System BER Research Articles

Power boosting factor determination in impulse postfix‐OFDM‐based positioning system

SummaryBased on recently introduced novel impulse postfix‐OFDM scheme, we proposed a joint time‐of‐arrival/angle‐of‐arrival positioning scheme, in which both channel estimation and positioning information can be realized by analyzing the channel impulse response estimated on an access point equipped with a uniform linear antenna array. However, the power boosting factor (PBF) determination of impulse postfix (IP) should be taken as an important issue, because a small PBF will result in imprecise channel estimation and deteriorate the communication quality, as well as positioning accuracy; in contrast, the huge power assignment on IP will lead to insufficient power allocated on date portion, when transmitted power is restricted, which also increases the system BER. In this paper, to obtain the optimal performance of both BER and positioning accuracy, we mathematically analyze the BER and positioning performance with increasing PBFs in the term of signal‐to‐noise ratio and confirm our assumption in the cases of quadrature phase‐shift keying and 16‐quadrature amplitude modulation, with computer simulation. The result applies that, as the PBF is increasing, the system BER is enhanced until PBF reaches 15 and starts deteriorating thereafter. According to the result, the decision criteria for determining PBF of IP should depend on practical preference of BER or positioning. Copyright © 2015 John Wiley & Sons, Ltd.

The effect of nonlinear distortion on the performance of MIMO systems

Nonlinear amplification in wireless systems results in in-band distortion which degrades system performance. The effect of nonlinear distortion is more severe in multiple-input multiple-output (MIMO) systems because signal encoding at the transmitter (such as transmitter precoding in singular value decomposition (SVD)-based MIMO) results in signals with higher peak-to-average ratio (PAPR) than single-input single-output (SISO) systems. In this paper, the effect of nonlinear amplification on the performance of a MIMO system is analyzed. The performance analysis is based on relating in-band distortion to system BER of a M-QAM modulated signals transmitted over a MIMO Rayleigh fading channel. It is shown that transmitter precoding results in increased in-band distortion and hence, increased system BER over the case when no precoding is used. The results presented in this paper can be used to derive limit of nonlinearity which allow energy efficient MIMO systems.

Wireless Sensor Network in the Virtual MIMO Energy-saving Transmission Scheme

Wireless sensor network (WSNs) is more and more attention from researchers in recent years. Wireless sensor network (WSN) is a large number of sensor through the way of wireless communication, mutual connection, the processing, the transmission of information network, can be real-time monitoring, perception and gathering network distribution area of various environmental monitoring object information, or information to process and transmit the information to the user. This article was based on the virtual MIMO STBC space-time coding technology combined with a cluster head cooperative transmission architecture, this paper proposes a suitable for clustering wireless sensor network based on STBC energysaving transmission scheme of virtual MIMO space-time coding based on STBC based spacetime coding in the MIMO system ber performance analysis, SCHCT scheme of the overall energy consumption model is established.

Real-time experimental demonstrations of software reconfigurable optical OFDM transceivers utilizing DSP-based digital orthogonal filters for SDN PONs.

Real-time optical OFDM (OOFDM) transceivers with on-line software-controllable channel reconfigurability and transmission performance adaptability are experimentally demonstrated, for the first time, utilizing Hilbert-pair-based 32-tap digital orthogonal filters implemented in FPGAs. By making use of an 8-bit DAC/ADC operating at 2GS/s, an oversampling factor of 2 and an EML intensity modulator, the demonstrated RF conversion-free transceiver supports end-to-end real-time simultaneous adaptive transmissions, within a 1GHz signal spectrum region, of a 2.03Gb/s in-phase OOFDM channel and a 1.41Gb/s quadrature-phase OOFDM channel over a 25km SSMF IMDD system. In addition, detailed experimental explorations are also undertaken of key physical mechanisms limiting the maximum achievable transmission performance, impacts of transceiver's channel multiplexing/demultiplexing operations on the system BER performance, and the feasibility of utilizing adaptive modulation to combat impairments associated with low-complexity digital filter designs. Furthermore, experimental results indicate that the transceiver incorporating a fixed digital orthogonal filter DSP architecture can be made transparent to various signal modulation formats up to 64-QAM.

