QPSK Research Papers - Academia.edu (original) (raw)

The continuous use of Internet services and applications triggers a sustainable growth of data transfer, therefore generating a necessity to develop an efficient and scalable transport platform. A novel-networking concept -Elastic Optical Networks (EONs) -can support bandwidth-demanding traffic from an advent of new services including cloud computing and content delivery networks. In this paper, we focus on dynamic routing of anycast and unicast traffic; anycast refers to cloud computing or content traffic served by data centers. We assume that EONs support various distance-adaptive modulation formats, namely BPSK, QPSK, and m-QAM, where m belongs to {8, 16, 32 and 64}. A higher modulation format consumes less spectrum, which can lead to a smaller blocking probability (BP) in dynamic routing. However, at the same time, a higher modulation format provides a smaller transmission distance, which triggers the need to use regenerators and increases CAPEX/OPEX network costs as well as power consumption. Therefore, the main goal of our research is to find a trade-off between the BP and using extra regenerators in the context of dynamic routing of anycast and unicast traffic in EONs.

- by
- •
- Routing, Modulation, Probability, BPSK

Using QAM mapped OFDM signal in radar applications it is possible to get from the signal constellations both the target velocity and target distance from the radar station. When in the reflected signal constellation we get the rotated and distorted mapping that is mean that the signal is reflected from the moving target, while on the other hand, when the mapping is only rotated around the zero, we have a reflected signal from static target. Getting that signals and passing them through frequency and target distance filter banks we get the Doppler frequency and time shift and, consequently, the velocity and the distance of the target.

- by Khachatur Tovmasyan
- •
- Radar, OFDM, QPSK

Wireless designers constantly seek to improve the spectrum efficiency/capacity, coverage of wireless networks and link reliability. Space-time wireless technology that uses multiple antennas along with appropriate signalling and receiver techniques offers a powerful tool for improving wireless
performance. More advanced MIMO techniques are planned for future mobile networks in wireless Local Area Network (LANs) and Wide Area Network (WANs). Multiple antennas when used with appropriate Space-Time Coding (STC) techniques can achieve huge performance gains in multipath fading wireless links. The Space Time Coding has evolved as a most vibrant research area in wireless communications. Recently, Space-Time Block Coding (STBC) has been trying to incorporate in the forthcoming generation of mobile communication standard which aims to deliver true multimedia capability. This paper presents the Space-Time Block Codes (STBC) for wireless networks that uses multiple numbers of antennas at both transmitter and receiver. The simulations have been done in MATLAB. The STBC which includes the Alamouti Scheme as well as an orthogonal STBC for 4 transmit antenna case has been simulated and studied.

In Digital modulation the message signal is in the digital form and the carrier wave is in sinusoidal form. In this technique the Amplitude, Frequency or Phase of carrier varies according to message (Baseband) signal. There are various type of digital modulation technique like Amplitude Shift Keying (ASK), Phase Shift Keying (PSK), Frequency Shift Keying (FSK), Quadature Phase Shift Keying (QPSK), Differential Phase Shift Keying (DPSK) and other digital demodulation technique.

- by neha sharma
- •
- Simulation, QPSK, PSK, Ask

This paper provides an overview of very small aperture terminal (VSAT) network systems for television transmission. In this context, "broadband" means that the application requires a data transfer rate greater than 100 kbps and should allow broadcast, multi and unicast, and interactive bi-directional services to fixed locations. The systems examined include digital broadcasting (e.g., DVB) with IP encapsulation, and bidirectional VSAT star networks. Detailed comparisons of various transmission parameters and standards are provided to help evaluate currently available satellite and ground equipment capabilities. In recent times, file transfer application requires support of file broadcast or IP multicast. Typical applications include audio and video broadcast. A VSAT network is inherently broadcast in nature. Thus VSAT networks naturally and efficiently support these new broadcast applications.

- by Cyril Grandy
- •
- Wireless Communications, DVB, SC-FDMA, Vsat

Usage of Software-Defined Radio (SDR) in digital communication systems can easily cater to sophisticated coding and modulation techniques, to meet the ever-increasing requirements of the wireless communication industry. Future generation of wireless communications will meet the requirements of Software Radio technology as it would provide the state-of-art design to complex radio designs. Software-defined radios are configurable devices in which the components can be reprogrammed to emulate various functionalities like data rate, modulation, filtering etc. Field programmable architectures provide a suitable platform to achieve such run-time reconfigurations of the components of the radio. Software defined radios are highly configurable that provide the technology for realizing the rapidly expanding third and future generation digital wireless communication infrastructure. There are a number of silicon alternatives available for implementing the various functions in a SDR, field programmable gate arrays (FPGAs) are an attractive option for many of these tasks for reasons of performance, power consumption and flexibility. The aim of this project is to study and understand SDR using Xilinx .

