Blind Estimation of Direct Sequence Spread Spectrum Signals(3)

Abstract—Self-recovering receivers for direct-sequence spreadspectrum signals with unknown spreading codes are discussed in this paper. Applications include signal interception, jamming, and low probability of intercept (LPI) communications. A multirate/m

TSATSANIS AND GIANNAKIS:BLIND ESTIMATION OF DIRECT SEQUENCE SPREAD SPECTRUM SIGNALS IN MULTIPATH

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Fig.3.Multirate model of DS/SS system.

order

(9)

,and the code

length

is a circular complex Gaussian white noise

process,uncorrelated

with

.

Of the above assumptions,AS1)may be difficult to meet

in some applications.

If

,which is a tool that is

commonly used in multirate theory(e.g.,[27]).

B.Multichannel Framework

Let vector representation

of

(11)

with

vector.Similarly,let us

define

.It can be shown that the operation of

oversampling

by(the interpolatingfilter

in Fig.3)is described in the polyphase domain by[27,ch.

4]

(12)

or in

the

is a scalar quantity

multiplying

is an

FIR vector system since the

original

(14)

where

is the polyphase representation

of

be the polyphase representation of the signal

received at array

element.Then,by stacking

all the polyphase vectors in a supervector,we obtain the

description

..

.

..

.

..

.