Introduction To Telecom Networks
This is my introduction to telecom networks.
The main objective is to cover basic network concepts and introduction to network architecture and the common network devices used in telecom. Also to provide the basic understanding of networking and commonly used abbreviations in network architecture.
A computer network is a group of computers, two or more, connected to each other through a wire or a cable or even wireless. You can share files with other computers this way easily. LAN is the acronym for local access network. A LAN network is a short distance network. It connects computers that are close together, usually within a room for a building. Very rarely, a LAN network will span a couple of buildings. An example of a LAN network is the network in a school or an office building. A LAN network does not need a router to operate.
WAN stands for wide area network. WAN's cover a huge geographical area. A WAN is a collection of LAN networks. LAN's connect to other LAN's with the help of a router. The router has a LAN address and a WAN address, which lets it send data to the desired location. The biggest WAN in the world is, of course, the internet. WAN's are different from LANs in that they are not owned by a single person or organization.
VPN stands for virtual private network. VPNs are very important today. They let you connect to your network from a remote location through the internet. This saves you time and money - you do not need to set up a physical connection with your network. The internet acts as a medium between you and your network. For example, you can access your computer at work through your computer at home.
2G, first introduced in 1992, is the second generation of cellular telephone technology and the first to use digital encryption of conversations. 2G networks were the first to offer data service3s and SMS text messaging, but their data transfer rates are lower than those of their successors.
3G networks succeed 2G ones, offering faster data transfer rates and are the first to enable video calls. This makes them especially suitable for use in modern smartphones, which require constant high speed internet connection for many of their applications.
3.5G high speed packet access is an amalgamation of two mobile protocols, high speed downlink packet access and high speed uplink packet access. It extends and improves the performance of existing 3G mobile telecommunications networks utilizing the WCDMA protocols.
4G is the fourth generation of mobile phone communication standards. It is a successor of the 3G and provides ultra broadband internet access for mobile devices. The high data transfer rates make 4G networks suitable for use in USB wireless modems for laptops and even home internet access.
2G - Also known as GSM
BSC - base station controller
BSS - base station subsystem
BTS - base transceiver station
GMSC - gateway mobile switching centre
HLR - home location register
MS - mobile station
MSC - mobile switching centre
VLR - visitor location register
3G - UMTS
AUT - authentication centre
CG - charging gateway
EIR - equipment identity register
GGSN - gateway GPRS support node
MGW - media gateway
RNC - radio access network
SGSN - serving GPRS support node
UE - user equipment
WBTS - wideband base transceiver station
4G - also known as LTE
HSS - home subscriber server
MME - mobility management entity
P-GW - packet data network (PDN) gateway
S-GW - serving gateway
CDMA - code division multiple access
EDGE - enhanced data rates for GSM evolution
GPRS - general packet radio services
GSM - global system for mobile communication
HSDPA - high speed downlink packet access
IMSI - international mobile subscriber identity
MMS - multimedia messaging service
MSISDN - mobile subscriber ISDN number
SIM - subscriber identity module
SMS - short messaging service
USSD - unstructured supplementary service data
The main objective is to cover basic network models OSI model and TCP/IP model. Also to provide the basic understanding of network oriented services.
What is a network model? When dealing with networking, we may hear the terms network model and network layer used often. Network models define a set of network layers and how they interact. The international standards organization has defined a standard called the open systems interconnection reference model. TCP/IP model is sometimes called the DOD model since it was designed for the department of defence. It is also called the internet model because TCP/IP is the protocol used on the internet.
The OSI model is a reference model for how applications can communicate over a network between two endpoints. It consists of seven layers. The seven layers of function are provided by a combination of application, operating systems, network card device drivers, and networking hardware. Each layer will pass information up and down to the next subsequent layer as data is processed.
The internet protocol suite is the computer networking model and set of communications protocols used on the internet and similar computer networks. It is commonly known as TCP/IP. The internet protocol suite provides end to end data communication specifying how data should be packetized, addressed, transmitted, routed, and received. This functionality is organized into four abstraction layers which are used to sort all related protocols according to the scope of networking involved.
Network devices are components used to connect computers or other electronic devices together so they can share files or resources. Networking devices are also called communicating devices. Most networks are small, like an office or home, and even large networks are often divided into smaller segments. That smaller segment is set apart from the larger network by a device that can filter data and help the network be more efficient.
