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ELEC0032 Networking Systems
Instructions
Deadline: Friday 6th January 2025 at 4pm (16:00) on Moodle.
Warnings:
1. Please note that this is an individual assignment hence no collaboration is allowed. Please pay attention to UCL’s regulations on plagiarism and collusion: https://www.ucl.ac.uk/academic-manual/chapters/chapter-6-student-casework framework/section-9-student-academic-misconduct-procedure#9.4
2. Please note that penalties will be applied for late submissions beyond the advertised date and time in accordance with UCL’s regulations: https://www.ucl.ac.uk/academic-manual/chapters/chapter-4-assessment-framework-taught programmes/section-3-module-assessment#3.12
Submission instructions
• Upload your solutions to the Moodle submission point as a single PDF document.
• All your code (where applicable) should appear in one or more appendices.
• Note that all code and answers to questions have to be in “text” format. This means that you should not use snapshots/screenshots of code or text in your document. Marks will be deducted if code or text appears in non-textual format.
Assignment brief
You are being contracted as a consultant to advise a large technology company on investing in new technologies and protocols across the entire OSI and IoT stacks.
• Each assignment part will be marked out of 100% and then scaled down to a 25-point grade. All four parts weigh equally towards the final assignment grade.
Part 1 – Medium Access Control
This part will assess your knowledge and skills in modelling an area over which things are distributed and building a MAC protocol.
The company is keen to explore advanced Medium Access Control strategies as part of its focus on optimizing network performance in distributed systems.
1. Implement and analyze a modified version of a slotted ALOHA network simulation (use plots and text for presenting your results). [80%]
Requirements
1. Slot Transmission Probability: Each node will have a probability P_transmit of attempting to transmit in each time slot. This probability will vary by window size (P_transmit = 1/window_size), simulating a dynamic probability of transmission based on network load.
2. Priority-Based Backoff Mechanism:
- Each node has a "priority level" from 1 (low) to 5 (high).
- Upon collision, nodes with higher priority have shorter TTL backoff times, which are weighted based on the priority level.
- Nodes of priority 5 will have a smaller backoff range (0 to window_size/2), while nodes with priority 1 have the full backoff range (0 to window_size).
3. Dynamic Slot Count: Allow TSLOTS to be an input parameter to experiment with different network loads.
4. Metrics Collection:
- Track and calculate the total number of collisions, retransmissions, and successful slots.
- Store the slot efficiency and the collision ratio (collisions/total slots) for each window size and node count.
5. Visualizations:
- Plot slot efficiency against the number of nodes for each window size, as in the original lab.
- Add a second plot showing the collision ratio for each window size.
Questions to Answer in Your Report
- How does varying window_size impact slot efficiency and collision ratio as the number of nodes increases?
- What effect does the priority-based backoff mechanism have on collision rates compared to a random backoff?
- Analyze the performance of the network with high and low values of TSLOTS. What insights do you gather from these results?
- Reflect on the trade-offs of using slotted ALOHA for higher priority and lower priority nodes in a congested network.
2. Now consider a multi-user scenario with N = 10 sources transmitting based on the Slotted-Aloha protocol. Assume that each source has a packet generation rate of λ=〖10〗^3 packets per second and packet length 〖M=10〗^3 bits, transmitting over a channel with transmission rate R. Given that a normalized traffic L = 1 is experienced, evaluate the transmission rate. What is the impact of a higher packet generation rate? [20%]
Part 2 – Physical Layer
The company is looking to acquire a new wireless technology. You have been told that the inventors are using a modulation scheme.
You have been asked to prepare a document evaluating the technology. The company has asked for the following issues to be considered in your document (maximum 3 pages):
3. 1. Channel Simulation and Initialization [20%]
- Define the OFDM and QAM modulation objects, using QPSK, 16-QAM, and 64-QAM.
- Set parameters for the tapped delay line (TDL) channel to introduce multipath fading.
- Initialize simulation variables, including bandwidth, FFT size, and cyclic prefix length.
2. Adaptive Modulation Based on CSI [20%]
- Implement a CSI feedback mechanism that evaluates the channel gain for each subcarrier.
- Based on the CSI, adaptively select the modulation scheme:
- PSK for low SNR values.
- 16-QAM for moderate SNR values.
- 64-QAM for high SNR values.
3. Symbol Transmission [20%]
- Transmit a sequence of symbols over the adaptive OFDM system.
- For each OFDM symbol, dynamically select the modulation type according to the real-time channel conditions.
- Add white noise to simulate a realistic communication environment.
4. OFDM Demodulation and One-Tap Equalization [20%]
- Perform one-tap equalization on each subcarrier to mitigate frequency-selective fading.
- For each subcarrier, adjust the equalization based on the modulation type chosen in the transmission phase.
5. Performance Evaluation [20%]
- Compute the Symbol Error Rate (SER) for each modulation type.
- Plot the SER for each modulation scheme across varying SNR levels.
- Discuss results, focusing on the trade-offs in throughput and robustness across different modulation schemes.
Part 3 – Network and Transport
The company needs to produce a design for an IP network of a commercial ISP in the UK. The ISP has about 30% of the market of UK commercial residential broadband uniformly around the country and provides to its users a 100 Mbit/s connection. You should include:
1. The backbone topology of the network with realistic IP addresses and OSPF weights. [25%]
2. Proposed capacity of each link taking into account population in each region/city. [25%]
3. Using Wireshark imagine you are capturing a portion of the traffic in one of the routers in the company network. Use Python to analyze the performances of the network and the factors that influence its functionality. [50%]
Part 4 – Data Analytics
The company works as subcontractor for a water pumps company.
Consider an AI-assisted scenario centred around predictive maintenance for water pumps. In this context, you've been given access to a dataset (sensor.csv) containing information from 52 distinct sensors, along with timestamps and the water pump's status.
1. Data Visualization: [20%]
(i) Create visualisations illustrating the variation of each sensor's value over time.
(ii) Generate a count plot displaying the quantity of the unique labels of the machine status.
What insights can you derive from the histogram?
2. Data Exploration: [40%]
(i) Plot the Pearson correlation of the data with a correlation coefficient greater than 0.9. What insights we can derive based on the produced results and task A.a? Is it possible to group any of the sensor data together? If yes, could you provide an example of such a group?
(ii) Produce a table containing descriptive statistics, summarizing the central tendency, dispersion and shape of a dataset’s distribution, for the sensor data.
(iii) Compute the duration, in terms of the number of days, for which the data was collected.
3. Data Pre-processing: [40%]
(i) Identify and count the number of null values per attribute, then remove entries with null values.
(ii) Identify and count any duplicated entries and remove them from the dataset.
(iii) Encode the data in the machine status column.
(iv) Determine the data types of the sensor data, and normalise the relevant input features.
Assessment
Evaluation of the coursework will be based on the quality of the report and presentation, as well as
the depth analysis conducted.
Completion of experiments: 50%
Quality of analysis in the report: 30%
Clarity and effectiveness of the presentation: 20%