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<title>Conference Proceedings</title>
<copyright>Copyright (c) 2013 Southern Illinois University Carbondale All rights reserved.</copyright>
<link>http://opensiuc.lib.siu.edu/ece_confs</link>
<description>Recent documents in Conference Proceedings</description>
<language>en-us</language>
<lastBuildDate>Sat, 26 Jan 2013 22:41:04 PST</lastBuildDate>
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<title>Bounding Worst-Case Response Times of Tasks under PIP</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/91</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/91</guid>
<pubDate>Tue, 21 Jul 2009 09:41:17 PDT</pubDate>
<description>
	<![CDATA[
	<p>Schedulability theory in real-time systems requires prior knowledge of the worst-case execution time (WCET) of every task in the system. One method to determine the WCET is known as static timing analysis. Determination of the priorities among tasks in such a system requires a scheduling policy, which could be either preemptive or nonpreemptive.</p>
<p>While static timing analysis and data cache analysis are simplified by using a fully non-preemptive scheduling policy, it results in decreased schedulability. In prior work, a methodology was proposed to bound the data-cache related delay for real-time tasks that, beside having a non-preemptive region (critical section), can otherwise be scheduled preemptively.</p>
<p>While the prior approach improves schedulability in comparison to fully non-preemptive methods, it is still conservative in its approach due to its fundamental assumption that a task executing in a critical section may not be preempted by any other task. In this paper, we propose a methodology that incorporates resource sharing policies such as the Priority Inheritance Protocol (PIP) into the calculation of data-cache related delay. In this approach, access to shared resources, which is the primary reason for critical sections within tasks, is controlled by the resource sharing policy. In addition to maintaining correctness of access, such policies strive to limit resource access conflicts, thereby improving the responsiveness of tasks. To the best of our knowledge, this is the first framework that integrates data-cache related delay calculations with resource sharing policies in the context of real-time systems.</p>

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<author>Harini Ramaprasad et al.</author>


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<title>Modified Beacon-Enabled IEEE 802.15.4 MAC for Lower Latency</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/90</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/90</guid>
<pubDate>Fri, 05 Jun 2009 08:03:04 PDT</pubDate>
<description>
	<![CDATA[
	<p>Industrial sensing, monitoring and automation offer a lucrative application domain for networking and communications. Wired sensor networks have traditionally been used for these applications because such networks adequately meet two vital requirements, i.e., low latency and high reliability, needed for an industrial deployment. Wired sensor networks, however, are not very cost effective due to higher components’ cost. These networks also lack the flexibility needed for subsequent topological changes. Wireless sensor networks (WSN), on the other hand, are less expensive and offer high degree of flexibility. Wireless networks, therefore, can offer an attractive and viable solution for industrial sensing and automation. IEEE 802.15.4 standard defines a specification for MAC and PHY layers for shortrange, low bit-rate, and low-cost wireless networks. However, the specified system is inefficient in terms of latency and reliability and fails to meet the stringent operational requirements for industrial applications. In this paper, we propose a set of new MAC superframes with an aim to enhance both performance metrics. We then use simulation to compare the performance of our proposed systems with that of the one specified in IEEE 802.15.4 standard.</p>

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<author>G. Bhatti et al.</author>


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<title>Switched Order Statistics CFAR Test for Target Detection</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/89</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/89</guid>
<pubDate>Fri, 05 Jun 2009 08:03:02 PDT</pubDate>
<description>
	<![CDATA[
	<p>In this paper we introduce a new switched order statistics CFARtest (SW-OS) for detecting a radar target in the presence ofnonhomogeneous clutter and/or multiple interfering targets situation. Whereas a switching CFAR test (S-CFAR) was recently proposed in the literature for addressing a similar background scenario, unlike the S-CFAR test, the test proposed here does not utilize the test cell statistic in classifying the cells surrounding the test cell as homogeneous or not. The SW-OS test has some similarity to the selection and estimation (SE) test, which was co-authored by the second author ofthis paper, but is simpler to design. Probability of detection performance results obtained for Rayleigh clutter and Rayleigh target indicate that the SW-OS performs nearly as good as an order statistic test (OS) in the homogeneous background condition and performs much better than OS under the presence of many interfering targets. When compared to S-CFAR, SW-OS performs slightly worse in the homogeneous background, but performs better under the condition of many interfering targets.</p>

