Systems Using Matlab And Simulink — Digital Communication

Together, they turn abstract theory into visible waveforms.

Consider designing a QPSK-based digital modem:

Step 1: Source Coding – Generate random bits using a Bernoulli Binary Generator.

Step 2: Modulation – Map each pair of bits to a complex symbol using the QPSK Modulator Baseband block. Set average power to 1.

Step 3: Pulse Shaping – Insert a Raised Cosine Transmit Filter with 50% roll-off. Oversample by 8 to avoid aliasing. Digital Communication Systems Using Matlab And Simulink

Step 4: Channel – Add AWGN with desired (E_b/N_0). If modeling multipath, insert a Multipath Rayleigh Fading block before AWGN.

Step 5: Receiver Front-End – The received signal passes through a Raised Cosine Receive Filter (matched filter). Then timing recovery (using Mueller & Muller or Gardner algorithm) corrects symbol timing offset.

Step 6: Demodulation & Decoding – The synchronized symbols enter a QPSK Demodulator Baseband block. Hard or soft decisions can be output.

Step 7: BER Analysis – Compare original bits with demodulated bits using the BER Calculator block. Export results to MATLAB workspace using an "To Workspace" block. Together, they turn abstract theory into visible waveforms

Example Simulink Model Structure:

[Bernoulli Gen] → [QPSK Mod] → [Tx Filter] → [AWGN] → [Rx Filter] → [Timing Rec] → [QPSK Demod] → [BER Calc]

Visual scopes can be placed at each stage to observe the constellation before/after filtering and the eye diagram after matched filtering.

Ready to build your own digital transceiver? Open MATLAB, type commqpsktxrx, and see a complete QPSK simulation running in seconds. Then, extend it—add fading, encoding, or SDR transmission. The spectrum is waiting.

Orthogonal Frequency Division Multiplexing (OFDM) is the cornerstone of 4G, 5G, Wi-Fi, and DVB-T. MATLAB provides the 5G Toolbox, featuring: Visual scopes can be placed at each stage

Simulink extends this with multi-carrier synchronization, cyclic prefix insertion, and fading channel simulation for vehicular environments (e.g., TDL-A, TDL-C models).

function ber = simulate_DigitalComm(EbNo_dB, modType, codeRate)
    % modType: 'bpsk', 'qpsk', '16qam'
    % Returns BER for given EbNo
end

To protect against errors, redundancy is added.

This is the core of the system, mapping bits to analog waveforms.