Data Communication. Introduction

We are using the internet, telecommunication, text messaging and others by smart phone. These invisible services are related to data communication. In related post I will try to describe data communication.

Data Communication

To start with, let's check means of telecommunication. In short, telecommunication is communication at a distance. Then, how about 'data' instead of 'tele'? That would be a data communication. In the same way, data communication is the exchange of data between two devices via some form of transmission medium such as a wire cable.

Five Components

Ref: Data Communications and Networking 5th edition, Forouzan, p 4

• Message
• Sender
• Receiver
• Transmission Medium
  - Path or tools for data (message) transfer.
• Protocol
  - Rules for data communication.

Data Flow

• Simplex
  - Unidirectional as on a one-way street ex) microphone, megaphone
• Half-duplex
  - Each station can both transmit and receive, but not at the same time
  Ex) walkie-talkie
• Full-duplex
  - Both stations can transmit and receive simultaneously ex) telephone

Networks

A network is a set of devices connected by communication links. In here, I just check a network topology.

• Mesh

Ref: Data Communications and Networking 5th edition, Forouzan, p 10

• Star

Ref: Data Communications and Networking 5th edition, Forouzan, p 10

• Bus

Ref: Data Communications and Networking 5th edition, Forouzan, p 11

• Ring

Ref: Data Communications and Networking 5th edition, Forouzan, p 12

I think a more detailed description is useless. So, I will skip it.


Network Types

• LAN (Local Area Network)
  - Small area network. Links the devices in a single office or building.
• WAN (Wide Area Network)
  - Network system for wide area. Provides long-distance transmission.
• MAN (Metropolitan Area Network)
  - This size between LAN and WAN.

The Internet

 In 1972(During the cold war), Vint Cerf and Bob Kahn develop the internet. The goal of the internet reduces the risk of the previous telecommunication system. For example, telephone system use star topology. If star topology's hub broke, all of stations could not do anything. This project was called Internetting Project and both Vint Cerf and Bob Kahn works with ARPANET group.

Ref: Data Communications and Networking 5th edition, Forouzan, p 18

   Tip

• ISP: Internet Service provider
• CBR: Constant Bit Rate (voice communication)
• DBR: Dynamic Bit Rate (data communication)

Protocols and standards

Protocols

• Definition: A protocol is a set of rules that govern data communications
• Role: defines what is communicated, how it is communicated and when it is communicated.

Standards

• Essential in creating and maintaining an open and competitive market for communications
• Two categories
  - De factor: Standards that have not been approved by an organized body, but have been adopted as standards (Ex. WiFi)
  - De jure: Standards that have been legislated by an officially recognized body.
    (Ex. LTE)

Standards Organizations

• ISO
• ITU-T/ITU-R → communication standards organization (T: tele, R: radio)
• ANSI
• IEEE → layer 1, 2 (WIFI)
• EIA
• 3GPP (Europe) /3GPP2 (US)  → layer 1, 2 (LTE)
        → This organization was founded when 3G was developed
• IETF → Takes charge of Internet protocol. Higher than layer 3 or TCP/IP
• TTA

In the next post I will try to describe the concepts of OSI-7-Layer and TCP/IP.