Data communicationsCommunication and Networking

Alanoud al Saleh

Data communicationsIt involves the transmission of data from one

location to another through the use of pathways which referred to as transmission or channels.

They include:-Telephone lines -microwaves-radio waves -coaxial cable-Satellites - optical fibers

Communication channels:

The choice of communication channel depends on several factors, of which data transmission speed is relatively important.

Data transmission speed depends on band rate and band width of the communication channel.

Transmission speed: Band rate:Refers to the number of discrete signal

elements (bands) transmitted per sec. Band width:Refers to the frequency capacity of the channel

and is expressed in bits per sec (bps).

Essentials for Communications: must have a message message must have a transmitter message must have a receiver Message must have a medium Message must be understood Message must have some level of security

Understanding Transmission Medium Medium is the physical path between

transmitter and receiver in a data transmission system

Medium types: Conductive: twisted pairs and coaxial cables Electromagnetic: microwave Light: lasers and optical fibers Wireless – inner/outerspace; satellite

Understanding Networking

Networks needs to interconnect at a distance by a form of point to point or point to multiple point connected media

A network is a group of computers connected together in such a way as to allow

Networks that are interconnected have proven to be low cost, reliable, and efficient means of communicating at a distance

Key Network Terminology Node: anything connected to the network, usually a

computer, but it could be a printer or a scanner Segment: any portion of a network that is separated

by a switch, bridge or a router from another part of a network.

Backbone: the main cabling of a network that all of the segment connect to. Usually, the backbone is capable of carrying more information than the individual segments.

Topology: The way each node is physically connected to the network

Networkarchitecture

Common Topologies - Bus Bus: each node is chained (connected one

right after the other) along the same backbone. Information sent from a node travels along the backbone until it reaches its destination node.

Common Topologies - Ring Ring: Similar to a bus network, rings have

nodes chained, but the end of the network in a ring topology comes back around to the first node, creating a complete circuit.

Common Topologies - Star star :In a star network, each node is

connected to a central device called a hub(host computer ). The hub takes a signal that comes from any node and passes it along to all the other nodes in the network.

Network Hardware Bridge: device to interconnect two LANs that

use the SAME logical link control protocol but may use different medium access control protocols.

Router: device to interconnect SIMILAR networks, e.g. similar protocols and workstations and servers

Gateway: device to interconnect DISSIMILAR protocols and servers.

Switches:

Allow different nodes of a network to communicate directly with each other.

Allow several users to send information over a network at the same time without slowing each other down.

WANs and LANs

Major Categories of Networks Local Area Networks (LAN) A network of computers that are in the same general

physical location, within a building or a campusare linked through a topology they create a local area network (LAN).

Wide Area Networks (WAN) If the LANs are connected across a region or a wide area

network (WAN) is created when computers are connected across the county.

Metropolitan Area Networks (MAN) interconnects a number of (LANs) using a high-capacity

backbone technology and provides up-link services to WANs and the internet .

Network communication technology:

LANs, MANs, WANs require a technology that allows fast communication of the signals. Ethernet is the common LAN technology

It is based on a bus topology in which computers share the same cable to send data.

Bit net and internet are other technologies which are characteristic of WANs.

The internet

The internetHistory: The internet is the largest computer network

system in existence because it connects users all over the world.

Software was then developed to facilitate the communication process. This software is referred to as transmission control protocol/internet protocol (TCP/IP)

History:

TCP:Manages the packets and their reassembly. IP:Components ensures the packets arrive at their

appropriate remote computers.

History:

In 1990, Dr .Berners-Lee developed the World Wide Web (www) to facilitate communications with remote computers through a set of links. His aim was to communicate more easily with his colleagues by linking with their computers.

Major components:The internet user must first access a server

computer called the internet service provider (ISP), using a phone line or direct cable connection. The server computer relays the user message to the internet. Finally the internet returns electronic mail (e-mail) or requested information to the user through the ISP server.

Web browser:

Allows the user to use a mouse to point and click on text, drawings and pictures to facilitate an internet search.

Two popular browser are Netscape and Internet Explorer.

Uniform resource locator (URL):

Web sites can be located with a Uniform Resources Locater (URL) that must conform to a specific format to ensure successful communications. The URL is the address of the site or file on the internet. Example:

http://www.med.harvered.edu/AANLIB/home .html

URL:-(http://) [hyper text transfer protocol] is the part of the URL

that enable users to access a web page or file include the protocol for communicating link.

-(www.med.hardvard.edu) or (www.ksu.sa.edu) the ISP address or domain name.

-The final portion (edu) of the domain name which demonstrates the type and purpose of the organization.

Search engines:

The internet also features search engines to help users find information in a systematic and organized manner. Example of search engines include Alta Vista, Lycos, Yahoo, and Google.

Computer in radiology:

In 1955 computers were used to calculate radiation dose distributions in cancer patients. Today, computer applications in radiology include two categories imaging and nonimaging applications.

Imaging applications:

They are those modalities in which the information acquired from the patient is subjected to computer processing. This involves digital image processing techniques to produce digital images. These images can be stored or displayed.

Several methods for creating images: computed radiography, digital fluroscopy, computed tomography and magnetic resonance imaging.

Imaging applications

Non imaging applications:Radiology information systems (RIS) patient admissions, scheduling, accounting, billing, film library functions, word processing, statistics, database management and data communications. RIS can connect to hospital information system (HIS) which address the needs of all departments in the hospital including laboratory, pharmacy, finance, admissions and hospital administration.

Communication protocol standards: Connectivity: refers to a measure of the effectiveness

and efficiency of computer based devices to communicate and share information and messages without human intervention. It is achieved by the use of communication protocol standards.

Protocols: deals with the specifics of how a certain task will be done.

Standard: it is an approved reference model and protocol determined by standard setting groups for building or developing products and services.

Communication protocol standards:

HIS, RIS and PACs are integrated using communication protocol standards. The two popular standards are health level 7 (HL-7) and digital imaging and communication in medicine (DICOM).

Communication protocol standards: HL-7 : standard application protocol most

used with HIS and RIS.

DICOM : is the imaging communication protocol for PACs.

Picture archiving and communications system (PACS)

An electronic system for archiving, transmitting, viewing, and manipulating images is now essential to the digital radiology department.

PACS:

Control databasesystem

Local area network(LAN)

Computermonitor

Film printer

Optical jukeboxor tape

RIS/HIS

Remoteinterface

Wide area network (WAN)

CT MRI CR

Communication

Archiving

Acquisition

Display