Maximum-length sequences (m-sequences) — LFSR properties and autocorrelation
m-sequences from linear feedback shift registers: period 2ⁿ−1, two-level autocorrelation, and their role as parents of Gold codes.
Spread Spectrum
Gold code generator — preferred pairs, correlation, and CDMA use
How Gold codes are built from preferred m-sequence pairs, their three-valued cross-correlation, and why they are used in CDMA/GNSS spreading.
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
Spread Spectrum Communications – Introduction
Spread spectrum system, originally developed for military applications, is extremely resistant to unauthorized detection, jamming, interference and noise. It converts a narrowband signal to wideband signal by the means of spreading. The original 802.11 and 802.11b used direct-sequence spreading. From 802.11a onward, Wi-Fi is OFDM. Bluetooth Classic hops; Bluetooth Low Energy hops as well, on … Read more