Chapter 7 Bts Signal Flows; Overview - Huawei Airbridge BTS3612A-1900 Technical Manual

Technical Manual
Airbridge BTS3612A CDMA Base Station

7.1 Overview

BTS signals include Abis traffic signal, Abis signaling message, O&M signal, clock
signal, and local Man-Machine Interface (MMI) signal. These signals form various flows
in the transmission from the Abis interface to the Um interface, as shown in Figure 7-1
(The flows are identified by different colors).
I. Abis signal
The Abis traffic signal, Abis signaling message and O&M signal are adapted and
carried through Asynchronous Transfer Mode (ATM) protocols. At different interfaces,
different physical links are used as ATM links.
At the Abis interface, the physical links are E1/T1 links.
Between the baseband processing boards, the physical link is cell bus.
The physical links for the IQ data exchange between the BRDM and various
BCPMs are electrical Gbit Ethernet buses.
The physical links for the IQ data exchange between the BRDM and various
BTRMs are optical Gbit Ethernet buses.
The baseband signals (including the Abis traffic signal, Abis signaling message and
O&M signal) are processed by the BTRM and converted into RF signals before the
transmission. In the reverse direction, the BTRM receives RF signals and converts
them into baseband signals.
II. Clock signal
As a synchronous system, the CDMA2000 1X requires precise clock reference for
synchronization. Figure 7-1 shows satellite synchronization signals are used as clock
reference.
III. Local MMI signal
The BTS provides an interface for local maintenance, through which users can perform
operations and maintenance using MMI commands. The local MMI signal is essentially
a kind of O&M signal from the local maintenance terminal (compared with the signal
coming from a remote terminal through the BSC), so it will not be introduced separately.

Chapter 7 BTS Signal Flows

7-1
System Principle
Chapter 7 BTS Signal Flows