30 09 09

BTEC ND Print–Based Media Year 2
Unit 54: Digital Communication
Learning Outcome 1: Understand digital communication systems
Assignment 1: Functions, Devices and Methods
Date of issue: 30th September 2009
Deadline: 6th November 2009
Lecturer: Martyn Moore

The purpose of this assignment is for you to gain and then demonstrate an understanding of digital communication technology and how it operates. The examples you select are entirely your choice. You are, however, encouraged to utilise the material provided within your timetabled sessions.

Task 1:
Identify a range of digital communication devices.
Provide a detailed explanation of the method each device employs to function as a communication tool.
Provide a detailed explanation of the protocols associated with each of the devices you have chosen to examine.

DIGITAL COMMUNICATION SYSTEMS (yes, some of it is from Wikipedia)

Understanding digital communication systems

Function of communication protocols: Hypertext Transfer Protocol (http);
Wireless Access Protocol (wap); Global System for Mobile (gsm); 3rd generation
protocols (3g); multimedia message service (mms); General Packet Radio Service
(GPRS), Bluetooth; Asymmetric Digital Subscriber Line (ADSL); broadband;
Voiceover Internet Protocol (VoIP)

Devices: ADSL modem; computer; wireless handheld devices (mobile phone,
personal digital assistant or pda); webcam; earphone/microphone headsets;
conferencing software, eg Netmeeting, Skype, BT Communicator, GoogleTalk

Methods: email; instant messaging (IM); Short Messaging System (SMS); Multimedia
Messaging System (MMS); internet; bulletin boards; discussion forums; weblogs
(blogs); newsgroups; internet telephony; conferencing (video conferencing, audio

A PROTOCOL is a set of rules which is used by computers to communicate with each other across a network. A protocol is a convention or standard that controls or enables the connection, communication, and data transfer between computing endpoints. In its simplest form, a protocol can be defined as the rules governing the syntax, semantics, and synchronization of communication. Protocols may be implemented by hardware, software, or a combination of the two. At the lowest level, a protocol defines the behavior of a hardware connection.

Typical properties
While protocols can vary greatly in purpose and sophistication, most specify one or more of the following properties:
Detection of the underlying physical connection (wired or wireless), or the existence of the other endpoint or node
Negotiation of various connection characteristics
How to start and end a message
Procedures on formatting a message
What to do with corrupted or improperly formatted messages (error correction)
How to detect unexpected loss of the connection, and what to do next
Termination of the session and or connection.

The protocols in human communication are separate rules about appearance, speaking, listening and understanding. All these rules, also called protocols of conversation, represent different layers of communication. They work together to help people successfully communicate. The need for protocols also applies to network devices. Computers have no way of learning protocols, so network engineers have written rules for communication that must be strictly followed for successful host-to-host communication. These rules apply to different layers of sophistication such as which physical connections to use, how hosts listen, how to interrupt, how to say good-bye, and in short how to communicate, what language to use and many others. These rules, or protocols, that work together to ensure successful communication are grouped into what is known as a protocol suite.

The widespread use and expansion of communications protocols is both a prerequisite for the Internet, and a major contributor to its power and success. The pair of Internet Protocol (or IP) and Transmission Control Protocol (or TCP) are the most important of these, and the term TCP/IP refers to a collection (a "protocol suite") of its most used protocols. Most of the Internet's communication protocols are described in the RFC documents of the Internet Engineering Task Force (or IETF).
Object-oriented programming has extended the use of the term to include the programming protocols available for connections and communication between objects.

Generally, only the simplest protocols are used alone. Most protocols, especially in the context of communications or networking, are layered together into protocol stacks where the various tasks listed above are divided among different protocols in the stack.

Common protocols

IP (Internet Protocol)
UDP (User Datagram Protocol)
TCP (Transmission Control Protocol)
DHCP (Dynamic Host Configuration Protocol)
HTTP (Hypertext Transfer Protocol)
FTP (File Transfer Protocol)
Telnet (Telnet Remote Protocol)
SSH (Secure Shell Remote Protocol)
POP3 (Post Office Protocol 3)
SMTP (Simple Mail Transfer Protocol)
IMAP (Internet Message Access Protocol)
SOAP (Simple Object Access Protocol)
PPP (Point-to-Point Protocol)

The Internet Protocol Suite
Application Layer
BGP · DHCP · DNS · FTP · GTP · HTTP · IMAP · IRC · Megaco · MGCP · NNTP · NTP · POP · RIP · RPC · RTP · RTSP · SDP · SIP · SMTP · SNMP · SOAP · SSH · Telnet · TLS/SSL · XMPP 
Transport Layer
Internet Layer
IP (IPv4, IPv6) · ICMP · ICMPv6 · IGMP · IPsec 
Link Layer
ARP · RARP · NDP · OSPF · Tunnels (L2TP) · PPP · Media Access Control (Ethernet, MPLS, DSL, ISDN, FDDI) 

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