BTS is the SDH/PDH network.

Abis over IP Abis over IP indicates that layer 3 of the Abis interface protocol stack uses the IP protocol. In this case, the Abis interface board is the GFGUB/GOGUB, and the transmission network between the BSC and the BTS is the IP network.

Abis over TDMIn the Abis over TDM networking mode, the Abis interface board in the BSC is the GEIUB/GOIUB. The GEIUB provides E1/T1 electrical ports, and the GOIUB provides STM-1 optical ports.

Figure 1 shows the E1/T1-based TDM networking on the Abis interface. Figure 2 shows the STM-1-based TDM networking on the Abis interface.

Figure 1 E1/T1-based TDM networking on the Abis interface

Figure 2 STM-1-based TDM networking on the Abis interface

NOTE: If the BTSs connected to the BSC are distributed on different PDH/SDH rings, additional ADM/DXC devices should be used. Advantages: The networking mode features maturity, flexible QoS, and security. Telecom operators can make full use of the SDH/PDH transmission network resources. Disadvantages: Compared with the IP transmission networking mode, the cost of this networking mode is high.

Abis over HDLC

In Abis over HDLC networking mode, the Abis interface board in the BSC is the GEHUB. The GEHUB provides E1/T1 electrical ports. The BSC can be connected to the BTS in HDLC transmission mode or to the Hub BTS. Figure 3 shows the E1/T1-based HDLC networking on the Abis interface.

Figure 3 E1/T1-based HDLC networking on the Abis interface

Advantages: If the networking mode is used, the utilization of the transmission resources over the Abis interface is improved without reconstruction of the existing SDH/PDH networks. Disadvantages: No support the high-speed transmission based on STM-1.

Hybrid Networking (Abis over TDM and Abis over HDLC)The Abis over TDM and Abis over HDLC networking modes can be used on the Abis interface simultaneously. In this case, the Abis interface supports the following configuration modes: The BSC is configured with the GEIUB/GOIUB and GEHUB. Where, the GEIUB/GOIUB supports TDM transmission and the GEHUB supports HDLC transmission. See Figure 4.

Figure 4 Hybrid networking (Abis over TDM and Abis over HDLC)

The characteristics of hybrid networking mode are as follows:

Advantages: If the Abis over HDLC networking mode is used, the utilization of the transmission resources over the Abis interface is improved without reconstruction of the existing SDH/PDH networks. Disadvantages: For hybrid combined cabinets and cabinet groups, as some BTSs use HDLC transmission and some use TDM transmission, at least two cables are required to connect the BTS to the BSC. Therefore, transmission resources are wasted.

Abis over IPIn Abis over IP networking mode, the Abis interface adopts the VLAN technology. In other words, signaling and service signals are labeled different VLAN IDs, which are used to differentiate the signaling, voice service signals, and data service signals over the same physical link. Thus, QoS is improved.

In the Abis over IP networking mode, the Abis interface board in the BSC is the GFGUB/GOGUB. The GFGUB provides FE/GE ports,The GOGUB provides GE ports.Based on the transmission networks, the Abis over IP networking modes can be classified into the following types:

Figure 5 shows the Multi-Service Transmission Platform (MSTP) based IP networking. Figure 6 shows the data-network-based IP networking.

Figure 5 MSTP-based IP networking on the Abis interface

Figure 6 Data-network-based IP networking on the Abis interface

Advantages of MSTP-based IP networking:

Applies to the telecom operators that have established the SDH network or MSTP network. Provides up to 100 Mbit/s transmission bandwidth through the FE/GE ports, thus facilitating the BTS upgrade and capacity expansion. Provides the VC trunk function, which enables the establishment of two VC trunk links between the BTS and the BSC and ensures the security of data transmission. These two links can be used to transmit real-time service data and non-real-time service data.

Disadvantages of MSTP-based IP networking: The MSTP network does not support the evolution from telecommunication networks to IP networks. Advantages of data-network-based IP networking:

Provides large-capacity bandwidth and reliable transmission on the Abis interface Supports the evolution from GSM networks to IP networks

Disadvantages of data-network-based IP networking: cannot ensure good QoS. The end-to-end QoS mechanism must be adopted. Parent topic: BSC Transmission and Networking


Transmission and Networking on the A InterfaceThis describes the transmission and networking between the BSC and the MSC/MGW.

Transmission Modes on the A InterfaceThe following transmission modes can be used on the A interface:

A over TDM A over TDM indicates that the TDM transmission is used on the A interface. In this case, the A interface board is the GEIUA/GOIUA, and the transmission network between the BSC and the MSC/MGW is the SDH/PDH network.

A over IP A over IP indicates that layer 3 of the A interface protocol stack uses the IP protocol. In this case, the A interface board is the GFGUA/GOGUA, and the transmission network between the BSC and the MGW is the IP network.

A over TDMIn A over TDM networking mode, the A interface board in the BSC is the GEIUA/GOIUA, which provides E1/T1 ports and STM-1 ports. The A over IP networking mode varies with whether the TC function is performed by the BSC.

E1/T1 Transmission on the A Interface

The TC function is performed by the BSC. For the networking mode in this case, see Figure 1. The TC function is performed by the MGW. For the networking mode in this case, see Figure 2.

