Adaptive Narrowband Interference Suppression in Multiband OFDM Receivers

The analysis and optimization of a notch filter to combat in-band narrowband interference (NBI) for multiband orthogonal frequency division multiplexing (MB-OFDM)-based ultra-wideband (UWB) systems is presented. Unintentional radiation of electronic devices can reside in the UWB band and jam the communication. Erasing the interference with a programmable analog notch filter reduces the requirement for the analog-to-digital converter resolution in the presence of NBI. The order and approximation of the notch filter are determined, and the filter’s bandwidth is optimized to minimize the packet error rate. Simulation results indicate that the UWB system with suppression scheme can handle up to 14 dB more in-band interference power.     

Fast SAR Imaging Algorithm for FLGPR

A fast SAR imaging algorithm for nearfield subsurface forward-looking ground penetrating radar （FLGPR） is presented. By using nonstationary convolution filter, the refocused image spectrum can be reconstructed directly from the baekseattered signal spectrum of target area. The experimental results show the proposed method can fast achieve image refocusing. Also it has higher computational efficiency than the phase-shift migration approach and the delay-and-sum （DAS） approach.     

A Fast Algorithm for Improving the Visual Distance in Fog

Images captured outdoor usually degenerate because of the bad weather conditions, among which fog, one of the widespread phenomena, affects the video quality greatly. The physical features of fog make the video blurred and the visible distance shortened, seriously impairing the reliability of the video system. In order to satisfy the requirement of image processing in real-time, the normal distribution curve fitting technology is used to fit the histogram of the sky part and the region growing method is used to segment the region of sky. As for the non-sky part, a method of self-adaptive interpolation to equalize the histogram is adopted to enhance the contrast of the images. Experiment results show that the method works well and will not cause block effect.     

A New Fuzzy Adaptive Genetic Algorithm

Multiple genetic algorithms (GAs) need a large population size, which will take a long time for evolution. A new fuzzy adaptive GA is proposed in this paper This algorithm is more effective in global search while keeping the overall population size constant. The simulation results of function optimization show that with the proposed algorithm, the phenomenon of premature convergence can be overcome effectively, and a satisfying optimization result is obtained.     

A New Neuro-Fuzzy Adaptive Genetic Algorithm

Novel neuro-fuzzy techniques are used to dynamically control parameter settings ofgenetic algorithms (GAs).The benchmark routine is an adaptive genetic algorithm (AGA) that uses afuzzy knowledge-based system to control GA parameters.The self-learning ability of the cerebellar modelariculation controller (CMAC) neural network makes it possible for on-line learning the knowledge onGAs throughout the run.Automatically designing and tuning the fuzzy knowledge-base system,neuro-fuzzy techniques based on CMAC can find the optimized fuzzy system for AGA by the renhanced learningmethod.The Results from initial experiments show a Dynamic Parametric AGA system designed by theproposed automatic method and indicate the general applicability of the neuro-fuzzy AGA to a widerange of combinatorial optimization.     

An Adaptive Clustering Algorithm for Intrusion Detection

1 IntroductionBefore data mining techniques are introduced into net-workintrusion detection,intrusion detection was heavily de-pended on a manually maintained knowledge base which con-tained signature of all known attacks.Features of monitorednetworktraff…     

Decision-Directed Frequency Tracking Algorithm for OFDM System in Fast Fading Environments

1IntroductionOFDM known as a multicarrier modulation schemehas recently received considerable attention for its ro-bustness to multipath selective fading,provided by onetap equalization in frequency domain. This technique isrecommendedin Europe bythe ITU-Ras atransmissionstandard for Digital Audio Broadcasting ( DAB) fromsatellite or terrestrial fixed stations to mobile users ;andit also being adopted by EBU for terrestrial DigitalVideo Broadcasting (DVB-T) .In wireless environments …     

A High-Performance Doubly-Balanced Mixer in 0.35-μm CMOS for Mode-1 MB-OFDM UWB Receivers

