9.3 Communication Systems
Glossary
Term Definition
Communication The system that enables people and systems to share and exchange
Systems data and information electronically. The communication occurs
between transmitting and receiving hardware and software
Protocols A formal set of rules and procedures that must be observed for two
devices to transfer data efficiently and successfully, e.g. HTTP, DNS,
FTP, SMTP, POP, IMAP, SSL
Handshaking The process of establishing and agreeing on the set of protocols for
communication between two or more devices
MAC Address Media Access Controller Address hardwired into each device. A
hardware address that uniquely identifies each node on a network
Node Any device on a network that is able to send and/or receive frames,
e.g. Phone connected to home network Wifi, school computers
connected to school network
HTTP HTTP is the primary protocol used by web browsers to communicate
and retrieve web pages from web servers.
TCP TCP, together with IP, are the protocols responsible for the
transmission of most data across the Internet. The primary
responsibility of transport layer protocols such as TCP is ensuring
messages are actually delivered correctly.
IP IP is the protocol that causes data packets (called datagrams) to
move from sender to receiver. It makes no attempt to acknowledge
datagrams that have been received but rather simply fires off each
datagram one after the other.
Ethernet A protocol aimed at dealing with data collisions. It uses a system
called Carrier Sense Multiple Access with Collision Detection
(CSMA/CD) to control the passing of information and to avoid
simultaneous transmission by two or more systems.
Bits per second The number of bits transferred each second. The speed of binary
(bps) data transmission.
Baud (or baud rate) The number of signal events occurring each second along a
communication channel. Equivalent to the number of symbols per
second.
Bandwidth The difference between the highest and lowest frequencies in a
transmission channel. Hence bandwidth is expressed in hertz (Hz),
, usually kilohertz (kHz) or megahertz -0(MHz).
Parity Bit Check An error checking method where a bit acts as a check on a set of
binary values, calculated in such a way that the number of 1s in the
set plus the parity bit should always be even, or always be odd.
Checksums A digit representing the sum of the correct digits in a piece of stored
or transmitted digital data, against which later comparisons can be
made to detect errors in the data.
Cyclic Redundancy A common technique for detecting data transmission errors. It is
Check (CRC) calculated by first considering the entire message to be a complete
number, then divided by another predetermined number and the
remainder becomes the CRC value, which is then recalculated at the
receiving end and compared to check for errors.
Teleconference A multi-location, multi-person conference where audio, video
and/or other data is communicated in real time to all participants.
Electronic Electronic commerce involves all examples of financial transactions
Commerce that occur over an electronic network, including withdrawing cash
from ATMs, paying for store purchases using EFTPOS and performing
transactions over the Internet.
Automatic Teller An electronic banking outlet, which allows customers to complete
Machine (ATM) basic transactions without the aid of a branch representative or
teller.
Electronic Funds An electronic payment system involving electronic funds transfers
Transfer at Point of based on the use of payment cards, such as debit or credit cards, at
Sale (EFTPOS) payment terminals located at points of sale.
Internet Banking An electronic payment system that enables customers of a bank or
other financial institution to conduct a range of financial
transactions through the financial institution’s website.
Virtual Organisation An organisation or business whose members are geographically
separated. They work together using electronic communication to
achieve common goals.
Client-Server The model that consists of two different types of computer present
Architecture/Model on the network: servers that provide specific processing services for
clients, and clients that request a service and wait for a response
while the server processes the request.
Physical Topology The physical layout of devices on a network and how the cables and
wires connect these devices.
Logical Topology How data is transmitted and received between devices on a network
regardless of their physical connections.
,Encoding Encoding organises the data into a form suitable for transmission
along the communication medium.
Decoding Decoding changes the organisation of the received data into a form
suitable for subsequent information processes.
Modulation The process of encoding digital information onto an analog wave by
changing its amplitude, frequency or phase.
Demodulation The process of decoding a modulated analog wave back into its
original digital signal. The opposite of modulation.
Network Operating The NOS is a computer operating system that is installed on one or
System (NOS) more servers where it provides various services to secure and
support the network’s resources and users.
