Code-Division-Multiple-Access - Computer Networks - Old Exam Paper, Exams of Computer Networks

Download Code-Division-Multiple-Access - Computer Networks - Old Exam Paper and more Exams Computer Networks in PDF only on Docsity! Cork Institute of Technology Bachelor of Science (Honours) in Software Development – Stage 2 (NFQ Level 8) Summer 2006 Computer Networks (Time: 3 Hours) Answer 4 questions, at least ONE from Section 1 and ONE from section 2 All questions carry equal marks. Examiners: Ms. D. Griffin Dr. J. Twomey Dr. M. O Cinneide Mr. M. Donnelly Section 1 Q1. (a) Explain with the aid of diagrams the difference between 'Baud Rate and Bit Rate? (5 marks) (b) A PC generates data at a rate of 21kbps. The data is encoded providing symbols each containing 128 binary levels prior to entering a transmission line. What is buad rate on the line and the required bandwidth of the line? (5 marks) (c) Discuss and explain the concept of sampling. A data spectrum has frequency components up to a maximum of 30Khz. Determine the minimum sampling rate required without any loss in information content. (5 marks) (d) What is PSK, use diagrams to illustrate your answer. Show the PSK constellation diagram for a system where the bandwidth required is reduced by a factor of three compared with the base requirement. (5 marks) (e) A telephone line has a bandwidth of 4000Hz and a Signal-To-Noise ratio of 36dB What is the maximum date rate for error free transmission? (Note log 2 X = 3.32xlog10 X). (5 marks) Q2. (a) Explain the main features of CDMA (Code-Division-Multiple-Access) Technologies. What are the main advantages and disadvantages of CDMA Technology? (5 marks) (b) Draw a block diagram of a frequency-hopped CDMA system and explain its operation. (6 marks) (c) In a slow binary Frequency -Hopped System FH-SH at one bit per hop the tone separation between '1' from ‘0’s is 60Hz in an FSK system. Determine the transmit frequency bandwidth BH to guarantee adequate separation and also the overall spreading or system bandwidth Bs if the frequency synthesiser has 18 addressing inputs. (6 marks) (d) Outline the basic construction of a fiber distributed data interface(FDDI) frame. Briefly define the functionality of the various components. (4 marks) (e) The latency of an FDDI optical ring consisting of 300 stations is 400 microseconds. Additionally the latency per station is one microsecond. Determine the total or composite latency both in microseconds and also in terms of bits of delay assuming a transfer rate 200Mbps. (4 marks) . Q3. (a) Explain the differences between hardware addressing, IP addressing and Ports. List one well known port number. (5 marks) (b) Compare and briefly describe the following types of multiplexing namely TDM, FDM and Statistical Multiplexing. (5 marks) (c) A number of low utilisation terminals each operating at 1200bps are to be connected to a leased line operating at 24000bps via a multiplexor. What type of multiplexor would you use and estimate the maximum number of terminals that may be employed? (5 marks) (d) Explain the terms BRI and PRI applicable to the European ISDN standard. What is overhead? (4 marks) (e) What are the essential features of ATM (Asynchronous Transfer Mode)? What are the main components of an ATM cell? Briefly outline some of the advantages of ATM over Frame Relay? (6 marks)