Information Technology (IT) Communications and Data

¶ … Communications

This age is often referred to as the information era: the last two decades have given birth to some of the most staggering advancements that the human race has ever been capable of -- advancements which have changed the way that we live, do business, stay healthy, fight disease and defend our nation. It's vital to have a comprehensive and concrete understanding of some of the more basic concepts which help to shape this technology, particularly because this data is only going to continue to evolve. This data will explore, compare and contrast some of those more basic terms.

Metropolitan Area Network (MAN)

A metropolitan area network (MAN) refers to a massive computer network that generally encompasses a city or a large campus, usually interconnecting a range of number local area networks, while engaging in high-capacity infrastructure technology, including fiber-optical links, and offering up-link services to wider area networks (WAN) including the Internet and in cable television (Princeton.edu). Other experts describe the MAN as not being large, but being medium sized and used primarily to construct networks with high data connection speeds for cities and towns (Janssen, 2013). "The working mechanism of a MAN is similar to an Internet Service Provider (ISP), but a MAN is not owned by a single organization. Like a WAN, a MAN provides shared network connections to its users. A MAN mostly works on the data link layer, which is Layer 2 of the Open Systems Interconnection (OSI) model.

Distributed Queue Dual Bus (DQDB) is the MAN standard specified by the Institute of Electrical and Electronics Engineers (IEEE) as IEEE 802.6. Using this standard, a MAN extends up to 30-40 km, or 20-25 miles" (Janssen, 2013).

Certain technologies which are used for the functionality of a MAN are things like the Asynchronous Transfer Mode (ATM, FDDI and SMDS though these technologies are rapidly being displaced by Ethernet-based connections in most regions (Janssen, 2013). MAN makes a connection among most local area networks without cables using radio or microwave links (Princeton.edu). Many firms will even rent circuits from standard carriers as a result of the fact that it can simply be expensive to lay long stretches of cable. DQDB, Distributed Queue Dual Bus, is largely considered the standard for data communication: using this standard, networks can extend to 20 miles and operate at higher speeds. It's important to note that certain networks began as MANs, such as MAE-West and MAE-East (Princeton.edu).

Bandwidth

Bandwidth refers to the amount of data that can be carried from one point to another in a particular time frame (habitually a single second in the time period used). "In computer networks, bandwidth is often used as a synonym for data transfer rate - the amount of data that can be carried from one point to another in a given time period (usually a second). This kind of bandwidth is usually expressed in bits (of data) per second (bps). Occasionally, it's expressed as bytes per second (Bps)" (Rouse, 2014). Thus, for example, a modem that functions at 57,600 bps has two times the amount of bandwidth than a modem that functions at 28,800 bps. Thus, the connection with a high bandwidth is that it needs to be able to move enough information to help satisfy the flow of images within a video presentation (Rouse, 2014). It's also really important to bear in mind that legitimate communications generally is made up of a series of links, each which have their own bandwidth. Thus, if one is slower than the others, it can be viewed as a bandwidth bottleneck (Rouse, 2014). It's also crucial to remember that at least pertaining to electronic communication, bandwidth is the width or narrowness of the range of frequencies which is depended upon by an electronic signal onto a particular transmission medium.

Thus, in this regard, bandwidth is demonstrated in terms of the distinctions between the highest frequency signal and the lowest frequency aspect of a signal: "Since the frequency of a signal is measured in hertz (the number of cycles of change per second), a given bandwidth is the difference in hertz between the highest frequency the signal uses and the lowest frequency it uses. A typical voice signal has a bandwidth of approximately three kilohertz (3 kHz); an analog television (TV) broadcast video signal has a bandwidth of six megahertz (6 MHz) -- some 2,000 times as wide as the voice signal" (Rouse, 2014). These are all really important distinctions to be aware of, as they can all engage in their own level of influence, particularly when dealing with a range of electronic and communicative goals.

