Receiver In Communication System Research Articles

Simplified and accelerated PPM receivers for VLC systems

This study presents two receivers for visible light communication (VLC) systems. First, modified pulse position modulation (PPM) (MPPMD) and variable pulse position modulation (VPPM) (MVPPMD) demodulators are considered for MPPM and traditional VPPM schemes. The aim of this study is to minimise complexity at the receiver. On the basis of the derived mathematical framework, the multiplication stage is removed from the coherent detector architecture. Moreover, the generation of mask signals is unnecessary for the proposed receiver because they would be multiplied by the modulated signal for the traditional coherent detector. The simulation results show that MPPMD has the same bit error rate (BER) performance compared with the traditional coherent demodulators. Additionally, the resource utilisation of MPPM and VPPM receivers is dramatically reduced with removing the multiplication stage and the mask generator. Second, an accelerated VPPM (A-VPPM) algorithm is proposed to achieve a fast demodulation of the VPPM signal under the unknown dimming-level condition. Compared with the earlier VPPM receivers, the A-VPPM receiver can also demodulate the VPPM signal without any iteration stage and the mask generator. The BER performance of A-VPPM receiver is close to that of the traditional VPPM demodulator at 30 and 70% dimming levels.

Neural Network-Based Receiver in Band-Limited Communication System with MPPSK Modulation

As a type of the spectrally efficient modulation, the m-ary phase position shift keying (MPPSK) has been considered to meet the increasing spectrum requirement in the future wireless system. To limit the signal bandwidth and cancel the out-band interference the band-pass filters are used, which introduce the waveform distortion and inter-symbol interference (ISI). Therefore, a single hidden-layer neural network (NN)-based receiver is proposed to jointly equalize and demodulate the received signal. The impulse response of the system is static and the network parameters can be obtained after off-line training. The number of the hidden nodes is also determined through simulations. Simulation results show that the NN-based receiver works well in the communication system with different allocated bandwidths. By observing the modified confusion matrix, the false symbol decision is relevant to modulation index, waveform distortions and the ISI.

Analytical Performance Evaluation of MRC Receivers in Massive MIMO Systems

In recent years, massive or large-scale multiple-input multiple-output (MIMO) systems that rely on very large antenna arrays have become a hot topic of research in the field of wireless communications. This is in part due to the nearly optimum performance and relative simplicity of massive MIMO linear receivers and transmitters. This paper investigates the performance of maximum-ratio combining linear receivers in massive MIMO communication systems in terms of signal-to-interference-plus-noise ratio (SINR), bit error rate (BER), and outage probability. The probability density function (PDF) of SINR is analytically calculated for the first time and verified by simulation. Due to its complexity, the use of obtained analytical expression for performance evaluation purposes is prohibitive. Hence, this PDF is approximated by a gamma distribution and the resulting expression is used to evaluate the outage probability and the BER performance of the receiver.

Monte Carlo Analysis of Molecule Absorption Probabilities in Diffusion-Based Nanoscale Communication Systems with Multiple Receivers.

For biomedical applications of nanonetworks, employing molecular communication for information transport is advantageous over nano-electromagnetic communication: molecular communication is potentially biocompatible and inherently energy-efficient. Recently, several studies have modeled receivers in diffusion-based molecular communication systems as "perfectly monitoring" or "perfectly absorbing" spheres based on idealized descriptions of chemoreception. In this paper, we focus on perfectly absorbing receivers and present methods to improve the accuracy of simulation procedures that are used to analyze these receivers. We employ schemes available from the chemical physics and biophysics literature and outline a Monte Carlo simulation algorithm that accounts for the possibility of molecule absorption during discrete time steps, leading to a more accurate analysis of absorption probabilities. Unlike most existing studies that consider a single receiver, this paper analyzes absorption probabilities for multiple receivers deterministically or randomly deployed in a region. For random deployments, the ultimate absorption probabilities as a function of transmitter-receiver distance are shown to fit well to power laws; the exponents derived become more negative as the number of receivers increases up to a limit beyond which no additional receivers can be "packed" in the deployment region. This paper is expected to impact the design of molecular nanonetworks with multiple absorbing receivers.

