|Notice: Exam Form BE IV/II & BAR V/II (Back) for 2076 Magh|
|Routine: BE IV/II & BAR V/II - 2076 Magh|
|Result: BCE I/II exam held on 2076 Bhadra|
|Result: All (except BCE & BEI) I/II exam held on 2076 Bhadra|
|Notice: Exam Center for Barrier Exam (2076 Poush), 1st Part|
|Electronics and Communication(BEX)|
General Applications: Email, WWW, Gopher, Online Systems
- Gopher is a TCP/IP application layer protocol used to distribute, search and retrieve documents over the Internet.
- It is the ultimate predecessor of World Wide Web before the existence of HTTP.
- It was released in mid 1991.
- Gopher appears like a mountable read only global network file system.
- The operation that can be performed on the CD-ROM can be performed on Gopher.
- The TCP port 70 was assigned to the Gopher protocol.
Multimedia and Digital Video/Audio Broadcasting
- Multimedia is a content that is the combination of different forms of media such as text, audio, images, graphics and animation.
- The uses of multimedia are as follows:
1. Industrial advertisement
5. Engineering simulation
Digital Audio Broadcast (DAB) vs Digital Video Broadcast (DVB)
- Digital Audio Broadcast is a completely synchronous system in which the data rate is constant for each data channel and the time slots of individual data channels are fixed.
- It facilitates unequal forward error correction method.
- It uses COFDM (Coded Orthogonal Frequency Division Multiplex) modulation method.
- The transmission link for digital audio broadcast is terrestrial.
- Digital Video Broadcast is a completely asynchronous system in which the data rate of individual data channel may be fixed or may vary and the time slots have no fixed allocation (allocated as per the necessity).
- It facilitates equal forward error correction method..
- It uses single carrier QPSK or QAM for modulation.
- The transmission link for digital video broadcast is satellite, cable or terrestrial.
Broadband Communications, Policy, xDSL and Cable Internet
Digital Subscriber Line (DSL)
- Digital subscriber line is a technology that utilizes high transmission frequencies to convert ordinary conventional phone line into high speed data conductor.
- It provides a secure dedicated connection with no bandwidth contention (disagreement).
- It is susceptible to high frequency cross talk due to the use of telephone wires.
- The overall set of different DSL technologies is termed as xDSL technology.
- The different DSL technology are as follows:
Asymmetric Digital Subscriber Line (ADSL)
- Asymmetric digital subscriber line is the DSL technology in which data flow speed in downstream direction is higher than in upstream direction.
- The available bandwidth of the local loop is divided unevenly for the residential customer.
- The local loop is connected to the filter to separate voice and data.
- The data goes to ADSL modem which modulates data using DMT.
Downstream Rate = 1.5 to 6.1 Mbps Upstream Rate = 16 to 640 kbps Distance = 12000 ft Twisted pair = 1 Line code = DMT (Discrete MultiTone)
High bit rate Digital Subscriber Line (HDSL)
- HDSL is a DSL technology in which data flow in both direction is same due to the use of 2 twisted pairs.
- It uses alternate mask inversion (AMI) data encoding.
- It is susceptible to attenuation at high frequency.
Downstream Rate = 1.5 to 2 Mbps Upstream Rate = 1.5 to 2 Mbps Distance = 12000 ft Twisted pair = 2 Line code = 2BIQ (Bi Phase)
Symmetric Digital Subscriber Line (SDSL)
- SDSL is a DSL technology in which provides full duplex symmetric communication.
- It allows data flow in both direction with same rate.
- It is suitable for businesses that send and receive huge amount of data in both direction.
Downstream Rate = 768 kbps Upstream Rate = 768 kbps Distance = 12000 ft Twisted pair = 1 Line code = 2BIQ
Very high bit rate Digital Subscriber Line (VDSL)
- VDSL is a DSL technology which is similar to ADSL but uses coaxial, fiber optic or twisted pair cable for short distances for attaining higher data bit rate.
Downstream Rate = 25 to 55 Mbps Upstream Rate = 3.2 Mbps Distance = 3000 to 10000 ft Twisted pair = 1 Line code = DMT
VoIP, FoIP and IP Interconnection
- FoIP stands for Fax over Internet Protocol.
- It is the process of sending and receiving fax over IP network.
- The trip of data transmission is on the packet switched network (mostly Internet).
- It reduces the cost of data transmission.
- The fax information are transferred in the form of IP packets via the Internet.
- It allows faster data transmission due to the use of Broadband channels.
Transmission methods in FoIP
1. Store-and-forward approach:
- The fax information is transferred from a fax server to a fax server as an e-mail attachment.
- It uses lower level Internet protocols like SMTP.
- The information exchange is not in real time.
- The sender does not receive instant confirmation that the receiver received each page.
2. Real time IP faxing:
- The fax information is transferred from a fax server to a fax server as IP data packets.
- It uses higher level Internet protocols like TCP.
- It provides real time connections between the fax machines.