Network Network administrators are the personnel responsible for the
Administrators ongoing maintenance of network hardware and software, and they
also provide support to new and existing users.
Header and Trailers Data relevant to the protocol operating at the particular layer during
transmission, and it wraps the data packet
Signal A series of electrical charges or pulses of light used to transmit data
Asynchronous Not in time. Communication in each direction occurs at a different
speed.
Synchronous Communication where data is received precisely in time with when
it was sent
Preamble A sequence of alternating zeros and ones and is used to synchronise
the phase of the sender and receiver’s clocks. Included at the start
of each frame.
Frame Large data packet
Router A device that directs messages to the intended receiver over the
most efficient path. Routers communicate between many networks
that may use different protocols
Client-server Where the browser is the client and the web server is the server
connection
URL Universal Resource Locator used to identify individual files and
resources on the internet
Datagrams Data packets
Fragmentation Mechanism of splitting complete datagrams into a series of smaller
datagrams suited to the protocol operating at the network, and
aren’t recombined until reached final destination
,Authentication The process of determining if someone, or something, is who they
claim to be
Fault Tolerance The ability of a system to continue operating despite the failure of
one or more of its components
Striping Storing single files across multiple physical disks
Mirroring Storing the same data on more than one disk
Firewall A software barrier around a network. Typically a firewall will decide
which data are allowed in and out of the network.
Common 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 packets when they arrive
● IP: Responsible for ‘routing’ each packet to correct destination
● HTTP: Hyper Text Transfer Protocol – allow the displaying of files containing hypertext
links across a network, over World Wide Web
● 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
● IMAP: Internet Message Access Protocol
Characteristics of Communication Systems
Communication Systems
- Enable people and systems to share and exchange data and information electronically
- Communication: transmitting and receiving hardware and software over network, devices
on the network called nodes
- Framework:
, - Data Source produces the data to be sent
- Transmitter encodes the data into a signal suitable for transmission
- Transmission Medium is a channel in which the signal is transmitted to the destination
- Receiver decodes the signal back into the original data
- Destination is the receiver of the transmission, may follow many different paths through
networks & connection devices
- Protocols classified into three levels: application, communication control and addressing,
and transmission level
- As message progresses, they are encoded using protocol/s operating at each level and then
decoded until it reaches destination
- OSI: Open Systems Interconnection, a more detailed model of transmission process
Elements that make up the Communication System
- Message/transmission medium: the data packets and hardware through which they travel
- Source/destination: the application where the message is created/ends up
- Switches and routers: where the address are attached and read so that data packets sent on
most suitable path to destination
- Three levels of protocols: where packets of data are encoded/decoded to a form suitable for
transmission process
- Transmitter/Receiver: where signals are generated or received such as a modem
- User/Participants: the people who are involved in the system in some way
Overview of Protocol Levels
- Software controls and directs operation of hardware
- Transmitter and receiver agree on how hardware will transfer messages, including which
operating systems, protocols, devices, transmission media, etc
- OSI model referred as OSI stack, where each packet of data must descend the stack, be
transmitted, then ascend
- Handshaking before any data transmitted/received to make communication successful
IPT Application Level
- Data to be transmitted is created by software app and organised in format to be understood
by receiving application e.g. compress image & representing as sequence of ASCII characters
- Protocols: HTTP, FTP, SMTP, SSL
IPT Communication and Control Level
- Communication with network established, commences and is maintained, determines when
session starts and ends e.g. in internet banking transaction session
- Corrects transmission of each data packet, ensuring packets that fail are retransmitted (TCP)
- Packets then directed to destination, IP (Internet Protocol) operates with the job to address
and forward packets to destination along best path
- TCP/IP, TCP, IP
IPT Transmission Level
- Defines how transmission media is actually shared, device drivers controlling physical
transmission operate, determining final size of transmitted packets & speed of transfer
- Switches operate directing messages based on MAC (Media Access Controller) addresses
- Performs the physical transfer: hardware, converting bits in each message into signals
transmitted down transmission media like fibre-optic, twisted pair in LAN
Glossary
Term Definition
Communication The system that enables people and systems to share and exchange
Systems data and information electronically. The communication occurs
between transmitting and receiving hardware and software
Protocols A formal set of rules and procedures that must be observed for two
devices to transfer data efficiently and successfully, e.g. HTTP, DNS,
FTP, SMTP, POP, IMAP, SSL
Handshaking The process of establishing and agreeing on the set of protocols for
communication between two or more devices
MAC Address Media Access Controller Address hardwired into each device. A
hardware address that uniquely identifies each node on a network
Node Any device on a network that is able to send and/or receive frames,
e.g. Phone connected to home network Wifi, school computers
connected to school network
HTTP HTTP is the primary protocol used by web browsers to communicate
and retrieve web pages from web servers.