Low-Noise Speed-Optimized Large Area CMOS Avalanche Photodetector for Visible Light Communication

Mean-gain and excess-noise measurements are presented for a 350 × 350 μm2 P+/N-well/P-sub and a 270 × 270 μm2 N-well/P-sub avalanche photodetectors fabricated using 0.13-μm CMOS technology. The active area of the P+/N-well/P-sub device was divided into multiple subsections to decrease transit time and increase speed. For the P+/N-well structure, remarkably low excess-noise factors of 4.1 and 4 were measured at a mean gain of 16 corresponding to a k value of approximately 0.1, using a 542 (633) nm laser. For a variant N-well/P-sub structure, excess-noise factors of 6.5 and 6.2 were measured at a mean-gain of 16 corresponding to a k value of approximately 0.3. The proposed CMOS APDs with high gain, low noise, low avalanche breakdown voltage (below approximately 12 V) and low dark-currents (approximately nA) would be attractive for low-cost optical receivers in visible-light communication systems.

MPPSK数字接收机位同步算法设计与实现

本文设计了一种用于MPPSK调制通信系统数字接收机的双窗实时位同步算法。该算法是一种反馈结构位同步算法，由定时误差检测单元、校正器等构成，基于数据辅助来计算定时误差。相较于现有的MPPSK接收机位同步算法，该算法具有同步建立时间短、不依赖冲击幅值、实时调整的优点。最后利用FPGA开发环境System Generator系统设计工具进行设计和仿真，并在基于Spartan-6系列FPGA设计的MPPSK数字接收机上进行了硬件协同仿真和验证。 This pager designs a double windows read-time symbol timing synchronization algorithm for the digital receiver of MPPSK modulation communication system. The algorithm is a feedback structure, which consists of timing error detection unit, corrector unit and so on and the timing error is calculated based on the auxiliary data. Compared with the existing symbol timing synchronization algorithm for MPPSK digital receiver, this algorithm has the advantages of short synchronization setup time, independent of impact amplitude and real-time adjustment. Finally we use the system generator development tools of Xilinx FPGA to do design and simulation, and we do hardware co-simulation and verification on MPPSK digital receiver based on Spartan-6 series FPGA design.

Leaky waveguide deflector for 40 GS/s and 6 bits all-optical analog-to-digital converters

Analog-to-digital converters (ADC) are an important part of realizing direct digital receivers in future communication systems, where broad bandwidth, high effective number of bits, and low DC power consumption are an important requirement of achieving it at microwave frequencies. Due to a number of physical limitations of electrical ADC, design of an all-optical analog-to-digital converter (AOADC) is pursued and presented here based on highly stable mode-locked laser based clock signal pulses for optical sampling, and a combination of leaky waveguide optical deflector using electro-optical (EO) polymers and stationary optical windows followed with high-speed photodetectors as optical quantizer. The reported principle of the AOADC is to convert a broadband RF signal into a spatially sampled light using optical deflection angle variation before quantizing it using either binary or Gray coded optical windows. The design and modeling of an AOADC working up to 20 GHz RF frequencies (with Nyquist sampling rate of over 40 GS/s) and for providing a resolution of better than 6 bits with under 4W of power consumption. Performance is currently limited by both optical and microwave attenuation in the available EO polymers.

The BLIXER, Integrated Balun-LNA-Mixer for ZigBee Application

Objectives: The main objective of this paper is to design a Blixer using noise-cancelling technique and balun –LNA-Mixer for better performance. Methods: As studied in literature of mixers, it shows they have less bandwidth disadvantage. This paper is concentrated to realize a wide bandwidth mixer by keeping the real part of the impedance of all RF nodes low, and using this mixer there is no capacitive loading problem. Findings: By avoiding use of inductors, the on chip size of circuit will be reduced and also the bandwidth extension requirement is fulfilled. This gives less DC-voltage drop after IF filtering. The design is implemented and simulated using Advanced Design System tool in CMOS 0.18um technology. The noise figure of the final BLIXER is obtained as 0.6dB and that of LNA is less than 2dB. This results are one of the best seen for a BLIXER. Applications: This design is well suited for wideband ZigBee receiver in wireless communication systems.

