BTS - base transceiver stationA base transceiver station (BTS) or cell site is a piece of equipment that facilitates wirelessmobile phones (handsets), WLL phones, computers with wireless internet connectivity, WiFi and WiMAX gadgets etc. The network can be that of any of the wireless communication technologies like GSM, CDMA, WLL, WAN, WiFi, WiMAX etc. BTS is also referred to as the radio base station (RBS), node B (in 3G Networks) or, simply, the base stationLTE standard the abbreviation eNB for enhanced node B is widely used. communication between user equipment (UE) and a network. UEs are devices like (BS). For discussion of the
Contents
BTS in Mobile Communication
A GSM network is made up of three subsystems:
Though the term BTS can be applicable to any of the wireless communication standards, it is generally and commonly associated with mobile communication technologies like GSM and CDMA. In this regard, a BTS forms part of the base station subsystem (BSS) developments for system management. It may also have equipment for encrypting and decrypting communications, spectrum filtering tools (band pass filters) etc. antennas
may also be considered as components of BTS in general sense as they
facilitate the functioning of BTS. Typically a BTS will have several
transceivers (TRXs) which allow it to serve several different
frequencies and different sectors of the cell (in the case of sectorised
base 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 BCF provides an operations and maintenance (O&M) connection to
the network management system (NMS), and manages operational states of each TRX, as well as software handling and alarm collection. The basic structure and functions of the BTS remains the same regardless of the wireless technologies.
General Architecture
A BTS in general has the following units:
- Transceiver (TRX)
- Quite widely referred to as the driver receiver (DRX). Basically
does transmission and reception of signals. Also does sending and
reception of signals to/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 also considered a part of the BTS.
- Alarm extension system
- Collects working status alarms of various units in the BTS and
extends them to operations and maintenance (O&M) monitoring
stations.
- Control function
- Control and manages the various units of BTS including any software.
On-the-spot configurations, status changes, software upgrades, etc. are
done through the control function.
- Baseband receiver unit (BBxx)
- Frequency hopping, signal DSP, etc.
Important terms regarding a mobile BTS
- Diversity techniques
- To improve the quality of the received signal, often two receiving
antennas are used, placed at an equal distance to an uneven multiple of a
quarter of wavelength (for 900 MHz the wavelength it is 30 cm). This
technique, known as antenna diversity or space diversity, avoids
interruption caused by path fading. The antennas can be spaced
horizontally or vertically. Horizontal spacing requires more complex
installation, but better performance is obtained in this configuration.
- Other than antenna or space diversity, there are other diversity techniques such as frequency/time diversity, antenna pattern diversity, and polarization diversity.
- Splitting
- The flow of power within a particular area of the cell, known as
sector. Every field can therefore be considered like one new cell. By
using directional antennas, the co-channel interference is reduced. A
typical structure is the trisector, also known as clover, in which there
are three sectors, each one served by separate antennas. Every sector
has a separate direction of tracking of 120° with respect to the
adjacent ones. If not sectorised, the cell will be served by an
omnidirectional antenna, which radiates in all directions. Bisectored
cells are also implemented with the antennas serving sectors of 180°
separation to one another.
See also
References
Further reading
Satoshi Maruyama, Katsuhiko Tanahashi, Takehiko Higuchi (2002). Base Transceiver Station for W-CDMA System. FUJITSU Sci. Tech. J. pp. 7. http://www.fujitsu.com/downloads/MAG/vol38-2/paper07.pdf.
External links
|
|