STM-1 Transmission on the A Interface

The TC function is performed by the BSC. For the networking mode in this case, see Figure 3. The TC function is performed by the MGW. For the networking mode in this case, see Figure 4.

Figure 1 E1/T1-based TDM networking on the A interface (1)

Figure 2 E1/T1-based TDM networking on the A interface (2)

Figure 3 STM-1-based TDM networking on the A interface (1)

Figure 4 STM-1-based TDM networking on the A interface (2)

Advantages: The networking mode features maturity, flexible QoS, and security. Telecom operators can make full use of the SDH/PDH transmission network resources. Disadvantages: Compared with the IP transmission networking mode, the cost of this networking mode is high.

A over IPIf IP transmission is used on the A interface, the TC function is performed by the MGW. In A over IP networking mode, the A interface adopts the VLAN technology. In other words, signaling and service signals are labeled different VLAN IDs, which are used to differentiate the signaling, voice service signals, and data service signals over the same physical link. Thus, QoS is improved. In A over IP networking mode, the A interface board in the BSC is the GFGUA/GOGUA, which provides FE/GE electrical ports and GE optical ports. Figure 5 shows the A over IP networking mode in which the transmission between the BSC and the MGW is the layer 2 IP network. Figure 6 shows the A over IP networking mode in which the transmission between the BSC and the MGW is the layer 3 IP network.

Figure 5 IP networking on the A interface (1)

Figure 6 IP networking on the A interface (2)

Advantages: This networking mode provides large-capacity bandwidth and reliable transmission on the A interface. It also supports the evolution from GSM networks to IP networks. Disadvantages: The BSC must be connected to the Huawei MGW. Parent topic: BSC Transmission and Networking


Transmission and Networking on the Pb InterfaceThis describes the transmission and networking between the BSC and the external PCU. Pb over TDM indicates that the TDM transmission is used on the Pb interface. In this case, the Pb interface board is the GEIUP/GOIUP, and the transmission network between the BSC and the PCU is the SDH/PDH network. The Pb interface supports only the TDM networking mode. The Pb interface board in the BSC is the GEIUP/GOIUP, which provides E1/T1 ports and STM-1 ports respectively.

Figure 1 shows the E1/T1-based TDM networking on the Pb interface. Figure 2 shows the STM-1-based TDM networking on the Pb interface.

Figure 1 E1/T1-based TDM networking on the Pb interface

Figure 2 STM-1-based TDM networking on the Pb interface

Parent topic: BSC Transmission and Networking


Transmission and Networking on the Ater InterfaceThis describes the transmission and networking between the BM subrack and the TC subrack. When the BM and the TC are configured in different subracks, they communicate with each other over the Ater interface. The Ater interface supports only the TDM networking mode. Based on the installation positions of the GTCS, several transmission and networking modes can be used on the Ater interface.

The GTCS is configured on the BSC side, and the E1/T1 transmission is used on the Ater interface. For the networking on the Ater interface in this case, see Figure 1. The GTCS is configured on the MSC side, and the E1/T1 transmission is used on the Ater interface. For the networking on the Ater interface in this case, see Figure 2. The GTCS is configured on the MSC side, and the STM-1 transmission is used on the Ater interface. For the networking on the Ater interface in this case, see Figure 3.

Figure 1 E1/T1-based networking on the Ater interface (GTCS configured on the BSC side)

Figure 2 E1/T1-based networking on the Ater interface (GTCS configured on the MSC side)

Figure 3 STM-1-based networking on the Ater interface (GTCS configured on the MSC side)

Parent topic: BSC Transmission and Networking


Transmission and Networking on the Gb InterfaceThis describes the transmission and networking between the BSC and the SGSN.

Transmission Modes on the Gb InterfaceThe following transmission modes can be used on the Gb interface:

Gb over FR Gb over FR indicates that the Frame Relay (FR) protocol is used on the sub NS layer of the Gb interface protocol stack. In this case, the Gb interface board is the GEPUG, and the transmission network between the BSC and the SGSN is the FR network.

Gb over IP Gb over IP indicates that the IP protocol is used on the sub NS layer of the Gb interface protocol stack. In this case, the Gb interface board is the GFGUG, and the transmission network between the BSC and the SGSN is the IP network.

Gb over FRIn Gb over FR networking mode, the transmission network between the BSC and the SGSN is the FR network. The Gb interface board in the BSC is the GEPUG, which provides E1/T1 ports,as shown inFigure 1 .

Figure 1 E1/T1-based FR networking on the Gb interface

Advantages: The networking mode features maturity and can make full use of the existing FR network. Disadvantages: The bandwidth on the Gb interface is insufficient, so large-capacity requirements of data services cannot be met.

Gb over IPIn Gb over IP networking mode, the transmission network between the BSC and the SGSN is the IP network. The Gb interface board in the BSC is the GFGUG, which provides FE/GE ports, as shown in Figure 2.

Figure 2 FE/GE-based IP networking on the Gb interface

Advantages: Compared with the FR networking mode, the bandwidth on the Gb interface in the IP networking mode is greatly increased, thus reducing the costs of network construction and OM. Disadvantages: The transmission in Gb over IP networking mode is less reliable than that in Gb over FR networking mode. Parent topic: BSC Transmission and Networking


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BSC Signaling Flows