Data Communications

Abstract

Data communications—the sending and receiving of facts, figures, details, and other information over a communications network—support us in our everyday activities both at home and at work. For businesses, data communications have become vital to success in the marketplace, particularly with the increasing trend toward globalization. Communications networks allow both individuals and teams to communicate faster and better, obviate the need for many in-person meetings, and even transfer funds electronically. Through local, metropolitan, or wide area networks, individual computers or workstations can be linked together to enable data sharing and communication. Networks can also be linked with each other to better meet the needs of the organization and the growing demands for communication and data in the Information Age.

Keywords Architecture; Bandwidth; Communications Channel; Communications Network; Data Communications; Server; Wireless Communications System; Workstation

Information Technology > Data Communications

Overview

Data communications have become so much a part of our lives that we often take them for granted, yet they provide an infrastructure for the way that we do so much in the 21st century. For example, to postpone the inevitable task of sitting down to write this article, I just ordered a book from a large, online-only bookstore. I was able to search the online database for books on the topic in which I was interested. When I had narrowed down the list to a few books that seemed to meet my requirements, I was not only able to read the book reviews that had been stored in another database, but was also able to read facsimiles of a chapter from each of the books online. Once I made my selection, I was able to place my order online, an activity made easier because the business had my shipping information saved in another database; all I had to do was confirm that the information was still correct. My payment was verified and approved via a secure transaction and funds were electronically transferred from my account to the business for the purchase. I was then sent an automatic e-mail confirming my order. The order request was also sent to the shipping department who will pick my order, pack it, generate a shipping receipt using my stored information to generate a shipping label, and enter the shipment into the system of the carrier. The carrier will then track the shipment—and allow me to do the same from the comfort of my own computer. Upon delivery, the driver for the shipping carrier will enter confirmation into the carrier's database that the package has been delivered. If I have problems with the delivery or the shipment itself, I will be able to contact customer service for the bookstore or the carrier, often communicating with people not only in other states but in other countries in order to get the proper book delivered to my desk. At no time, however, will I have actually talked to a live person. The entire transaction and the sub-steps that make it possible will all have been done through the technology of data communications networks.

Even if I had decided that I would prefer to physically go to a local bookstore and peruse the book over a cup of coffee, data communications networks would have made my task easier. I might have gone to an electronic kiosk in the store or to the information desk to find out what books they had on the topic and where they were located. In either case, I would have received the information from a remote database delivered over their network. When my order was placed with the barista in the coffee shop, it would have been entered into the computerized cash register which would not only have rung up my transaction, but would have most likely also entered it into another database that keeps track of inventory and would either remind the store manager to order more sugar-free hazelnut syrup or have automatically ordered it itself. Sales information on my cup of coffee would also have been transmitted to corporate headquarters at the end of the day. After picking up my purchase, I would have then sat down with my book and coffee, perhaps also tapping into the wireless Internet connection to read my e-mail or compare prices for the book with those of the online bookstore.

Data communications—the sending and receiving of facts, figures, details, and other information over a communications network—is a vital part of our lives today. Information transmission is no longer limited to what we can place on paper. Large computer systems can hold and manipulate quantities of data in ways that just a few decades ago would have seemed impossible. Not only can these be linked together in a myriad of ways, but can also be transmitted nearly instantaneously over communications networks—sets of locations (or nodes) with concomitant hardware, software, and information that are linked together to form a system that transmits and receives information.

There are three types of data communications networks. Local area networks comprise multiple desktop computers that are located near each other and linked into a network that allows the users to share files and peripheral devices such as printers, fax machines, or storage devices. Local area networks are used to connect computers in an office or series of offices, and span distances from a few hundred feet to a few miles. The computers linked into a local area network are also referred to as workstations, clients, or nodes. These are connected to a server—a host computer for the network that provides services to the clients. The server usually has more storage capacity and can process at higher speeds than the client computers.

A second type of network used in many businesses is the metropolitan area network. This type of network transmits data and information citywide (up to 30 miles) and at greater speeds than a local area network. As opposed to local area networks, metropolitan area networks are optimized for both voice and data transmissions and can, therefore, carry more forms of data than can be carried over local area networks. These include combinations of voice, data, image, and video data. Metropolitan area networks typically operate over a city-wide network of fiber optic cables. These networks enable metropolitan area networks to provide high quality multimedia transmissions at higher speeds than is possible over local area networks.

