Computer Networks Exam Questions, IT Degree, Manchester Metropolitan University, 1999/2000, Exams of Electrical Engineering

Download Computer Networks Exam Questions, IT Degree, Manchester Metropolitan University, 1999/2000 and more Exams Electrical Engineering in PDF only on Docsity! S464 02/09/02 THE MANCHESTER METROPOLITAN UNIVERSITY FACULTY OF SCIENCE AND ENGINEERING DEPARTMENT OF ENGINEERING AND TECHNOLOGY SESSION 1999/2000 Examination for the BSc (HONS) INFORMATION TECHNOLOGY FINAL YEAR UNIT 64EE3038 : COMPUTER NETWORKS Tuesday 23 May 2000 9.30 am to 12.30 pm Instructions to Candidates Answer FIVE questions. 1 02/09/02 continued 1. D e scrib e th e classes of service w h ich are available using A TM netw ork s giving an exam ple of an application for each service. [6] Broadcast television signals are to b e sent across an A TM netw ork . A b roadcast television picture com prises 720 pixels x 576 lines w ith a fram e rate of 25 fram es/sec. Calculate th e uncom pressed bit rate for th e digitized signal assum ing th at 12 b its are used to encode each pixel. [3] A reasonable approxim ation to th e natural inform ation b it rate versus tim e ch aracteristic for th e b roadband television signal is sh ow n in Figure Q 1. Find th e burstiness B of th e signal and th e com pression factor, w h ere compression factor = uncompressed bit rate average natural information bit rate [4] 0 1 2 3 4 5 6 7 8 Figure Q 1 D iscuss w h eth er th e signal sh ould be processed prior to transm ission by th e ATM netw ork and outline h ow such processing w ould occur. Select th e m ost approriate A TM service to be used in th is case and justify th e decision. [7] t 30 20 15 10 5 0 Natural Information Bit Rate (MBits/s) Time NATURAL INFORMATION BIT RATE VERSUS TIME 02/09/02 continued 4 5. Sum m arise briefly th e lim itations of FD D I w h ich resulted in th e need to develop th e FD D I-II standard. [4] Explain h ow FD D I-II provides th e functions w h ich overcom e th e lim itations of th e FD D I standard. [6] D e duce th e data rates provided by th e types of service offered by FD D I-II [6] D e scrib e b riefly h ow a video signal can b e sent over an FD D I-II netw ork . [4] 6. D e scrib e h ow discrete m ultitone signalling (DMT) is em ployed in asym m etrical digital sub srib e r line tech nology and calculate th e m axim um th eoretical bandw idth of DMT. Explain w ith reference to Figure Q 6 w h y th is th eoretical bandw idth lim it is unlik ely to b e ach ieved in practice. [6] D iscuss th e causes of th e im pairm ents sh ow n in Figure Q 6 and explain h ow D MT operates in such situations. [8] Figure Q 6 Com pare and contrast th e various digital sub scrib e r line tech nologies. [6] 02/09/02 continued 4 5 S464 02/09/02 7. Explain w h y error control sch em es are necessary in com puter com m unications. [3] D e scrib e th e operation of th e selective ack now ledgem ent error control tech nique including th e h andling of corrupted inform ation fram es and corrupted ack now ledgem ent fram es. [7] Explain th e operation of th e Go-Back -N error control sch em e including th e cases of both corrupted inform ation and ack now ledgem ent fram es. [7] D iscuss th e ch aracteristics of each sch em e. [3] 8. O utline th e functions of th e Internet Protocol. [4] Explain h ow th e Internet Protocol m ay be used to transfer m essages across an Eth ernet local area netw ork . [8] D iscuss th e function of th e ‘tim e to live’ field in th e IP h eader and its role in th e operation of th e Internet Protocol. [8] END