An actual BTS device (Siemens

BS11µBTS)

Base transceiver stationFrom Wikipedia, the free encyclopedia

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A base transceiver station (BTS) is a piece of equipment thatfacilitates wireless communication between user equipment (UE) and anetwork. UEs are devices like mobile phones (handsets), WLL phones,computers with wireless internet connectivity, WiFi and WiMAX devicesand others. The network can be that of any of the wirelesscommunication technologies like GSM, CDMA, Wireless local loop,WAN, WiFi, WiMAX, etc.

BTS is also referred to as the radio base station (RBS), node B (in 3GNetworks) or, simply, the base station (BS). For discussion of the LTEstandard the abbreviation eNB for evolved node B is widely used.

Though the term BTS can be applicable to any of the wirelesscommunication standards, it is generally associated with mobilecommunication technologies like GSM and CDMA. In this regard, aBTS forms part of the base station subsystem (BSS) developments forsystem management. It may also have equipment for encrypting anddecrypting communications, spectrum filtering tools (band pass filters),etc. antennas may also be considered as components of BTS in generalsense as they facilitate the functioning of BTS. Typically a BTS will haveseveral transceivers (TRXs) which allow it to serve several differentfrequencies and different sectors of the cell (in the case of sectorisedbase stations). A BTS is controlled by a parent base station controller via the base station control function (BCF).The BCF is implemented as a discrete unit or even incorporated in a TRX in compact base stations. The BCFprovides an operations and maintenance (O&M) connection to the network management system (NMS), andmanages operational states of each TRX, as well as software handling and alarm collection. The basic structure andfunctions of the BTS remains the same regardless of the wireless technologies.

Contents

1 General architecture

2 Terms regarding a mobile BTS

3 See also

4 Further reading

5 External links

6 References

General architecture

A BTS in general has the following parts:

Transceiver (TRX)

Quite widely referred to as the driver receiver (DRX), DRX are either in the form of single (sTRU),

A typical BTS tower which holds the

antenna. The tower is quite widely

misinterpreted as the BTS itself. The

shelter which houses the actual BTS

can also be seen.

A mobile BTS

double(dTRU) or a composite double radio unit (DRU). Itbasically does transmission and reception of signals. It also does

sending and reception of signals to and from higher network

entities (like the base station controller in mobile telephony).

Power amplifier (PA)

Amplifies the signal from DRX for transmission through antenna;

may be integrated with DRX.Combiner

Combines feeds from several DRXs so that they could be sent out

through a single antenna. Allows for a reduction in the number of

antenna used.

Duplexer

For separating sending and receiving signals to/from antenna. Does

sending and receiving signals through the same antenna ports

(cables to antenna).Antenna

This is the structure that lies underneath the BTS; it can be installedas it is or disguised in some way (Concealed cell sites).

Alarm extension systemCollects working status alarms of various units in the BTS and

extends them to operations and maintenance (O&M) monitoringstations.

Control functionControls and manages the various units of BTS, including anysoftware. On-the-spot configurations, status changes, software

upgrades, etc. are done through the control function.Baseband receiver unit (BBxx)

Frequency hopping, signal DSP, etc.

Terms regarding a mobile BTS

Diversity techniques

To improve the quality of the received signal, often two receivingantennas are used, placed at an equal distance to an uneven

multiple of a quarter of wavelength (for 900 MHz the wavelength itis 30 cm). This technique, known as antenna diversity or space

diversity, avoids interruption caused by path fading. The antennascan be spaced horizontally or vertically. Horizontal spacing

requires more complex installation, but brings better performance.

Other than antenna or space diversity, there are other diversitytechniques such as frequency/time diversity, antenna pattern

diversity, and polarization diversity.

Splitting refers to the flow of power within a particular area of the cell, known as a sector. Every field cantherefore be considered like one new cell.

A BTS mounted on a building

Directional antennas reduce LORA interference. If not sectorised, the cell will be served by an omnidirectionalantenna, which radiates in all directions. A typical structure is the trisector, also known as clover, in which there arethree sectors served by separate antennas. Each sector has a separate direction of tracking, typically of 120° withrespect to the adjacent ones. Other orientations may be used to suit the local conditions. Bisectored cells are alsoimplemented. These are most often oriented with the antennas serving sectors of 180° separation to one another,but again, local variations do exist.

See also

OpenBTSCell ID

Cell siteCell on wheelsMobile cell sites

Radio masts and towers

Further reading

Satoshi Maruyama, Katsuhiko Tanahashi, Takehiko Higuchi

(2002). Base Transceiver Station for W-CDMA System(http://www.fujitsu.com/downloads/MAG/vol38-2/paper07.pdf) .

FUJITSU Sci. Tech. J. pp. 7.http://www.fujitsu.com/downloads/MAG/vol38-2/paper07.pdf.

External links

U.S. Patent 6,577,878 (http://www.google.com/patents?vid=6577878)

References

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Categories: Wireless networking

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