Code Division Multiple Access (CDMA)

"CDMA (Code-Division Multiple Access) refers to any of several protocols used in so-called second-generation (2G) and third-generation (3G) wireless communications. As the term implies, CDMA is a form of multiplexing, which allows numerous signals to occupy a single transmission channel, optimizing the use of available bandwidth. The technology is used in ultra-high-frequency (UHF) cellular telephone systems in the 800-MHz and 1.9-GHz bands" (Rouse, 2014). CDMA uses analog-to-digital conversion (ADC) in conjunction with spread spectrum technology in order to function: the audio input is first digitized into binary pieces and the frequency of the transmitted signal is than allowed to vary in accordance with a set pattern, so that it can only be disturbed by a receive that has a frequency response which is programmed with the same code, following precisely along with the transmitter frequency (Rouse, 2014). It's important to bear in mind that there are trillions of potential frequency-sequencing codes that can enhance privacy and make cloning very challenging (Rouse, 2014).

The CDMA channel is generally 1.23 MHz wide and uses a scheme known as a soft handoff which can minimize a signal breakup as a handset moves from one cell to a different cell (Rouse, 2014). Thus, the link of combination of digital and spread-spectrum modes can assist in buttressing multiple times as many signals per unit of bandwidth as analog modes are able to. Thus, the CDMA can work with other cellular technologies thus making things like nationwide roaming and other capabilities (Rouse, 2014).

It's important to understand the fundamental concept of CDMA, as one of the most rock-bottom conceptions in data communication as a whole is the notion of permitting a range of transmitters to move information simultaneously over one channel, a phenomenon known as multiplexing (Rouse, 2014). Such a dynamic allows users to share a range of frequencies: thus in this arena CDMA can allow a range of users to be multiplexed across the same physical channel (Princeton.edu). To compare, certain things like time division multiple access (TDMA) makes those distinctions by time and other things like frequency division multiple access (FDMA) multiples it by frequency: CDMA is a type of spread-spectrum signaling as the modulated coded signal has a much more significant data bandwidth than the data which is being communicated (Princeton.edu). "An analogy to the problem of multiple access is a room (channel) in which people wish to talk to each other simultaneously. To avoid confusion, people could take turns speaking (time division), speak at different pitches (frequency division), or speak in different languages (code division). CDMA is analogous to the last example where people speaking the same language can understand each other, but other languages are perceived as noise and rejected" (Princeton.edu).

FireWire

Firewire is a term that generally comes up in reference to digital video, as it is a means of connecting different pieces of equipment so that they can readily share information. Firewire was invented by Apple and is very comparable to Universal Serial Bus cables (USB), though the creators had certain achievable goals in mind when it comes to FireWire: rapid movement of data, ability to store lots of devices on the bus, easy to use, access of power through the cable; plug and play performance, and low cost (Tyson & Layton, 2014).

Firewire offers twp specific forms of data movement: asynchronous and isochronous. "Asynchronous is for traditional load-and-store applications where data transfer can be initiated and an application interrupted as a given length of data arrives in a buffer. Isochronous data transfer ensures that data flows at a pre-set rate so that an application can handle it in a timed way" (Rouse, 2014). The latter type can be useful as it reduces the necessity for buffering and can assist in ensuring an uninterrupted

For multimedia applications, this kind of data transfer reduces the need for buffering and helps ensure a continuous presentation for the viewer. FireWire is a fast device as some of the latest forms of firewire can accomplish speeds of up to 800 Mbps, and is only expected to get greater in the future (Tyson & Layton, 2014). Currently, you can connect 63 devices to FireWire bus and FireWires are supported by both Windows and Mac OS. Consider the following example of how FireWire works: if one has one's digital camcorder connected to one's home computer, when the computer powers up, it will query all devices connected to the bus and give one an address (a procedure known as denumeration (Tyson & Layton, 2014). Thus, because FireWire is plug_and_play, connected a new FireWire device to one's computer means that the system will ask the driver for a disc (though if the disc has already been installed, the computer will find it and communicate with it (Tyson & Layton, 2014). Unlike other forms of communication, FireWire can be disconnected or reconnected whenever, even if the computer or other devices are turned on (Tyson & Layton, 2014).