TCP TCP, together with IP, are the protocols responsible for the
transmission of most data across the Internet. The primary
responsibility of transport layer protocols such as TCP is ensuring
messages are actually delivered correctly.
IP IP is the protocol that causes data packets (called datagrams) to
move from sender to receiver. It makes no attempt to acknowledge
datagrams that have been received but rather simply fires off each
datagram one after the other.
Ethernet A protocol aimed at dealing with data collisions. It uses a system
called Carrier Sense Multiple Access with Collision Detection
(CSMA/CD) to control the passing of information and to avoid
simultaneous transmission by two or more systems.
Bits per second The number of bits transferred each second. The speed of binary
(bps) data transmission.
Baud (or baud rate) The number of signal events occurring each second along a
communication channel. Equivalent to the number of symbols per
second.
Bandwidth The difference between the highest and lowest frequencies in a
transmission channel. Hence bandwidth is expressed in hertz (Hz),
, usually kilohertz (kHz) or megahertz -0(MHz).
Parity Bit Check An error checking method where a bit acts as a check on a set of
binary values, calculated in such a way that the number of 1s in the
set plus the parity bit should always be even, or always be odd.
Checksums A digit representing the sum of the correct digits in a piece of stored
or transmitted digital data, against which later comparisons can be
made to detect errors in the data.
Cyclic Redundancy A common technique for detecting data transmission errors. It is
Check (CRC) calculated by first considering the entire message to be a complete
number, then divided by another predetermined number and the
remainder becomes the CRC value, which is then recalculated at the
receiving end and compared to check for errors.
Teleconference A multi-location, multi-person conference where audio, video
and/or other data is communicated in real time to all participants.
Electronic Electronic commerce involves all examples of financial transactions
Commerce that occur over an electronic network, including withdrawing cash
from ATMs, paying for store purchases using EFTPOS and performing
transactions over the Internet.
Automatic Teller An electronic banking outlet, which allows customers to complete
Machine (ATM) basic transactions without the aid of a branch representative or
teller.
Electronic Funds An electronic payment system involving electronic funds transfers
Transfer at Point of based on the use of payment cards, such as debit or credit cards, at
Sale (EFTPOS) payment terminals located at points of sale.
Internet Banking An electronic payment system that enables customers of a bank or
other financial institution to conduct a range of financial
transactions through the financial institution’s website.
Virtual Organisation An organisation or business whose members are geographically
separated. They work together using electronic communication to
achieve common goals.
Client-Server The model that consists of two different types of computer present
Architecture/Model on the network: servers that provide specific processing services for
clients, and clients that request a service and wait for a response
while the server processes the request.
Physical Topology The physical layout of devices on a network and how the cables and
wires connect these devices.
Logical Topology How data is transmitted and received between devices on a network
regardless of their physical connections.
,Encoding Encoding organises the data into a form suitable for transmission
along the communication medium.
Decoding Decoding changes the organisation of the received data into a form
suitable for subsequent information processes.
Modulation The process of encoding digital information onto an analog wave by
changing its amplitude, frequency or phase.
Demodulation The process of decoding a modulated analog wave back into its
original digital signal. The opposite of modulation.
Network Operating The NOS is a computer operating system that is installed on one or
System (NOS) more servers where it provides various services to secure and
support the network’s resources and users.