- by Prasad Karagaonkar
- •
- Wireless Communications, Synchronization, Spectral Efficiency, QPSK

Software defined radio (SDR) technology enables implementation of wireless devices that support multiple airinterfaces and modulation formats, which is very important if consider proliferation of wireless standards. To enable such functionality SDR is using reconfigurable hardware platform such as Field Programmable Gate Array (FPGA). In this paper, we present design procedure and implementation result of SDR based QPSK modulator on Altera Cyclone IV FPGA. For design and implementation of QPSK modulator we used Altera DSP Builder Tool combined with Matlab/Simulink, Modelsim and Quartus II design tools. As reconfigurable hardware platform we used Altera DE2-115 development and education board with AD/DA daughter card. Software and Hardware-in-the-loop (HIL) simulation was conducted before hardware implementation and verification of designed system. This method of design makes implementation of SDR based modulators simpler ad faster.

- by Merima Kulin
- •
- FPGA, Digital Signal Processing, Field-Programmable Gate Arrays, Modulation

This paper investigates rotor modulation on the gain and input impedance of an antenna mounted on a helicopter's fuselage. The rotor blades, which are rotating about an axis with a given angular velocity, continuously modulate the signal transmitted by the antenna and adversely affect the established communication links. In this study, particular emphasis is placed on wire antennas operating within the high frequency (HF) and very high frequency (VHF) bands. Specifically, the Doppler spectrum of the magnitude and phase of the radiated field by a vertical and a horizontal short dipole underneath the rotors is computed and analyzed. The variation of the corresponding antenna gain as a function of rotor angle and frequency is also investigated. The same type of analysis is then extended to a 14-ft towel-bar antenna mounted on the tail boom of a 10:1 scaled helicopter model. In addition to gain, the variation of input impedance versus angle and frequency is computed within the HF band. Finally, the bit error rate (BER) assuming a quadrature phase-shift keying (QPSK) modulation is evaluated assuming linearly and circularly polarized receiving antennas.

- by Anastasis Polycarpou
- •
- Frequency, Bit Error Rate, BER, Angular velocity

A new digital implementation of a receiver for digital communications is presented. The receiver structure performs the integration of a maximum a posteriori probability (MAP) carrier and clock synchronisation with the maximum likelihood (ML) demodulation. It is shown that the key feature of the receiver structure is that the same hardware is able to perform both operations; thus the receiver implementation complexity is greatly reduced. This scheme can be adapted to different modulation techniques suitable for digital communications, such as QPSK, 0-QPSK and MSK. As examples, the application to QPSK and MSK signals is considered, owing to the interest of these modulation schemes for satellite communications.

- by Enrico Del Re
- •
- Computer Science, Modulation, Satellite Communication, Maximum Likelihood

In this paper we presents the bit error rate (BER) performance of the Cyclic Redundancy Check (CRC) coded Long Term Evolution (LTE) system under various digital modulations (BPSK, QPSK and 16PSK) over an additative white gaussian noise (AWGN) and other multi path fading (Raleigh and Rician) channels. It is apparent from the Matlab based simulation study that the proposed LTE system outperforms with BPSK as compared to other modulation schemes under AWGN noisy and Rayleigh and Rician fading channels. The transmitted data is found to have retrieved effectively at the receiver end under the implementation of CRC coding/decoding algorithm. It has been also predictable that the performance of the CRC-based LTE system degrades with the increase of noise power.

- by Scientific Research Journal
- •
- Wireless Communications, OFDM, Performance Analysis, MIMO

Software defined radio (SDR) technology enables implementation of wireless devices that support multiple air-interfaces and modulation formats, which is very important if consider proliferation of wireless standards. To enable such functionality SDR is using reconfigurable hardware platform such as Field Programmable Gate Array (FPGA). In this paper, we present design procedure and implementation result of SDR based QPSK modulator on Altera Cyclone IV FPGA. For design and implementation of QPSK modulator we used Altera DSP Builder Tool combined with Matlab/Simulink, Modelsim and Quartus II design tools. As reconfigurable hardware platform we used Altera DE2-115 development and education board with AD/DA daughter card. Software and Hardware-in-the-loop (HIL) simulation was conducted before hardware implementation and verification of designed system. This method of design makes implementation of SDR based modulators simpler ad faster.

