Mobile Network & Wireless Communication Assignment 2 – Semester 2 2019
? Deadline: Sunday 29 September, 2019 (11:55pm midnight on Moodle)
? Submission format: PDF only. You can use any freely available pdf converter to make pdf file from editable one.
? Submission platform: upload via Moodle on course website ? Files to submit:
? You need to submit only one file: Assign2(student_id).pdf
? Create a single file that contain answer to all questions
? No late submissions unless SPECIAL CONSIDERAION IS PROCESSED
Plagiarism: It is an academic requirement that your submitted work be original. Zero marks will be awarded for the whole submission if there is any evidence of copying, collaboration, pasting from websites, or copying from textbooks. –Plagiarism policy applies to all assessments
• This assignment is worth 20% of the total marks.
• The assignment is marked out of 50 nominal marks.
• For example, if you obtain 30 marks for this assignment, it will contribute (30/50)*20=12 marks to you final grade.
Q1. In relation to access to wireless network (e.g, WiFi), answer the following questions:
a. What is media access control and why is it important?
b. Give one example each of the controlled access methods and contention based media access methods?
c. When might one access method be preferred over another in a network, and why?
d. Under what conditions do contention-based media access control techniques outperform controlled-access techniques (i.e., have lower response time)? Explain.
Q2. Four users (U1, U2, U3 and U4) are using CDMA access techniques to transmit data to their respective receivers (U1- R1, U2- R2, U3- R3 and U4- R4). The followings are the spreading codes and the data that each user wants to send.
Users Spreading code Data to send
U1 1 1 1 1 0 0 0
U2 0 0 1 1 1 0 0
U3 1 0 0 1 0 0 1
U4 1 0 1 0 1 1 1
Using a spreadsheet similar to the one shown in Week 7 tutorial,
(a) show the composite signal that each receiver will receive;
(b) show how each receiver can retrieve its own data using the corresponding spreading code.
Note: encode ‘1’ in data as ‘+1’ and ‘0’ in data as ‘-1’ for this work.
Q3. Use internet resources and describe the Australian Academic and Research Network’s (AARNet) national and international network with diagram and information about the speed and the coverage.
Describe how AARNet is connected to the Internet in Australia and overseas.
Your description should be of minimum 500 words.
Part B – Scanning Wireless Access Points [Total 20 marks]
Q4. The software inSSIDer from metageek lets you scan surrounding WiFi networks. Download inSSIDer 22.214.171.124 from the following link:
a. Investigate wireless networks available in a shopping centre. Use the inSSIDer package installed on your laptop and walk through a shopping centre. Record the wireless networks available in at least three spots (you may consider going close to a McDonnalds). Capture the inSSIDer screen shots.
Give the list of available networks/access points including their technical characteristics like channel number, signal (SNR, signal to noise ratio in dB), security, etc. Include your screenshots from the software. Make some observations based on the data you collected, like, how do you relate SNR with the distance (from your own location to access points), overcrowded channels (i.e., multiple networks are transmitting using the same set of channels), etc.
b. Use inSSIDer at you home (or place of residence where you have other WiFi networks) and observe the signal strength and channel number of your own network and other networks. Can you suggest any way to change your access point’s (i.e., home router’s) transmission setting to get better reception within your home?