CONTENTS
1. GENERAL
2. GLOBAL SYSTEM FOR MOBILE COMMUNICATION (GSM)
3. UNIVERSAL MOBILE COMMUNICATIONS SYSTEM (UMTS)
4. 4G
5. 5G
6. WIRELESS FIDELITY (WIFI)
7. IP MULTIMEDIA SUBSYSTEM (IMS)
8. TRANSMISSION
9. RADIO N ETWORK OPERATIONS (RNO)
10. HLR FEATURES
11. IN OPERATIONS & VALUE ADDED SERVICES (VAS)
12. NETWORKING
1. GENERAL
1)OSI stands for Open Systems Interconnection and is a conceptual framework for how
applications communicate over a network.
There are seven layers within the model and the layers depiction is used to help users identify
what is happening within a networking system.
The OSI model layers are typically described from the top layer down. The layers are described
as Application, Presentation, Session, Transport, Network, Data Link, and Physical.
These layers are provided by a mixture of network card drivers, operating systems,
applications, and networking hardware that facilitate the transmission of signals over Ethernet,
Fiber Optic, Wi-Fi, or other wireless protocols.
OSI Reference Model stands for Open system interconnection reference model which is used for
communication in various networks.
Open system interconnection (OSI) reference model consists of seven layers or seven steps
which concludes the overall communication system.
The architecture of the OSI Reference model
seven layers of OSI Reference Model:
7.Application Layer
6.Presentation Layer
5.Session Layer
4.Transport Layer
3.Network Layer
2.Data link Layer
1.Physical Layer
1) Layer 1 – Physical layer
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The physical layer is the first and bottom-most layer of the OSI Reference Model.
It mainly provides the bit stream transmission.
It also characterizes the media type, connector type and signal type to be used for
communication.
Basically, the raw data in the form of bits i.e. 0’s & 1’s are converted into signals and
exchanged over this layer.
Data encapsulation is also done at this layer.
The sender end and the receiving end should be in synchronization and the
transmission rate in the form of bits per second is also decided at this layer.
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It provides a transmission interface between the devices and the transmission media
and the type of topology to be used for networking along with the type of transmission
mode required for transmission is also defined at this level.
Usually, star, bus or ring topologies are used for networking and the modes used are
half-duplex, full-duplex or simplex.
Examples of layer 1: devices include hubs, repeaters & Ethernet cable connectors. These
are the basic devices that are used at the physical layer to transmit data through a given
physical medium which is suitable as per the network need.
Simply this is the Mechanical and electrical interfacing.
In troubleshooting problems this is typically the 1st place to start.
2) Layer 2 – Data-link Layer
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Data-link layer is the second layer from the bottom of the OSI Reference Model.
The main function of the data-link layer is to perform error detection (not correction)
and combine the data bits into frames.
It combines the raw data ⟶ bytes ⟶frames and transmits the data packet to the
network layer of the desired destination host.
At the destination end, the data-link layer receives the signal, decodes it into frames and
delivers it to the hardware.
Data link control (framing, error control).
There are 2 sub layers in this layer.
1) Media Access Control (MAC)
2) Logical Link Control (LLC)
A MAC address is a unique device address and each device or component in a network has a
MAC address on the basis of which we can uniquely identify a device of the network. It is a 12
digit unique address.
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Examples of data link protocols are Ethernet for local area networks (multi-node), the Pointto-Point Protocol (PPP), HDLC and ADCCP for point-to-point (dual-node) connections.
3) Layer 3 – Network Layer
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The network layer is the third layer from the bottom.
This layer has the accountability to accomplish the routing of data packets from the
source to destination host between the inter and intra networks operating on the
same or different protocols.
The function of this layer is to route the packets from the source to destination by using
the logical IP addressing and routers for communication.
4) Layer 4 – Transport Layer
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This layer guarantees an end to end error-free connection between the two
different hosts or devices of networks.
This is the first one which takes the data from the upper layer i.e. the application
layer, and then splits it into smaller packets called the segments and dispenses
it to the network layer for further delivery to the destination host.
It ensures that the data received at host end will be in the same order in which
it was transmitted.
It provides an end to end supply of the data segments of both inter and intra
sub-networks.