- by Merima Kulin
- •
- FPGA, Digital Signal Processing, Field-Programmable Gate Arrays, Modulation

An analysis is made of Maximum Likelihood Decoding (MLD) in a wireless Space Division Multiplexing (SDM) link, where information is transmitted and received simultaneously over several transmit and receive antennas to achieve large data rates and high spectral efficiencies. It is proven that maximum likelihood decoding obtains a diversity order equal to the number of receive antennas, independent of the number of transmit antennas, while conventional processing techniques such as the Minimum Mean Square Error (MMSE) technique obtain a diversity order equal to the number of receive antennas minus the number of transmit antennas plus one. Hence, compared to conventional techniques, maximum likelihood decoding has a significant signalto-noise ratio advantage which grows with the number of transmit antennas. Maximum likelihood decoding even works when the number of transmit antennas is larger than the number of receive antennas, which is not possible for conventional techniques.

- by richard van nee
- •
- Space Technology, Information Analysis, Qam, Space Division Multiplexing

This paper presents performance evaluation of the different Modulation Schemes (BPSK, QPSK, GMSK) in terms of Bit
error rate (BER) in cellular mobile environment with GSM standard parameters. The main objective of this paper is to investigate the
factors that go into selection of the particular modulation scheme in the wireless environment. To analyze the cellular mobile
environment GSM standard is selected. There are a number of factors that enter into the choice of a modulation scheme for use in a
wireless application. Performance of a cellular system is dependent on the efficiency of the modulation scheme in use. Gaussian
channel model was used. The various modulation schemes like BPSK, QPSK, and GMSK will be simulated in SystemVue software.
After simulation of the all this, BER was carried out. Then using these parameters, the various modulation techniques were compared.

- by IJSRP Journal
- •
- BPSK, BER, QPSK, Gmsk

White LEDs are set to penetrate many areas of everyday life. An interesting property of these devices (in addition to their lightening capabilities) is that they can be utilised for data transmission. In the past, primarily OOK (on-off keying) has been used for digital data modulation of such devices. OOK imposes limitations on the achievable data rates. Therefore, in this paper OFDM is considered in combination with higher order modulation schemes. A hardware demonstrator with an entire link chain (transmitter and receiver) is developed and measured BER (bit error ratio) results are reported. The system uses pilot sub-carriers to correct frequency synchronisation errors, training sequences for channel estimation and time synchronisation routines. Forward error correction (FEC) coding is used. It is shown that for COFDM (coded OFDM) with QPSK (quadrature phase shift keying) modulation and a single LED, a BER of 2 times 10-5 is achieved for a distance of 90 cm between transmitter and...

- by Cảnh Thanh
- •
- Wireless Communications, Everyday Life, Channel Estimation, Radio Frequency

ABSTRACT The paper presents the design and performance of a baseband modem for wireless LAN systems. The modem fully complies with the IEEE 802.11g standard draft 4.0. It is capable of operating in any of available modes such as ERP-DSSS/CCK, ERP-OFDM, Extended Rate PBCC, and CCK-OFDM. It offers different data rates from 1 Mbps to 54 Mbps and handles DBPSK, DQPSK, QPSK, 8-PSK, BPSK, 16-QAM, and 64-QAM modulation schemes. We show the BER performance of the presented modem as the result of simulation under AWGN and multipath channels.

- by Yoon Seok Choi
- •
- OFDM, BPSK, Bit Error Rate, Qam

This straightforward design shows how to assemble commercial components into a low-noise 14.4-to-15.5-GHz frequency synthesizer with 625-kHz tuning steps for digital microwave radio systems.... more

This straightforward design shows how to assemble commercial components into a low-noise 14.4-to-15.5-GHz frequency synthesizer with 625-kHz tuning steps for digital microwave radio systems. ______________________________________________________________________________ Frequency synthesizers are an essential part of modern digital-microwave-radio (DMR) communications systems. With new ITU-R recommendations for DMR communications bands at 15, 18, 23, 38, and 55 GHz, frequency synthesizers are needed for use as local oscillators (LOs) for the frequency upconversion chores in transmitters and the frequency downconversion in receivers for a variety of different frequency architectures. The design of a Ku-band (14.4 to 15.5 GHz) frequency synthesizer offers practical benefits for several of these bands, since with multiplication by four it can be made to provide frequency coverage as high as 60 GHz. The programmable frequency synthesizer, which switches in 625-kHz steps and can be used with quadrature phase-shift-keying (QPSK) and quadrature-amplitudemodulation (QAM) transmission schemes, is a straightforward design that features low phase noise and reliable operation using commercially available oscillator and phase-lockloop (PLL) integrated circuits (ICs). The PLL concept was developed in the 1920s. 1 The technology has been widely used in a variety of communications systems but until recently, has been too costly and complicated for use in many consumer and industrial applications. But with the growing availability of PLL ICs, the technology is economical enough for most systems. One main area of interest for applying PLLs is in oscillators, to stabilize output frequencies and lower noise levels. 2-4 In addition, DMRs represent a growing market for PLLs. DMRs and other high-capacity digital communications systems require low-cost but high-quality frequency sources. Frequency synthesizers provide stable local oscillator (LO) signals for microwave transceivers, supporting frequency upconversion for transmit operation and frequency downconversion for receive operation. Synthesizer noise is particularly critical in such applications since a digital radio link is sensitive to phase noise. 5-7 The phase noise is detected in such a system along with desired modulated signals. Excessive phase noise degrades the DMR system's biterror-rate (BER) performance.

