通信辅导 | 网络COSC1111/2061 Assignment1

Data Communication and Net-Centric Computing (COSC1111/2061) Assignment 1 (S2 2019)
Aims
• Explore data communication over the Internet
• Understand and practice towards implementing a communication related
algorithm
Instructions
This assignment is individual, includes tasks 1, 2 and 3 (optional with bonus) It contributes 20 plus 5 marks bonus towards your overall result of DCNC.
• Due date (Tasks 1 and 2): 11:59PM 25th August, 2019
• Submission via Canvas. Pease zip all your documents and use your student
number(s), as the file name for submission. PDF format is preferred.
Late submission policy
Task 1 (15 marks)
Figure 1 shows a cycle of sampling the sinusoidal signal using Pulse Amplitude Modulation (PAM) with a bit depth of 4.
a) Explain the three steps of Pulse Code Modulation (PCM).
b) If scale-up rule applies, give the output of PCM for the first four sampled points.
c) WhataretheerrorsincurredduringthePCM?
d) If the bit depth is 9, what would be the result of the first four sampled points.
e) If the size of PCM output in one cycle equals your student number (e.g. student
ID 3576218, then the size is 358kB). Calculate the sampled data size in 1
minute.
f) What technology could be used to reduce resource consumption in data storage
and transmission?
• There will be a late submission period of 5 working days for this assignment.
• Late submissions will incur a penalty of 10% (of the total score), unless prior
arrangements are made with the head tutor regarding an extension.
• Submissions that are received after the late submission period will not be marked
and will receive no mark.

Figure 1. Pulse Amplitude Modulation (PAM) (horizontal: time in millisecond; vertical: scaled sampled amplitude).
Task 2 (5 marks)
An application layer entity is sending an L-byte message to its peer using an existing TCP connection. The TCP segment consists of the message plus 20 bytes of header. The segment is encapsulated into an IP packet that has an additional 20 bytes of headers The IP packet in turn goes inside an Ethernet frame that has 18 bytes of header and trailer. What percentage of the transmitted bits in the physical layer correspond to message information, if:
a) L= 80 bytes?
b) L= 1400 bytes?
Task 3: (Optional with bonus due on 4th September) Implement an algorithm related to data communication.
a) Draw a signal flow chart or sequence diagram to show how this algorithm is implemented?
b) Implement the algorithm in any programming language you prefer (code should have comments).
The bonus part will be submitted separately with Tasks 1 and 2.

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