Information Processes and TechnologyCommunication Systems

Characteristics of Communication SystemsWireless

Ethernet Cable

A communication system allows its users to send and receive data and information The framework in which communication systems function is shown in the diagram

below, where it represents Skype/MSN as a communication system.

 Network Interface Card

Functions performed within communication systems to send a message:

Message creation Organisation of packets at the interface between source and transmitter Signal generation by the transmitter Transmission via a medium Synchronising the exchange Addressing and routing Error detection and correction Security and management

Protocols in communication:

A protocol is a set of rules that governs a communication process ‘Handshaking’ is the process of establishing a communication link and agreeing on

which protocol to use A communications protocol must define the following:

Rate of transmission (in baud or bps)

Whether transmission is to be synchronous or asynchronous Whether data is to be transmitted in half-duplex or full-duplex mode

Also, protocols can include sophisticated techniques for detecting and recovering from transmission errors and for encoding and decoding data.

Common protocols:

TCP/IP: Transmission Control Protocol/Internet Protocol – rules that split data into packets for transfer across the internet

HTTP: Hyper Text Transfer Protocol – allow the displaying of files containing hypertext links across a network

FTP: File Transfer Protocol – the protocol defining the transfer of files over a network or the internet

SMTP: Simple Mail Transfer Protocol – sending of e-mail messages POP: Post Office Protocol – retrieves e-mail messages SSL: Secure Sockets Layer – used for encryption of data for secure data transmission

The client-server architecture:

 The client sends a request to the server using its IP address and the port. The server receives the request and responds using the client IP address and port.

The client controls the user interface and application The server controls access to the network Thin clients:

A thin client is designed to be especially small so that the bulk of the data processing occurs on the server; a thin client is a network computer without a hard disk drive.

Thin clients can be found in medical offices, airline ticketing, schools, etc. Easy to install, lower total costs than fat clients

Fat clients: Performs the bulk of the processing in client/server applications Can handle higher bandwidths, operating systems and software that do not run

on thin clients can run on fat/thick clients as it has its own resources. Some examples of clients include; web browsers and e-mail clients Some examples of servers include; print servers, mail servers and web servers

Print servers control access to printers on the network and queue data waiting to be printed

Mail servers route email Web servers store and cache web pages

Advantages: Centralised resources; given that the server is the centre of the network, it can

manage resources that are common to all users

It is possible to remove or add clients without affecting the operation of the network and without the need for major modification

Disadvantages: Client-server networks can become congested and overload the server with

requests Increased costs due to the technical complexity of the server

Examples of Communication SystemsTeleconferencing systems:

Teleconferencing (video conferencing) is an alternative to face to face meetings, using electronic hardware and software such as camera and internet connections to transfer video and audio data. Commonly used for education and conferencing.

How data is transmitted and received: The video and audio data is captured, digitised (by assigning a number -binary

code- to each pixel on the image to represent its colour), transmitted over the internet, and then decoded when received.

Advantages: Facilitates flexible meeting scheduling Achieves worldwide connectivity; thus avoids expensive travel costs

Disadvantages: Can be expensive and requires fast processors and high transmission speeds Reduces personal contact; lack of social skills develop

Messaging systems:Email:

Users are able to send text messages and attached files to individuals or groups of people via the internet (e.g. used in schools to send notices and make appointments)

How data is transmitted and received: Use computers to send and receive text messages and attached documents via

the internet Advantages:

Very fast transmission of mail compared to conventional postal mail Capable of transmitting and receiving text, graphics, sound and video as

attachments Free of charge to send an email; only monthly ISP fee

Disadvantages: Viruses, which can be attached to email messages Only available to those who have a computer, internet connection and email

addressVoice mail:

Voice mail allows transmission of vocal messages between users via telephone systems. How data is transmitted and received:

Audio messages are recorded and then transmitted by telephone system for storage (when someone is unavailable)

Advantages:

The receiver does not have to be present, and messages are stored and can then be later retrieved by the recipient

No extra hardware needed besides a telephoneDisadvantages:

Voicemail can be viewed as impersonal by callers Only users with a voice mail account can access its functionality

Voice over internet protocol (VOIP):