For an end to end communication over the networks, all devices are equipped
with a Transport service access point (TSAP) and are also branded as port
numbers.
A host will recognize its peer host at the remote network by its port number.
(ii) The two transport layer protocols include:
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Transmission control protocol (TCP)
User Datagram Protocol (UDP)
5) Layer 5 – Session Layer
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This layer permits the users of different platforms to set up an active
communication session between themselves.
The main function of this layer is to provide sync in the dialogue between the two
distinctive applications.
The synchronization is necessary for efficient delivery of data without any loss at the
receiver end.
It will help in keeping the data safe and the whole data host will never
completely get lost if some crash happens.
Also, token management, will not allow two networks of heavy data and of the
same type to transmit at the same time.
6) Layer 6 – Presentation Layer
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The presentation layer will present the data to its end users in the form in which
it can easily be understood.
Hence, this layer takes care of the syntax, as the mode of communication used by
the sender and receiver may be different.
It plays the role of a translator so that the two systems come on the same platform
for communication and will easily understand each other.
The data which is in the form of characters and numbers are split into bits
before transmission by the layer.
It translates the data for networks in the form in which they require it and for
devices like phones, PC, etc in the format they require it.
The layer also performs data encryption at the sender's end and data
decryption at the receiver's end.
It also performs data compression for multimedia data before transmitting, as the
length of multimedia data is very big and much bandwidth will be required to
transmit it over media, this data is compressed into small packets and at the
receiver's end, it will be decompressed to get the original length of data in its
own format.
7)Top Layer – Application Layer
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This is the topmost and seventh layer of the OSI reference model. This layer will
communicate with the end users & user applications.
This layer grants a direct interface and access to the users with the network.
The users can directly access the network at this layer.
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There is vagueness in this layer as is not all user-based information and the software
can be planted into this layer.
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Software testing programs will work on this layer as the application layer
provides an interface to its end users to test the services and their uses. The HTTP
protocol is mostly used for testing at this layer but FTP, DNS, TELNET can also be
used as per the requirement of the system and network in which they are operating.
2. Frequency Hopping: Frequency Hopping Spread Spectrum (FHSS) is a method used to
rapidly switch transmitting radio signals among several frequency channels.It is kind of a
communication scheme between a transmitter and a receiver. It has mainly the purpose of
avoiding interference.So Frequency hopping is a technique mainly used to keep two or more
RFID readers from interfering with each other while reading RFID tags in the same area.
Frequency Hopping Parameters:
Hopping Sequence Number(HSN)
Mobile allocator index(MAIO)
3.A signaling protocol is a type of protocol used to identify signaling encapsulation.
Signaling is used to identify the state of connection between telephones or VOIP terminals
4.The advantages of CCS(SS& signaling) compared to CAS
uses the same channel as for data
provides intelligence to the network, and allows quicker call setup and teardown saving time
and money
Faster call setup times (compared to in-band signaling using multi-frequency (MF) signaling
tones)
More efficient use of voice circuits
Support for Intelligent Network (IN) services which require signaling to network elements
without voice trunks (e.g., database systems)
Improved control over fraudulent network usage
2. GLOBAL SYSTEM FOR MOBILE COMMUNICATION (GSM)
5)GSM Architecture with Interfaces
6)GSM protocol stack
7)GSM channel types
8) GSM Frequency Band Allocation
Frequency band(MHz)
Bandwidth(MHz
Frequency
Carrier frequency
)
number
number (pair)
GSM900
Up 890–915
Down 935–960
25
1–124
124
DCS1800
Up 1710–1785
Down 1805–1880
75
512–885
374
9)
a) MSC-Mobile switching Centre
A telephone exchange which makes the connection
 Between Mobile users within network
 From mobile users to the public switched telephone network
 From mobile users to other mobile networks
Control BSCs, RNCs, User Management, Call Control, Mobility Management, CDR
Creation, Resource allocation etc.
b) HLR- Home Location Register
Component of GSM which gives the information of the subscriber to the MSC. Store
Permanent Subscriber Data such as IMSI, MSISDN and granted services such as Voice,
SMS etc.
