Performance of Direct-Sequence Spread-Spectrum Systems in the Presence of Multiple-Access Interference and Jamming

Optimization of a Multiple-Tone Jammer Operating against an Asynchronous Direct-Sequence Multiple-Access Spread-Spectrum System

“…The computational technique used in this research is described in [ 1 ], and summarized here. The statistics of the individual independent tones of a multiple-tone jammer are described in [8].…”

“…An expression for the pdf of the kth individual multiple-access user at the ith receiver is derived in [ 1] and presented here. First define Ok,i(lk) to be either Ok,i(lk) or Ok,i(lk) and Ok,i(lk + 1) to be either Ok,i(lk + 1) or Ok,i(lk + 1) as in (2) …”

“…First, the cdfs are used to find the exact probabilities of the individual interference random variables lying in the given sub-interval of a mesh. The cdfs are computed in [1]. These probabilities are then concentrated to the right (left) limit of each subinterval and convolved by discrete convolution with the right-shifted (left-shifted) probabilities from other interference terms to obtain the pi's (p-'s) for use with the corresponding xj's (xj's) in (1I) and (18).…”

“…The research described in this paper uses the alternative unified method described in a companion paper [ 1 ] because of its utility in analyzing the multipleaccess and/or jamming problem. An additional advantage of the method is that its computational complexity is calculated to be polynomial-like and is thus useful in ad hoc optimization strategies which rely on computer-aided analysis.…”

“…For the case of a multiple-tone jammer, M J(t) = E 2JV cos (27rfmt + bm) (5) The parameters are defined as follows sinc(x) sin x Afm = the difference of the mth jammer frequency from the carrier frequency of the system C(t) = the aperiodic autocorrelation of the code used by receiver i [ 1].…”