Purpose: To allow voice calls to be made over a broadband internet connectionParticipants: Residential home users, small businessesData/information: Sound waves converted to digital audio signalsInformation technology: Broadband internet connection, computer, VOIP software (for computer-to-computer connections), microphone, speakers, sound card, modemHow data is transmitted and received:

Sound waves are recorded by microphone The computer compresses it into data packets for transmission over the IP

network The sending computer places an address on each packet telling the network

devices where to send them Inside of each packet is a payload; a voice recording digitally converted The sending computer sends the packet(s) to a router which directs it to the

receiver The receiving computer decodes the transmission to output sound waves

Advantages: Except for your normal monthly ISP fee, there is usually no charge for computer-

to-computer calls, no matter the distance VOIP consumes less transmission time

Disadvantages: Phone conversations can become distorted, garbled or lost because of

transmission errors (e.g. packet loss) No power means a call cannot be made Susceptible to worms, viruses and hacking

Transmitting and Receiving in Communication SystemsTransmission media:

Wired transmission: Twisted pair:

Twisted pairs are insulated copper wires. They can transfer text, sound, video and graphics as electric currents. The twists in the cable reduce interference/noise during transmission.

A twisted pair is installed to an Ethernet cable (RJ-45) for use to connect computers in a local area network (LAN)

Least expensive, reliable data communication Coaxial cable:

Coaxial cables are thick cores of copper surrounded by insulating material. The insulation is enclosed by a woven mesh. This is surrounded by a plastic layer for protection.

Mostly used for Internet connections and Foxtel (cable television) It is very fast and is capable of a high bandwidth and long transmission distances

Optic fibre: Fibre optic cables are very thin glass strands well protected by insulation Transmit using light and have greater bandwidth and a higher speed than other

cables. Fibre optic cable is less susceptible to interference and they do not corrode like

the metal cables. Most expensive of the three wired transmission mediums Often used for long distance connections (e.g. Sydney to Melbourne)

Wireless transmission:

Microwave: Microwaves are electromagnetic waves that can be used for data transmission

Satellite: Geostationary object (in space) functioning as a repeater Used for internet connections mainly in remote areas where other internet

connections may be unavailable Advantages: carry very high bandwidth over very large distances

Radio waves: Radio waves have the longest wavelengths in the electromagnetic spectrum. Radio waves do more than just bring music to your radio; they also carry signals

for your television and mobile phones Infrared:

Wireless signals, mainly used in devices such as remote controls where it is transmission over very short distances

Advantages: add devices without cables Transmission speed:

Transmission speed is the time it takes data to travel from the source to the destination. The hardware being used and the transmission medium will greatly affect this speed. It can be best described in terms of bandwidth, baudrate and bits per second (bps).

Bandwidth: The ability of the transmission medium to handle a particular amount of data in a given time; the higher the bandwidth the more data that can be sent

Baudrate: A measure of the speed of transmission in a communication medium; measures how many times the medium can change its state

Bits per second (bps): A measure of the speed of transmission in communication medium; measures how many bits of data are transmitted (or received) in one second

Application level protocols: HTTP: Hyper Text Transfer Protocol – allow the displaying of files containing hypertext

links across a network SMTP: Simple Mail Transfer Protocol – sending of e-mail messages

SSL: Secure Sockets Layer – used for encryption of data for secure data transmission

Communication control and addressing level protocols: TCP/IP: Transmission Control Protocol/Internet Protocol – rules that split data into

packets for transfer across the internet TCP: Responsible for breaking data down into IP packets before they are sent, and for

assembling the packets when they arrive IP: Responsible for ‘routing’ each packet to the correct destination

Transmission level protocols: Ethernet: The Ethernet protocol allows for bus, star, or tree topologies, depending on

the type of cables used and other factors Token ring: A token ring network is a local area network (LAN) in which all computers

is connected in a ring or star topology and a bit (or token) passing scheme is used in order to prevent the collision of data between two computers that want to send messages at the same time.

 Asynchronous – uses start and stop bits

Synchronous – no start/stop bit

 

Strategies for error detection and error correction:Parity:

Parity is the method used to check data in asynchronous transmission, where one character is checked at a time. The eighth bit of the byte is the parity bit, which is used to check the accuracy of transmission. The parity checking can be either odd or even.