- by Mahmoud Moghavvemi
- •
- OFDM, Antenna Design, Frequency Synthesizer, Upconversion

Mobile WiMAX standard defines air interface for mobile broadband wireless access (BWA) systems and aimed to provide high data rate with seamless mobility while maintaining the quality of service (QoS). However, QoS of real - time applications depends on the link quality, which necessitate the channel -aware
connection admission control (CAC) and scheduling schemes. In this paper Modulation aware CAC scheme and base station (BS) uplink scheduling algorithm are proposed to improve the system capacity and QoS performance respectively. The proposed CAC scheme aims to increase the admission of higher priority real time services by degrading the bandwidth of admitted lower priority connections on the basis of their channel status without deteriorating their QoS performance much. The performances of proposed algorithms are evaluated through simulation by considering the metrics like throughput, delay and number of connections admitted
.

The channel estimation techniques for OFDM systems based on pilot arrangement are investigated. The channel estimation based on comb type pilot arrangement is studied through different algorithms for both estimating channel at pilot frequencies and interpolating the channel. The estimation of channel at pilot frequencies is based on LS and LMS while the channel interpolation is done using linear interpolation, second order interpolation, low-pass interpolation, spline cubic interpolation, and time domain interpolation. Time-domain interpolation is obtained by passing to time domain through IDFT (Inverse Discrete Fourier Transform), zero padding and going back to frequency domain through DFT (Discrete Fourier Transform). In addition, the channel estimation based on block type pilot arrangement is performed by sending pilots at every sub-channel and using this estimation for a specific number of following symbols. We have also implemented decision feedback equalizer for all sub-channels followed by periodic block-type pilots. We have compared the performances of all schemes by measuring bit error rate with 16QAM, QPSK, DQPSK and BPSK as modulation schemes, and multi-path Rayleigh fading and AR based fading channels as channel models.

In this paper, we present the true Cramér-Rao lower bounds (CRLBs) for the estimation of phase offset for common quadrature amplitude modulation (QAM), PSK, and PAM signals in AWGN channels. It is shown that the same analysis also applies to the QAM, PSK, and PAM CRLBs for frequency offset estimation. The ratio of the modulated to the unmodulated CRLBs is derived for all QAM, PSK, and PAM signals and calculated for specific cases of interest. This is useful to determine the limiting performance of synchronization circuits for coherent receivers without the need to simulate particular algorithms. The bounds are compared to the existing true CRLBs for an unmodulated carrier wave (CW), BPSK, and QPSK. We investigated new and existing QAM phase estimation algorithms in order to verify the new phase CRLB. This showed that new minimum distance estimator performs close to the QAM bound and provides a large improvement over the power law estimator at moderate to high signal-to-noise ratios.

- by Mark Rice
- •
- Performance, Cramer Rao Lower Bound, Power Law, Phase Estimation

process is best. Generally, to chose the particular modulation schemes different parameters are taken into consideration i.e. bandwidth efficiency, bit error rate, signal to noise ratio, cost, effectiveness and easy implementation, but since from very long time bandwidth efficiency is that parameter which plays important role in choosing any modulation scheme. As the waveform of all existing modulation scheme is separated in time domain which makes it difficult to improve their bandwidth efficiency. Since, from last decade researchers are continuously trying to overcome this problem and finally, they were able to discover such a technique which is able to reconstruct the original signal form aliasing environment named as compressive modulation (CM). The working principle of CM has a key part called compressive sensing, by the help of this former one is able to have larger bandwidth efficiency than our modulation techniques. In this paper, we proposed superior Compressive modulation technique and its comparative analysis with QPSK in regard of bandwidth efficiency and BER .The simulation results and theoretical analysis shows that CM has greater bandwidth than QPSK even at high as well as low SNR.