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<author>Anas Tom et al.</author>


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<title>Decision Combining in Relay Networks</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/88</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/88</guid>
<pubDate>Fri, 05 Jun 2009 07:59:57 PDT</pubDate>
<description>
	<![CDATA[
	<p>We consider non-coherent detection of <em>M-ary</em> FSK modulated signals transmitted over a slow, Rayleigh fading channel in a wireless relay network. The network consists of a single source-destination pair and a number of relays (<em>L</em>), which employ cooperative diversity. Performances of a counting rule and square law combiner are studied. We derive closed form expressions for probabilities of error for equal relay channel average SNR. For unequal relay channel SNRs, we resort to Monte Carlo simulations to estimate the error probabilities. We examine different combinations of <em>M</em> and <em>L</em> for a range of average SNR values. Although the square law combiner outperforms the counting rule for equal and small average SNRs, the loss in performance is not high. Simplicity of counting rule may be advantageous in these cases.</p>

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<author>Sharmin R. Ara et al.</author>


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<title>Ultra Wideband Channel Characterization and Ranging in Data Centers</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/87</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/87</guid>
<pubDate>Fri, 05 Jun 2009 07:55:14 PDT</pubDate>
<description>
	<![CDATA[
	<p>This paper presents a detailed measurement based characterization of the Ultra Wideband (UWB) channels in a data center environment and examines the accuracy of direct ranging using Time of Arrival (ToA) measurements. Modern data centers present a unique indoor environment that to our knowledge has not yet been characterized. Our ranging experiments indicate that it is possible to achieve an accuracy of fraction of a meter via direct ranging and point to the feasibility of locating individual servers using more sophisticated cooperative ranging.</p>

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<author>N. Udar et al.</author>


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<title>Signal-to-Noise Ratio Comparison of Amplify-Forward and Direct Link in Wireless Sensor Networks</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/86</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/86</guid>
<pubDate>Fri, 05 Jun 2009 07:55:12 PDT</pubDate>
<description>
	<![CDATA[
	<p>We compare the signal-to-noise ratio performances of an amplify-forward relay link and a direct link in a wireless sensor network. For a slow Rayleigh fading channel, an exact expression for the probability that the SNR of an amplify-forward relay link exceeds the SNR of a direct link is obtained. For a Rician fading channel, an upper bound for the corresponding probability is obtained. Numerical results indicate that, among the two fading channels considered, Rayleigh fading is more detrimental to the SNR performance of the amplify-forward relaying scheme.</p>

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<author>R. Viswanathan</author>


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<title>A Weighted Sum of Gaussian-Derived Pulse Design for UWB</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/85</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/85</guid>
<pubDate>Fri, 05 Jun 2009 07:55:11 PDT</pubDate>
<description>
	<![CDATA[
	<p>With 7.5 GHz of spectrum, ultra wide band (UWB) is an ideal candidate for achieving high data rates over short distances with low cost and low power consumption. In this paper, we propose a simple pulse design method that uses a linear combination of two Gaussian derivatives to meet the FCC spectral mask requirements. With distance and data rate analysis, it is demonstrated that the proposed pulse design is efficient as compared to previously proposed standard Gaussian monocycles. In quest of making UWB a universal standard, the proposed pulse is shown to satisfy the ETSI proposed UWB spectral requirements.</p>

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<author>H. Ray et al.</author>