c) VLR- Visitor Location Register
Keep a temporary record of HLR data with relevant information captured from Access Network
such as LAI(The Location Area Identity)
d) BTS- Base Transceiver Station
BTS controls the radio interface to the Handset
e) BSC- Base Station Controller
Manage Connected BTS (Base Transceiver Station)
Responsible for the allocation of radio resources to a mobile call and for the handovers
that are made between base stations under his control.
f) EIR- Equipment Identity Register
Store the IMEI (International Mobile Equipment Identity) information of the User
Equipment related subscribers IMSI (International Mobile Subscriber Identity) and
perform Black list, White list and grey list functions
g) AuC- Authentication Centre
Store SIM card Authentication Data such as KI and issue Authentication vectors upon
the request from MSC/SGSN
10)Call flow of GSM MO call and MT voice call
11)Call flow of GSM MO sms and MT sms
MO sms
MT sms
12)
a) SGSN/GGSN- The Serving GPRS Support Node (SGSN) is a main component of the
GPRS network, which handles all packet switched data within the network, e.g. the
mobility management and authentication of the users. The SGSN performs the same
functions as the MSC for voice traffic. The Gateway GPRS Support Node (GGSN) is a
main component of the GPRS network. The GGSN is responsible for the interworking
between the GPRS network and external packet switched networks, like the Internet and
X. 25 networks
b) GMSC- The Gateway Mobile Switching Centre (GMSC) is a special kind of MSC that is
used to route calls outside the mobile network. Whenever a call for a mobile subscriber
comes from outside the mobile network, or the subscriber wants to make a call to
somebody outside the mobile network the call is routed through the GMSC
c) SMSC- The Short Message Service Centre (SMSC) is an element in a GSM network
responsible for the delivery of short messages (SMS). All messages are sent to the SMSC.
The SMSC stores the messages, extracts the destination from it and tries to deliver the
message.
13) Function of SGSN- Handles all packet switched data within the network.
Function of GGSN- Responsible for the interworking between the GPRS network and external
packet switched networks
14) Function of SMSC- Responsible for handling the SMS operations of a wireless network.
When an SMS message is sent from a mobile phone, it will reach an SMS center first. The SMS
center then forwards the SMS message towards the destination. An SMS message may need to
pass through more than one network entity (e.g. SMSC and SMS gateway) before reaching the
destination. The main duty of an SMSC is to route SMS messages and regulate the process. If the
recipient is unavailable (for example, when the mobile phone is switched off), the SMSC will
store the SMS message. It will forward the SMS message when the recipient is available
15)
a) IMSI-(The International Mobile Subscriber Identity) GSM Identity which is used for
correct identification over the radio path and through the GSM PLMN network. The IMSI
is stored in the SIM, in the HLR
and VLR.
IMSI= MCC + MNC + MSIN
b) IMEI-(International Mobile Equipment Identity) It’s a GSM Identity which is used for
equipment identification
c) ICCID-(Integrated Circuit Card Identifier) It’s a GSM Identity which is the unique serial
number that a SIM card contains.
d) MSISDN-(Mobile Station International Subscriber Directory Number) It’s a GSM Identity
which is a number which uniquely identifies a mobile telephone subscription in the
PSTN numbering plan.
MSISDN = CC + NDC + SN
e) LAI- (The Location Area Identity) It’s a GSM Identity which is used for paging, and tells
the MSC which the MS is
located
in. It is also used for location updating of
mobile subscribers.
LAI= MCC + MNC + LAC
f) CGI- (Cell Global Identity) It’s a GSM Identity which is a globally unique identifier for a
Base Transceiver Station in mobile phone networks. It consists of four parts: Mobile
Country Code (MCC), Mobile Network Code (MNC), Location Area Code (LAC) and Cell
Identification (CI)
16)GPRS network architecture
17) Types of Handovers in GSM network
1. Intra-cell handover
Such a kind of handover is performed to optimize the traffic load in the cell or to improve
quality of a connection by changing carrier frequency.
2 Inter-cell handover
It is also known as Intra-BSC handover.
Here the mobile moves from one cell to another but remains within the same BSC (Base station
controller).
Here the BSC handles the handover process
3 Inter-BSC handover
It is also called as Intra-MSC handover.