A new design of CMOS doubly-balanced down-conversion mixer intended for Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) receiver of UWB group#1 bands and optimized for 0.35-μm technology is presented. The proposed mixer uses the current-bleeding technique in both the driver and switching stages with wideband impedance matching, consisting of a bandpass filter embedding the RF stage. The mixer performances are optimized for the AMS 0.35 μm CMOS process parameters. Over 3.1–4.8 GHz, the circuit drawing 6 mA from 3-V supply, shows a conversion gain of 14.0±1.0 dB, IIP3 of 0±2 dBm, doubly-sideband noise figure of 4.5–4.8 dB, and port-to-port isolation above 61.0 dB.

A Parallel Amplifier Structure for Increasing Dynamic Range of EW Receivers

In Electronic Warfare （EW） receivers, the desired Dynamic Range （DR） often far exceeds the dynamic range attainable with available Analog-to-Digital Converter （ADC） technology. ADC is the key bottleneck in achieving the needed dynamic range. In this paper, an approach for improving the effective DR by utiliTing multiple amplifiers is presented. The amplifiers, arranged in parallel channels with different gains, can increase the dynamic range greatly.     

A 70-MHz Continuous-Time CMOS Band-Pass ΣΔ Modulator for GSM Receivers

A 70-MHz continuous-time CMOS band-pass modulator for GSM receivers is presented. Impulse-invariant-transformation is used to transform a discrete-time loop-filter transfer function into continuous-time. The continuous-time loop-filter is implemented using a transconductor-capacitor (G _m -C) filter. A latched-type comparator and a true-single-phase-clock (TSPC) D flip-flop are used as the quantizer of the modulator. Implemented in a MOSIS HP 0.5-m CMOS technology, the chip area is 857 m × 420 m, and the total power consumption is 39 mW. At a supply voltage of 2.5 V, the maximum SNDR is measured to be 42 dB, which corresponds to a resolution of 7 bits.     

A New Enhanced Fast Handover Algorithm in Hierarchical Mobile IPv6 Network

1　Introduction　MobileIPv6requirestheMobileNode (MN)toregisterwiththeHomeAgent (HA)andtheCorre spondentNode (CN)whenitchangesitspointofattachmentintheInternet[1～ 3] .Therefore ,thiscauseMobileIPv6toincurlongdelayintheregis tration process,andaddsignalingtraffictothebackbonenetworkespeciallywhentheHAandCNarefarawayfromtheMN .Inordertominimizethisdelay ,andthesignalingoverhead presentinMobileIPv6,literatures[4～7] proposeHierarchicalMobileIPv6(HMIPv6)architectureandafasthan dover…     

A New Learning Algorithm for the Fusion of Adaptive Audio–Visual Features for the Retrieval and Classification of Movie Clips

This paper presents a new learning algorithm for audiovisual fusion and demonstrates its application to video classification for film database. The proposed system utilized perceptual features for content characterization of movie clips. These features are extracted from different modalities and fused through a machine learning process. More specifically, in order to capture the spatio-temporal information, an adaptive video indexing is adopted to extract visual feature, and the statistical model based on Laplacian mixture are utilized to extract audio feature. These features are fused at the late fusion stage and input to a support vector machine (SVM) to learn semantic concepts from a given video database. Based on our experimental results, the proposed system implementing the SVM-based fusion technique achieves high classification accuracy when applied to a large volume database containing Hollywood movies.     

A Study of the Partially Adaptive Concentric Ring Array

Concentric ring arrays can provide effective beamforming and achieve frequency invariant beampatterns. For long range signal acquisition, the array has a large number of array elements, and partial adaptation is often necessary to increase tracking ability and reduce computation. The topic of this paper is the study of a partially adaptive concentric ring array for three-dimensional audio signal acquisition. We develop the partially adaptive array through partition matrix formulation, provide the associated adaptive structure, and derive the steady state residual interference and noise power that can serve as a criterion to evaluate different partition structures. A comparison of several partition schemes using the criterion is given, and the theoretical results are supported by simulations. The research is supported by US AFOSR under contract FA9550-04-C-0058 and partially supported by the Polytechnic University of Puerto Rico.     