Checksum: If the 1 digits of a binary code are added they give a total which is called a

checksum. The receiving computer calculates the checksum and compares it to the transmitted checksum, and if they do not match, an error is detected.

Cyclic redundancy checks (CRC): The transmitted data is treated as one large binary sum (similar to checksum).

The sum is then divided by a constant and the remainder is sent to the receiver. The receiver then works out the sum of the transmitted data divides it by the same constant and compares the remainder with the transmitted data. CRC has the highest probability of detecting errors.

NetworksNetwork topologies:Star networks:

 One central node (computer or other network device) and distant nodes are connected along communications lines that radiate as spokes from the central node.

Advantages: Fast; if the central computer is fast Non-centralised failure will not cause the entire network to fail Multiple nodes can be easily connected Files can be simultaneously accessed by multiple nodes

Disadvantages: The network operation depends on the functioning of the central node; hence,

the failure of the central node leads to the failure of the entire network Bus networks:

 Several devices are connected to a single communications channel.

Advantages: It is easy to handle and implement; only one main line Cheaper; no extra hardware is required (such as a central server) Easy error detection since there is only one main line and few connections

Disadvantages: Slow; can perform well only for a limited number of nodes If the main line (bus) is broken, transmission will fail

Ring networks:

 The topology is that of a continuous circle, with nodes around the circumference.

Advantages: Cheaper, a central server is not required for the management of this topology Easily set up/implemented – using cables

Disadvantages: If one node of the ring breaks down or a part of the network is disconnected, the

network will not workHybrid networks:

 Hybrid networks use a combination of any two or more of the basic topologies.

Advantages: Able to be used where different types of networks are required

Disadvantages: Expensive, errors may be hard to detect within the network

Wireless networks:

 The data packets are converted into radio frequencies which travel through the air to the receiving node.

Advantages: Cables aren’t needed to connect the nodes together; portable applications are

available, e.g. laptops, wireless printers, etc. Easy to add stations as there are no cables required

Disadvantages: Disconnections are more common than with cable connections Quality of transmission is not as high as other methods Devices which are not Wi-Fi enabled cannot be connected to the network Wireless signal can be intercepted and accessed by hackers

Hubs:

A multiport device used to connect computers in a local area network Passes network traffic to all devices connected, therefore slowing down the network Cheaper Half duplex; therefore inefficient under high network traffic

Switches: A multi-port device that allows small sections of LANs to connect and switch traffic

directly from the source to the destination Transmits to the destination port only Faster data transmission as it reduces collisions

Routers: Directs data traffic, is protocol dependent Selects the best path on the network to route data (efficient) by reading the packet

address and understanding the network topology Fast data transmission as it reduces collisions Connects different network

Bridges and gateways: Bridges are used to connect two LANs together in a simple network topology which

use the same protocol to communicate. Gateways provide the ability for one protocol to talk to a different one (protocol

conversion). They are more complex than bridges and will translate data in one protocol to another protocol for transmission.

Network interface cards (NIC): Provides a physical link to a computer network; this connection allows computers to

communicate with servers, as well as other computers on the network.

Mobile phones: Transmit and receive voice calls via radio waves

Cables: Connects communication systems together, allowing for data transmitting and

receiving

Wireless access points: A wireless access point (WAP) is a device that allows wireless communication devices

to connect to a wireless network. Common hardware devices that connect to a WAP include laptop computers.

Bluetooth devices: Bluetooth is a wireless network protocol for exchanging data over short distances

(using short length radio waves) from fixed and mobile devices, creating personal area networks (PANs). Common hardware devices that connect to Bluetooth include mobile phones to send and receive data.

Network operating software:

Operating systems are required to run the workstation plus any peripheral devices connected to it and to allow data transfer.

Usually there is a main computer called a server on a network and it stores the main operating system for the network, but each workstation also needs workstation software to run it. The network operating system software enables all the network hardware and all other network software and makes it all work together as one organised system.

Each workstation has a local operating system that works in collaboration with the network operating system to allow processes such as file sharing, data sharing, peripheral sharing and remote processing where needed.

Internet, intranets and extranets:

The Internet consists of a worldwide network of computer networks that use the TCP/IP network protocols to facilitate data transmission and exchange.

An Intranet is a private computer network that uses the protocols of the Internet. An intranet is not accessible by computers on the outside of the private network.