Network cards are also known as network interface cards. They are hardware devices that connect a computer with the network. They are installed on the motherboard. They are responsible for developing a physical connection between the network and the computer. Computer data is translated into electrical signals sent to the network via network interface cards.
A Hub is a connectivity device to which network cables are attached to form a network segment. Hubs typically do not filter data, but instead retransmit incoming data packets or frames to all parts. Almost all networks today use a central hub or switch to which the computers on the network connect.
A network switch is a computer networking device that connects devices together on a computer network, by using packet switching to receive, process, and forward data to the destination device. Unlike less advanced network hubs, a network switch forward data only to one or multiple devices that need to receive it, rather than broadcasting the same data out of each of its ports.
A router is a device that forwards data packets based on logical addresses on networks. A router is connected to at least two networks, commonly known as LANs or WANs. Routers are an essential part of any large network. In fact, without the development of network routers and TCP/IP routing protocols, the internet would not have become as extensive.
A bridge is a computer networking device that builds the connection with another bridge that uses the same protocol. It works at the data link layer of the OSI model and connects different networks together and develops communication between them.
Brouters are the combination of both the bridge and routers. They take up the functionality of both networking devices serving as a bridge when forwarding data between networks, and serving as a router when routing data to individual systems. Brouter functions as a filter that allows some data into the local network and redirects unknown data to the other network.
A firewall is a network security system designed to prevent unauthorized access to or from a private network. Firewalls can be implemented in both hardware and software, or a combination of both. Network firewalls are frequently used to prevent unauthorized internet users from accessing private networks connected to the internet, especially intranets. All messages entering or leaving the intranet pass through the firewall, which examines each message and blocks those that do not meet the specified source criteria.
VoLTE and Vo-WiFi
LTE is a mobile internet technology standard. It is an abbreviation of Long Term Evolution. You may wonder why LTE keeps popping up in the context of 4G. Well, 4G is just a common name given to LTE technology. In short, 4G and LTE are synonyms. LTE is considered a technological evolution on both CDMA and GSM standards that were used several years ago. Nowadays, LTE is fast becoming available across the globe and mobile internet service providers are upgrading their networks from 3G to 4G. LTE is at present the fastest data transfer technology.
VoLTE stands for voice over LTE and it is more or less exactly what it says on the tin. It is voice calls over a 4G LTE network, rather than the 2G or 3G connections which are usually used. We tend to think of 4G as mostly being about downloading, streaming, and web browsing, and indeed that is primarily what it has been used for so far, but it can also be used to improve calls. Technically, voice over long term evolution is a standard for high speed wireless communication for mobile phones and data terminals. It is based on the IP Multimedia Subsystem network, with specific profiles for control and media planes of voice service on LTE defined by GSMA.
The benefits of Vo-LTE include superior call quality, improved coverage, improved connectivity, better battery life, video calling, and ability to use voice and data at the same time.
Wi-Fi calling has been around for a long time. Voice calls have been transmitted over Wi-Fi either in the form of over the top content apps like Skype. The problem with OTT applications from an operator's perspective is that the operator loses control. The technology has been available for some time but operators have been hesitant. They have wanted to protect their voice related revenue including revenue from roaming charges.
Wi-Fi is everywhere. People are already running the vast majority of their data through Wi-Fi. At the moment as much as 80% of all mobile data is going over Wi-Fi and a big portion of this is, of course, indoor traffic including traffic from within people's homes.
In short, Vo-Wi-Fi is keeping customers connected without a mobile signal. Technically, Vo-Wi-Fi simply stands for voice over Wi-Fi. It is a complementary technology to VoLTE and uses IMS technology to provide a packet voice service that is delivered over IP via a Wi-Fi network. Where possible, VoLTE calls may be seamlessly handed over between LTE and Wi-Fi and vice versa.
There are several benefits to Vo-Wi-Fi. Consumers can make calls without the need for a mobile signal. They can benefit from security being based on SIM based authentication. There is also better indoor coverage. Network operators experience many benefits also. There is better indoor coverage compared to cellular macro base stations. This solves an increasing problem with the radio tight modern building structures. They have high customer acquisition rates. Wi-Fi is a low cost solution to enhance voice service coverage. Operators do not necessarily invest in a Wi-Fi footprint. Instead they are relying on existing Wi-Fi networks. Wi-Fi calling is sharing similar infrastructure with IMS based VoLTE.
