Tutorial 1


(i) Hypertext Transfer Protocol (Http) and Hypertext Transfer Protocol Secure (Https)
  • Hypertext Transfer Protocol, is a set of standards that allow users of the World Wide Web to exchange information found on web pages. 
  • Transmission Control Protocol/Internet Protocol establishes the connection to the web server. 
  • It too enables the web server software and client software communicate. 
  • HTTP is used in browsers because of the need to access other protocols such as File Transfer Protocol through the browser.
  • Hence, the Hypertext Transfer Protocol over Secure ( HTTPS), is a secure method of accessing or sending information across a web page. 
  • All data sent over HTTPS is encrypted before it was sent, this prevents anyone from understanding that information if intercepted. 
  • Because data is encrypted over HTTPS, it is slower than HTTP, which is why HTTPS is only used when requiring login information or with pages that contain sensitive information such as an online bank web page or a business web pages and any others that contain personal details.
( ii )Packet-Switched Network

  

  • Packet switching is the approach used by some computer network protocols to deliver data across local or long distance connection. 
  • Packet switching entails packaging data specially formatted units that are typically routed from source to destination using network switches and routers. 
  • Every packet contains address information that identifies the sending computer and intended recipient. 
  • Using these addresses, network switches and routers determine how best to transfer the packet between hops on the path to its destination.
  • Packet switching is the alternative to circuit switching protocols used historically for telephone networks. 
  • It's more efficient to use of overall network bandwidth due to flexibility in routing the smaller packets over shared links. 
  • Packet switching networks are often cheaper to built due to less equipment is needed given this ability to share.
( iii ) Differences of cellular transmission General packet radio service (GPRS) and 4G

 a)GPRS

  • GPRS stands for General Packet Radio Service. 
  • It is the slowest one, it is a data connection standard available in GSM networks - the second generation cellular networks (2G). 
  • GSM traditionally work on 900, 1800 and 1900 MHz and they were initially designed for circuit-switched voice service. Channels are spaced 200 kHz, usually several of them per base station, each channel having 8 time-slots. 
  • GPRS made the wireless cellular data revolution, as in GPRS data is sent in packets, just like on computer networks (as opposed to circuit-switching). 
  • This of course required a major redesign of the operator's core network, adding packet-switching nodes to support IP packet data, hence a GSM network with GPRS is sometimes called 2.5G. Expect speeds of several tens of kbps.
b) 4G
  • 4G is the 4th generation network called LTE (Long Term Evolution), works in a very different manner than 2nd and 3rd generations. 
  • Shared access is done by OFDMA - the available channel is divided into subchannels (also called subcarriers) and each of them is treated separately; groups of those subcarriers are assigned to different mobile phones. 
  • Also LTE is designed as a data-only network so all of the traffic is IP-based and there are no more circuit-switched connections. 
  • In fact unless the operator has VoLTE service (Voice over LTE), your 4G connection will only handle sending data, and to make/receive a voice call your phone will have to fall back to a 2G or 3G network. Of course the data speeds will be quite higher, you can expect tens of Mbps.
iv) Video of History of Internet

Eric Ling Kaiyue 1001437025

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