As BSC can control only a limited number of cells, we might usually need to transfer a mobile
from one BSC to another BSC.
Here the MSC handles the handover process.
4 Inter-MSC handover
It occurs when a mobile moves from one MSC region to another MSC.
MSC cover a large area. It can be imagined as a handover from one Continent MSC to another
Continent MSC while travelling.
3. UNIVERSAL MOBILE COMMUNICATIONS SYSTEM (UMTS)
18)
a) NodeB- NodeB is a term used in UMTS equivalent to the BTS (base transceiver station)
description used in GSM .NodeB controls the radio interface to the UMTS Handset
b) RNC- Radio Network Controller Manage Connected NodeBs
c) HSDPA/HSUPA- HSPA (High Speed Packet Access), commonly referred to as 3.5G. It is
an upgrade to WCDMA networks that allows for much higher data speeds for internet
connectivity. There are two aspects to this technology and each is more or less
independent of the other.
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HSDPA (High Speed Downlink Packet Access) is the one that improves the
downlink of the data transmission.
HSUPA (High Speed Uplink Packet Access) is the one that improves the uplink or
transmission from the mobile device to the network.
d) MIMO- MIMO (multiple input, multiple output) is an antenna technology for wireless
communications in which multiple antennas are used at both the source (transmitter)
and the destination (receiver). It is a method for multiplying the capacity of a radio
link to exploit multipath propagation.
19)3G network architecture with interfaces and protocols
20)3G UMTS physical and logical channels
21)Main functions of RNC
RNC is a governing element in the UMTS radio access network (UTRAN) and is responsible for
controlling the NodeBs that are connected to it. The RNC carries out radio resource
management, some of the mobility management functions and is the point where encryption is
done before user data is sent to and from the mobile.
4. 4G
22)LTE network architecture
23) Voice over Long-Term Evolution (VoLTE)
This is a standard for high-speed wireless communication for mobile phones and data terminals,
including Internet of things (IoT) devices and wearables.
This approach results in the voice service (control and media planes) being delivered as data
flows within the LTE data bearer, with no dependency on the legacy circuit-switched voice
network to be maintained.
24)OFDMA concept
Orthogonal frequency-division multiple access (OFDMA) is a multi-user version of the
popular orthogonal frequency-division multiplexing (OFDM) digital modulation scheme,
Multiple access is achieved by assigning subsets of sub-carriers to different users, allowing
simultaneous data transmission from several users. In OFDMA, the radio resources are twodimensional (2D) regions over time (an integer number of OFDM symbols) and frequency (a
number of contiguous or non-contiguous sub-carriers).
OFDMA concept:FFT
5. 5G
25)5G network architecture with interfaces
26)Features of 5G
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5G has better coverage area and high data rate at the edge of the cell.
It has low battery consumption.
Availability of multiple data transfer rate.
Around 1 Gbps data rate is easily possible.
Security is more.
Energy efficiency and spectral efficiency are good.
6. WIRELESS FIDELITY (WIFI)
27) WiFi network architecture
7. IP MULTIMEDIA SUBSYSTEM (IMS)
28) IMS architecture
8. TRANSMISSION
29) The importance of the tower on the BTS is to have a clear Line of Sight for the PDH/SDH
radio & give room for easy radiation of radio signals by the sectorial antenna. The different
hierarchies having different bit rates are combined. These hierarchies will comprised of many
such bit streams/channels
SDH network- Synchronous Digital Hierarchy (SDH) are microwave commonly used on the
Base Station System. SDH has a capacity of 75 E1.Its used basically on the Hub stations for
transmission to the BSC on the Ater interface.
PDH network- Plesio synchronous Digital Hierarchy (PDH ). PDH microwave has a capacity of
16E1 making it the mostly used for BTS transmission since it gives room for upgrade and it is
very efficient in terms of radio transmission to the BSC on the Abis interface.
30) Equipments used in transmission network
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Microwave antennas
IDU/ODU
Muxes
Repeaters
31) The types of Huawei microwave links. Draw the structure of any of those links
Huawei microwave link types:
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RTN 620
RTN 950
The structure of any of those links:
32) safety, redundancy methods used in microwave links
One of the best ways to retain some level of control during uncontrollable events is to build
redundancy into the communications network. Backing up fiber and microwave links with high
capacity, low latency point-to-point radio links offers the ability to maintain the mission critical
operations in the event that the primary network fails.