- by IOSR Journals
- •
- Compressive Sensing, QPSK

In this paper we propose the method for the detection of Carrier-in-Carrier signals using QPSK modulations. The method is based on the calculation of fourth-order cumulants. In accordance with the methodology based on the Receiver Operating Characteristic (ROC) curve, a threshold value for the decision rule is established. It was found that the proposed method provides the correct detection of the sum of QPSK signals for a wide range of signal-to-noise ratios and also for the different bandwidths of mixed signals. The obtained results indicate the high efficiency of the proposed detection method. The advantage of the proposed detection method over the "radiuses" method is also shown.

The OFDM technique is an interesting approach in mobile communications in order to achieve a high spectral efficiency and to combat the frequency selectivity of the channel. Another interesting technique is a CDMA system with Rake-receiver. The main advantages of CDMA are well known, but its capacity is limited by multiuser interference. The aim of this study is to combine the principle of a CDMA system with OFDM. This combination allows one to perform a maximum-likelihood detection (MLD), to use the spectrum in an efficient way, to exploit frequency diversity, and to retain many advantages of a CDMA system. In addition, it permits simple cell-separation by using frequency hopping, and a simple hardware realization. Two examples for mobile communication system using CDMA/OFDM with Walsh-Hadamard codespreading for the downlink (Base-Mobile) are studied. Different coherent detection algorithms such as conventional detection, MLD, and iterative detection are analyzed. The analytical performance of MLD is evaluated. It is shown that by using BPSK modulation, one can transmit 64 active users at rate of about 16.664 kbit/sec in a 1.28 MHz bandwidth, resulting in a spectral efficiency of 0.8332 bit/sec/Hz. By using QPSK modulation half of this bandwidth will be used. It is also analytically shown that the performanceof a CDMA/OFDM wit,h MLD, using frequency-diversity is comparable to an optimum CDMA system with Rake-receiver using mutipath diversity. However, in practice providing diversity with OFDM is much simpler than a Rake-receiver. In addition, the OFDM technique simplifies the channel-estimation problem. Hence using CDMA/OFDM for the downlink is a promising approach since the receiver at the mobile station should be very simple.

¡ -An ¢ adaptive receiver is presented in this paper for the £ reception of linearly modulated signals transmitted over a time-£ and frequency-selective fading channel. The channel is modeled ¤ as a truncated power series [1] which represents the dispersive ¥ fading channel as a sum of three elementary flatfading ¦ channels. The proposed receiver consists of a sequence estimator § with a parallel channel estimator. The channel estimator £ recovers the instantaneous fading processes associated witḧ each elementary channel and filters them to generate onestep © predictions of each fading process. Some implementation difficulties ¥ and solutions are also discussed. Computer simulations using quadrature phase-shift keying (QPSK) and channels with moderate ¤ delay spreads and fade rates have been used to evaluate the £ performance of the receiver. The results show that our technique has potential in channels with delay spread of about 20%, signal-to-noise © ratio (SNR) greater than 15 dB, and applications requiring bit-error rates (BER's) less than 10 . Index Terms-Adaptive ¢ receiver, selective fading channel. Wing Seng Leon (S'91-M'97) was born in Singapore. ¬ He received the B.Eng. degree from McMaster University, ± Hamilton, Ont., Canada, in 1992 and the M.E. degree from the

- by Wing Seng Leon
- •
- Performance, Fading Channel, Estimation Theory, Parameter estimation

This paper presents a selected-mapping (SLM) based peak-to-average power ratio (PAPR) reduction technique for the localized single carrier frequency division multiple access (LFDMA) uplink system. The SLM is a distortionless technique as it selects the transmit signal with low PAPR from a set of alternative signals representing the same information. Extensive Matlab simulations have been carried out to validate the proposed idea. At the clip rate of 10 À4 with user's subcarriers M = 16, system's subcarriers N = 512 and dissimilar phase sequences V = 32: the PAPR gain of the proposed SLM based LFDMA system is 7.8 dB and 3.8 dB respectively, when compared with the conventional localized orthogonal frequency 18 division multiple access (OFDMA) uplink systems and the conventional LFDMA uplink systems for QPSK modulation.

- by Imran Baig
- •
- QPSK

This paper presents a tool for the analysis, and simulation of direction-of-arrival estimation for MIMO OFDM signal over the Rayleigh fading channel. The performance of the proposed technique is tested for wavelet denoising based CYCLIC MUSIC algorithm. Simulation results demonstrate that the proposed system not only has good ability of suppressing interference, but also significantly improves the DOA estimation of the system. In this paper, it is proposed to find DOA of the received MIMO OFDM signal, and the performances are analyzed using matlab simulation by the Monte Carlo computer iteration. This paper provides a fairly complete image of the performance and statistical efficiency with QPSK signal model for coherent system at a lower SNR(18dB) and interference environment.