An Extranet is a private network that uses Internet protocols. It can be viewed as part of a company's intranet that is extended to users outside the company, usually via the Internet.

Other Information Processes in Communication SystemsCollecting:

A phone is a collection device for the use of voice mail An EFTPOS terminal is a collection device for electronic banking

Digital data:

Digital Data is data that is stored and transmitted in two possible states; each digit can be either on or off, represented using electrical impulses that are of high or low voltage

Much of our technology relies on digital data Computers use the binary system to store and transmit data, i.e. the digits 1 and 0

Analogue data:

Analogue data is represented in a continuous form in which there are many different possibilities

Analogue data can be represented as a wave It is more difficult to handle this type of data as transmitting it accurately involves

sending it in its exact form, and because there are so many more variables it is more easily corrupted

Processing:Encoding and decoding analogue and digital signals:

Communication systems use both analogue and digital data, for this reason it is often necessary to encode and decode signals

Analogue data to analogue signal - Telephone conversations are the best example here. The system encodes speech and transmits it from sender to receiver.

Digital data to analogue signal - A digital device will often have to display data in an analogue form for humans to understand. This will require encoding the 0’s and 1’s.

Digital data to digital signal - This form of transmission has both sender and receiver speak the same language. One computer on a network is able to communicate directly with another computer.

Analogue data to digital signal - The analogue data is encoded to a series of 0’s and 1’s by dividing the data into two groups across an illogical line.

Formation of data packets: A packet is the unit of data that is routed between an origin and a destination on a

network The structure of a packet depends on the type of packet it is and on the protocol.

Normally, a packet has a header and a payload For example, an IP packet includes;

The source IP address

The destination IP address

The sequence number of the packets

The type of service, etc.

The payload is the data it carries

Routing: Routing is the process of selecting paths in a network along which to send

network traffic Routing is performed for many kinds of networks

Encryption and decryption: Encryption is the process of transforming information (referred to as plaintext)

using an algorithm (called cipher) to make it unreadable to anyone except those possessing special knowledge, who obtain the ‘key’.

Decryption is the reverse process where the receiver requires the ‘key’ to decrypt the data.

Error checking: Parity bit check Check sum Cyclic redundancy check (CRC)

Displaying:

A phone is also a display device for the use of voice mail An EFTPOS terminal is also a display device for electronic banking

Managing Communication SystemsNetwork administration tasks:

Adding/removing users

Assigning users to printers Giving users file access rights Installation of software and sharing with users Client installation and protocol assignment Network-based applications Logon and logoff procedures

o Where user enters username and password to validate access. A user session is opened and the user can access resources they have rights to.

o Log-off disconnects that user form network – important for security as open network can be used by unauthorised users

  network administration tasks, such as:

adding/removing users o Username and password along with details of any assigned policies or

privilegeso Individual profiles can be stored on a server

assigning users to printers o Users have access to a printer physically close to the workstation

giving users file access rights o Also known as permissionso Determine processes a user can perform on a file or directory

installation of software and sharing with users o Automate installation of software to multiple userso Can be installed on individual workstations where they are available for use by

any user that logs onto the workstation client installation and protocol assignment

o Steps to install a new client: New machine needs compatible NIC Client needs to be compatible with NOS Physically connect NIC to network using patch cable Network administrator needs to create machine within NOS and assign

any profiles Legitimate username and password required

logon and logoff procedures network-based applications

Issues Related to Communication SystemsTeleconferencing systems:

Changing the nature of work as individuals around the world can work on a project and share information

May lose interpersonal skills as communication via microphones and speakers

Messaging systems: Cyber bullying Misinterpretation (may not understand abbreviation, cannot see facial

expressions) Privacy

Employers have rights to read employee emails sent from work Social networking companies may sell user information without user’s

knowledge

Child grooming for sexual assault (using fake Facebook accounts) Diminishing of interpersonal skills

E-commerce: Hacking Loss of jobs as machine replace humans Globalisation: access to unreliable sellers – loss of money

Electronic banking: Jobs and bank branches close as ATM machines replace bank tellers Extra costs for businesses who need to train staff in IT E-crime more common (phishing scams, key logging)

EFTPOS: Similar to e-commerce

Changing nature of work (working from home):Advantages:

Flexibility over when to work when productivity is high and when it suits private life (taking care of children)

Save costs on travel Allows disabled and rural workers to find jobs Reduced office needs for employers

Disadvantages: Need self-motivated staff who can cope with isolation

Virtual communities:

Network of individuals who pursue similar interests; e.g. forums created in Facebook and online dating sites

Advantages: People from around the world can communicate

Disadvantages: Young people can become addicted Loss of social skills

The Internet:The need for ethical behaviour when using the internet

Do not attack others through insulting messages – cyber bullying Do not copy and paste information without proper referencing – plagiarism Do not impersonate others to extract personal data – follow netiquette

These behaviours make the internet safe and enjoyable for everyone.

Issues that have arisen from internet use Availability of material normally restricted

Internet saturated with pornography and children with internet access can easily view sites if no filter (leading to sexualisation of children)

Internet used to spread child pornography in file sharing sites (abuse of children)

Australian Government implementing a mandatory filter: will this restrict material that is legally available

Domination of content and control of access to internet Previously, large media organisations decided what news people would receive.

But individuals have greater control and power through blogs – where they can report news.

Access to internet controlled by a few large companies. There is less competition, leading to higher internet prices, which limits access to the poor.

Other Systems Dependent on Communication TechnologyEFTPOS (Electronic Funds Transfer at Point Of Sale):

EFTPOS is a financial network for processing credit cards, debit cards and ATM transactions at ‘point of sale’.How data is transmitted and received:

Employee swipes card in a magnetic strip reader Customer enters password/PIN Card details collected and funds transferred from customer to retailer’s account

Advantages: Easier than manually transferring funds from bank branch Efficient, secure form of payment

Disadvantages: Cards are not practical for buying small items Both buyer and the seller have to pay charges for use of the cards Many people don’t have bank accounts or prefer to use cash

E-commerce:

E-Commerce (electronic commerce) consists of the buying and selling of products or services over electronic systems such as the internet and other computer networks. Can be used with computers, mobile phones, ATMs, telephone, etc.Advantages:

Customers are more easily able to compare products and services Less labour and paper involved in electronic transactions Reduced waiting time as products and services are more quickly obtained by

customersDisadvantages:

Potential customers may not like having to reveal their financial and personal information online

Fraud, hacking, identity theft, etc. Electronic banking:

Serves as a substitute for cheques and other paper transactions for bank customers who have a personal computer, an internet connection and an electronic banking account. Fund transfers or enquires are made through the use of devices such as cards or codes to gain access to the account.

Advantages: Allows people greater convenience in the process of banking as electronic

banking is available 24/7 Saves people from going into the bank to withdraw or deposit money – travel

time and costs It is simple and free

Disadvantages: People who are not computer literate and people who do not have access to a

personal computer are denied this function Customers may be sucked into phishing scams where they disclose their private

details to scammers believing them to be the actual bank Unauthorised individuals can intercept banking transactions; gaining access to

people’s private banking details which they can use for criminal activities such as fraud

Current and Emerging Trends in Communication SystemsCurrent and emerging trends in communications:Blogs:

Online personal journal which other users can read; entries are dated & has a journal design

Only updated by blog owner Gives individual the power of the media as they can share opinion – but the

information may not be accurate Wikis:

An internet resource allowing individuals to seek answers to questions Can be updated by any internet user with a wiki account Powerful educational resource – but the information may not be accurate

RSS feeds:

A format for delivering regularly changing web content Many news-related sites, weblogs and other online publishers

syndicate/organise their content as an RSS feed to whoever wants it Podcasts:

Cheap to create and can be downloaded for listening anywhere, anytime. Uploading an MP3 file to a webpage

Online radio, TV and video on demand:

Stream live broadcasts 3G technologies for mobile communications:

Higher speed internet and better multimedia access Expensive and requires compatible devices