Synchronous Optical Network (SONET)

SONET was created by the American National Standards Institute (ANSI) for the American public phone network in the 1980s. It is "…a physical layer network technology designed to carry large volumes of traffic over relatively long distances on fiber optic cabling" (Mitchell, 2014). There are particular traits which are specific to SONET which can be quite useful for the internet today. For example, SONET allows the clear interoperability levels among different vendors products while allowing the ability to carry almost any high-level protocol while containing built-in support for the ease of management and maintenance (Mitchell, 2014). SONET is able to function at truly high speeds: "At the base signaling level called "STS-1," SONET supports 51.84 Mbps. The next level of SONET signaling, STS-3, supports triple the bandwidth, or 155.52 Mbps. Higher levels of SONET signaling increase the bandwidth in successive multiples of four, up to approximately 40 Gbps!" (Mitchell, 2014).SONET is also appealing because of its competitive pricing along with these high speeds, thus making it a contender among alternative like ATM and Gigabit Ethernet (Mitchell, 2014).

Cyclic Redundancy Checksum (CRC)

"CRC32 is one of hash functions based on the "polynomial" division idea. The CRC is acronym for Cyclic Redundancy Code (other variants instead "Code" is "Check" and "Checksum") algorithm. The number 32 is specifying the size of resulting hash value (checksum) - 32 bits. The checksum is used to detect errors after transmission or storage of any piece of information" (accuhash.com). CRCs are generally compared to checksums, as they're quite similar in concept, but one distinction is that they use a polynomial division to determine the value of the CRC (Tyson, 2013). One reason that CRCs are often used is that they are extremely accurate: for instance, if a lone bit is not correct, the CRC value will not match up, a fact which is beneficial at thwarting random errors from occurring and offering some protection from an intentional attack on one's data (Tyson, 2013). Thus, CRC is yet another tool which can be used in combination with other processes to offer more insurance that the information being sent is in fact secure. In fact, if one thinks about it, sending information over a computer is often times one of the safest ways of sending it, when compared to other forms of communication: conversations on phones can be privy to eavesdropping and people with bugs or recording devices or radio scanners can record them. Traditional mail is generally passed through a range of hands before it reaches its destination, thus making it more vulnerable to corruption. CRCs are another method of encryption which ensure that sensitive information sent over the Internet is secure and protected, offering all users a higher level of peace of mind (Tyson, 2013).

Network Interface Card (NIC)

A NIC offers the hardware interface among a computer and a network: in the most technical language, a NIC refers to a network adapter hardware which generally manifests in the form factor of an add-in card like a PCI or PCMCIA card (Mitchell, 2014). Some of these cards are able to function with wired networks, others depend on wireless connections. Many NICs can bolster either a wired Ethernet or WiFi standards: "Ethernet NICs plug into the system bus of the PC and include jacks for network cables, while WiFi NICs contain built-in transmitters / receivers (transceivers)" (Mitchell, 2014). In many new computers NICs are already installed by the manufacturing company, and they all feature a specific speed rating like 11 Mbps, 54 Mbps or 100 Mbps which then describe the overall performance of the unit general (Mitchell, 2014).

Essentially one can view a NIC as a card located within a computer that allows the computer to be connected to a network. This card allows the computer to enjoy a devoted, full-time connection to a network: personal computers and public work station on a local area network generally contain a network interface card which is meant for LAN transmission technology (Rouse, 2014).

Server

A server refers to a specific computer that bestows data to other computers: it might provide data to the local area network (LAN) or to a wide area network (WAN) via the internet (techterms, 2014). A range of servers are available, such as web, mail, and file servers, all requiring a type of software which is specific to the function of the server (techterms, 2014). A good example of this might be a web server which runs Microsoft IIS, which gives access to sites over the worldwide web. It's important to bear in mind that while server software is particular to the type of server, hardware does not have to be as specific: many experts have been able to transform regular desktop computers into servers by giving it the necessary software: for instance, a computer which is part of a home network can receive designation as a file server, a print server or both (techterms, 2014). Even though any computer has this capability, most business uses rack-mountable hardware which is designed particularly for functionality in this regard: these systems are ideal as they occupy minimal space and have features like LED status lights and hard drive bays (techterms, 2014). One of the major benefits of servers is that they can be accessed remotely, making input devices not necessary (techterms, 2014).