OFDM with the IFFT — mapping constellation symbols onto orthogonal subcarriers
OFDM part 3: packing QAM symbols onto subcarriers, IFFT to time domain, and how this builds the multicarrier waveform.
Mathuranathan
Introduction to OFDM — multicarrier idea, FDM vs OFDM, and the five-lesson path
OFDM study path — 5 lessons (same on every page in this series) 1. Introduction (you are here) → 2. Orthogonality → 3. IFFT modem → 4. Cyclic prefix → 5. BER in AWGN Tools: OFDM CP overhead calculator · Eb/N0 ↔ SNR converter In one sentence: OFDM shares bandwidth among many tightly spaced carriers … Read more
BPSK BER vs Eb/N0 — Rayleigh fading compared with AWGN (Matlab)
Why flat Rayleigh fading costs SNR versus AWGN for BPSK: BER vs Eb/N0 curves, formulas, and Matlab simulation comparison.
Clarke’s Rayleigh fading model — sum-of-sinusoids simulation
Fading & Diversity — 6 lessons (same on every page in this path) 1. Rayleigh BER → 2. Clarke’s model (you are here) → 3. Young’s model → 4. SIMO models → 5. Selection combining → 6. MRC Tools: BER vs Eb/N0 · 3GPP TDL · CDL / Doppler Lesson 2 of 6. You saw … Read more
Correlative Coding – Modified Duobinary Signaling
Modified duobinary is the partial-response cousin of duobinary that puts a spectral null at DC. It correlates symbols two baud intervals apart, so the controlled ISI sits on the alternate sample rather than the neighbour. The Nyquist zero-ISI condition is relaxed to The minus sign at lag \(2T\) is what opens the null at DC. … Read more
Correlative coding – Duobinary Signaling
The condition for zero ISI (Inter Symbol Interference) is which states that when sampling a particular symbol (at time instant nT=0), the effect of all other symbols on the current sampled symbol is zero. As discussed in the previous article, one of the practical ways to mitigate ISI is to use partial response signaling technique … Read more
Walsh–Hadamard codes — generate the matrix and simulate in Matlab
Walsh–Hadamard spreading codes: how to build the Hadamard matrix, orthogonality properties, and a Matlab simulation for CDMA-style use.
Spreading and Scrambling Codes in CDMA: Walsh, PN, Gold, and OVSF
Code Division Multiple Access (CDMA) systems multiplex users over identical time and frequency slots. Separation occurs entirely in the code domain. Fifty people talk at once in one room. Each pair speaks a different language, so you still follow your friend. That is CDMA. All users share the same frequency and the same time, and … Read more
FFT spectral leakage — causes, scalloping, and how windows help
Why FFT bins leak when tones miss bin centers, what scalloping loss is, and how windowing + ENBW trade leakage against noise bandwidth.
Understand Moving Average Filter with Python & Matlab
This post contains interactive python code which you can execute in the browser itself. The moving average filter is a simple Low Pass FIR (Finite Impulse Response) filter commonly used for smoothing an array of sampled data/signal. It takes (L) samples of input at a time and takes the average of those (L)-samples and produces … Read more