Bandwidth: What And How It Can Affect Your Business.

what is bandwidthWith the rise of the internet over the past 20 years and the concomitant development of various technologies that require the capability to move ever larger amounts of data from place to place, the term “bandwidth” has come into wide circulation, but relatively few people have stopped to think: just what is bandwidth? The term has slightly different interpretations in various communication contexts, but here the main focus will be on the concept of bandwidth in computers and computer networks.

Bandwidth is often inappropriately characterized as “speed”, as in “high-speed internet”, but this is very much a misnomer. Within very small bounds largely defined by the switches and routers that provide connections, electronic data communication all moves at the speed of light, whether it moves through a telephone wire or through a fiber-optic cable. The difference lies in just how much data can flow through a given medium. A good metaphor through which to view bandwidth is as a road network.

One can generally drive just as fast on a well-maintained country road as on a multi-lane highway, but a considerably greater number of cars can move through a given chunk of highway in a given length of time than can move through a corresponding section of the country road over the same time frame. The highway thus has a much larger bandwidth than does the country road. Thinking of cars as the data packets that make up the data streams that represent network communications should illustrate the relevance of this metaphor. Bandwidth is ultimately data transfer rate.

Bandwidth affects the performance of a computer on more levels than just network communications. Most modern personal computers employ the serial ATA (SATA) bus interface for moving data between hard drives and optical drives and the CPU. The SATA technology has gone through several revisions, those in widespread use in early 2013 range in throughput from 150 megabits per second to 600 megabits per second. A fast drive or a solid state drive capable of data transfer of 600 Mbps is frequently backward compatible with earlier revisions, but will not able to move as much data through the channel and thus the computer might be perceived as “slower”. A similar context exists in moving graphics data in a machine. The PCI Express (PCIe) interface, used most frequently for graphics adapters, has gone through several iterations that have increased its bandwidth by a factor of almost 6.5. Current graphics cards have not been able, however, to fully utilize the bandwidth supported by all but the earliest of PCIe standards.

Closely corresponding to the use of the term in computers and computer networks, bandwidth in signal processing (as in radio and television broadcasting) refers to the width between the upper and lower bounds of a set of frequencies. That width determines how large a signal can be transmitted. The recent federally-mandated move from analog to digital broadcast TV in the US was largely dictated by the smaller bandwidth required for digital transmission, which allows sections of the electromagnetic spectrum to be reallocated to other uses.

Ironically, many mobile and fixed Internet users use a portion of electromagnetic bandwidth to deliver generally quite respectable Internet bandwidth within the range of the pertinent carrier signal. Though there are subtle differences between the use of the term bandwidth in signal processing and in computing, in general they both refer to the width of the path the data takes.  It is vital to know what is bandwidth because it is directly proportional to speed, which is vital factor that affects click-through rates and conversion rates.

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