Network Network administrators are the personnel responsible for the
Administrators ongoing maintenance of network hardware and software, and they
also provide support to new and existing users.
Header and Trailers Data relevant to the protocol operating at the particular layer during
transmission, and it wraps the data packet
Signal A series of electrical charges or pulses of light used to transmit data
Asynchronous Not in time. Communication in each direction occurs at a different
speed.
Synchronous Communication where data is received precisely in time with when
it was sent
Preamble A sequence of alternating zeros and ones and is used to synchronise
the phase of the sender and receiver’s clocks. Included at the start
of each frame.
Frame Large data packet
Router A device that directs messages to the intended receiver over the
most efficient path. Routers communicate between many networks
that may use different protocols
Client-server Where the browser is the client and the web server is the server
connection
URL Universal Resource Locator used to identify individual files and
resources on the internet
Datagrams Data packets
Fragmentation Mechanism of splitting complete datagrams into a series of smaller
datagrams suited to the protocol operating at the network, and
aren’t recombined until reached final destination
,Authentication The process of determining if someone, or something, is who they
claim to be
Fault Tolerance The ability of a system to continue operating despite the failure of
one or more of its components
Striping Storing single files across multiple physical disks
Mirroring Storing the same data on more than one disk
Firewall A software barrier around a network. Typically a firewall will decide
which data are allowed in and out of the network.
Common 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 packets when they arrive
● IP: Responsible for ‘routing’ each packet to correct destination
● HTTP: Hyper Text Transfer Protocol – allow the displaying of files containing hypertext
links across a network, over World Wide Web
● 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
● IMAP: Internet Message Access Protocol
Characteristics of Communication Systems
Communication Systems
- Enable people and systems to share and exchange data and information electronically
- Communication: transmitting and receiving hardware and software over network, devices
on the network called nodes
- Framework:
, - Data Source produces the data to be sent
- Transmitter encodes the data into a signal suitable for transmission
- Transmission Medium is a channel in which the signal is transmitted to the destination
- Receiver decodes the signal back into the original data
- Destination is the receiver of the transmission, may follow many different paths through
networks & connection devices
- Protocols classified into three levels: application, communication control and addressing,
and transmission level
- As message progresses, they are encoded using protocol/s operating at each level and then
decoded until it reaches destination
- OSI: Open Systems Interconnection, a more detailed model of transmission process
Elements that make up the Communication System
- Message/transmission medium: the data packets and hardware through which they travel
- Source/destination: the application where the message is created/ends up
- Switches and routers: where the address are attached and read so that data packets sent on
most suitable path to destination
- Three levels of protocols: where packets of data are encoded/decoded to a form suitable for
transmission process
- Transmitter/Receiver: where signals are generated or received such as a modem
- User/Participants: the people who are involved in the system in some way
Overview of Protocol Levels
- Software controls and directs operation of hardware
- Transmitter and receiver agree on how hardware will transfer messages, including which
operating systems, protocols, devices, transmission media, etc
- OSI model referred as OSI stack, where each packet of data must descend the stack, be
transmitted, then ascend
- Handshaking before any data transmitted/received to make communication successful
IPT Application Level
- Data to be transmitted is created by software app and organised in format to be understood
by receiving application e.g. compress image & representing as sequence of ASCII characters
- Protocols: HTTP, FTP, SMTP, SSL
IPT Communication and Control Level
- Communication with network established, commences and is maintained, determines when
session starts and ends e.g. in internet banking transaction session
- Corrects transmission of each data packet, ensuring packets that fail are retransmitted (TCP)
- Packets then directed to destination, IP (Internet Protocol) operates with the job to address
and forward packets to destination along best path
- TCP/IP, TCP, IP
IPT Transmission Level
- Defines how transmission media is actually shared, device drivers controlling physical
transmission operate, determining final size of transmitted packets & speed of transfer
- Switches operate directing messages based on MAC (Media Access Controller) addresses
- Performs the physical transfer: hardware, converting bits in each message into signals
transmitted down transmission media like fibre-optic, twisted pair in LAN
