PERFORMANCE EVALUATION OF LOW DENSITY PARITY CHECK CODES FOR DIGITAL RADIO MONDIALE (DRM) SYSTEM

In Digital Radio Mondiale (DRM) system, achieving good audio quality becomes a challenge due to its limited band-width of 9 or 10kHz and the very bad fading channels. Therefore, DRM needs highly efficient channel coding schemes. This paper, proposes the schemes which use the Low-Density Parity-Check (LDPC) coded Bit-Interleaved Coded Modulation (BICM) schemes for the implementation of DRM systems. Simulation results show that the proposed system is more efficient than the Rate Compatible Punctured Con volutional (RCPC) coded DRM system on various broadcast channels, and may be recommended as a coding technology for Digital Amplitude Modulation Broadcasting (DAMB) systems of China.

EXPLICIT SOLUTIONS OF THE OPTIMUM WEIGHTS OF LAYERED NEURAL NETWORKS

It is shown in this paper that if the hidden layer units take a sinusoidalactivation function,the optimum weights of the three-layer feedforward neural networkcan be explicitly solved by relating the layered neural network with a truncated Fourier se-ries expansion.Based on this result,two approaches are presented of which one is suited tothe case that the detailed statistical information is available or can be easily estimated.An-other is of data-adaptive type,which can be treated as a solution of standardleast-squares.The later is best suited to realtime processing and slowly time-varying ap-plications since it can be straightforwardly implemented by the traditional LMS or RLSadaptive algorithms.It is also shown that for both the approaches,the resulting networksown an ability of forming arbitrary mappings.By using the present approaches,theconventional training procedure,which is usually very time-consuming,can be avoided.

JOINT SOURCE-CHANNEL DECODING OF HUFFMAN CODES WITH LDPC CODES

In this paper, we present a Joint Source-Channel Decoding algorithm (JSCD) for Low-Density Parity Check (LDPC) codes by modifying the Sum-Product Algorithm (SPA) to account for the source redun-dancy, which results from the neighbouring Huffman coded bits. Simulations demonstrate that in the presence of source redundancy, the proposed algorithm gives better performance than the Separate Source and Channel Decoding algorithm (SSCD).

AN INVESTIGATION OF BANDWIDTH IN DIELECTRIC SLAB LOADED RECTANGULAR WAVEGUIDE

Several technical problems of numerical method in TLM procedures arediscussed.The bandwidth of single mode in four kinds of dielectric slab loaded rect-angular waveguides is investigated,and the optimum bandwidth which is related tothe dimensions and dielectric constants is obtained.These results are useful to the de-sign of dielectric slab loaded rectangular waveguide.

ANALYSIS OF MICROWAVE N-PORT NETWORK BY A MODIFIED BOUNDARY ELEMENT METHOD

A new approach based on resonance technique and modified boundary ele-ment method is presented to calculate the impedance parameter matrix of a microwaveN-port network of waveguide structure.A two port network is taken as a numerical ex-ample and the results show that the approach occupys the advantages of high accuracyand less computation effort.

STUDY OF GROOVE NONRADIATIVE DIELECTRIC WAVEGUIDE AND LEAKYWAVE ANTENNA

A new structure of dielectric waveguide for millimeter waveband namedgroove nonradiative dielectric(GNRD)waveguide and a leakywave antenna based on thisstructure are developed in this paper.The GNRD structure overcomes the difficulty of as-sembling precisely the dielectric strip in the nonradiative dielectric(NRD)structure.Thedispersion characteristics of the GNRD waveguide,and the propagation and radiationcharacteristics of the GNRD leakywave antcnna have been analysed by the use of thetransverse rcsonance mcthod.The theoretical results are in good agreement with the exper-imental data.

IMPEDANCE THEORY AND BANDWIDTH OPTIMIZATION OF THE TWIN-LOOP ANTENNA

The Twin-Loop Antenna(TLA)has been widely used because of itsbroadband property and simply feeding,and some modified structures have been devel-oped from its prototype by Chinese engineers.But the exact design theory for TLA accord-ing to the impedance calculation has not yet been published.In this paper,the impedanceof loop in a TLA is analysed and computed by using the method of moments,and the de-sign formulae and a two-step optimization program for extending the bandwidth of inputimpedance of TLA are detailed.An example of optimized design shows that the bandwidthcan be increased up to 36.4% for VSWR≤1.10,which is wider than the bandwidth of ra-diation pattern.

AN ANALYSIS ON INPUT IMPEDANCE OF A SINGLE MICROSTRIP PATCH IN THE QUASI-OPTICAL CAVITY

The electromagnetic field integral equation in the quasi-optical cavity is obtained using the dyadic Green’s function. An expression is derived for the input impedance of a single microstrip patch cavity excited by a coaxial probe using moment method. The input impedance of a rectangular microstrip patch is discussed with this method. The result of this paper is similar to that of the microstrip antenna. This paper is of very important value for designing microstrip quasi-optical oscillator.

