IST 220: Networking and Telecommunications, Fall 2019                       Homework Assignment 1

Note:

       This is an individual assignment. Each student needs to work on and submit his/her own assignment independently.

       There are four questions in this assignment. Questions 1-3 are worth 100 points in total. Question 4 is for Midterm exam preparation purpose only and will not be graded.

       Be sure to explain your answers and/or show the steps. You will not get any point if only showing the results.

       Submit a single .doc or .pdf file to the corresponding Dropbox on Canvas. The submission may be either typed or a scanned copy of your handwritten work.

       Due: Friday 9/20 at 11:59pm.

  1. Traceroute (40 points). On personal.psu.edu (130.203.28.46), we trace route to cs.berkeley.edu (128.32.125.5). Assume the output of the traceroute command is:

 

1. lcs.mit.edu (18.26.0.115) 15ms 16ms 15ms

2. dmc.berkeley.edu (128.32.126.1) 85ms 65ms 100ms

3. cs.berkeley.edu (128.32.125.5)  214ms 216ms 220ms

Answer the following questions:

(1)                   Draw the route from the source host to the destination host.

(2)                     H ow many hosts are in the route?

(3)                     How many hops are in the route? 

(4)                     What is the average round trip time from personal.psu.edu to cs.berkeley.edu ?

(5)                     How many packets are forwarded by lcs.mit.edu ?

 

 

  1. Signals (20 points). Consider the following analog signal:

Answer the following questions:

 

(1)                   Draw the frequency domain representation of the signal.

(2)                     What is the bandwidth of this signal?

 

 

  1. Channel Capacity (40 points). Answer the following questions:

 

(1)                   If an 800-baud system is to be used to achieve a bit rate of 3200 bps, how many signal levels need to be used?

(2)                     Assume the bandwidth for a wire is B=5000Hz. If there are 10 possible levels of voltages, what is the maximum bit rate enabled by the wire? Assume a noiseless channel.

(3)                     If there are noises, assume the average signal power level is 150 units, and the average noise level is 10 units. What is the maximum bit rate enabled by the same wire as in (2)?

(4)                     If a telephone system can be created with signal-to-noise ratio of 20dB and analog bandwidth of 8000Hz, how many bits per second could be transmitted?

 

  1. Channel Coding (For Midterm preparation only. No need to turn in). Answer the following questions:

 

(1)                   Compute the Hamming distance for the following pairs: (0000, 1000), (0101, 0010), and (1111, 1001).

(2)                     Generate a Row And Column (RAC) parity matrix with even parity checking for a (20, 12) coding of the data word 100011011111.

(3)                     Suppose that one bit in the following RAC code has been changed during transmission, and that the sender and receiver have agreed to use odd parity checking. Please determine which bit is in error and explain why.

1

0

1

1

0

1

1

1

1

1

1

  1

0

  0

1

  0

0

  0

1

1

0

0

0

1

0