Describe and explain with the aid of graphs and diagrams how Frequency Division Multiplexing (FDM) with 4 input channels can be implemented. Your diagrams and graphs should also include the demultiplexing stage. (5 marks)
(b) Describe and explain with the aid of graphs and diagrams how Orthogonal Frequency Division Multiplexing (OFDM) can be implemented and the differences with respect to FDM. Your answer should also address how OFDM and Orthogonal Frequency Division Multiple Access (OFDMA) are used in digital communications. (5 marks)
(c) Describe and explain Nyquist’s sampling theorem and its relevance in communications systems. Using graphs of sine waves with different frequencies, explain the importance of sampling rate and quantisation as well as explaining the term ‘aliasing’. (6 marks)
(d) With the aid of graphs, explain what signal conditioning would be desirable prior to transmission of a rectangular pulse train signal down a communications channel. (4 marks)
Please mention the Matlab code