Department Of Engineering Ele4net Communications Networks Assignment 2 Total 35 Mark 3215577

Department of Engineering ELE4NET – Communications Networks Assignment 2 Total: 35 marks QUESTION 1: Assume that the signal level for the preceding bit for NRZ-I was high; the most recent preceding 1 bit for AMI has a negative voltage; and the most recent preceding 0 bit for Pseudoternary has a negative voltage. For the bit-stream 01001110, sketch the waveforms using the following encoding schemes: a) NRZ-L [2 Marks] b) NRZ-I [2 Marks] c) Bipolar-AMI [2 Marks] d) Pseudoternary [2 Marks] e) Manchester [2 Marks] QUESTION 2: (a) In the CRC error detection scheme, the chosen pattern is P(x) = x 4 + x + 1. Given the message bits D=10010011011, determine the FCS bits to be added to make the complete frame for transmission. [5 Marks] (b) Suppose we transmit this signal over the channel and the channel introduces an error, and the received signal is 000110110111100. Show how the error in the received data can be detected. [5 Marks] QUESTION 3: A data source produces 7-bit IRA (International Reference Alphabet) characters. Suppose a file of 10,000 IRA characters is to be sent over a line at 4800 bps. Assume that asynchronous transmission is used with 1 start bit, 1 stop bit and 1 parity bit. Calculate the overhead in bits and time. [5 Marks] QUESTION 4: Consider the network in Figure 1. Figure 1 a) Use Table 1 below to determine the least-cost paths from node 1 to all other nodes using Dijkstra’s algorithm for the network in Figure 1. [5 Marks] Iteration T L(2) Path L(3) Path L(4) Path L(5) Path L(6) Path 1 {1} 1 1-2 ?? – 4 1-4 ?? – ?? – 2 3 4 5