User Manual
Airbridge cBTS3612 CDMA Base Station
System Description
1 System Overview
1-20
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Note:
Reliability refers to the product capability of performing specified functions in the specified conditions
and specified time.
There are 3 main indices to describe the reliablity of a system:
MTBF: Mean Time Between Failures, normally applicable to recoverable systems.
MTTR: Mean Time To Repair, inlcuding the time of fault checking, isolation, unit replacement and
recovery.
A: Availability , a comprehensive index to measure the system availability.
1.5.1 Hardware Reliability Design
cBTS3612 is designed with substantial hardware reliability, such as board
active/standby operation, load sharing and redundancy configuration. In addition,
system maintainability is improved with fault detection and isolation technology on
the board and system. In respect of hardware reliability, the following considerations
have been taken:
I. De-rating design
To improve system reliability and prolong the service life of components,
components are carefully selected and strictly tested, and less stress (electrical
stress and temperature stress) is to be borne than its designed rating.
II. Redundancy design
Redundant configuration of key units is applied in the BTS system. The system or
equipment will not fail unless the specified sets of units fail. In the BTS system,
common measures such as active/standby and load-sharing modes are adopted,
e.g. for BCIM, BCPM and BCKM.
III. Selection and control of components
The category, specifications and manufacturers of the components are carefully
selected and reviewed according to the requirements of the product reliability and
maintainability. The replaceability and normalization of components is one of the
main factors for the decision, which help to reduce the types of components used
and hence improve the availability of the system.