Working of FoIP
- It works with T.38 protocol.
- So, the system needs T.38 capable gateway.
- The phases of fax session are as follows:
1. Establishing the connection
2. Exchanging control signals
3. Sending the data
4. Confirmation for successful reception of data
5. Sending and confirming multi page alerts
6. Terminating the session
- VoIP stands for Voice over Internet Protocol.
- It is the process of transmitting voice communications and multimedia sessions over IP network.
- The transmission is done in the form of IP packets via a packet switched network over Internet.
- It does not ensure the transmission of all data packets and sequential order of delivery of data packets.
Methods for VoIP setup
1. ATA (Analog Telephone Adapter)
2. IP Phones
Working of VoIP
1. A signal is sent to ATA.
2. ATA reveives a signal and sends a dial tone confirming Internet connection.
3. Phone number is dialed. ATA converts tones into digital data.
4. The data is sent to VoIP service provider.
5. The call processor maps the receiver by converting phone number into IP address.
6. A signal is sent to receiver ATA.
7. When the receiver picks the phone, session is established.
8. The system implements two channels, for two directions.
9. During the conversation, transmission of packets take place.
10. When receiver is put down, the session is closed.
Data Center and Data warehousing; Packet Clearing House
- Data center is the facility that centralizes all the IT operations and equipment along with the storage, management and retrieval of the data of an organization.
- Security and reliability of the data center must be managed by the organization.
- Data center is the critical system of the network.
- It is classified as follows:
1. Internet-facing data center
2. Internal data center
Elements of data center
1. Facility (location or space)
2. Support Infrastructure (Sustain security and reliability - biometrics for security, UPS)
3. IT Equipment (Actual equipment for IT operation and data storage)
4. Operation Staff (Monitor IT operation and maintain infrastructure)
Packet Clearing House
- Packet clearing house is a non profit institute that supports operations and analysis of the Internet traffic exchange, routing economics and global network development.
- The purpose of Packet Clearing House are as follows:
1. To provide efficient regional and local network interconnection.
2. To provide route servers overall the globe.
3. To provide operational support and security to Internet infrastructure.
4. To provide educational resources on Internet topology, routing, and technology through classes, meetings and educational material distribution.
Unified Messaging System
- Unified messaging system is the system that handles voice, fax and regular text messages as objects in a single mailbox that a user can access with a regular e-mail client or by telephone.
- It integrates and delivers the group of messaging services through a single platform.
- It only manages the non-real time messaging.
Features of UMS:
1. Single platform for all messaging services
2. Easy interface
3. Management of non-real time messaging
Fundamentals of e-Commerce
What is e-Commerce?
- E-Commerce is the process of buying and selling goods or services online through the use of electronic network such as Internet.
- It allows the customer to deal with the producer remotely and more efficiently.
Benefits of e-Commerce
1. Available at all time
2. Speed of access
3. Availability of goods and services for the customer
4. Easy Access
5. Reach from any geographic location
Types of e-Commerce
1. Business to business
2. Business to consumer
3. Consumer to consumer
4. Consumer to business
Components of e-Commerce
The components of e-Commerce are as follows:
2. Shopping cart software
3. Ecommerce payment methods
4. Payment gateway
5. Merchant Bank
Shopping Cart Software
This is the most important component that allows shoppers to select products from
a list, place an order for them and also make online payment. Not long ago vendors used
to hire programmers to develop customized shopping cart software for their ecommerce
sites, but now it has become all the more easy.
Ecommerce service provider’s offer ready shopping cart software that you can plug
and play, making it easy for merchants to launch online business sites.
Merchant banks are financial institutions. Whenever a person clicks on the checkout
page and puts in the credit card payment details, the merchant bank processes and
verifies the credit card details and gives instant notification to the customer as well as to
This component is inbuilt within the Payment Gateway. Merchants need to open a
Merchant Account to avail this service.
Thorough knowledge of Merchant Bank and Merchant Account is thus needed to
make your ecommerce a success.
In the simplest of terms, a merchant account is a specialized account provided by
a bank or other financial institution to enable real time e-commerce transactions. It allows
businesses to accept payment online through credit/debit card and e-check. The account
is set up under a contractual agreement between business/merchant and the bank.
Broadly, under this agreement the bank agrees to pay the merchant for all valid
online business transactions, including credit card, debit card and e-check and processes
the payment made.
Payment Gateway is the connector between the buyers and the financial network.
It helps to process the online payments and credit card processing made by the customer,
with utmost speed and accuracy. A third party like Verisign or Paypal often provide this
The correct choice of payment gateway that suits your ecommerce needs is crucial
and this is where the role of an authentic ecommerce service provider comes in.
Secure Socket Layer provides the security factor in payment transaction. With the
help of a private key for data encryption, SSL transmits confidential user data, like credit
card information, over the Internet.
Use of SSL in your site assures the customer that their credit card and other
personal information are NOT being made public or being misused by the merchant.