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<title>A Simple Algorithm that Adapts one of Two Packet Sizes in a Wireless ARQ Protocol</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/84</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/84</guid>
<pubDate>Fri, 05 Jun 2009 07:51:29 PDT</pubDate>
<description>
	<![CDATA[
	<p>A recent algorithm of Modiano selects packet sizes in a selective repeat ARQ protocol based on the acknowledgement history of the most recently transmitted packets. In this paper we modify this algorithm so that the choice of packet size is restricted to one of two pre-specified values. We provide a strategy for switching between these packet sizes and show that is optimal in the sense of maximizing the one step efficiency. The throughput efficiency of the proposed adaptive scheme is analyzed for a constant bit-error-rate channel and for two state Gilbert-Elliot channel. The results show that the throughput efficiencies of this scheme under high and moderate bit-error-rates are slightly less than that of Modiano's algorithm. However the scheme is attractive because of its simplicity.</p>

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<author>Shiji M. Enchakilodil et al.</author>


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<title>Further Results on the Impact of Quality of Wireless Sensor Links on Decentralized Detection Performance</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/83</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/83</guid>
<pubDate>Fri, 05 Jun 2009 07:51:28 PDT</pubDate>
<description>
	<![CDATA[
	<p>In this paper we consider the impact of quality of wireless sensor links on the overall detection performance of a large sensor network system. Independent and identical sensors gather observations regarding the presence or the absence of a phenomenon of interest and then transmit their binary decisions to a fusion center over parallel, non-interfering but slow Rayleigh fading, wireless links. We derive asymptotic error exponents of the probability of false alarm and the probability of miss at the fusion center for the following cases: (a) BPSK modulation and (i) maximal ratio combining (ii) equal gain combining (iii) decision fusion (b) BFSK modulation and (i) square law combining (ii) decision fusion. In the case of BPSK, the EGC performs the best for low and moderate SNR, with the DF achieving the next best performance. The DF scheme performs the best for large SNR values, whereas the MRC performs the best for very low SNR values. Similar relative performance results were obtained by others for the case of a finite number of sensors. In the case of BFSK, square law combining outperforms DF, except for large SNR values. Finally, we show how the false alarm and the detection probabilities of the decision of a sensor, as seen at the fusion center, are altered by changes to the threshold of the matched filter receiver.</p>

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</description>

<author>Venkateshwara R. Kanchumarthy et al.</author>


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<title>Distributed Detection with Channel Errors</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/82</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/82</guid>
<pubDate>Fri, 05 Jun 2009 07:47:49 PDT</pubDate>
<description>
	<![CDATA[
	<p>Performances of distributed detection (DD) systems employing a set of geographically dispensed sensors have been investigated for the past two decades. In this paper we study the variations in the false alarm and detection probabilities of a DD system due to the errors caused by the links between sensors and the fusion center. Both asymptotic and finite sample performances are studied. The results bring out the exact dependence of these probabilities on the link reliability. Such a study is meaningful because of the recent research interests in wireless sensor networks.</p>

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</description>

<author>M. Madishetty et al.</author>


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<title>Signal Parameter Estimation Based on one-bit Quantized Data from Multiple Sensors</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/81</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/81</guid>
<pubDate>Fri, 05 Jun 2009 07:47:47 PDT</pubDate>
<description>
	<![CDATA[
	<p>We consider the problem of signal parameter estimation using a collection of distributed sensors. Each sensor quantizes its data to one-bit information and sends it to a fusion processor for the estimation of the parameter. Estimation of a constant signal in additive noise is considered. Since the emphasis is for the case of a moderately large number of sensors, we consider in this study two cases of estimation with 8 sensors and 20 sensors. We formulate several estimators based on one-bit sensor data and evaluate their mean squared error performances through simulation studies. Two parametric noise densities are simulated to ascertain the efficacies of various estimators. Results from this study show that robust estimation of parameter is possible by using a moderately large number of one-bit quantized sensor data.</p>