The third type of network is the wide area network. These networks comprise multiple computers that are widely dispersed and that are linked into a network. Wide area networks typically use high speed, long distance communications networks or satellites to connect the computers within the network. There are many uses for a wide area network. A retail chain, for example, may use a wide area network to connect its stores across the country or across the world, allowing them to share inventory and sales data and to send e-mail messages to each other. Similarly, computerized cash registers can be used to collect and transmit sales data at each location and transmit them to the company's corporate headquarters as part of the closing procedure each day.

Wide area networks link their network using services provided by a common carrier—a company that provides public communications transmission services. The speed at which the data are transmitted is determined by the bandwidth. This is the data transfer rate, or the amount of data that can be transmitted within a given time period. The higher the bandwidth of a transmission is, the higher the transfer rate is. Bandwidth is expressed in thousands of bits of information per second (kbps), millions of bits per second (mbps), or billions of bits per second (gbps). For example, a typical page of typed correspondence contains approximately 275 words, which translates to 2000 bytes or 16,000 bits of information. To transmit this amount of data over a 56 kbps modem takes approximately .28 second, whereas sending the same page over a high speed network transmitting at 1.544 mbps would only take .01 second. A small difference if one is only transmitting one page. However, transmission of a 600 page document at 2,400 Bps would take nearly two hours, at 56,000 Bps would take only 5 minutes, and at 1.544 mbps would take a mere 10.8 seconds. Although it is seldom that most people need to transmit a 600 page text, higher bandwidths are also necessary to transmit video transmissions which are made up of a succession of images. Wide area networks sometimes also may transmit over a T-carrier, a very high speed channel that connects lower speed networks or computers at different sites. Wide area networks also can transmit data over fiber optic cables that allow even faster data transmission.

A fourth kind, heterogeneous and small cell networks (HetSNets), was proposed in the early 2010s to accommodate increasing data traffic by deploying more cells more closely together and hence closer to devices depending on them for transmission (Hwang, Song & Soliman, 2013).

Networks are linked through network channels (also called network media). These channels may be physical channels (as in the case of copper or fiber optic cables) or wireless channels (which transmit using radio waves). There are a number of different types of media used to transmit data. The transmission speeds of some of these channels is given in Table 1.

Physical communication channels include twisted pair, coaxial, and fiber optic cable. Twisted pair cables are used in telephone wires and consist of pairs of copper wire twisted together to form a cable. This medium was designed for the transmission of voice and text messages and is considered by information technology specialists to be a voice-grade medium. Twisted pair channels transmit at a variety of rates ranging from 100 Bps to 100 mbps. The carrier determines the feasible speed of transmission on the cable. However, it is the hardware and software attached to the network that determine the actual speed of transmission (e.g., no matter how fast data can be transmitted over the network cables, if the modem attached to the workstation is slow, the actual receipt of the data will be concomitantly slow). Another type of commonly used physical communications medium is coaxial cable. This type of cable comprises one or more central wire conductors surrounded by an insulator and sheathed in wire mesh or metal. Fiber optic cables—the most recently introduced physical cable medium—use light from a laser to transmit data. This allows the fastest data transmission of the physical network media.

In addition to physical network media, various wireless channels are available. These media transmit data using radio waves sent over the open air or through space. Technology supporting the development of software based radios, that would themselves provide wi-fi as an application was one avenue of R&D active since the 1990s, though its promise had not been fulfilled by 2013. Most wireless systems utilize microwaves with or without the concomitant use of various types of satellites. Microwaves are high frequency radio signals that transmit either through the open air using terrestrial stations or through space using satellites. Terrestrial stations use relay towers about 30 miles apart. Since microwaves travel in a straight line, these stations must be unobstructed and have a clear line between them. Increasingly, however, wireless transmission is done using satellites. In this system, microwaves are beamed from a terrestrial station to a communications satellite which in turn relays the signal to another terrestrial station or stations.

Networks can be structured in a number of different ways using various system architectures that determine how the various components interact and cooperate. In a centralized architecture, the server hosts all of the network's hardware and software, performs all the network's processing, and manages the network from a central site. In centralized architectures, the hardware and software frequently are found in a centralized computer center. In a distributed architecture, however, the various computers are at different locations and connected by a network. In this type of architecture, an application may run on one or more locations on the network simultaneously. For example, in a big box store with a distributed network, data on individual sales transactions may be automatically transmitted to a distribution center. Suppliers may also connect using their own networks to monitor inventory in the distribution centers and replenish them as necessary. Each of these approaches to network architecture has advantages and disadvantages. For example, centralized systems are easier to manage, but distributed systems keep information where it is most needed. To leverage the advantages of both types of architectures, some enterprises use hybrid systems that combine the strengths of both approaches.

