Results 1 
8 of
8
Narrowband interference suppression in CDMA spread spectrum communications
 IEEE Trans. Commun
, 1994
"... ..."
Narrowband Interference Suppression in Spread Spectrum CDMA
, 1994
"... this paper is to provide an overview of these techniques. An excellent review of those methods developed prior to 1988 can be found in a survey paper authored by Milstein [12]. Thus, although we will review all of the methods that have been proposed, we will treat these earlier methods only briefly, ..."
Abstract

Cited by 17 (1 self)
 Add to MetaCart
(Show Context)
this paper is to provide an overview of these techniques. An excellent review of those methods developed prior to 1988 can be found in a survey paper authored by Milstein [12]. Thus, although we will review all of the methods that have been proposed, we will treat these earlier methods only briefly, and we will focus instead on those that have been developed more recently. It should also be noted that much of the work in this area has been motivated by the application of spread spectrum as an antijamming signaling method for military use; however it is equally applicable to the problem of NBI in cellular CDMA. Current research makes a more conscious effort to incorporate methodologies that allow for performance improvements when considering the spread signal as a CDMA signal, as we will discuss later. We begin, in the following section, with a brief review of NBI mitigation techniques based on the linear signal processing regimes of adaptive linear transversal filtering, and Fourierdomain filtering. These methods represent the original approaches to this problem, and they are quite well developed. Most of this paper, on the other hand, will be concerned with recently developed modelbased techniques that employ nonstandard signal processing methods to enhance the interference rejection capabilities in CDMA systems beyond those of standard methods. In particular, in the second section we consider techniques based on nonlinear filtering [15] in which the spread spectrum CDMA signal (which is digital) is modeled as a nonGaussian noise in the interference suppression process. Further, in the third section we consider the situation in which the NBI is also a digital communications signal. In this situation, multiuser detection techniques [16] can be used to give quite ...
Multiuser detection techniques for narrowband interference suppression in spread spectrum communications
 IEEE Trans. Commun
, 1995
"... ..."
Suppression of Multiple Narrowband Interferers in a Spreadspectrum Communication System
 IEEE J. Select. Areas Commun
, 2000
"... We consider the problem of estimating and suppressing many unknown independent and timevarying interferers in a spreadspectrum communication system. The interferers are assumed to be present in a wide frequency range. In order to detect, estimate and track the interference, we use a bank of hidden ..."
Abstract

Cited by 6 (0 self)
 Add to MetaCart
(Show Context)
We consider the problem of estimating and suppressing many unknown independent and timevarying interferers in a spreadspectrum communication system. The interferers are assumed to be present in a wide frequency range. In order to detect, estimate and track the interference, we use a bank of hidden Markov model lters operating in the frequency domain. The hidden Markov model lters' outputs are then used to suppress the existing interference. The computational complexity of our scheme is only linear in the number of interferers. The simulation studies show that our proposed novel schemes adapt quickly in tracking the timevarying nature of the interference. 1 Introduction In this paper, we consider the problem of detecting, tracking and suppressing interference in a spreadspectrum communication system. The interference is assumed to consist of many unknown, independent and timevarying narrowband interferers. There are several advantages with spreading the spectrum of the signal th...
Interacting Multiple Model For Adaptive Narrowband Interference Rejection In Spread Spectrum Systems
"... This paper presents an adaptive codeaided technique for the suppression of narrowband interference (NBI) in directsequence codedivision multiple access (DSCDMA) systems. This technique uses a multiuser detector based on the Interacting Multiple Model (IMM) algorithm. This detector is based on th ..."
Abstract
 Add to MetaCart
This paper presents an adaptive codeaided technique for the suppression of narrowband interference (NBI) in directsequence codedivision multiple access (DSCDMA) systems. This technique uses a multiuser detector based on the Interacting Multiple Model (IMM) algorithm. This detector is based on the concept that the effective model of the received signal at a time instance can be approximated by one of models in the IMM algorithm. Simulations are used to compare the performance of the proposed technique with that of the recursive least squares (RLS) version of the minimum meansquare error (MMSE) for multiuser detection [1].
Joint Iterative MMSE Multiuser Detection and Narrowband Jammer Suppression in Coded DSCDMA Channels
"... Abstract  Existing narrowband jammer suppressors for DSCDMA, typically function independently of the multiuser interference cancellation strategy used. Besides, certain highperformance jammer suppression techniques, e.g., linear MMSE suppression, assume that the powers and frequencies of the i ..."
Abstract
 Add to MetaCart
(Show Context)
Abstract  Existing narrowband jammer suppressors for DSCDMA, typically function independently of the multiuser interference cancellation strategy used. Besides, certain highperformance jammer suppression techniques, e.g., linear MMSE suppression, assume that the powers and frequencies of the interfering signals are known, or that they can be adaptively estimated. The former is never true in practice and the latter is not feasible when long spreading codes are used. The present work eliminates these restrictions, by applying the idea of iterative MMSE multiuser interference suppression, introduced earlier by the authors, to this context. The rst iteration in this procedure is effectively MMSE multiuser interference cancellation; the parameters of the jammers are unknown at this stage. The outputs of all users ' soft decoders (applied to the demodulator outputs of this iteration) are then fed back to subtract their (estimated) cumulative contribution from the received signal vector; the residue comprises the narrowband jammers embedded in wideband noise, so that the former can be piecewise interpolated over chip intervals of appropriate duration, and thence subtracted from the received signal for the succeeding iteration. The softdecoded feedback estimates of the interferes ' signals are also used in each iteration to perform soft MMSE multiuser interference suppression, in conjunction with subtractive interference cancellation. The approach is extended to exploit the enhanced separation (in the spatial sense) that is aorded by employing multisensor receivers. I.
3Filtering Techniques for Mitigating Microwave Oven Interference on 802.11b Wireless Local Area Networks by
, 2003
"... With the increasing popularity and assimilation of wireless devices into the everyday lives of people, the issue of their feasibility for coexisting with other radio frequency (RF) devices arises. Particularly strong interferers for the IEEE 802.11b standard are microwave ovens, since both operate a ..."
Abstract
 Add to MetaCart
With the increasing popularity and assimilation of wireless devices into the everyday lives of people, the issue of their feasibility for coexisting with other radio frequency (RF) devices arises. Particularly strong interferers for the IEEE 802.11b standard are microwave ovens, since both operate at 2.4 GHz. The interference mitigation techniques all exploit the differences between the interference and the signal, since the former is sinusoidal in nature while the latter can be viewed as noise. The first mitigation filter operates in the frequency domain and filters the received signal’s Fast Fourier Transform (FFT) sequence by detecting and removing peak sinusoidal components over the flat 3dB bandwidth of the signal. The second is a Least Mean Square (LMS) Adaptive filter that produces an estimate of the interference through a recursive approximation method and subtracts it out from the received signal. The third and last is the Adaptive Notch Filter (ANF) which implements a lattice structure and has a timevarying notch frequency parameter that converges to and tracks the frequency of the interference in the received signal. The three filters are shown to produce improvements in the bit error rate (BER) and frame error rate (FER) performance of the receiver under various relative strengths of the signal with respect to the interference.