Multi Carrier Research Articles

Reconfigurable Filter Bank Multicarrier Modulation for Cognitive Radio Spectrum Sharing - A SDR Implementation

Background/Objectives: Cognitive radio is used as promising technologies for dynamic spectrum access and optimization of wireless resources. Under dynamic spectrum access to provide the ability of working any band of frequency based on need, the reconfigurable cognitive radio is designed. Methods/Statistical Analysis: Multicarrier modulation is the feasible method to share the spectrum without interference. OFDM is one of the efficient multicarrier techniques available for the system design. One of the problems in OFDM for spectral sharing is the side band leakage that will inject interference from secondary radio sub carrier to primary radio sub carrier. To avoid this, in this work a Filter Bank based Multi Carrier (FBMC) modulation is used. Findings: Few simulation works are reported for the interference free spectrum sharing by using FBMC. But this work analyzes the real time practical implementation of the interference free dynamic spectrum sharing. Reconfigurable is another important aspect of the implementation which is provided by the Kintex 7 FPGA implementation of the reconfigurable filter bank multicarrier modulation using NI USRP 2943R SDR platform. This FBMC based Transceiver is implemented by using fast Xilink IP cores of FFT and systolic array based FIR filter IP core. The transceiver is realized to produce output for every clock after a fixed latency 240 clocks or 6 microsecond for 40Mz clock rate. This performance is achieved using single clock loop architecture of LABVIEW FPGA tool and the parallel, pipelined architecture realization of IP cores and other building blocks. Applications/Improvements: Experimental study shows that the BER of primary user for the implemented system is better than the OFDM system by the factor of 10 -1 .

Energy Management Optimizing in Multi Carrier Energy Systems Considering Net Zero Emission and CHP Temperature Effects

Energy Management Optimizing in Multi Carrier Energy Systems Considering Net Zero Emission and CHP Temperature Effects

Performance of Spread Spectrum Based Multi-Carrier System in Underwater Communication Using Transmitter Pre-Processing

In this paper, we evaluate the bit-error-rate (BER) performance of a turbo-coded, transmitter pre-processing-assisted spread spectrum technology-based multi-carrier (MC) system for the acoustic information transmission in underwater communication. Our primary goal is to improve the power efficiency of the system in terms of signal-to-noise ratio (SNR) while obtaining achievable BER in underwater communication. In underwater communication, inter-symbol-interference and acoustic interference are the two most important issues, which affect the system performance. We use spread spectrum technique to mitigate the effects of unwanted information in the presence of ambient noise. Multi-user transmitter pre-processing (MUTP) is the digital processing method, which is carried out at the transmitter side to offer the low complexity of the receiver. We formulate the singular value decomposition-based pre-processing matrix using noisy feedback of vector quantized (VQ) estimated channel information (CI). We consider the MC communication to mitigate the effects of multi-path propagations. We realize iterative style of decoding algorithm at the receiver to retrieve the acoustic information from the ambient noise contaminated acoustic signals. In particular, we evaluate the error-rate analysis of MC system for realistic channel model based on shallow water channel model, which consists of 11 tap delay. Simulation results emanating from this paper bring to surface the considered coded MC system with MUTP offering a better BER performance with power efficiency regarding SNR while retaining the low complexity of the receiver. Furthermore, we observe that there is an improvement in the system performance when perfect CI is utilized to frame the pre-processing matrix compared with noise contaminated VQ-CI.

Concatenated and interleaving codes for MC DS CDMA using Cadence virtuoso

Multi carrier DS CDMA technique is the next generation mobile communication system for future advances. Error correcting codes and concatenated codes are used for correcting the errors in data transmission. In this paper, hybrid concatenated codes for MC DS CDMA structure has been proposed and parameters like usage time, power consumption and area are estimated. Further system performance can be attained by serially concatenating the proposed scheme with outer and inner codes. The interleavers are used for concatenated codes and it reduces the burst errors between outer and inner code of encoding and decoding operation in the MC DS CDMA model. In this paper, Verilog code is used for designing the entire structure of CDMA model. The simulation and estimated parameters is done by Cadence design environment.

OFDM Channel Estimation Based on Novel Local Search Particle Swarm Optimization Algorithm

A novel Channel Estimation (CE) approach in multi-carrier wireless communication systems, such as Orthogonal Frequency Division Multiplexing (OFDM) system and Code Division Multiple access (CDMA) via a combination of Local Search (LS) and Particle Swarm Optimization (PSO) algorithm is proposed in this study. The CE is vital towards overcoming the effect of channel fading, which causes the degradation of the Bit Error Rate (BER) and the jamming of pilot symbols. The CE expressions were derived as an objective function to study the effect of improving BER in MC-CDMA/OFDM for a frequency selective Rayleigh fading environment. The number of particles for each single swarm was used to determine the best fitness solution, and is being computed from an average BER value. The proposed channel estimator was tested under the fast fading channel in a multi carrier communication system with and without interpolation methods. The simulation showed that the proposed CE of the MIMO-OFDM system can significantly result in better BER performance compared with other techniques at different modulation types, mean square error (MSE), Signal-to-Noise Ratio (SNR) values, and channel lengths.

