DSDAS

1. GSM is an open and digital cellular technology used for transmitting mobile voice and
data services operate at the 850MHz, 900MHz, 1800MHz, and 1900MHz frequencybands.
GSM technology was developed as a digital system using the time division multiple access
(TDMA) technique for communication purposes.
 Network and Switching Subsystem (NSS)
 Base-Station Subsystem (BSS)
 The mobile station (MS)
 Operation and Support Subsystem (OSS)
Network switching subsystem (NSS) (or GSM core network) is the component of a GSM
system that carries out call out and mobility management functions for mobile phones
roaming on the network of base stations.
A mobile switching center (MSC) is the centerpiece of a network switching
subsystem (NSS). The MSC is mostly associated with communications switching
functions, such as call set-up, release, and routing. However, it also performs a
host of other duties, including routing SMS messages, conference calls, fax, and
service billing as well as interfacing with other networks, such as the public
switched telephone network (PSTN).
HLR (Home Location Register) is a database that contains various information about all of the
mobile subscribers of a mobile network such as the mobile numbers, services, whether the
numbers have been ported to another network and similar information. Once an operator
turns ON his/her phone, and then the phone registers through the network so
that it is probable to decide which base transceiver station is communicating
so that incoming calls can be connected properly.
The Visitor Location Register (VLR) is a database in a mobile communications network
associated to a Mobile Switching Centre (MSC). The VLR contains the exact location of all mobile
subscribers currently present in the service area of the MSC. This information is necessary to route
a call to the right base station.
The EIR (Equipment Identity Register) is the unit that makes a decision
whether specified mobile gear may be permitted over the network. Every
mobile gear includes a number identified like the IMEI or International Mobile
Equipment Identity.
So, this IMEI number is fixed within the mobile equipment & is verified through
the network while registration. It mainly depends on the information that is
held within the EIR, and the mobile device may be assigned one of 3
conditions which allowed over the network, barred access, otherwise watched
in case its problems.

2. The base station subsystem (BSS) is the section of a traditional cellular telephone network
which is responsible for handling traffic and signaling between a mobile phone and the
network switching subsystem.
The BTS system is the part of a GSM network that is responsible for the reception and
transmission of radio signals from mobile phones. A Base Transceiver Station is a general
description of equipment consisting of the telecommunication technology and the air
interface of the mobile network (GSM, UMTS etc.).
What is base station controller?
A base station controller (BSC) is a network element that controls and monitors a
number of base stations and provides the interface between the cell sites and the
mobile switching center (MSC).
In GSM, a mobile station consists of four main components: Mobile termination (MT) - offers
common functions such as: radio transmission and handover, speech encoding and
decoding, error detection and correction, signalling and access to the SIM. The IMEI code
is attached to the MT.
The OSS or operation support subsystem is an element within the overall GSM mobile
communications network architecture that is connected to components of the NSS and
the BSC. It is used to control and monitor the overall GSM network and it is also used to control
the traffic load of the BSS.
ISDN or Integrated Services Digital Network is a circuit-switched telephone network system
that transmits both data and voice over a digital line. You can also think of it as a set of
communication standards to transmit data, voice, and signaling. These digital lines could be
copper lines.
PSTN is the traditional circuit-switched telephone network. PSTNcomprises all the
switched telephone networks around the world that are operated by local, national or
international carriers. These networks provide the infrastructure and services for public
telecommunication.
Packet switching is easier and more affordable than circuit switching. Since all the bandwidth
can be used at once, packet switching is more efficient because it doesn't have to deal with a
limited number of connections that may not be using all that bandwidth.

3. Wideband CDMA is a third-generation (3G) wireless standard which allows use
of both voice and data and offers data speeds of up to 384 Kbps.
The frequency bands for WCDMA are as follows: Europe and Asia - 2100MHz,
North America - 1900MHz and 850MHz.
WCDMA is also called UMTS and the two terms have become interchangeable.
Some parts of the WCDMA are based on GSM technology and the networks
are designed to integrate the GSM networks at some levels.
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4. In telecommunications, Long-Term Evolution (LTE) is a standard for wireless
broadband communication for mobile devices and data terminals, based on
the GSM/EDGE and UMTS/HSPA standards. It improves on those standards' capacity and speed by
using a different radio interface and core network improvements.[1][2]
LTE is the upgrade path for
carriers with both GSM/UMTS networks and CDMA2000 networks. Because LTE frequencies and
bands differ from country to country, only multi-band phones can use LTE in all countries where it is
supported.
Worldwide Interoperability for Microwave Access (WiMAX) is a family of wireless
broadband communication standards based on the IEEE 802.16 set of standards, which provide
physical layer (PHY) and media access control (MAC) options.
The WiMAX Forum was formed in June 2001 to promote conformity and interoperability, including
the definition of system profiles for commercial vendors.[1]
The forum describes WiMAX as "a
standards-based technology enabling the delivery of last mile wireless broadband access as an
alternative to cable and DSL".[2]
IEEE 802.16m or WirelessMAN-Advanced was a candidate for 4G,
in competition with the LTE Advanced standard.
WiMAX was initially designed to provide 30 to 40 megabit-per-second data rates,[3]
with the 2011
update providing up to 1 Gbit/s[3]
for fixed stations.
Orthogonal FrequencyDivision Multiplexing (OFDM) is a digital multi-carrier modulation
scheme that extends the concept of single subcarrier modulation by using multiple subcarriers
within the same single channel.
OFDM: Orthogonal Frequency Division Multiplexing, is a form of signal modulation that
divides a high data rate modulating stream placing them onto many slowly modulated
narrowband close-spaced subcarriers, and in this way is less sensitive to frequency selective
fading. Orthogonal Frequency Division Multiplexing (OFDM) is another widely used modulation
method used to achieve high data rates and spectral efficiency. It is known as a multicarrier
modulation method as many carriers are used instead of just one.
Orthogonal FrequencyDivision Multiplexing (OFDM) is an efficient modulation format
used in modern wireless communication systems including 5G. OFDM combines the
benefits of Quadrature Amplitude Modulation (QAM) and Frequency Division Multiplexing (FDM)
to produce a high-data-rate communication system.16-Apr-2020