An expert mobile user who has good command over his
Smartphone often lacks the knowledge of the underlying mobile technology which
is helping him in making calls, connecting him to his favorite video or music
streaming services, etc.
Also sometimes I come across my friends who have good command over their mobiles, much more than me at least, and they even work for some mobile companies in a non-technical department, however their knowledge of the technology and the connectivity is quite weak.
Also sometimes I come across my friends who have good command over their mobiles, much more than me at least, and they even work for some mobile companies in a non-technical department, however their knowledge of the technology and the connectivity is quite weak.
When I tried to search
internet to find a simple tutorial then I found many good articles on Wikipedia,
etc but they were a bit more technical which forced me to contribute to this
field, I hope some people will like it, in shaa Allah.
In order to keep the article brief technical terms used in the tutorial are not explained in further details, the readers who are more interested in these may find Wikipedia and other internet resources more informative.
In order to keep the article brief technical terms used in the tutorial are not explained in further details, the readers who are more interested in these may find Wikipedia and other internet resources more informative.
What is a Mobile Network composed of
A generic Telecom network is composed of different components supplied by a long list of vendors, these networks are organized in an interwoven topology based on the needs of inter-connectivity, Network Security and resilience.
However in order to
understand the Telecom Network it can be segregated in a number of Building Blocks
each with distinct capabilities and offering different and distinct services to
other blocks, also these blocks have distinct interfaces to connect to other
blocks with detailed specifications written and agreed through internationally
accepted and agreed governing bodies like ITU, IEEE, etc.
Below is a list of generally known blocks and the service they offer and the interfaces they
have:
RAN
(Radio Access Network)
RAN is comprised of the equipment that connects the user on
Air Interface, in simple words it connects any mobile phone or data device like tablets to the wireless
network, further it aggregates the data from a large number of users and send it
towards the core network where the user can get access to different
services offered by the Network Operator.
Based on the Wireless Technology RAN
equipment can have different names, however from a user's point of view all
these components have the similar usability, i.e. to allow the users to use the
network services.
Wireless Air Aggregation
Technology Interface Equipment
Equipment
2G BTS BSC
3G NodeB RNC
4G eNodeB ePC
(Part
of Core Network)
RAN network looks very simple in the picture however it is
very complex in nature as the connectivity of user to the network is on
wireless media and it needs a lot of planning and optimization and thorough drive tests to ensure full network availability in coverage areas because any problem
in RAN has its immediate effect on the end user experience.
Transmission
Transmission is an essential part of Telecom Network, it
provides the backbone on which all other blocks connect to each other, in many
cases it also provides the connectivity within then blocks as well.
Even though it is not separately mentioned in any of the
pictures however the connecting lines in these picture which are within the blocks
connecting small blocks and between the blocks may be passing through
Transmission devices especially if the entities are not co-located
geographically.
Transmission is comprised of many flavors; Physical
Infrastructure wise from Coaxial Cables to Microwave Radio to Optical Fiber to
VSAT, Technology wise from SDH to ATM to IP/MPLS, capacity wise from Fractional
E1 to STM64 and from FE to 400GBPS.
Core Network
Core Network is the heart of the Network and it is most
crucial as well because this is where many entities meet. Financially this
is most vulnerable area because this is where all data is stored and where
charging/billing takes place.
Each component of Core network has a specific thing to do,
below we will briefly describe the function of each component:
MSC: Mobile Switching Center, this is where the calls
are connected, however this connection is on Circuit Switch basis generally
referred as the 2G/3G voice calls.
SGSN: Serving GPRS Support Node, this is where the
data sessions are handled, browsing internet, making video calls is handled
here, these sessions/calls are generally referred as Packet Switched as they
are based on data packets not mere voice signals.
GGSN: Gateway GPRS Support Node, this is the
equipment by which the users are connected to the Internet.
Charging is the component which keeps track of the
billing of pre-paid and post paid customers.
ePC: Evolved Packet Core, this is the place where the
4G eNodeBs connect, there is no Packet or Circuit based segregation in ePC as
all the users are handled in a data only manner, all voice, video and services
are packet data based or generally speaking IP based.
One special ability of ePC is the offloading to the Wi-Fi
network, if the LTE network is in congestion or the user is in a area of a
better coverage of Wi-Fi or Femtocell then it can be smoothly offloaded to this
network bringing ease to the precious LTE air interface to serve other
customers.
EIR: Equipment Identity Register is a database of the
all active mobile handsets, this can be used to track the mobile theft and
providing device based services.
AAA: Authentication, Authorization, Accounting server, this is the server where all user records are maintained, the users are authenticated, granted permission to use different resources.
Services/Application Network
These are different entities providing different services to
the end users, i.e. the mobile user.
Whatever we do in our Smartphone, from making calls to browsing
the internet, sending SMS to chatting on social network, making of video calls
to streaming videos is called a service and each service is provided through
the services network.
PSTN: Public Switched Telephone Network, this is the
service which the user uses to make calls to landline network of the same
company whose Mobile service is being used by him.
PLMN: Public Land Mobile Network, this is the
interface from where you connect to other Mobile or Fixed Line operators, if
you call to other networks then your call is connected through this entity.
Internet: As the name suggests this is from where you
connect to the Internet
IMS: IP Multimedia Subsystem, this is your gateway to
your operator's IP network, in the present day architecture all the IP services
are being converged to an all IP network through IMS, this architecture will
ease the way for managing and delivering new services to the end user.
Application Servers: This is the area where your
mobile operators has put all the application servers and any user who is trying
to access any service is connected to the Application Servers through the IP
Multimedia Subsystem.
I hope this topic was useful for a general user to
understand the Mobile network in a brief, below is the whole picture integrated
together to fully understand end to end.
Picture Source: LTE Testing Brochure from Spirent
www.spirent.com