Analysis on the Effects of Atmospheric Turbulence on Line-of-Sight Ultraviolet Communication System Performance

In the ultraviolet communication system, optical signals being transmitted are not only attenuated in energy, but also affected by the atmospheric turbulence. The effects of atmospheric turbulence intensity and information transmission rate on the BER performance of UV communication system are analyzed and simulated in this paper. It can be found that when the atmospheric turbulence intensity changes from weak to strong, the BER performance deteriorates along, and under the certain atmospheric turbulence intensity, information transmission rate will also have an impact on the system BER performance, the information transmission rate becomes faster, the BER performance gets worse.

BER ANALYSIS OF WIMAX IN MULTIPATH FADING CHANNELS

In this paper, an effort has been made to inspect the performance of WiMAX OFDM physical layer under the effect of noise. An End-to-end baseband WiMAX OFDM physical layer has been modelled in Multipath fading environment using MATLAB Simulink. BER has been evaluated for the Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), 16 Quadrature Amplitude Modulation (16 QAM) and 64 Quadrature Amplitude Modulation (64 QAM) schemes over a range of SNR (dB). The BER of a digital communication system is an important figure of merit for quantifying the integrity of data transmitted through the communication system. Several plots between BER and SNR (dB) for the abovementioned modulation schemes in Rayleigh and Rician fading channels have been investigated for the analysis.

A Beamforming Approach to Smart Grid Systems Based on Cloud Cognitive Radio

In this paper, we desire to use cognitive radio (CR) channels for communication among a wireless network of smart meters. However, self-interference critically limits the performance of CR systems. This is due to the coexistence of many unplanned systems simultaneously accessing the same signaling bands in an uncoordinated manner. To solve this problem, we show a beamforming approach that effectively mitigates the self-interference effects of the smart meter channel. The beamforming approach is based on minimum mean squared error (MMSE) method in smart meter systems. The MMSE beamformer usually requires accurate channel estimates and noise-plus-interference power estimates for effective mitigation of self-interference in CR systems. In this paper, we propose novel channel estimation and noise-plus-interference power estimation methodologies that efficiently exploit the preamble feature of the IEEE802.22 wireless regional area network (WRAN). Our framework is premised upon the utilization of a cloud computing smart grid infrastructure that hosts the IEEE 802.22 WRAN CR standard. The simulation results for a smart grid system with the MMSE beamformer illustrate significant improvements in system capacity and BER.

Unified Analysis of Multiuser Scheduling for Downlink MIMO Systems with Imperfect CSI

In this paper, unified BER performance and outage probability analyses of downlink multiuser scheduling for multiple-input multiple-output (MUS-MIMO) transmission/combining (transceiving) systems with imperfect channel state information (CSI) caused by feedback over Rayleigh fading channels is presented. The unified analysis is applicable to MIMO transceiving systems whose received signal-to-noise ratio (SNR) is given as largest order statistic of chi-square distribution. The performance of MUS-MIMO employing selective transmission/selective combining (ST/SC), ST/maximum ratio combining (MRC) and space-time block codes (STBC) can be analyzed by this general framework. Accurate and approximate unified closed-form BER and outage probability expressions of the MUS-MIMO transceiving system with normalized SNR-based scheduling in heterogeneous networks are derived. Based on the approximate BER and outage probability expressions, diversity gains are analyzed at high SNR. The results indicate that the MUS-MIMO for using the three transceiving schemes can achieve full diversity order for perfect CSI, while the diversity gain is degraded differently for the three transceiving schemes under imperfect CSI. Computer simulation shows that the theoretical analysis is in good agreement with simulation results, and the approximate BER expressions are very close to the accurate ones but with lower computational complexity.

