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CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Semester 2 Examinations 2010
Module Title: Networks
Module Code: CTEC
School: School of Electrical & Electronic Engineering
Programme Title: Bachelor of Engineering (Honours) in Electronic Systems Engineering
Programme Code: EELES_8_Y
External Examiner(s): Dr. A. Donnellan and Dr. Paula O’Sullivan Internal Examiner(s): Mr. F. O Reilly
Instructions: Answer THREE questions. All questions carry equal marks.
Duration: 2 Hours
Sitting: Summer 2010
Requirements for this examination:
Note to Candidates: Please check the Programme Title and the Module Title to ensure that you have received the correct examination. If in doubt please contact an Invigilator.
Q1. (a) Explain briefly your understanding of the following terms as applied to communication networks. o Medium
o Protocol
o Message
(10 marks) (b) Compare and contrast the ISO/OSI model and the IETF TCP/IP models for communications. What are the similarities? What are the differences? Both models use layers, what is the benefit of building a layered system? (12 marks)
(c) Describe the roles of two of the following in communications standards. (ITU, IEEE, EIA). Your answer should include, who they represent, naming some members, their areas of specialisations and one standard promoted by each of them. (12 marks) [Total: 34 marks]
Q2. (a) CSMA comes in two varieties, The first useful for wired networks. The second useful for wireless networks. Compare both types explaining how the wireless version differs from the wired one. (12 marks)
(b) A voice conversation requires a bandwidth of approximately 3.2kHz. Describe what technique a telecommunications company can use to carry multiple phone conversations over a single cable of 48kHz bandwidth. If a 800Hz guard band is used how many voice calls can be carried over the cable? (10 marks)
(c) Four data channels are multiplexed using TDM, each channel is 100 bytes per second. We multiplex the channels on a byte basis. Draw a representation of one frame and calculate the following. (i) What is the size of the output frame in bytes? (ii) What is the output frame rate? (iii) What is the duration of the output frame? (iv) What is the output data rate? (12 marks)
[Total: 34 marks]