IVR(interactive voice response)
Interactive voice response is a technology that allows a computer to interact with humans through the use of voice and DTMF tones input via keypad. In telecommunications, IVR allows customers to interact with a company's host system via a telephone keypad or by speech recognition, after which services can be inquired about through the IVR dialogue. IVR systems can respond with prerecorded or dynamically generated audio to further direct users on how to proceed. IVR systems deployed in the network are sized to handle large call volumes and also used for outbound calling., as IVR systems are more intelligent than many predictive dialler systems.
IVR systems can be used for mobile purchases, banking payments and services, retail orders, utilities, travel information, and weather conditions.
Introduction To Intelligent Network
The intelligent network is the standard network architecture specified in the ITU-T Q.1200 series recommendations. It is intended for fixed as well as mobile telecom networks. It allows operators to differentiate themselves by providing value added services in addition to the standard telecom services such as PSTN, ISDN, and GSM services on mobile phones. The intelligence is provided by network nodes on the service layer, distinct from the switching layer of the core network, as opposed to solutions based on intelligence in the core switches or telephone equipment. The IN nodes are typically owned by telecommunications operators.
IN is supported by the SS&(signaling system 7 protocol) between telephone network switching centers and other network nodes owned by network operators. By using additional technology, such as a SCP(service control point) and a SMS(service management system), these advanced networks can accommodate services like call screening or call waiting, as well as more complex services like variable charging, caller ID services and international messaging.
The call flow usually refers to how calls/sms from calling party number to called party number are handled and passed through the system. We have different types of call flows in telecom: mobile originated call flow, mobile terminated call flow, mobile originated sms flow, and mobile terminated sms flow.
Introduction to SCP
SCP(service control point) is a standard component of the Intelligent Network telephone system which is used to control the service. Standard SCPs in the telecom industry are deployed using SS7, SIGTRAN, or SIP technologies. The SCP queries the service data point which holds the actual database and directory. SCP, using the database from the SDP, identifies the geographical number to which the call is to be routed. SCP may also communicate with an intelligent peripheral to play voice messages, or prompt for information to the user, such as the prepaid long distance using account codes. This is done by implementing telephone feature codes like #, which can be used to terminate the input for a user name or password or can be used for call forwarding.
Active and standby mode is a process by which the complete set of data in one system is replicated into the other. In case of any failover in the primary system the secondary system takes care of the functionalities there by. This ensures system availability in case of any component failure. In this system only one system at any time actively participates within the session. For example, all our data sessions, our internet browsing are maintained on two servers at the same time so that if one system goes down the other standby system shall come up and provide the required services to the customer. On the other hand, it helps in recording of proper CDR's during system failure and proper updating of customer databases.
Introduction to IP
IP stands for internet protocol. An internet protocol is a set of rules that govern internet activity and facilitate completion of a variety of actions on the world wide web. An IP address is a fascinating product of modern computer technology designed to allow one computer to communicate with another via the internet. IP addresses allow the location of literally billions of digital devices that are connected to the internet to be pinpointed and differentiated from other devices. In the same sense that someone needs your mailing address to send you a letter, a remote computer needs your IP address to communicate with your computer.
There are two versions of the internet protocol: IP version 4 and IP version 6. Each version defines an IP address differently. The generic term IP address typically still refers to the addresses defined by IPv4. The gap in version sequence resulted from the assignment of the number 5 to the experimental Internet Stream Protocol in 1979, which was never referred to as IPv5.
An IP address in IPv4 is 32 bits in size. IPv4 reserves some addresses for special purposes such as private networks or multicast networks. So, IPv4 addresses can be either private or public.
IPv4 addresses are usually represented in dot-decimal notation, consisting of four decimal numbers, each ranging from 0 to 255, separated by dots, 172.16.254.1. Each part represents a group of 8 bits(octet) of the address.
The new generation of the internet protocol was named IPv6. The address size was increased from 32 to 128 bits(16 octets). The intent of the new design was not to provide just a sufficient quantity of addresses, but also redesign routing in the internet by more efficient aggregation of sub0network routing prefixes. This resulted in slower growth of routing tables in routers. The smallest possible individual allocation is a subnet for 2^64 hosts, which is the square of the size of the entire IPv4 internet.
In IPv6 each system can take one or more IP addresses. An IPv6 has three types of addresses:
Link Local - each system will have permanent link local addresses. The Link Local addresses are generated from the MAC address of the system.
Site Local - Similar to private addresses in IPv4.
Global - Similar to public addresses in IPv4.