Performance Analysis of a Modified SC-FDMA-DSCDMA Technique for 4G Wireless Communication

Single-carrier FDMA (SC-FDMA) is becoming more and more popular in multiuser communication because of its lower PAPR value. Apart from this, many other hybrid access techniques have also been explored in the literature for application to 4G wireless mobile communication. Still there is a need to explore newer techniques which could further reduce the PAPR value without any degradation in system BER. Keeping this in view, a modified hybrid technique SC-FDMA-DSCDMA has been proposed in this paper and it is found to provide significantly lower PAPR than SC-FDMA system with no degradation in BER performance. This paper extensively compares the BER and PAPR performance of various other multicarrier techniques for 4G wireless communications such as OFDMA, MC-DS-CDMA, and SC-FDMA with proposed SC-FDMA-DSCDMA scheme. Simulation results show that SC-FDMA-DSCDMA technique performs better than any other OFDM-CDMA based system for wireless communication.

An Efficient Algorithm for Improving Ber and Papr of Ofdm System by Using Nonlinear Companding Transform

One of the challenging issues for OFDM (Orthogonal Frequency Division Multiplexing) systems are its PAPR. Proposed review and analysis of various OFDM PAPR reduction methods are based on computational, complexity, spectral spillage and performance. Our aim is a non linear companding technique is proposed to reduce high PAPR of OFDM. Which can use companding for Peak to Average Power Ration control is explored for linking a nonlinear transmit power amplifier with OFDM. In this article analyses the improvement in Bit Error Rate and overall system performance by employing non linear companding technique for PAPR reduction in Digital Video Broadcasting system. Index-terms: Bit Error Rate (BER), DVB-T, OFDM, PAPR.

Precoding method interference management for quasi-EVD channel.

The Cholesky decomposition-block diagonalization (CD-BD) interference alignment (IA) for a multiuser multiple input multiple output (MU-MIMO) relay system is proposed, which designs precoders for the multiple access channel (MAC) by employing the singular value decomposition (SVD) as well as the mean square error (MSE) detector for the broadcast Hermitian channel (BHC) taken advantage of in our design. Also, in our proposed CD-BD IA algorithm, the relaying function is made use to restructure the quasieigenvalue decomposition (quasi-EVD) equivalent channel. This approach used for the design of BD precoding matrix can significantly reduce the computational complexity and proposed algorithm can address several optimization criteria, which is achieved by designing the precoding matrices in two steps. In the first step, we use Cholesky decomposition to maximize the sum-of-rate (SR) with the minimum mean square error (MMSE) detection. In the next step, we optimize the system BER performance with the overlap of the row spaces spanned by the effective channel matrices of different users. By iterating the closed form of the solution, we are able not only to maximize the achievable sum-of-rate (ASR), but also to minimize the BER performance at a high signal-to-noise ratio (SNR) region.

基于DCO OFDM的帧内信号时域调整技术研究

In conventional OFDM system,an OFDM symbol will exceeds its guard interval(GI)and seriously interfere with its neighboring symbols when channel characteristic is unsatisfactory.This will cause inter-symbol interference(ISI)and inter-carrier interference(ICI).In high-speed incoherent optical OFDM communication system,a novel time domain reshuffling method for mitigating ISI and ICI based on DCO-OFDM was proposed.This scheme utilized the properties of Fourier Transform.By simple preprocessing subcarrier channels in frequncy domain,sampling sequence of a DCO-OFDM symbol in time domain was exchanged interactively.Thus signal energy was centralized in the central part of a symbol.Numerical simulation indicates that ISI and ICI is significantly reduced and system BER performance is improved effectively due to signal surpassing the GI.In optical OFDM systems with insufficient GI for the popurse of higher information transmission efficiency,the reshuffling scheme also has a great value.

New Expressions for TWDP Fading Statistics

Two infinite series expressions are derived for the TWDP fading PDF and CDF. The derived series are shown to rapidly converge over the range of practical TWDP fading parameters. An efficient low-complexity algorithm is also proposed for evaluation of these series. Infinite series solution are derived for the TWDP moments, and the integral of the TWDP fading PDF against the complementary error function for performance analysis purposes. The BER of a BPSK system operating in TWDP fading is evaluated as an application of the results.