A Novel Adaptive Optimized Fast Blind Channel Estimation for Cyclic Prefix Assisted Space–Time Block Coded MIMO-OFDM Systems

In this paper an adaptive optimized fast blind channel estimation using cyclic prefix supported with Space Time Block Coded Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (STBC-MIMO-OFDM) system is presented. The main aspire of our technique is to support multiple users at the same time over same frequency band based on the Multi-Carrier Code-Division Multiple Access (MC-CDMA) approach. High complexity and low convergence is the main obstacle in earlier blind channel estimation techniques. Modified flower pollination algorithm is implemented to overcome this problem. The MC-CDMA approach is utilized to implement the blind channel estimation. The proposed MC-CDMA is used to reduce the error rate included in the Blind Channel Estimation. As a part of wireless communications, time block coding technique is utilized to transmit several copies of information across the number of antennas. To develop the consistency of data transfer different received data is used and then MFPA results in lower fuel cost compared to FPA. MFPA produces better results compared with previous methods.

     

A Modified max-log-MAP Decoding Algorithm for Turbo Decoding

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A New Algorithm for the Weighted Reliability of Networks

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A Carrier Synchronization Algorithm for IEEE 802.11a System

1　Introduction　OFDMisaneffectivetransmissionschemetocombatmultipathfading[1～2 ] .Ithasbeenappliedinmanycommunicationfields,suchasDigitalAudioBroadcast (DAB ) [4] ,AsymmetricalDigitalSub scriberLoop (ADSL) [5] andIEEE 80 2 1 1 .a[6] .OneoftheprincipaldisadvantagesofOFDMisthesensi tivitytofrequencyoffset.TheCFOdestroystheor thogonalityofthesubcarriers,inducesInter CarrierInterference (ICI)anddegradesthesystem perfor mancesignificantly[7～8] .　Manymethodshavebeen proposedtoestim…     

A Novel Dynamic Bandwidth Assignment Algorithm for Multi-Services EPONs

1IntroductionIt seems that providing broadband services is thesaver of telecom industry. Long-haul and Metro corenetworks are capable of carrying broadband servicessince they have experienced a dramatic i mprovement inbandwidth capacity and efficiency with the advent oftechnologies such as Dense Wave length Division Multi-plexing (DWDM)[1 ~3]and other newtechnologies .Buta clear bottleneckexistsinthe“first mile”of access net-work[4]. Without eli minationthe bandwidth bottlenecksthat exis…     

A Novel Multiuser Detection Algorithm for CDMA-Based MIMO-OFDM System

1Introduction Recently,MultipleInputMultipleOutput(MIMO)wirelesstechnologieshavecapturedalotofresearchin terest,giventhatthecapacityincreaseturnsouttobe achievable[1-2].OrthogonalFrequencyDivisionMulti plexing(OFDM)techniquehastheremarkablecharac teristic…     

Performance Analysis and Optimization Based on Adaptive Modulation and Chaotic Interleaving for Helicopter-Satellite Communications

Overcoming periodic blockage of the received signal and the carrier frequency fluctuations caused by rotor blades and Doppler shift, respectively, are considered the most challenging issues in helicopter-satellite communication systems. In this study, we propose an automatic frequency control method based on an adaptive modulation scheme. We employ a hybrid modulation not only depending on quadrature phase shift keying, but also based on binary phase shift keying for accurate cancellation of periodic blockage. On the other hand, we apply a chaotic interleaving scheme with a hybrid modulation scheme in order to achieve a better Bit Error Rate (BER) performance in LOS and NLOS environments. Finally, we validate the mathematical analysis of the proposed scheme through simulations. We evaluated the performance of the proposed scheme and performed a comparison with conventional schemes. Our results show that the proposed scheme is significantly capable of reducing the acquisition time and working with various velocities of helicopter blades in addition to providing a better BER performance in shadow fading environments.