OSI Model – TCP/IPLayers 7-5 = Upper Layers

Layers 4-1 = Lower Layers  Layer 7, Application: End-user orientated where user created data communicates this data to other applications on another or the same host. The Application layer provides services to the software through which the user requests network services. Your computer application software is not on the Application layer. This does not involve regular applications such as MS Word on your computer, but instead mail clients, FTP clients and web browsers. Layer 6, Presentation: This layer is concerned with data representation and code formatting, for example Rich Text Formatting, Hypertext Mark-up Language, Plain Text…etc. Essentially it transforms the data into a format that the program can understand. Layer 5, Session: The Session layer establishes, maintains, and manages the communication session between computers. Initiates and terminates the connection from local host to remote application. Layer 4, Transport: The functions defined in this layer provide for the reliable transmission of data segments, as well as the disassembly and assembly of the data before and after transmission. Layer 3, Network: This is the layer on which routing takes place. The Network layer defines the processes used to route data across the network and the structure and use of logical addressing. It decides the most viable path to send data in which to reach its destination, involves TCP/IP to achieve this. Layer 2, Data Link: As its name suggests, this layer is concerned with the linkages and mechanisms used to move data about the network, including the topology, such as Ethernet or Token Ring, and deals with the ways in which data is reliably transmitted. Breaks data up into packets (or frames), which are chunks of a file which are sent one after the other to the receiver. Also involves the process of detecting and possibly correcting any errors. Layer 1, Physical: The Physical layer's name says it all. This layer defines the electrical and physical specifications for the networking media that carry the data bits across a network. Traditional Ethernet cables send data as binary through a very specific voltage, with a positive voltage representing a 1 and no voltage determining a 0, the speed and frequency of these voltages is entirely dependent on the speed of the internet connection itself, and whether the signals are synced with the receiver to ensure maximum speed.Fibre-optic cables send data as positive and negative light intensities, again representing binary data, this is by far the fastest transmission medium in existence today and the frequency and speed of altering light intensities is extremely rapid.   TCP/IP: Transmission Control Protocol & Internet Protocol Model Describes a set of design guidelines and implementation of certain network protocols which allow computers to connect over a network, protocols in this context meaning rules.The Layering system of this model is often compared with the OSI model, which is appropriate since TCP/IP allows the OSI model to undertake its network-based tasks (particularly transmission).TCP/IP provides end-to-end connectivity (the reliable transmission of data between two points) specifying how data should be formatted, addressed, transmitted, routed and received at the destination.  KEY ARCHITECTURE

 Application Layer (process-to-process): Like the OSI model, this is the layer in which applications create user data and communicate this data to other processes or applications on another or the same host. Communication partners are often referred to as peers. This is where protocols defined as “high level” operate, such as SMTP (Simple Mail Transfer Protocol), FTP (File Transfer Protocol), SSH (Secure Shell), HTTP (Hyper Text Transfer Protocol)…etc. Transport Layer (host-to-host): Connects two network hosts together, either on the local network or remote networks separated by routers. This is where processes such as flow-control, error-correction and connection protocols exist. Basically, the layer deals with opening and maintaining the connection between two or more hosts.  Internet Layer (internetworking): Exchanges datagrams (known as IP packets) across network boundaries. Defines the addressing and routing structures which are used for the TCP/IP protocol suite. The main protocol in this is the Internet Protocol which defines IP addresses. Its main function is routing, meaning transporting datagrams to the next IP router that has the connectivity to a network closer to the actual final destination (which are known as next-neighbour hosts).  Link Layer: This layer defines the networking methods used within the boundaries of the local network link on which hosts communicate without interfering with other routers. Describes the local network topology and interfaces which are required to affect transmission of Internet Layer datagrams to next-neighbour hosts.

Compare and Contrast Electronic Communication with Traditional Face-to-Face Methods

Physical interaction is the most notable form of information among people. One of the major points of this is its ability to confirming and strengthening relationships. The most successful businessmen are those who introduce their products in person rather than calling or commercialising it online.

Physical interaction eliminates misunderstandings. We can elaborate what we mean as part of a conversation and therefore, clarify our main purpose. As facial expressions are involved, we are able to convey our feelings of sympathy, happiness or love to the other person, which is impossible by phone call or email, which strengthens the effectiveness of face-to-face contact.

Through digital interaction, phones and emails have made interaction easier. Through the internet, we can send emails to our friends or see their photos and videos free of charge. In addition, phones and the internet provides us with the fastest way to communicate, by calling an emergency service centre in a few seconds after an incident, we can report it and possibly save a person's life. Therefore, they are an efficient way of communication despite being imprecise.