9. RADIO NETWORK OPERATIONS (RNO)
33) The equipments site engineer has to carry when attending a site survey
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Camera: for photos.
Batteries: for the Camera.
Keys and Locks Secrets: for both your company and competitors, when their sites can be shared
Binoculars: to view other distant points, such as possible transmission sites.
Compass: orientation of azimuths.
Phones with Test Mode enabled: to check the signal.
Proper Climbing Equipment: if you need to climb a tower.
Small Notepad: for quick notes, that fits in your pocket.
Template printed with key data to be collected: Use one sheet for each candidate, to record all
relevant and necessary information.
34) The information contains in a site surveying report
REFERENCE:
Site name:
Address:
Coordinates: N:
E:
Participants
Option:
Site ID:
Infra Height: (Tower/Pole)
Type(GF/RT):
Building Height for RT sites:
Name
Date
RNO
Civil
Transmission
Power
SA
Site owner/ Site Acquisition team’s Special
Requirements
Signature & Dates
( Site Acquisition Division)
COC & other affiliated approval status:
Cost confirmation
Construction related
additional scope of work
Civil
Power
Other
Total site additional cost
Amount
LKR
…………………………………….
Head-Radio Network Planning & Optimization
35.) Components of a BTS
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Antennas
RRU
BBU
Transceiver (TRx)
Battery bank
Name, Signature & Date
(Area responsible Eng./Mgr.)
…………………………………..
Date
36) PAT- preliminary acceptance test
Evaluate whether the installation has been carried out properly by the vendor according to the
service providers requirements. PAT report is created per a site hence it should contain the site
name site ID and the data of evolution. If the installation has not been carried out for the
relevant requirements PAT is rejected and service provider won’t accept it. Then it has to be
redone by correcting the faults mentioned in the punch list to get passed. PAT is conducted after
completion of the equipment by the parties involved in the installation.
Civil PAT is done at first to make sure the structure of the tower is according to the standards.
Then BTS PAT is conducted to check the following parameters
Earthing
Hardware installation
Cabling
Antenna and feeders
External alarm test
RFU power output test
Call test
PAT is also done to check the radio parameters like handovers, call drops ect .
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37) The tools used for drive testing
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Test phone
Nemo handy software installed in firmware in the test phone
38) Antenna tilt means
There are two types of antenna tilt as explained in figure. They are;
I.
Electrical tilt – Changing the vertical directions of the plates in transmitters. It does not
affect the other transmitters.
II.
Mechanical tilt – Changing the vertical direction of the antenna. It changes the direction
of all the transmitters in the antenna.
Examples of Electrical and Mechanical Tilt Respectively
39) Process of planning an IBS
• Solution description
• Coverage plan
• System diagram
• Power budget calculation
• Proposed antenna location photograph
• System layout on floor plan ( ACAD)
• Measurement results
40)The components of DAS (Distributed Antenna system)
A Distributed antenna system (DAS) is a network of antennas, connected to a common source,
distributed throughout a building or an area to improve network performance. The spacing
between antennas is such that each antenna gives full coverage without overlapping with other
antennas, hence reducing the number of antennas needed to cover the whole building. This
network of antennas is also power efficient in comparison to a single, larger antenna covering a
wide area.
A Distributed Antenna System can be designed for use
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Indoors or outdoors
To provide wireless coverage in hotels, subways, airports, hospitals, businesses,
roadway tunnels etc.
The wireless services typically provided by a DAS include PCS, cellular, Wi-Fi, police, fire, and
emergency services
10.
HLR FEATURES
41)
a.) Roaming
Roaming is the ability for a customer of mobile communications to automatically make and
receive telephone calls, send and receive data, or access other services while travelling outside
the geographical coverage area of the home network, by means of using a network of another
operator.
I.
Inbound roaming
Inbound roaming allows subscribers from other operators to access the local network and
services. Foreign Network Mobile Subscriber that is currently roaming in the Home
Mobile Network.