SDR implementation of the receiver of adaptive communication system

AbstractThe paper presents software implementation of a receiver forming a part of an adaptive communication system. The system is intended for communication with a satellite placed in a low Earth orbit (LEO). The ability of adaptation is believed to increase the total amount of data transmitted from the satellite to the ground station. Depending on the signal‐to‐noise ratio (SNR) of the received signal, adaptive transmission is realized using different transmission modes, i.e., different modulation schemes (BPSK, QPSK, 8‐PSK, and 16‐APSK) and different convolutional code rates (1/2, 2/3, 3/4, 5/6, and 7/8). The receiver consists of a software‐defined radio (SDR) module (National Instruments USRP‐2920) and a multithread reception software running on Windows operating system. In order to increase the speed of signal processing, the software takes advantage of single instruction multiple data instructions supported by x86 processor architecture.

Research on target information optics communications transmission characteristic and performance in multi-screens testing system

To enhance the stability and reliability of multi-screens testing system, this paper studies multi-screens target optical information transmission link properties and performance in long-distance, sets up the discrete multi-tone modulation transmission model based on geometric model of laser multi-screens testing system and visible light information communication principle; analyzes the electro-optic and photoelectric conversion function of sender and receiver in target optical information communication system; researches target information transmission performance and transfer function of the generalized visible-light communication channel; found optical information communication transmission link light intensity space distribution model and distribution function; derives the SNR model of information transmission communication system. Through the calculation and experiment analysis, the results show that the transmission error rate increases with the increment of transmission rate in a certain channel modulation depth; when selecting the appropriate transmission rate, the bit error rate reach 0.01.

Decision directed iterative channel estimation and Reed–Solomon decoding over flat fading channels

Iterative channel estimation and decoding over flat Rayleigh fading channels have been shown in literature to improve the performance of receivers in wireless communication systems. Turbo and low density parity check codes have mostly been used as the forward error correction (FEC) scheme in the iterative receiver structures. This study proposes a decision directed iterative channel estimation and decoding receiver using Reed–Solomon codes. In particular, the Koetter and Vardy, Reed–Solomon (KV–RS) soft decision decoder is adopted in the receiver structure as the FEC scheme. Two methods of deriving a priori information in joint iterative channel estimation and decoding receiver structures are also analysed in this study. The first method derives the a priori information employing the log likelihood ratio (LLR) method. A priori information derived using the LLR method is mostly used in iterative receiver structures in the literature. The second method derives the a priori information employing the distance metric (DM) method. The DM method is proposed in this study as an alternative approach to the LLR method of deriving a priori information in the iterative receivers. Hard and soft feedback information from the KV–RS decoder is considered to verify the performance of these methods. The performance of the two a priori information methods is documented through computer simulation assuming an M-ary quadrature amplitude modulation system. Simulation results verify the improvement in symbol error rate (SER) performance in the KV–RS iterative receiver structure in comparison with the KV–RS receiver without feedback. Also, the proposed DM method exhibits the same SER performance in comparison with the LLR method which is mostly used in the literature. More importantly, the proposed DM method has the advantage of less computational delay and time complexity compared with the LLR method.

SER performance analysis of MPPM FSO system with three decision thresholds over exponentiated Weibull fading channels

In this work, the symbol error rate (SER) performance of the multiple pulse position modulation (MPPM) based free-space optical communication (FSO) system with three different decision thresholds, fixed decision threshold (FDT), optimized decision threshold (ODT) and dynamic decision threshold (DDT) over exponentiated Weibull (EW) fading channels has been investigated in detail. The effects of aperture averaging on each decision threshold under weak-to-strong turbulence conditions are further studied and compared. The closed-form SER expressions for three thresholds derived with the help of generalized Gauss–Laguerre quadrature rule are verified by the Monte Carlo simulations. This work is helpful for the design of receivers for FSO communication systems.

