Theory of data communication

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BTEC IT Practitioners Unit 8

        Communication Technologies

This assessment provides the opportunity to meet the grading criteria for the unit as indicated in the grid below.

Student Name:        

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If you copy from someone else or allow another candidate to copy from you, or if you cheat in any way you may be disqualified from at least the assignment concerned.

Any help or information you have received from people other than your subject teacher must be clearly identified in the work itself

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I have read and understood the above statements. I have produced the work without help except for help from my subject lecturer and the help which I have declared in the work itself. I have acknowledged all source material in the work itself.


__________________________(Learner)       Date  ____________________

To be read in conjunction with the Grading Criteria Grid for the unit and the Assignment General Instructions in the Student Handbook.

The theory of data communications


  • types of communication devices, signal theory, error reduction techniques, protocols, OSI and TCP/IP models


In this assignment you will need to show that you:

  • know the main elements of data communications
  • understand transmission protocols and models


In this assignment you will:

  • explain the theory that lies behind data communications, including the basic types of   communication devices, signal theory, protocols and error reduction techniques
  • describe protocols in common use and explain their importance
  • compare the OSI and TCP/IP protocol models


You have taken a job as a junior technician at NetCo, a company that makes networking hardware (switches, routers, etc.). They are planning to set up a networking academy (rather like the Cisco Network Academy) and create related qualifications. The project manager has asked you to prepare some learning materials for ‘Chapter 1’ of the online course. Chapter 1 is entitled ‘The Theory of Data Communications’. The chapter is subdivided into a number of sections. The materials can be produced in the form of a Word document or a series of linked web pages.


Task 1a

P1        Identify and explain types of communication devices

P2        Explain the principles of signal theory

Write suitable materials for Chapter 1, section 1 which explains the purpose and workings of basic communication devices and the principles of signal theory.

Task 1b

M1         Explain techniques that can be used to reduce errors in transmissions

Add a section 2 to your guide (entitled ‘Error detection and correction’) which explains the techniques that can be used to reduce data transmission errors.


Task 2

P3        Describe communication protocols used and explain why they are important

D1        Critically compare the OSI seven layer model and the TCP/IP model 

Write section 3 (entitled ‘Communication protocols’), which should include a description of the communication protocols in common use and explain why protocols are important. Write a detailed comparison of the OSI seven layer model and the TCP/IP model, commenting on the approach taken and the suitability of each of the models.


This assignment is very much about explaining the basic theory that lies behind communication technology. There are lots of sources for this information in books and on the internet, but remember what you write must be in your own words; you cannot copy material directly from these sources.

For Task 1a you will need to list the various types of communication devices and explain how they are used. Note that the unit content makes a distinction between ‘general’ communication devices, network components (servers, workstations, NICs, etc.) and interconnection devices (hubs, routers, switches, etc.). For this task (covering P1) you should be describing general communication devices, not specific components which are covered in Assignment 3. In practice, it might be quite difficult to make this distinction, but don’t spend too much time describing network components in this assignment.

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In terms of communication devices, the unit content mentions wired devices, such as DTE devices (e.g., a computer) and DCE devices (such as a modem), and wireless devices (such as mobile phones, PDAs and laptops, etc.). You need to explain in outline the way these devices can be connected to a network.

To cover P2 an explanation of digital signal theory is required. Refer again to the unit content to see the issues you must cover.

For Task 1b you need to write an explanation of the techniques used for error reduction. The only technique mentioned in the unit ...

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