II.
Outbound roaming
Outbound roaming allows subscribers from the local network to access another operator's
network and services. Home Network Mobile Subscriber that is currently roaming in a
foreign Mobile Network.
b.) Call Forwarding
a.CFU – Call forwarding unconditional; all calls are forwarded to third party
b.CFB – Call forwarding busy; call forwarded to thord party when the subscriber is busy. Thos
service has 2 types; Network determined user busy(NDUB),User determined user busy (UDUB)
c.CFNRc – Call forwarding on mobile subscriber not reachable; If the radio channel between the
network and the subscriber is disconnected, all the calls are forwarded to third party. No
response for paging, Radio channel assignment failure, UE power off can be the reasons for
triggering the service
d.CFNRy –Call forwarding no reply; When subscriber des not answer for a call for an incoming
call for a long time after being alerted, the call is forwarded to third party after the answer time
expires.
c.) Call barring
Call Barring is a service that allows subscribers to stop all calls (either incoming or outgoing) on
their sim.
d.) Call waiting
With call waiting, a party can be notified of a new incoming call while on a call. Call waiting is a
telecommunication service offered by a telephone service provider to a subscriber by which the
subscriber may suspend a telephone call already in progress to accept a second call.
e.) Call diversion
Call diversion enables the user to forward or redirect their incoming calls to an alternate
number. When call divert is enabled, the phone does noit ring at the original number of the
incoming call, but rather only at the locations the call had been diverted to.
f.) Call conference
One can talks to several people at the same time using call conference. Allows subscriber to
establish a multiparty conversation.
g.) Miss call alert
This is a service provided to customers enabling them to be alerted via SMS notifications
indicating who they have received incoming calls at a given time when they were not reachable
due to a various number of reasons such as no coverage, battery power out etc. which will
enable them to return the calls missed.
11.
IN OPERATIONS & VALUE ADDED SERVICES
42.) Protocols used in Intelligent network
INAP stands for Intelligent Network Application Protocol or Intelligent Network
Application Part. It is the signalling protocol used in Intelligent Networking (IN).
43.) Diagram to show prepaid call flow
44.) VAS
VAS- Value added services
Mobitel offers a wide range of value added features while roaming to make customer’s roaming
experience a good one
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Data Roaming
SMS Roaming
CALL HOME & SMS HOME
Roaming self-service portal
Roaming Call Screening
GPRS Roaming Self-Activation/Deactivation
45.) OCS
OCS- Online Charging System. It is a specialized communications function that allows a service
provider to charge a user for services in real-time. The OCS handles the subscribers account
balance, rating, charging transaction control and correlation. With the OCS, a telecom operator
ensures that credit limits are enforced and resources are authorized on a per transaction basis.
Traditional online charging systems charge the customer after a service is rendered, whereas
the OCS charges as services are rendered. OCS is more flexible than Intelligent Network (IN)
prepaid solutions.
46.) The basic functions of OCS nodes
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SCP – Service control Point (Call control function)
CBP – Convergent Billing Point (Charging function, provides a unified rating & billing
engine, periodic charging, event, session based charging, accumulates usage realtimely and generates rated CDRs for future query)
BMP – Business Management Point (Web interface to customer care and
Provisioning, prepaid features configuration, account balance management, pricing
management, subscriber management)
UVC – Universal Voucher System (Recharge card management)
BQ – Bill Query (TO query CDR/ customer history)
URP – Universal Resource Point (IVR – Interactive Voice Response)
RBI – Record Bill Interface (CDR storage and transfer to mediation)
DCC proxy/CBP Adapter (Interfaces third party services to OCS via Diameter)
USAU – Universal Signaling Access Point (Protocol conversion between IP and SS7)
47.) PCRF
Policy and Charging Rules Function (PCRF) is the software node designated in real-time to
determine policy rules in a multimedia network.
12.
NETWORKING
48.) An IP address
IP- Internet protocol is used to identify computers on the internet. An IP Address is a numerical
representation unique for a device when connected to internet. All devices that are connected to
an internet connection have a unique IP address
49.) A protocol
Protocol is a standard used to define a method of exchanging data over a computer network. By
adopting these rules, two devices can communicate with each other and can interchange
information.