X- and K-Band SiGe HBT LNAs With 1.2- and 2.2-dB Mean Noise Figures

This paper presents low-noise amplifiers (LNA) at X- and K-band frequencies in a 0.18- μm SiGe HBT technology. A method of noise match optimization with respect to base inductance in SiGe LNA design with large transistors is proposed. The measured X- and K-band LNAs result in 1.2- and 2.2-dB mean noise figure in their frequency bands, with an associated peak gain of 24.2 and 19 dB at 8.5 and 19.5 GHz, respectively. The measured IIP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> is -11 and -4 dBm at 10 and 20 GHz, for a power consumption of 32.8 mW (X-band LNA) and 22.5 mW (K-band LNA). To the authors' best knowledge, these results outperform all available CMOS designs and achieve the lowest mean noise figure at X- and K-bands in any SiGe or CMOS process. The main application areas are in low-noise receivers for terrestrial communication systems and low-cost radars.

An Improvement on Sensitivity Test for Micro-Power Wireless Communication

This paper mainly introduces the assessment methods of bit error performance which can effect the sensitivity of the receiver in micro power wireless communication system,use simple Poisson distribution and binomial distribution to analyzes the quota such as FBR, BER and average bit error rate impact of the bit error performance. In order to enhance the accuracy and reliability of sensitivity test,we give a true random bit stream generator to improve the emission signal which is used to detect the error performance.

Average BER of subcarrier intensity modulated free space optical systems over the exponentiated Weibull fading channels.

The average bit error rate (BER) for binary phase-shift keying (BPSK) modulation in free-space optical (FSO) links over turbulence atmosphere modeled by the exponentiated Weibull (EW) distribution is investigated in detail. The effects of aperture averaging on the average BERs for BPSK modulation under weak-to-strong turbulence conditions are studied. The average BERs of EW distribution are compared with Lognormal (LN) and Gamma-Gamma (GG) distributions in weak and strong turbulence atmosphere, respectively. The outage probability is also obtained for different turbulence strengths and receiver aperture sizes. The analytical results deduced by the generalized Gauss-Laguerre quadrature rule are verified by the Monte Carlo simulation. This work is helpful for the design of receivers for FSO communication systems.

A Novel Receiver in Visible Light Communication Based on RGB LEDs

In this paper, we demonstrate a novel receiver in visible light communication system based on RGB LEDs. It contains three major parts the collimating lens, the spectro-device and the photodetector. The mixed RGB signal lights are captured, separated and received by the collimating lens the spectro-device and the photodetector respectively. Through the adjustment of the collimating lens, the receiver can receive enough light even if the distance between the signal light source and the receiver is changed. The receiver has the advantages of strong mobility and strong ability of receiving signal light. Based on the designed receiver the high-speed visible light communication system using RGB wavelength division multiplexing technology can have better performance.

Suppression of the Narrow Band Jamming Signal in the Receiver of Spread Spectrum Communication System

This paper describes the design of adaptive finite impulse response (FIR)filter with least mean square(LMS) algorithm by which we can reduce the narrow band jamming impacting the performance spreadspectrum communication system (SSS).Simulation results shows that the jamming is rejected and theoutput signals free from error.

