ZTE Corporation ZXG-OB06 Manuale Utente
Chapter 3 - Interfaces and Communications
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The Ums interface is designed with a hierarchical model. The circuit
service protocol hierarchy is shown in Figure 12, and the packet service
protocol hierarchy is shown in Figure 13. The packet service protocol is
protocol hierarchy is shown in Figure 13. The packet service protocol is
implemented in the BSC, so it is not introduced here.
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LAPDm
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Sig.L1
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RR
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Um interface
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BSS
SGSN
BSSGP
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L1bis
relay
BSSGP
L1bis
RLC
MAC
GSM RF
relay
RLC
MAC
GSM RF
SNDCP
IP/X.25
application
LLC
Network
Service
On the Um interface, the circuit service protocols fall into three layers:
1. The first layer is the physical layer and also the bottom layer. It
consists of various channels and provides the basic wireless channels
for upper-level message transmission.
2. The second layer is the data link layer and also the medium layer, with
the LapDm adopted. It comprises various data transmission structures
and controls data transmission.
and controls data transmission.
3. The third layer (L3) is the highest layer. It comprises various messages
and programs and provides service control. L3 consists of three sub-
layers: radio resource management (RR), mobility management (MM)
layers: radio resource management (RR), mobility management (MM)
and connection management (CM).