Performance Analysis of OFDM Synchronization Using Customized Floating Point for Low Complexity

Orthogonal frequency-division multiplexing (OFDM) is a multi carrier modulation scheme mainly used for digital communications. The performance of OFDM system heavily depends on the synchronization scheme used. In most cases, the accuracy level of synchronization will be worsened by the error caused in fixed point arithmetic involved. In this paper, we analyze the impact of the fixed point arithmetic on the performance of the coarse timing and frequency synchronization. Here with an analytical approach through numerical simulations bit length of IEEE 754 standard single precision format is optimized according to the required degree of accuracy for low complexity. Also, a complete precision level requirement for FFT computations with all possible modulation types is obtained. The proposed precision model is compared with IEEE standard single precision model and its efficiency in OFDM synchronization process is proved through MATLAB simulations. Finally, the complexity reduction of proposed precision model in both addition and subtraction is proved against single precision format using hardware synthesis. Here we proved that more than 50% complexity reduction is achieved as compared to standard precision models without compromising quality. The quality retention of proposed model is proved in both timing and frequency synchronization process.

Big Data-based Self Optimization Networking in Multi Carrier Mobile Networks

With regard to the increasing growth of demands in order to provide various services and high-speed in new generation of mobile telecommunications, one of the challenges ahead, are the available limited resources. In early cellular systems, with regard to the type of services that were provided, techniques such as the use of this frequency were enough. But in the telecommunications of the next generation, we have to use different techniques and features that are provided with resources in the area covered by the network, leading to an exponential increase in the operational complexity of these kinds of networks will be optimized in the scheme and optimization point of view. Therefore, to achieve an acceptable level of performance on these networks, intercellular performance management will be of great importance. One of the techniques that are recommended to enhance further the efficiency of cellular networks is the usage of self-optimization techniques in these kinds of networks. The foundation of our proposed scheme is presenting a self-optimizing model based on neighboring indices by which we can make feasible the possibility of controlling resources and the respective indices relevant to neighboring connections of cellular network without the interference of human force and merely by relying on the network’s intelligence. In order to better the efficiency of the intended scheme, we used the Big Data technique to analyze the data and network’s better decision-making process in allocating resources. In a way that in the uplink direction, user’s data from the user layer to the network core are analyzed in one register and based on semantic information extracted from these data, the decision-making center will be able to allocate resources in a more intelligent way. The works done on this Category to provide distributed solution of non-self-optimization or has paid for resources allocation that also may not to be close to the optimized solution or have passed up the effect of changes of network conditions. Gained results in the use of this model represent more efficient use of network resources and also reducing the load rate of the imposed signalling on the network.

Modeling of clustering and spread of diseases with multidrug pathogens

The epidemiology model for the non-immune disease with both ordinary and multi drug resistant carriers tuberculosis is considered via cellular automata algorithm on a square lattice. The early stage and stationary state of the disease are studied in various epidemiology regimes, as well as relative prevalence of multi drug resistant carrier, spatial patterns and clusterisation of infected individuals.

Case Study for Ship Ad-hoc Networks under a Maritime Channel Model in Coastline Areas

ITU-R M.1842-1, as a well-known specification dedicated to maritime mobile applications, has standardized wireless transmission protocols according to the particular characteristics of a maritime communications scenario. A time division multiple access (TDMA) frame structure, along with modulation schemes to achieve a high data rate, has been described clearly in ITU-R M.1842-1. However, several specification items are still under “to be decided” status, which brings ambiguity to research works. In addition, the current version of ITU-R M.1842-1 is focused mainly on maritime transmissions in open-sea areas, where the cyclic prefix (CP) is set to zero and only 16-QAM is used in the multi-carrier (MC) system. System performance might be dramatically degraded in coastline areas due to the inter-symbol interference (ISI) caused by selective fading. This is because there is a higher probability that the signal will be reflected by obstacles in coastline areas. In this paper, we introduce the transmission resource block (TRB) dedicated to ITU-R M.1842-1 for a ship ad-hoc network (SANET), where the pilot pattern of TRB is based on the terrestrial trunked radio (TETRA). After that, we evaluated SANET performance under the maritime channel model in a coastline area. In order to avoid noise amplification and to overcome the ISI caused by selective fading, several strategies are suggested and compared in the channel estimation and equalization procedures, where the link-level simulation results finally validate our proposals.