BER 성능 향상을 위해 제안하는 새로운 CDSK 수신기

카오스 방정식의 초기 조건이 미세하게 변하면 전혀 다른 신호가 생성되기 때문에 카오스 통신은 초기 조건에 민감한 특징을 갖는다. 또한, 카오스 통신 시스템은 비주기성, 광대역성, 신호의 비예측성, 구현의 용이성 등의 특성을 가지고 있다. 이런 특징으로 인해 카오스 통신 시스템은 다른 시스템에 비해 보안성이 우수하게 평가된다. 하지만 기존 카오스 통신 시스템의 송신기와 수신기는 간섭 신호나 잡음에 영향을 많이 받기 때문에 BER 성능은 다른 디지털 시스템보다 나쁘게 평가된다. 그래서 카오스 통신 시스템의 BER 성능을 향상시키기 위한 연구가 지속적으로 이루어지고 있다. 본 논문에서는 BER 성능 향상을 위한 새로운 CDSK 수신기를 제안한다. 기존 CDSK 수신기와 제안한 CDSK 수신기의 BER 성능 비교와 제안한 CDSK 수신기의 BER 성능 향상을 평가한다. 또한, 새로운 CDSK 수신기를 사용할 때, 확산인자에 따른 BER 성능을 평가하여 최적의 확산인자를 찾는다. 새로운 CDSK 수신기를 사용하면 기존 CDSK 수신기보다 BER 성능이 향상되며 간섭 신호나 잡음의 영향을 거의 받지 않기 때문에 확산인자 값이 커질수록 BER 성능은 향상된다. Chaos communication system has a sensitive characteristic to initial conditions, because completely another signal is generated when initial condition of chaos equation is changed subtly. Also, chaos communication systems have the characteristics of non-periodic, non-predictability, the broadband signal, such as ease of implementation. Due to these characteristics, security of chaos communication system generally is evaluated better than other systems. However, BER(Bit Error Rate) performance is evaluated worse than other digital system, because existing chaos communication system's transmitter and receiver are strong influence by interference signal and noise. So, research to improve the BER performance of the chaotic communication system is performed continuously. In this paper, We will propose a new CDSK(Correlation Delay Shift Keying) receiver for BER performance improvement. After we compare to the performance of existing CDSK receiver and proposed CDSK receiver, BER performance of proposed CDSK receiver evaluate. Also, when using the new CDSK receiver, we evaluate the BER performance according to the spreading factors and find an optimum spreading factor. If chaos communication system use a new CDSK receiver, BER performance is improved than existing CDSK receiver. Also, if spreading factor's value is increased, BER performance is improved, because it is not nearly affected by interference signal and noise.

A code-aided synchronization IP core for iterative channel decoders

Abstract. Synchronization and channel decoding are integral parts of each receiver in wireless communication systems. The task of synchronization is the estimation of the general unknown parameters of phase, frequency and timing offset as well as correction of the received symbol sequence according to the estimated parameters. The synchronized symbol sequence serves as input for the channel decoder. Advanced channel decoders are able to operate at very low signal-to-noise ratios (SNR). For small values of SNR, the parameter estimation suffers from increased noise and impacts the communication performance. To improve the synchronization quality and thus decoder performance, the synchronizers are integrated into the iterative decoding structure. Intermediate results of the channel decoder after each iteration are used to improve the synchronization. This approach is referred to as code-aided (CA) synchronization or turbo synchronization. A number of CA synchronization algorithms have already been published but there is no publication so far on a generic hardware implementation of the CA synchronization. Therefore we present an algorithm which can be implemented efficiently in hardware and demonstrate its communication performance. Furthermore we present a high throughput, flexible, area and power efficient code-aided synchronization IP core for various satellite communication standards. The core is synthesized for 65 nm low power CMOS technology. After placement and routing the core has an area of 0.194 mm2, throughput of 207 Msymbols/s and consumes 41.4 mW at 300 MHz clock frequency. The architecture is designed in such a way that it does not affect throughput of the system.

Chaos Based Optical Communication

 Abstract—Chaos based communication has been a very attractive research field from last couple of decades due to its potential of providing secure communication. In this paper, we reviewed principles and theory governing the field of chaos. We studied governing principles and different methods for chaotic signal generation and schemes used to modulate message signal with chaotic signal in optical fiber communication systems. We also reviewed the principal concepts governing chaos synchronization, types of chaos synchronization and some proposed techniques used for the synchronization of transmitter and receiver in optical fiber communication systems.