Any Bias Point Control Technique for Mach–Zehnder Modulator

A versatile any point bias control scheme for the Mach-Zehnder modulator is proposed. The ratio of first-order harmonic and average output power was used as feedback signal. We also demonstrate its effectiveness with simulations and experiments. This technique has been shown to be independent of optical input power to the modulator. The results show that this is an effective bias control technique suitable for a variety of modulation formats. The penalty for locking is small and it is 0.5 dB in OSNR penalty. The system BER performance has been observed for 72 h without degradation.

Performance Analysis of Ultraviolet Communication System in Fog Environment

Based on the analysis of ultraviolet single scattering channel model, the attenuation model of fog and its impact on signal attenuation is investigated. Under foggy environment, the study on the performance of ultraviolet communications is carried, simulation results show that the fog will not only make ultraviolet communication system BER performance deterioration, but also make information transmission rate substantially lowered. In addition, to guarantee a certain system performance indicators, the average transmitted optical power will have higher requirements.

Impact of STBC Scheme on BER Performance Assessment of a Single Amplify and Forward Relaying Protocol Based Cooperative MIMO-OFDM System

Cooperative communication is a novel class of wireless communication technique which wireless nodes help each other relay information to the intended destination. Orthogonal frequency division multiplexing (OFDM) has become a popular technique for the high data rate and performance. The integration of OFDM and cooperative communication in next generation wireless leads to the design of an efficient and reliable wireless network. A mathematical model for cooperative MIMO-OFDM system has been developed in the present study. Simulation results are provided to evaluate the BER and Text message performance of proposed system. It is observed that a quite satisfactory system performance is achieved in cooperative MIMO-OFDM with STBC under AAF relay for the MMSE detection scheme. It has been estimated from the simulation study that the performance of the cooperative MIMOOFDM communication system improves with the increasing of SNR.

BER and SER Performance of Rateless Codes Aided Multi-Hop Systems with Receiver Imperfections

BER and SER Performance of Rateless Codes Aided Multi-Hop Systems with Receiver Imperfections

Research on Channel Codec of DCR System Based on CMX7141

This article introduces a digital private network of mobile communication dedicated chipset CMX7141 that used for the 4FSK modulation and demodulation in DCR system, and introduces the application of CMX7141 inthe DCR system. Focus research on the channel codec techniques of the chip and have a simulation on the channel coding and decoding. The simulation results indicate that, through channel error correction technique in CMX7141, the BER of DCR system reduces greatly and the transmission quality of DCR system is improved.

Performance on OCDMA Encoder Based on Photonic Crystal

Encoder with a hexagonal lattice photonic crystal was performed by OCDMA simulation model. Filtering of photonic crystal cavity was used for encoding in spectral domain, and the distance between the dot defects was used for encoding in time domain because of its slow light effects caused by dispersion, whose time delay reached orders of ns magnitude. According to the simulation, the BER of OCDMA system with PC encoder is 10-23, while BER is 10-18 in the system with FBG encoder. By contrast, it is indicated that PC encoder requires strict demands on its own structure. With mismatching of encoder and decoder in receiving terminal, BER decrease to 10-7, and the performance of OCDMA system is serious affected.

A Combining Rate Adaptation Scheme of Channel Coding and Network Coding in None-relay Downlink Wireless System

We propose rate adaptation in the entire downlink process of transmission in channel-network combining coding systems. In current literatures, rate adaptation is discussed in channel coding or network coding separately and in traditional channel-network combining coding cases, network coding rates are generally 1. This paper is based on a one-source multi-destination wireless downlink communication system and a novel scheme of rate adaptation is applied. Our scheme of adaptation works between channel coding rate and network coding rate and its influence on system performance, which is given in form of simulation in the last chapter of this paper, shows that it works well for deducing system BER.