Design of Space-Time Coded Single-Carrierand Multi-Carrier MIMO-CDMA systems

CDMA is one of the channelization protocols that support more number of users simultaneously and asynchronously. Uses spreading technique that spreads information bearing signals, so that only intended receiver can able to receive it thus provides security. MIMO technology has been widely used in wireless communications provides higher data rate and reliability. In this paper single and multi carrier CDMA systems with multiple antennas has been implemented with Space-Time Coding technology (STC) and simulation results are shown. Rotated QSTBC is outperforming for both single and multi carrier systems.

Multi Carrier based Multilevel Inverter with Minimal Harmonic Distortion

<p>This paper presents performance features of Asymmetric Cascaded Multilevel inverter. Multilevel inverters are commonly modulated by using multicarrier pulse width modulation (MCPWM) techniques such as phase-shifted multicarrier modulation and level-shifted multicarrier modulation. Amongst these level-shifted multicarrier modulations technique produces the best harmonic performance. This work studies about multilevel inverter with unequal DC sources using level shifting MCPWM technique. The Performances indices like Total Harmonic Distortion (THD), reduction of switches and number of DC Sources are considered. A procedure to achieve the appropriate level shifting is also presented is this paper.</p>

DFT based Channel Estimation in OFDM System

Multi carrier modulation is Orthogonal Frequency Division Multiplexing (OFDM), dividing the large band spectrum into small (narrow) band spectrum. OFDM offers flexibility in adaptation to time varying channel condition by adopting the parameters at each subcarrier accurately. Due to the multipath effect the OFDM system suffers Inter Symbol Interference (ISI).ISI can be reduced by introducing the guard band (cyclic prefix).Time-varying channel estimation is an important activity in next generation wireless communication. Channel estimation is required mainly for the significant signal processing operation in multiple input multiple output MIMO- OFDM systems. In this project DFT – based channel estimation based on block type arrangement is implemented in MAT Lab. The bit error rate (BER) of DFT (Discrete Fourier Transform)based channel estimation is less than the BER of LS (Least Square) and MMSE (Minimum Mean Square Error) based channel estimation with same signal to noise ratio (SNR).

English

Orthogonal Frequency Division Multiplexing (OFDM) is the key technology for 4G and 3GPP LTE systems due to its highly efficient bandwidth and multi carrier modulation. The benefit of using OFDM is that it avoids ISI (Inter Symbol Interference) and ICI (Inter carrier Interference) by using timing synchronization technique. For this the symbols must be in properly synchronized form. It also have Higher transmission rate. So SC (Schmidl and Cox) algorithm is designed, It provides timing synchronization and lowers BER( Bit Error Rate). Based on the research of Schmidl & Cox, Minn and Bhargava and Park et al. synchronization algorithm, this paper proposed a comparison on these three timing synchronization algorithms.

Computational Intelligence and Application of Frame Theory in Communication Systems

In this study, we have to discuss the reduction of noise due to peak amplitude and power ratio in multi carrier modulation scheme like Orthogonal Frequency Division Multiplexing (OFDM) process using Frame theory. The frame operator of the frame which is positive, self adjoint, invertible and it commutes with synthesis operator. If X is dual frame in H with frame operator S and analysis operator T, then T is quasi normal operator. If Y is dual frame for X, T is quasi unitary operator. If T and Q are pseudo inverse and sum of its inverse with its ad joint multiplication is frame operator, then X is Bessel’s sequence and dual frame.

Computer Aided BER Performance Analysis of FBMC Cognitive Radio for Physical Layer Under the Effect of Binary Symmetric Radio Fading Channel

The wireless communication has undergone a revolution due to advancements in technology. For each new user or application to be a part of communication network the preliminary requirement is the allocation of frequency spectrum band. This frequency band is a limited resource and it is impossible to expand its boundaries. So the need is to employ intelligent, adaptive and reconfigurable communication systems which can investigate the requiremenmts of the end user and assign the requisite resources in contrast to the traditional communication systems which allocate a fixed amount of resource to the user under adaptive, autonomic and opportunistic cognitive radio environment. Cognitive radio technology has emerged from software defined radios wherein the key parameters of interest are frequency, power and modulation technique adopted. The role of cognitive radio is to alter these parameters under ubiquitous situations. The spectrum sensing is an important task to determine the availability of the vacant channels to be utilised by the secondary users without posing any harmful interference to the primary users. In multi carrier communication using digital signal processing techniques, filter bank multi carrier has an edge over other technologies in terms of bandwidth and spectral efficiency. The present paper deals with the multi rate FIR decimation and interpolation filter approach for physical layer of cognitive radio under binary symmetric fading channel environment.

