KFUPM-EE DEPT.

EE573- Digital Communications II

Dr. Ali Muqaibel

Spread Spectrum

Summary of Main Points, v. 1.0

· Introduction

o Definition of Spread Spectrum and Bandwidth Expansion Factor

o Major Applications (Jamming, anti-jamming, covert, CDMA, radar)

o Definition of CDMA

o Coding and pseudo-randomness

· Types of Spread Spectrum

o Direct Sequence Spread Spectrum (DSSS)

o Frequency Hopping Spread Spectrum (FHSP)

· Model of DSSS Digital Communication System see figure 13.1-1

o Integration of Coding

· Types of Interference (Jamming)

o Broadband, narrowband, tone, multi-tone

o Continuous, pulsed

o Fixed, time varying

· Type of modulation considered and when?

o PSF and FSK

· Modulator Demodulator digital Circuits (13.2)

· Error Rate Performance of the Decoder (13.2.1)

o Jamming Margin, Jammer to signal ratio (JSR), processing gain,…etc with example

o Performance of the un-coded system

o Hard decision versus soft decision decoding

o Derivation for the performance of SS under different jamming Conditions. See to examples 13.2-1 and 13.2-2

o Performance under Pulsed Jamming (Partial Time Jamming)

§ Interleaving

§ Performance under different codes

· Generation of PN Sequences

o Criteria:

§ Auto-correlation

§ Cross-correlation

o Maximum Length Shift Register

o Gold Sequences

o Welsh Bound

o Kasami Codes

· Frequency Hopping (FH)

o Definition

o Features

o Slow Frequency Hopping (SFH) vs Fast Frequency Hoping (FFH)

o Detection Procedure

o Processing Gain

o Performance of SFH in Jamming Environments

§ Broadband Jamming

§ Partial-band Jamming

· Comparison FH vs. DS (7 points)

· CDMA Practical Example: Forward and reverse link IS-95 (748-753)

· CDMA vs. TDMA/FDMA : Viterbi debating himself in three published papers.

· Check Matlab for useful CDMA and SS codes

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Dr. Ali Muqaibel