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</description>

<author>Antonios Mengoulis et al.</author>


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<title>A Modified Grouped-Tag TDMA Access Protocol for Radio Frequency Identification Networks</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/80</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/80</guid>
<pubDate>Fri, 05 Jun 2009 07:44:16 PDT</pubDate>
<description>
	<![CDATA[
	<p>In this paper we describe a new medium access protocol termed as the modified grouped-tag TDMA protocol (MGTDMA) for networking radio frequency identification tags. It is known that the previously proposed grouped-tag TDMA (GTDMA) protocol performs very well under the conditions of uniform destination distribution and not so well for heterogeneous traffic conditions. The MGTDMA differs from GTDMA in the sense that MGTDMA allows groups experiencing high traffic to steal (cooperatively) from low traffic groups at regular time intervals. Performance of an access scheme is assessed in terms of average packet delay and average energy consumption. Approximate analytical equation for average delay is derived. More accurate estimates for delay are obtained through simulation studies. We compare the performances of MGTDMA, GTDMA, and a pseudo random protocol and show the usefulness of the new scheme.</p>

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</description>

<author>Nicos Pastos et al.</author>


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<title>Order Statistics Based Diversity Combining for Fading Channels</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/79</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/79</guid>
<pubDate>Fri, 05 Jun 2009 07:44:15 PDT</pubDate>
<description>
	<![CDATA[
	<p>In this paper we present a new order statistics based diversity combining scheme (OSDC) for combining a set of independently fading signal amplitudes. The OSDC orders all the received signal amplitudes and uses only the two strongest signals in the combining process. The decision as to whether to use only the strongest or both the strongest and the next strongest is made depending on the relative strengths of these two highest order statistics. Signal-to-noise ratio performance of the new scheme is compared with that of the traditional schemes such as, selection combining, maximal ratio combining, equal gain combining, and a second order selection combining (SC2), for three channels, namely Rayleigh, Nakagami and exponential. The results show that OSDC performs as well as SC2.</p>

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</description>

<author>S. Gollakota et al.</author>


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<title>Diversity Combining in Antenna Array Base Station Receiver for DS/CDMA System</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/78</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/78</guid>
<pubDate>Fri, 05 Jun 2009 07:41:39 PDT</pubDate>
<description>
	<![CDATA[
	<p>This paper analyses few schemes for combining base station antenna array signals in wireless DS/CDMA. The performances of equal gain combining (EGC), likelihood rank test (LRT) and a modified rank test (MRT) are evaluated using simulation studies. The results indicate that, under certain assumptions on multiple access interference statistics, the probability of error of MRT is lower than that of EGC, if a few high power interfering users are present along with a low power user of interest. If there are a moderately large number of users and if the received power of all the users are nearly the same, then EGC outperforms MRT. In fact, under this condition, the performance of EGC is close to that of the optimal likelihood ratio test.</p>

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<author>C. H. Gowda et al.</author>


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<title>Performance of Distributed CFAR Tests in Nonhomogeneous Background</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/77</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/77</guid>
<pubDate>Fri, 05 Jun 2009 07:41:37 PDT</pubDate>
<description>
	<![CDATA[
	<p>We evaluate the performances of several distributed CFAR tests operating in nonhomogeneous background conditions. The analysis considers the detection of Rayleigh target in Rayleigh clutter sith the possibility of differing clutter power levels in the test cells of distributed radars. The tests considered include the previously defined maximum order statistic detector (MOS), belonging to a class of signal-plus- order statistic (S+OS) detectors, a new normalized test statistic (NTS), also belonging to the S+OS class, the OR and the AND fusion rules. Numerical results studied for a two radar system show how the false alarm rate of the MOS test changes with differences in the clutter power levels of the test cells. Results also indicate that, with differing test cells' power levels, the OR fusion rule can be quite competitive to more complex tests, viz. NTS and MOS.</p>

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<author>C. H. Gowda et al.</author>


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<title>Performance Loss Computation in Distributed Detection</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/76</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/76</guid>
<pubDate>Fri, 05 Jun 2009 07:36:54 PDT</pubDate>
<description>
	<![CDATA[
	<p>The loss associated with a distributed signal detection system as compared to a centralized scheme is evaluated with respect to probability of error. Such a loss is numerically computed for several members of the exponential family.</p>

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<author>Hamid Amirmehrabi et al.</author>