Distributed networks were expanded in the 2010s, most notably by Adobe, which innovated a new model of software sales whereby the user would license Adobe's software rather than own a physical or downloaded copy of the application. The software would be be housed on a "cloud" server that users would access over the Internet. This is referred to as software as a service (SaaS). Platform as a service (PaaS) is aimed at application developers; infrastructure as a service (IaaS) is virtualized hardware and can provide online storage; and network as a service (NaaS) provides optimized connectivity.

Applications

As illustrated by the example of ordering a book above, data communications networks offer a number of service applications to their users. Electronic mail (e-mail) allows users to transmit written messages and attachments of various text, graphic, or other documents over communications networks. Messages are sent via a computer or workstation over a network and stored on a reserved area of the server or host computer accessed by the recipient. Most people are familiar with the use of e-mail for various personal uses including corresponding with friends, family, or businesses. E-mail, however, is invaluable in most workplaces. Transmission is exponentially faster than traditional mail, a fact that allows businesses to be more efficient by cutting down response time to messages and receiving documents and information needed for work performance in a timelier manner. Although this can be invaluable when communicating locally, it is essential as organizations increasingly take their business global. In this situation, the use of e-mail also helps the organization overcome problems resulting from having personnel in different time zones. E-mail enables everyone in such transactions to respond at their leisure without having to go to work early or stay late, and still gets the information where it needs to be faster than was previously possible. E-mail is not just for person-to-person messages, however: It can be used to distribute enterprise-wide memos and announcements, communicate with all members of a workgroup or team, or hold an on-going conversation with multiple interested parties.

Another application of network communications technology is voicemail. This network application is often thought of as a kind of glorified answering machine that allows users to send and receive voice messages via a telephone connected to a computer. However, voicemail is more than the digital equivalent of an analog recording device. The voice message is converted from analog to digital, which allows it to be stored in voice mailboxes on a computer. As with e-mail messages, voicemail messages are not only for person-to-person communication. The use of voicemail over a communications network allows a message to be sent to large number of people simultaneously. For example, when the terrorist attacks of 9/11 resulted in the cancellation of flights, United Airlines was able to send personalized messages to its customers' homes using an automated system.

Not all communication can be done by e-mail or voicemail, however. Sometimes it is necessary for groups of people to meet to discuss projects or products. In the past, this always had to be done in person, engendering extra costs to the organization not only for travel expenses but also for time lost while in the car or on the airplane. Communication networks, however, have reduced the need for in-person meetings by providing the ability to teleconference. Videoconferencing allows not only the participants to be heard at remote locations, but to be seen as well. This technology coupled with electronic bulletin boards that allow users to post documents electronically allows group members to participate fully, sharing not only audio and visual communications in real time, but sharing documents as well. Electronic bulletin boards can also allow users to share documents for update and comment. A related technology to teleconferencing is collaborative conferencing or workgroup conferencing. This network application uses software that provides tools to help workgroups communicate, coordinate, and organize their activities. Conference participants work from their individual workstations or computers and communicate through the network.

Documents and verbal messages are not the only types of information that can be transmitted over data communications networks. In the banking world, information about money—rather than the physical money itself—is constantly changing hands. This electronic movement of money over a communications network is called electronic funds transfer. This transparent method of funds transfer affects many of our financial transactions. For example, the PLUS ATM network comprises over 800,000 automated teller machines in nearly 130 countries and territories around the world. These can be accessed by over one billion credit and debit cards. Similarly, credit card transactions are settled by electronic funds transfer between the user and the issuer of the credit card. Automatic deposit of payroll checks, government support checks, and other deposits are also done by electronic funds transfer.

Another use of data communication networks is for electronic data interchange. This is a standard format used in exchanging business data such as price or product identification number. Parties exchanging this information are called trading partners. It has been estimated that one-third of all business documents including purchase orders, invoices, and payments are transmitted using electronic data interchange technology. This technology is particularly important in international commerce where paperwork required for international trade creates costs of up to seven percent of the value of the items being traded. Shippers, carriers, customs agents, and customers all can send and receive documents through electronic funds transfer, thereby saving both time and money for international transactions.

