Data Transmission

Data Transmission

Introduction:
In this blog post, I will be explaining the different types of factors for data transmissions and what they do overall. Additionally, I will give examples to the content and provide limitations of each data transmissions wherever possible. These include:

• Bandwidth
• Noise
• Compression

When data is split into packets and are sent across a network, there are many factors mentioned above that can affect the transmission of data in a positive or negative way such as its quality in general.

Bandwidth:

During the transfer of data, data is sent using bandwidth and it is essentially how fast it is transmitted from the sender device to the recipient device within a certain time. The amount of bandwidth can be based upon the network type used, such as wireless or wired. In a wireless the network, a limitation for bandwidth is it may be noticeably slower because the Wi-Fi travels through air to the device whilst being affected by potential interferences such as obstacles and by the adjacent signals in the surroundings. Another limitation of this is also to do with speed because the amount of users on a router can also dictate how much bandwidth you receive, this is because the router is the device in the network infrastructure that divides the bandwidth by the amount of users for an equal and fair amount. Furthermore for wired networks, bandwidth is indeed faster and a more reliable method of sending data because of the usage of cables e.g. Ethernet avoids interferences and prioritises the device alone.

Other than factors of network choice, services and applications ran on the device can be another limitation that affects the overall bandwidth. An example would be the Skype application (VoIP – voice over internet protocol) which the network will attempt to ensure perfect connection by prioritising the user’s device to have the most internet bandwidth. As a result, this affects other people nearby that are using the same wireless network and may cause a bottle neck (constant traffic of data collision). Resultantly, the benefits of this are that it avoids delays and therefore no data are lost, being an efficient and reliable approach.

Noise:

Noises are another way of referring to interferences by either internally or externally. A common example of an external noise is background noises “caused by metal-framed buildings (causing reflection and acting like a Faraday cage)” (Anderson et al, 2011). This is because the conductor material used in construction can be a way of attracting electrical pulses. Other than buildings interfering, any transmission method without the use of shielding (such as UTP) can also be affected internally and externally altogether. Furthermore, regarding about copper cables such as STP (shielded twisted pair) requiring electrical-magnetic to send data, the closeness of the cables can also interfere with the adjacent wire making it a limitation. Lastly, fibre optic cables are composed of very thin glass for the fastest and most reliable speed, however this means that the thinness of the material can allow other interferences to again to affect it.

Compression:

During data transmission, compression techniques can be applied to lower the file size and still remain the original quality of the file for easier transport – this is because it will then require fewer packets to be sent and checked across a network. Compressions are mainly found in networks that have a lower bandwidth for more effectiveness. Familiar examples include “applications, games, images, videos, and audio” (Anderson et al, 2011).

Despite these criticisms, Huffman coding is applied to many scenarios. It is an effective method of compressing a specific text such as individual alphabets, symbols and numbers by assigning the most frequent characters to a specific sequence binary code. This it to lower the amount of bandwidth required to send a piece of data.

Take this piece of text as an example “Hello, how are you?”
As you can see in the table, the most used character has been assigned to the lowest code for the quickest speed, (see table 1).

Table 1

Character	Frequency	Huffman Code
O	3	0
‘ ‘	3	1
H	2	01
E	2	10
L	2	11
A	1	000
U	1	001
R	1	010
W	1	011
Y	1	100
,	1	101
?	1	11

However, the drawback and limitation of Huffman coding is that the text message needs to be encoded and assigned the shortest code at the start and to be decoded at the end every time because Huffman coding is not fixed unlike ASCII - this may take time but it will help the speed of the process throughout.

Harvard Referencing: (In order of reference)
- Anderson, K. Atkinson-Beaumont, D.Kaye, A. Lawson, J. McGill, R. Phillips, J and Richardson, D. 2011. Information Technology Level 3 Book 1 BTEC National. Harlow: Pearson Education Limited.