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<title>Crosscorrelation Functions of DS Codes and Probability of Error Evaluations for a Multiple Access Channel</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/75</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/75</guid>
<pubDate>Fri, 05 Jun 2009 07:33:56 PDT</pubDate>
<description>
	<![CDATA[
	<p>We derive a computationally feasible closed form error expression for probability of error for a small multiple access DS-BPSK system operating in a Rayleigh fading environment. Two properties of the crosscorrelation functions of the DS codes help reduce the number of error probability evaluations required when one considers all possible phase shifts of the users’ codes. Examination of the error rates for different phases of three maximal-length codes reveal that the probability of error is only weakly dependent on the phases.</p>

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<author>Osmar Coronel et al.</author>


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<title>Performance of a Rank Sum Combiner for FFH-MFSK Signaling in Partial Band Interference</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/74</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/74</guid>
<pubDate>Fri, 05 Jun 2009 07:33:54 PDT</pubDate>
<description>
	<![CDATA[
	<p>We consider the performance of a fast frequency hopping M-ary frequency shift keying spread spectrum rank sum diversity combiner. The spread signals are received in partial band interference and the parameters of this intentional interference are unknown. For the BFSK (M=2) case and a Rayleigh fading channel, the analytical performance of the rank sum receiver is compared to that of the linear receiver. Simulations are carried out for the rank sum receiver in a non-fading channel and compared to simulated performance of the clipper receiver and product combiner receiver (PCR). The performance of the rank sum combiner, in the non-fading channel, is comparable to the product combiner receiver and almost always is worse than the clipper receiver. In the Rayleigh fading channel, the rank sum receiver performs considerably better than the linear receiver when the jamming fraction is relatively small.</p>

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<author>James Colling et al.</author>


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<title>On SNR as a Measure of Performance for Narrowband Interference Rejection in Direct Sequence Spread Spectrum Systems</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/73</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/73</guid>
<pubDate>Fri, 05 Jun 2009 07:31:24 PDT</pubDate>
<description>
	<![CDATA[
	<p>We simulate a nonlinearized Kalman [5], Kalman and a modified Kalman (linear) filter for suppressing a narrowband Gaussian interference in direct sequence spread spectrum receiver and examine the suitability of Signal-to-Noise Ratio (SNR) of the test statistic as a measure of performance of the receiver. We consider Gaussian autoregressive interference with a peaked spectrum and the three cases: small processing gain (PG) and short pseudonoise (PN) sequence, small PG and long PN sequence, and moderate PG and PN sequence. Based on the simulations, we conclude that for the two cases corresponding to small processing gain, if the thermal noise variance is small and the interference is strong, the Gaussian approximation to the test statistic does not yield the correct BER for any of the receivers. For small PG and short PN sequence, even though the SNR corresponding to nonlinear filter is significantly higher than the SNRs of the two linear filters, the BER of the non-linear is higher than that of the linear receivers. SNR is not a useful measure in these situations.</p>

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<author>Arif Ansari et al.</author>


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<title>Performance Study of Maximum-Likelihood Receivers and Transversal Filters for the Detection of Direct-Sequence Spread-Spectrum Signal in Narrowband Interference</title>
<link>http://opensiuc.lib.siu.edu/ece_confs/72</link>
<guid isPermaLink="true">http://opensiuc.lib.siu.edu/ece_confs/72</guid>
<pubDate>Fri, 05 Jun 2009 07:28:56 PDT</pubDate>
<description>
	<![CDATA[
	<p>Linear least squares estimation techniques can be used to enhance suppression of narrowband interference in direct-sequence spread-spectrum systems. Nonlinear techniques for this purpose have also been investigated recently. Here, we derive maximum-likelihood receivers for direct-sequence signal in Gaussian interference with known second order characteristics. It is shown that if the receiver uses samples from outside the bit interval, then the receiver structure (called ML II)is nonlinear. The bit error rate performances of these ML receivers are compared to those of linear receivers employing one-sided and two-sided least squares estimation filters, for the case of Gaussian autoregressive interference, It is shown that the ML II receiver outperforms the matched filter, the one sided and the two sided transversal filters.</p>

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<author>Arif Ansari et al.</author>


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