Terms & Concepts

Architecture: The structure of a communications network, including how the various components are linked, interact, and cooperate. Network architectures may be centralized, distributed, or a combination of the two.

Bandwidth: The data transfer rate, or the amount of data that can be transmitted within a given time period. The higher the bandwidth of a transmission, the higher the transfer rate. Bandwidth is expressed in thousands of bits of information per second (kbps), millions of bits per second (mbps), or billions of bits per second (gbps).

Communications Channel: A communications channel (sometimes called a communications medium); can be a physical or cableless medium that links the components of a network.

Communications Network: Sets of locations (or nodes) with concomitant hardware, software, and information that are linked together to form a system that transmits and receives information.

Data Communications: The sending and receiving of facts, figures, details, and other information over a communications network.

Information Technology: The use of computers, communications networks, and knowledge in the creation, storage, and dispersal of data and information. Information technology comprises a wide range of items and abilities for use in the creation, storage, and distribution of information.

Local Area Network (LAN): Multiple computers that are located near each other and linked into a network that allows the users to share files and peripheral devices such as printers, fax machines, or storage devices.

Metropolitan Area Network (MAN): Computer networks that transmit data and information citywide and at greater speeds than a local area network.

Network: A set of computers that are electronically linked together.

Server: The computer that hosts a network and provides services to the other computers in the network (e.g., a web serve serves up web pages). The term server is also used to refer to the software running on the server computer.

Wide Area Network (WAN): Multiple computers that are widely dispersed and that are linked into a network. Wide area networks typically use high speed, long distance communications networks or satellites to connect the computers within the network.

Wireless Communications System: A communication system that transmits data using radio signals over the air or through space as opposed to through wire or optical cables.

Workstation: A desktop computer that is connected to a network. Workstations are also sometimes referred to as clients or nodes.

Table 1: Transmission Speeds of Communications Channels

Bibliography

Helland, P. (2013). Condos and clouds. Communications of the ACM, 56, 50–59. Retrieved October 31, 2013, from EBSCO Online Database Business Source Complete. http://search.ebscohost.com/login.aspx?direct=true&db=bth&AN=84631586&site=ehost-live

Hwang, I., Song, B., & Soliman, S. (2013). A holistic view on hyper-dense heterogeneous and small cell networks. IEEE Communications Magazine, 51, N.PAG. Retrieved October 31, 2013, from EBSCO Online Database Business Source Complete. http://search.ebscohost.com/login.aspx?direct=true&db=bth&AN=88057936&site=ehost-live

Partridge, C. (2011). Realizing the future of wireless data communications. Communications of the ACM, 54, 62–68. Retrieved October 31, 2013, from EBSCO Online Database Business Source Complete. http://search.ebscohost.com/login.aspx?direct=true&db=bth&AN=67134749&site=ehost-live

Senn, J. A. (2004). Information technology: Principles, practices, opportunities (3rd ed.). Upper Saddle River, NJ: Pearson/Prentice Hall.

Sharma, A. (2013). M2M: A growing need for reliable, secure data communications. Wireless Design & Development, 21(3), 22–24. Retrieved December 4, 2015 from EBSCO Online Database Business Source Premier. http://search.ebscohost.com/login.aspx?direct=true&db=buh&AN=87659533&site=bsi-live

Suggested Reading

FitzGerald, J., Dennis, A., & Durcikova, A. (2015). Business data communications and networking (12th ed.). Hoboken, NJ: Wiley.

Lucas, H. C. Jr. (2005). Information technology: Strategic decision making for managers. New York City, NY: John Wiley and Sons.

Nolle, T. (2007). Will "new wires" mean "new networks"? Business Communications Review, 37, 8–11. Retrieved May 19, 2007, from EBSCO Online Database Business Source Complete. http://search.ebscohost.com/login.aspx?direct=true&db=bth&AN=23933954&site=ehost-live

Williams, B. (2007). Metro Wi-Fi networks: What are they and how can they benefit your community? Public Management, 89, 16–19. Retrieved May 19, 2007, from EBSCO Online Database Business Source Complete. http://search.ebscohost.com/login.aspx?direct=true&db=bth&AN=24316461&site=ehost-live