- by The International Journal of Multimedia (IJMA) - ERA Indexed
- •
- Music, OFDM, MIMO, SNR

Worldwide Interoperability for Microwave Access (WiMax), standardized asIEEE 802.16d is a popular technology for broadband wireless communication system. Orthogonal Frequency Division Multiplexing (OFDM) is the core of this technology.OFDMreduces Inter-symbol Interference (ISI) and hence improves system performance (i.e., Bit Error Rate (BER)). To improve system performance further error correction coding schemes have been included in WiMax. It is widely accepted thata coded system outperforms an uncodedsystem. But, the performance improvement of a coded system depends on the channel conditions. In this paper, we investigated and compared the performances of a coded and an uncoded WiMaxsystem under a practical channel model called Stanford University Interim (SUI). Different modulation schemes namely BPSK, QPSK, 16-QAM, and 64-QAM have been considered in this work. It is shown that the selection of codedoruncoded WiMaxsystem should depend on the channel condition as well as on the modulation used. It is also shown that anuncoded system outperforms a coded system under some channel conditions.

- by International Journal of Computer Networks & Communications (IJCNC)
- •
- OFDM, Wimax, BPSK, BER

This paper presents a comparative performance analysis of wireless orthogonal frequency division multiplexing (OFDM) system with the implementation of comb type pilot-based channel estimation algorithm over frequency selective multi-path fading channels. The Minimum Mean Square Error (MMSE) method is used for the estimation of channel at pilot frequencies. For the estimation of channel at data frequencies different interpolation techniques such as low-pass, linear, and second order interpolation are employed. The OFDM system simulation has been carried out with Matlab and the performance is analyzed in terms of bit error rate (BER) for various signal mapping (BPSK, QPSK, 4QAM, 16QAM, and 64QAM) and channel (Rayleigh and Rician) conditions. The impact of selecting number of channel taps on the BER performance is also investigated.

A new direct-conversion wide-band (23-31 GHz) six-port receiver is proposed suitable for millimeter-wave integrated system design. This new hardware receiver is found to be robust, rugged, low cost, and suitable for use in broad-band wireless mass-market QPSK communications. The prototype circuits are fabricated to validate this new concept with our miniaturized hybrid microwave integrated-circuit technology and the proposed receiver topology is also suitable for monolithic-microwave integrated-circuit fabrication. This application-specific integrated receiver is designed on the basis of a wide-band six-port junction and other analogical circuits in the form of a simple multichip module. Bit-error-rate measurements and simulation results are shown and discussed in the presence of noise, adjacent signal interference, local-oscillator (LO) phase shift, and LO phase noise. The maximum bit rate is fundamentally limited by the speed of the video and decoder circuits. Nevertheless, several hundred megabits per second can be achieved at low cost.

- by Serioja Tatu
- •
- Analog Circuits, Noise, Hardware, Microwave Communication

Future wireless communication system have to be designed to integrate features such as high data rates, high quality of service and multimedia in the existing communication framework. Increased demand in wireless communication system has led to demand for higher network capacity and performance. Higher bandwidth, optimized modulation offer practically limited potential to increase the spectral efficiency. Hence MIMO systems utilizes space multiplex by using array of antenna’s for enhancing the efficiency at particular utilized bandwidth. MIMO use multiple inputs multiple outputs from single channel. These systems defined by spectral diversity and spatial multiplexing. The aim of this paper is to design and implement of channel estimation method and modulation technique for MIMO system. The design specifications are obtained using MATLAB. The RTL coding is carried for the design to be implemented on Xilinx FPGA.

We study the blind symbol estimation problem in digital communications and propose a novel algorithm by exploiting a special data structure of an oversampled system output. Unlike most equalization schemes that involve two stages-channel identification and channel equalizatiodsymbof estimation-tbe proposed approach accomplishes direct symbol estimation Without determining the channel characteristics. Based on a detenninistic model, the new method can provide a closed-form solution to the symbol estimation using a small set of data samples, which makes it particularly suitable for wireless applications with fast changing environments. Moreover, if the symbols belong to a finite alphabet, e.g., BPSK or QPSK, our approach can be extended to handle the symbol estimation for multiple sources.

- by Hui Liu
- •
- Performance, Algorithm, Multidisciplinary, Estimation Theory

Starting with an ordinary parallel concatenated turbo encoder in a block fading Rayleigh channel, we introduce bit-interleaving of the outputs, not for time diversity, but to increase the coding gain. We develop a guideline metric for designing QPSK space-time codes which reveals both the coding and diversity advantage of the systems as well as showing that it is unnecessary to guarantee full space diversity to achieve good performance in Rayleigh fading. Using channel a priori information in the MAP iterations for decoding, we achieve frame error rates within 1 dB of the outage probability with only modest increases in decoding complexity.

