Communication Systems Assignment - QPSK and Error Control Coding

You are not required to submit a separate report on the two experiments. Only one report is needed. It will be in two parts.

1. Quaternary Phase Shift Keying and

2. Error Control

The report should answer the questions given. You will need to refer to notes and laboratory manuals together with the advice given in the laboratory briefing in order to give full answers.

Questions for QPSK -

Q1. Design a QPSK modulation and demodulation block which includes an AWGN channel using Matlab-Simulink. Submit the .mdl file in Blackboard with the following format: QPSK_yourname.mdl.

Q2. Using the system designed in Q1, explain your understanding on the effect of AWGN and on the BER.

Q3. View the constellation of the QPSK modulator. Explain your understanding on the constellation in detail.

Q4. Show that QPSK has the same BER as BPSK with and without channel coding, given the same range of E_b/N₀ in an AWGN channel. Explain your understanding from the results obtained.

Questions for Error Control -

1. Hamming Code:

a) Create an m-file for encoding and decoding a (15, 11) Hamming code. Provide commentaries on the source code and submit the m-file in the submission link in Blackboard. Verify the functionality/performance of your proposed Hamming code using Simulink.

b) Supposedly that the received data is 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0. Using Matlab, verify if there are any errors in the received data. If so, recover and show the correct data.

2. Convolutional Code:

A convolutional code is described by: g₁ = [1 0 1], g₂ = [1 1 1], g₃ = [1 1 1]

a) Produce the poly2trellis command for the given polynomials.

b) Encode the information of 1 1 0 0 1 0. Show the relevant Matlab command and its output.

c) Produce the Matlab command of the Viterbi decoder if the received message is 0 1 0 0 0 0 1 1 1 0 0 0 for the convolutional code. What is the decoded information?

d) Design a Simulink model for convolutional encoder and Viterbi decoder which includes an AWGN channel. Verify and discuss its performance under different values of E_b / N₀.