50.) The important topologies for networks
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Bus Topology.
Ring and Double Ring Topology. ...
Star and Extended Star Topologies. ...
Tree/Hierarchical. ...
Mesh Topology.
51.) The classes of IP addresses with IP range
Class A
Class B
Class C
Class D
Class E
1.0.0.1 to 126.255.255.254 .
128.1.0.1 to 191.255.255.254
192.0.1.1 to 223.255.254.254
224.0.0.0 to 239.255.255.255
240.0.0.0 to 254.255.255.254
52.) DHCP
The Dynamic Host Configuration Protocol (DHCP) is a network management protocol used on
Internet Protocol networks whereby a DHCP server dynamically assigns an IP address and other
network configuration parameters to each device on a network so they can communicate with
other IP networks.
53.) The length of ipv6 address
128 bits
54.) The difference between TCP and UDP
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TCP Transmission Control Protocol is a connection-oriented and reliable protocol.
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UDP User Datagram Protocol is a connectionless and unreliable protocol.
55.) Two routing protocols
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Distance Vector Routing Protocol – These protocols selects best path in the basis of hop
counts to reach a destination network in the particular direction. Dynamic protocol like
RIP is an example of distance vector routing protocol. Hop count is each router which
occurs in between the source and the destination network. The path with the least hop
count will be chosen as the best path.

Link State Routing Protocol – These protocols know more about the Internetwork than
any other distance vector routing protocol. These re also known as SPF (Shortest Path
First) protocol. OSPF is an example of link state routing protocol.
56.) How many layers are there under TCP/IP and What are they?
4 layers
1.
2.
3.
4.
Process/Application Layer
Host-to-Host/Transport Layer
Internet Layer
Network Access/Link Layer
57.) A MAC address
A media access control address (MAC address) is a unique identifier assigned to a network
interface controller (NIC) for use as a network address in communications within a network
segment. It is a hardware identification number that uniquely identifies each device on a
network like a wireless card or an ethernet card
58.) The colour codes of 568A &568B cable standards
Pin # Wire Color
1
White/Green
2
Green
3
White/Orange
4
Blue
5
White/Blue
6
Orange
7
White/Brown
8
Brown
Pin # Wire Color
1
White/Orange
2
Orange
3
White/Green
4
Blue
5
White/Blue
6
Green
7
White/Brown
8
Brown
568-A Color Code
568-B Color Code
59.) The benefits if implementing VLANs(Virtual LAN)

VLANs enable logical grouping of end-stations that are physically dispersed on a
network.
When users on a VLAN move to a new physical location but continue to perform the same
job function, the end-stations of those users do not need to be reconfigured. Similarly, if
users change their job functions, they need not physically move: changing the VLAN
membership of the end-stations to that of the new team makes the users' end-stations local
to the resources of the new team.

VLANs reduce the need to have routers deployed on a network to contain broadcast
traffic.
Flooding of a packet is limited to the switch ports that belong to a VLAN.

Confinement of broadcast domains on a network significantly reduces traffic.
By confining the broadcast domains, end-stations on a VLAN are prevented from listening
to or receiving broadcasts not intended for them. Moreover, if a router is not connected
between the VLANs, the end-stations of a VLAN cannot communicate with the end-stations
of the other VLANs
60.) The difference between cross over cable and straight through cable
Straight through and crossover cables are wired differently from each other. One easy way to
tell what you have is to look at the order of the colored wires inside the RJ45 connector. If the
order of the wires is the same on both ends, then you have a straight through cable. If not, then
it’s most likely a crossover cable or was wired wrong.
61.) Bandwidth and Latency


Latency is the amount of time it takes for data to travel from one point to another. It
is dependent on the physical distance that data must travel through cords, networks and
the like to reach its destination.
Bandwidth is the rate of data transfer for a fixed period of time. Bandwidth, as its
name implies, is the width of a communication band. The wider the communication
band, the more data that can flow through it simultaneously.
62.) The categories of transmission media
Guided
Unguided
Twisted Pair Cable
Coaxial Cable
Optical Fibre Cable
Radiowaves
Microwaves
Infrared