THEORETICAL STUDY OF A STRIPLINE PLANAR ANTENNA

Numerical results,of the aperture field,radiation pattern and directivity of a stripline planarantenna element are obtained by the moment method.The difficulty of singularities in the integral equationhas been overcome by a simple shift of the testing functions.

A NOVEL LINK ADAPTATION SCHEME TO ENHANCE PERFORMANCE OF IEEE 802.11G WIRELESS LAN

A novel link adaptation scheme using linear Auto Regressive (AR) model channel estimation algorithm to enhance the performance of auto rate selection mechanism in IEEE 802.11g is proposed. This scheme can overcome the low efficiency caused by time interval between the time when Received Signal Strength (RSS) is measured and the time when rate is selected. The best rate is selected based on data pay load length, frame retry count and the estimated RSS, which is estimated from recorded RSSs. Simulation results show that the proposed scheme enhances mean throughput performance up to 7%, in saturation state, and up to 24% in finite load state compared with those non-estimation schemes, performance enhancements in average drop rate and average number of transmission attempts per data frame delivery also validate the effectiveness of the proposed scheme.

Sound transducer calibration of ambulatory audiometric system utilizing delta learning rule

An efficient calibration algorithm for an ambulatory audiometric test system is proposed. This system utilizes a personal digital assistant (PDA) device to generate the correct sound pressure level (SPL) from an audiometric transducer such as an earphone. The calibrated sound intensities for an audio-logical examination can be obtained in terms of the sound pressure levels of pure-tonal sinusoidal signals in eight-banded frequency ranges (250, 500, 1 000, 2 000, 3 000, 4 000, 6 000 and 8 000 Hz), and with mapping of the input sound pressure levels by the weight coefficients that are tuned by the delta learning rule. With this scheme, the sound intensities, which evoke eight-banded sound pressure levels by 5 dB steps from a minimum of 25 dB to a maximum of 80 dB, can be generated without volume displacement. Consequently, these sound intensities can be utilized to accurately determine the hearing threshold of a subject in the ambulatory audiometric testing environment.

A CLASS OF BAND-LIMITED CHIP WAVEFORMS FOR DS-CDMA SYSTEMS

In Direct Sequence Code Division Multiple Access (DS-CDMA) systems,the chip wave-form affects the implementation,system bandwidth,envelope uniformity,eye pattern and Multiple user Access Interference (MAI). In this paper,based on an elementary density function of a second order polynomial,a class of second order continuity pulses is proposed. From this class of pulses,we can find some members having faster decaying rate,bigger eye opening,more uniform envelope and stronger anti-MAI capability than the Nyquist waveform. The normalized-bandwidth-pulse-shape-factor product,the decaying rate of the tail of the time waveform,the opening of the eye diagram,and the envelope uniformity of the second order continuity pulses are addressed in the paper that provide the basic information for the selection of the chip pulse for CDMA systems.

Feasibility Study of 60 GHz UWB System for Gigabit M2M Communications

In this paper,the feasibility and performance of millimeter wave(mm Wave)60 GHz ultra-wide band(UWB)systems for gigabit machine-to-machine(M2M)communications are analyzed.Specifically,based on specifications,channel measurements and models for both line-of-sight(LOS)and non-LOS(NLOS)scenarios,60 GHz propagation mechanisms are summarized,and 60 GHz UWB link budget and performance are analyzed.Tests are performed for determining ranges and antenna configurations.Results show that gigabit capacity can be achieved with omni-directional antennas configuration at the transceiver,especially in LOS conditions.When the LOS path is blocked by a moving person or by radiowave propagation in the NLOS situation,omni-directional and directional antennas configuration at the transceiver is required,especially for a larger range between machines in office rooms.Therefore,it is essential to keep a clear LOS path in M2M applications like gigabit data transfer.The goal of this work is to provide useful information for standardizations and design of 60 GHz UWB systems.

Analysis of Higher Order System with Impulse Exciting Functions in Z-Domain

This paper deals with mathematical modelling of impulse waveforms and impulse switching functions used in electrical engineering. Impulse switching functions are later investigated using direct and inverse z-transformation. The results make possible to present those functions as infinite series expressed in pure numerical, exponential or trigonometric forms. The main advantage of used approach is the possibility to calculate investigated variables directly in any instant of time;dynamic state can be solved with the step of sequences (T/6, T/12) that means very fast. Theoretically derived waveforms are compared with simulation worked-out results as well as results of circuit emulator LT spice which are given in the paper.