- by Dale Hocevar
- •
- Performance, Channel Coding, Probability, Fading

It is widely accepted that SC-FDE (Single-Carrier with Frequency-Domain Equalization) is an excellent candidate for broadband wireless systems, especially when an efficient power amplification is intended. If grossly nonlinear power amplifiers are employed, conventional QPSK (Quaternary Phase Shift Keying) or QAM (Quadrature Amplitude Modulation) modulations should be replaced by offset modulations such as OQPSK (Offset QPSK) and OQAM (Offset QAM). In fact, offset signals have much lower dynamic range than non-offset signals, with OQPSK signals being able to have an almost constant envelope.

- by Rui Dinis
- •
- Broadband Networks, Frequency-domain analysis, GNSS receivers, Interference

- by Mustafa Ergen and +1
- •
- System Identification, Wireless Communications, Orthogonal Frequency Division Multiplexing (OFDM), Fading Channel

We perform an experimental investigation of a maximum likelihood-based (ML-based) algorithm for bulk chromatic dispersion estimation for digital coherent receivers operating in uncompensated optical networks. We demonstrate the robustness of the method at low optical signal-to-noise ratio (OSNR) and against differential group delay (DGD) in an experiment involving 112 Gbit/s polarization-division multiplexed (PDM) 16-ary quadrature amplitude modulation (16 QAM) and quaternary phase-shift keying (QPSK).

- by Darko Zibar
- •
- Digital Signal Processing, Maximum Likelihood, Optical physics, Qam

This paper presents a tool for the analysis, and simulation of direction-of-arrival (DOA) estimation in wireless mobile communication systems over the fading channel. It reviews two methods of Direction of arrival (DOA) estimation algorithm. The standard Multiple Signal Classification (MUSIC) can be obtained from the subspace based methods. In improved MUSIC procedure called Cyclic MUSIC, it can automatically classify the signals as desired and undesired based on the known spectral correlation property and estimate only the desired signal’s DOA. In this paper, the DOA estimation algorithm using the de-noising pre-processing based on time-frequency conversion analysis was proposed, and the performances were analyzed. This is focused on the improvement of DOA estimation at a lower SNR and interference environment. This paper provides a fairly complete image of the performance and statistical efficiency of each of above two methods with QPSK signal.

- by The International Journal of Multimedia (IJMA) - ERA Indexed
- •
- Music, MIMO, Doa, QPSK

Abstract-This paper concerns the Cramer-Rao lower bound (CRB) for the data-aided (DA) , the DA parameter esti- mation, the CRB typically varies with the training sequence. This indicates that different training se- quences offer fundamental different performance. In this manuscript, we derive a closed-form formula of the CRB for timing and phase recovery with respect to any particular training sequence.

- by Feng-Wen Sun
- •
- Performance, Synchronization, Parameter estimation, Cramer Rao Lower Bound
- by Imed Ben-Dhaou
- •
- Channel Coding, Source Coding, VLSI, Circuits and Systems

Orthogonal Frequency-Division Multiplexing (OFDM) is essentially identical to coded OFDM (COFDM) and discrete multi-tone modulation (DMT). It is a frequency-division multiplexing (FDM) scheme, which is used as a digital multicarrier modulation method. The paper is aimed at analyzing the BER performance of the MIMO (Multi-Input Multi-Output) OFDM system for AWGN (Additive White Gaussian Noise) Channel, Rayleigh Fading Channel along with a simulation channel using different modulation technique. Also the result of the analysis suggest for the better technique in order to improve the BER characteristic of the MIMO-OFDM system.

- by Yudhishthir Raut
- •
- OFDM, Qam, MIMO OFDM, QPSK

In this thesis paper, first build up a wireless communication simulator including Gray coding, modulation, different channel models (AWGN, flat fading and frequency selective fading channels), channel estimation, adaptive equalization, and demodulation. Next, test the effect of different channel models to the data and image in receiver with constellation and BER (bit error rate) plots under 4QPSK modulation which is a high data rate then QPSK. For Image data source, we also compare the received image quality to original image in different channels. At last, give detail results and analyses of the performance improvement with channel estimation and adaptive equalization in slow Rayleigh fading channel. For frequency selective fading channel, use linear equalization with both LMS (least mean squares) and RLS (Recursive Least Squares) algorithms to compare the different improvements. We will see that in AWGN channel, the image is slight degraded by random noise; in flat fading channel,...

