Introduction
In Mobile Communication, BTS(Base Transceiver Station) or Wireless Base are communication node placed appropriately within the area of region where Mobile Communication Network is to be deployed. How they are placed is subject to mobile network planning but in brief they are usually placed at the separation of 1km to 2 km from each other. The radio signal coverage of the BTS depends on many factors such as the transmitting power, height of BTS antenna, the sectoring of patch antenna and requirements of the coverage area. BTS is also commonly called as Base station Radio or simply Wireless Base. This article explains in details the Base Station System- how configuration of Base Station Radio is done, types of Base Station System, on what factors the configuration depends on, the different kinds of BTS modules such as transceiver modules, antenna equipment modules, fan module. All this module are component of Wireless base and they are assembled together as BTS. The Transceiver Module for example is the module responsible for transmitting, receiving of radio signals to or from the wireless base, the PDM(Power Distribute Module) is for the power to transceiver station.the Note that the Base Transceiver Architecture depends upon base station manufacturer but most of the design and working principle are the same.
About BTS Configuration
•BTS configuration is determined by the traffic volume and the traffic distribution.
•BTS configuration is associated with the number of the TRXs and the antenna system.
•BTS can be omni directional
•BTS can be sectored.
•Number of TRXs can vary from site to site and that number determines the BTS configuration of that site.
2. BTS Cell Configuration:
BTS supports the following cell configurations
- Omni cell
- One sector cell
- Two sectors cell
- Three sectors cell
•BTS configuration is presented as S1/1/1 where S means sector
•Above configuration shows that the BTS is sectored.
•It has 3 sectors and each sector has 1 TRX.
•S2/3/2 means BTS has 3 sectors.
•First sector has 2 TRXs, second sector has 3 TRXs and third sector has 2 TRXs
•BTS configuration can be S2 where the BTS is sectored with only one sector having only two TRXs.
•BTS configuration can be S3/3 where the BTS has two sectors with each sectors of 3 TRXs.
•Omnidirectinal BTS is presented as O2 where the BTS has only 2 TRX.
•Similarly O4 means the BTS is omnidirectional with 4 TRXs.
•O1 means omnidirectional BTS with only one TRX.
•Supports the omni directional and directional coverage
•Combination of two cabinets to form one group
• Combination of three cabinets to form a group.
One single cabinet supports upto 12 TRXs in the full configuration
•Use as few as possible cabinets for cell configurations
•All TRXs of a cell are configured in the same cabinet
•TRXs are configured in the basic cabinet in preference and the number of TRXs in the basic cabinet is not less than that in any extension cabinet
3. Configuration Principle:
•In full configuration, the BTS configuration will be O36 or S12/12/12.
•The Transmit power will be 40W or 80W.
•For 40W the maximum configuration is S12/12/12 or O36
•But for 80W BTS, additional modules called power amplifier (PA) are required so the capacity of the BTS decreases and BTS maximum configuration will be S6/6/6 or O18.
BTS Hardware Configuration
Fig: BTS hardware configuration
Interface of BTS with BSC(Base Station controller) and MS(Mobile Station)
Fig: Interface of BTS with BSC and MS
Modules of a BTS
The main modules of a BTS are as follows:
- CMM:Controller & Maintenance Module
- TRM:Transceiver Module
- AEM:Antenna Equipment Module
- FCM:Fan Control Module
- PDM:Power Distribute Module
TRM (Transceiver Module)
It has 3 parts:
- TPU:Transceiver Process Unit
- RCU:Radio Carrier Unit
- PAU:Power Amplifier Unit
AEM (Antenna Equipment Module)
Its components are:
- CDU/DCDU/ECDU:Combiner Distribution Unit
- CEU:Combiner Extension Unit
CMM module funtions are:
•BS interface functions
•Providing various clocks needed by BS
•Operation & maintenance function of BTS
•Equipment alarm collection
• Active/standby hot backup
TRM Module
Fig: Transceiver Module of a BTS
AEM (Antenna Equipment Module)
Fig: Antenna Equipment Module (AEM)
CDU(Combiner Distribution Unit) Module
Fig: Combiner Distribution Unit
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