Performance analysis of turbo-coded MIMO–OFDM system for underwater communication

In this article, we investigate the performance of a coded multiple-input multiple-output (MIMO) multi-carrier (MC) system in underwater communication, where acoustic interference and ambient noise are the two major channel impairments. The channel model considered in this work is based on the shallow water model that has eleven paths. In our work, the acoustic signal is spread with the aid of a high rate spreading sequence to alleviate the effects of acoustic interference. At the receiver, non-linear detectors based on Zero-Forcing (ZF) and Minimum-Mean-Square-Error (MMSE) are employed for signal detection. The simulation results reveal that the system under consideration with the MMSE detector provides better performance in terms of the achievable bit error rate than the system with the ZF detector while achieving higher data rates.

Performance enhancement of MC-CDMA system through novel sensitive bit algorithm aided turbo multi user detection.

Multi carrier code division multiple access (MC-CDMA) system is a promising multi carrier modulation (MCM) technique for high data rate wireless communication over frequency selective fading channels. MC-CDMA system is a combination of code division multiple access (CDMA) and orthogonal frequency division multiplexing (OFDM). The OFDM parts reduce multipath fading and inter symbol interference (ISI) and the CDMA part increases spectrum utilization. Advantages of this technique are its robustness in case of multipath propagation and improve security with the minimize ISI. Nevertheless, due to the loss of orthogonality at the receiver in a mobile environment, the multiple access interference (MAI) appears. The MAI is one of the factors that degrade the bit error rate (BER) performance of MC-CDMA system. The multiuser detection (MUD) and turbo coding are the two dominant techniques for enhancing the performance of the MC-CDMA systems in terms of BER as a solution of overcome to MAI effects. In this paper a low complexity iterative soft sensitive bits algorithm (SBA) aided logarithmic-Maximum a-Posteriori algorithm (Log MAP) based turbo MUD is proposed. Simulation results show that the proposed method provides better BER performance with low complexity decoding, by mitigating the detrimental effects of MAI.

AN APPROACH TO CONTROL INTER CELLULAR INTERFERENCE USING LOAD MATRIX IN MULTI CARRIER MOBILE COMMUNICATION SYSTEMS

This paper deals with reduction of inter cellular interference in Multi-carrier communication systems. In the past, Load Matrix(LM) is proposed to allocate power to different users in a network based upon Signal to noise plus interference ratio (SNIR) so as to reduce inter cellular interference and is observed for single carrier systems. In Multi carrier systems the SNIR is affected distinctly in each carrier thus a single SNIR for power allocation is not optimal. In this paper, to obtain the optimization of power allocation in Multi-Carrier system, Load Matrix coding with bifurcated SNIR (LM-BFSNIR) is proposed. Using this approach it is observed that inter cellular interference is reduced better when compared to a single carrier system evaluated over a 3GPP-LTE standard. Keywords−Power allocation, Inter cellular interference, Multi-Carrier mobile Communication system. -------------------------------------------------------------------***------------------------------------------------------------------

A Review on OFDM and PAPR Reduction Techniques

OFDM is a multi carrier transmission technique where a single set of data is transmitted over a number of sub-carrier. OFDM takes the advantage of multi-path propagation and reduces the fading effect. The idea of OFDM is to split the total transmission bandwidth into a number of orthogonal subcarriers which reduces the inter-symbol-interference, power consumption and increases the capacity and efficiency of the system. Peak-Average-Power-Ratio (PAPR) is one of the dis-advantage of OFDM which reduces the efficiency of system. In first part of this review, We have describe the OFDM characteristics of signals and its designing by combining the different block and in next part of this work, we have consider the PAPR effect in OFDM signals and have compared and review a several PAPR Reduction Techniques. The aim of this article is to provide a comprehensive detail about the implementation of an OFDM System and to study the different PAPR reduction techniques.

Multi User Performance On Mc Cdma Single Relay Cooperative System By Distributed Stbc In Rayleigh Fading Channel

Increasing data rate and high performance is the target focus of wireless communication. The multi carrier on multi-hop communication system using relay's diversity technique which is supported by a reliable coding is a system that may give high performance. This research is developing a model of multi user and two scheme of multi carrier CDMA on multi hop communication system with diversity technique which is using Alamouti codes in Rayleigh fading channel. By Alamouti research, Space Time Block Code (STBC) for MIMO system can perform high quality signal at the receiver in the Rayleigh fading channel and the noisy system. In this research, MIMO by STBC is applied to single antenna system (Distributed-STBC/DSTBC) with multi carrier CDMA on multi hop wireless communication system (relay diversity) which is able to improve the received signal performance. MC DS CDMA on multi hop wireless communication system with 2 hops is better performing than MC CDMA on multi user without Multi User Detector. To reach BER 10-3 multi hop system with MC CDMA needs more power 5 dB than MC DS CDMA at 5 users using Alamouti scheme for symbol transmission at the relay.