SPEECH ENHANCEMENT USING CONSTRAINED SPECTRAL AMPLITUDE SUBTRACTION BASED ON NONCAUSAL A PRIORI SNR

Two gain forms of spectral amplitude subtraction are derived theoretically without neglecting the correlation of speech and noise spectrum during the period of a frame. In the implementation, the constrained gain is expressed as a function of noncausal a priori SNR (Signal-to-Noise Ratio). Noise and noncausal a priori SNR are estimated from the multitaper spectrum of the noisy signal with algorithms modified to be suitable for the multitaper spectrum. Objective evaluations show that in case of white Gaussian noise the proposed method outperforms some methods based on LSA (Log Spectral Amplitude) in terms of MBSD (Modified Bark Spectral Distortion), segmental SNR and overall SNR, and informal listening tests show that speech reconstructed in this way has little speech distortion and musical noise is nearly inaudible even at low SNR.

Super energy flows in a waveguide filled with air and left-handed materials

The phenomena of super energy flows are studied theoretically and numerically in a parallel-plate waveguide which is filled with two layered equally-thick different media, i.e. air and specific left-handed materials (LHM) with ∈r1 = 1/(1 + δ) + iγ and r1 = (1 + δ) + iγ. In this special waveguide, two-directional super-energy flows are excited by a three-dimensional horizontal electric dipole at the same time, which has transmission patterns different from those of two-dimensional source and three-dimensional vertical electric dipole. We also show that the retardation and loss in LHM are sensitive to the amplitude of super power densities, and the dimensions of waveguide determine the propagating modes, which makes super energy flows more practical.

The New Enhanced Simple Authenticated Key Agreement Algorithm

Simple authenticated key agreement algorithm is one of the Diffie-Hellman key agreement variations. It prevents man-in-the-middle attack with only two more packets required to agree on the secret session key, but it has some weaknesses. In this paper, a new enhanced simple authenticated key agreement algorithm is proposed to overcome these weaknesses on the basis of analyzing the weaknesses of the related protocols. The new enhanced simple authenticated key agreement algorithm can get over replay attack and password guessing attack, provide perfect forward secrecy, and hold the merits of the simple authenticated key agreement algorithm.

ON MINIMUM-ERROR-PROBABILITY CHANNEL EQUALIZATION AND ITS REALIZATIONS USING k-NEAREST NEIGHBOR RULE AND NEURAL NETS

This paper deals with the minimum-error-probability(MEP)channelequalization problem and its realizations using k-nearest neighbor rule andbackpropagation(BP)neural nets.The main contributions include:(1)it shows that in thecase of the maximum possiblc value of the intcrsymbol intcrfcrcnce less than the magni-tude of the dcsircd symbol,the channcl equalization problcm is always lincarly separable;(2)the basic concepts and rclations of the MEP equalization are introduccd,and somenumcrical rcsults are providcd to indicate the performance advantage over the linear equal-izer;(3)subsequently prescntcd are the MEP adaptive equalizer implemented by k-nearestneighbor rule and the theorems regarding the asymptotic convergence and error bounds;(4)and finally it shows that the BP neural nets with appropriatc laycrs and nodes,whichtake minimization of mcan square crror(MSE)as the optimization goal,can also minimizethe error probability,thus leading to another realization of the MEP cqualizer.

A SINGLE-CAVITY MULTIPLE-DEVICE HARMONIC OSCILLATOR AT W-BAND

The equivalent circuit of single-cavity multiple-device fundamentaloscillator(SCMDFO)and that of single-device harmonic oscillator(SDHO)proposed byK.Kurokawa and K.Solbach,respectively,are extended and applied to a single-cavitymultiple-device harmonic oscillator(SCMDHO).By means of describing the functions ofnonlinearity of Gunn diodes,the performances of the SCMDHO are analyzed.It is foundthat the voltage amplitudes are similar to those of SDHO,and the ratio of maximum pow-er of harmonic to that of fundamental is identical to that in SDHO when the devices havesame parameters.The harmonic injection locking behavior is also investigated.The injec-tion locking range is greater than that of SDHO if locking gain remains constant.A2-Gunn diode harmonic oscillator was designed.It delivers 30mW output power at103GHz.The mechanical tuning range is 4.15GHz when the output power remains morethan 10mW.The desired operation mode is stable.

A SINGLE-TONE SERIAL HF MODEM SCHEME

A HF receiver for data transmission based on Kalman filter and channelestimator is proposed.The simulation results show that the performance of the proposedscheme is about 2 dB better than that of Decision-Feedback Equalizer based onSquare-Root Kalman Algorithm(SRKA/DFE)and its computational complexity islower than that of Maximum Likelihood Sequence Estimation(MLSE).