- by Sipon Miah
- •
- ISI, Channel Estimation, RLS, QPSK

This paper presents a series of numerical experiments conducted to investigate the error performance of a simulated digital time-division multiple-access (TDMA) radio link between a portable handset and the base station serving it, subject to interference coming from other portable handsets. The experiments take radio channel impairments such as fading, shadowing, and distance loss into account. Analytical expressions for the bit-error probability in uncoded digital radio transmission bursts under interference from nearby analog FM or digital minimum-shift keying (MSK) transmitters are reviewed. Numerical methods are used to extend analytical estimates of symbol error probability of a link with a single interferer, without channel impairments, to the case where the interference is due to a random distribution of transmitters whose signals are subject to fading, shadowing, and distance power loss. Specifically, three links, each based on one of three different modulation methods, MSK, quadrature phase-shift keying (QPSK) (proposed in the North American Digital Cellular Standard IS-54), and Gaussian MSK (GMSK) [used in the global standard for mobile communications (GSM)] are simulated, and the bit-error rate (BER) results reported. The BER results generated thus indicate the sensitivity of the digital radio link to the user density for a given radio frequency (RF) bandwidth and, where applicable, to fading depth and postmodulation intersymbol interference (ISI) removal method. Possible extensions and applications of the simulation model to the problem of resource sharing between coexisting networks are suggested.

- by Mustafa Kocaturk
- •
- Engineering, Resource sharing, Mobile Communication, Numerical Method

Starting with an ordinary parallel concatenated turbo encoder in a block fading Rayleigh channel, we introduce bit-interleaving of the outputs, not for time diversity, but to increase the coding gain. We develop a guideline metric for designing QPSK space-time codes which reveals both the coding and diversity advantage of the system, as well as shows that it is unnecessary to guarantee full space diversity to achieve good performance in Rayleigh fading. Using channel a priori information in the MAP iterations for decoding, we achieve frame error rates within 1 dB of the outage probability with only modest increases in decoding complexity.

- by Dale Hocevar
- •
- Performance, Channel Coding, Probability, Fading

In this paper, a new phase precoding technique is developed to combat the intersymbol interference (ISI) resulting from a frequency-selective slowly fading channel in a personal communication system using quadrature phase shift keying (QPSK). Based on a new dimension partitioning technique, the precoder predistorts only the phase of the transmitted signal to keep a constant transmitted signal amplitude and, therefore, to ensure the stability of the precoder even in equalizing a non-minimum-phase channel. Under the constraint of the constant amplitude, the dimension partitioning method is developed to guarantee the possibility of correct detection for all transmitted information symbols and to further improve the transmission accuracy by increasing the size of decision regions. Analytical and simulation results demonstrate that, over frequency-selective Rayleigh and Rician fading channels, the system using the proposed channel precoder can achieve a bit error rate comparable with that using a conventional decision-feedback equalizer (DFE). The precoder can outperform DFE in an indoor environment where there is a strong direct propagation path. The main advantage of using the precoder is that the impairment of ISI due to multipath propagation on the transmission performance can be mitigated without increasing the complexity of the portable unit receiver. The proposed technique is especially useful for personal communications, where ISI due to multipath fading channels can severely deteriorate the BER transmission performance and where the simplicity of portable units is a vital characteristic of the system.

- by Weihua Zhuang
- •
- Engineering, Technology, Channel Coding, ISI

A comprehensive set of acoustic communication data is analyzed using a complete receiver algorithm which includes a Doppler pre-processor, equalizer configuration algorithm and the decision feedback equalizer (DFE). The signal used for the tests is 1250 symbol per second QPSK (2500 bps) transmitted at a carrier of 2.25 kHz. Source-receiver ranges of up to 44 km were achieved at this data rate. The test environments include the New England Continental Shelf (less than 200 m), the shelf break (200-1200 m) and deep water (2500 m). In each environment the impulse response, the ambiguity function and the performance level of the receiver are presented. The link was very reliable to the maximum test range of 44 km on the shelf and to 20 km at the shelf break. In deep water the performance was good at less than 10 km and also at 35-44 km

- by Lee Freitag
- •
- Data Analysis, Acoustic Communication, Underwater Acoustics, Underwater Communication

The research in wireless communication has developed rapidly for the last decades as a result of raising the demand for efficient data transmission with more security and accuracy. This paper proposed a system based on the special multiplexing (SM) technique and linear minimum mean square error (LMMSE) detection method with the assistance of the hamming code as well as the interleaving techniques for a better enhanced performance of an audio transmission. Moreover, the comparison was done between the two systems for different antenna configurations and with the presence of two types of modulation: binary phase shift key and quateradure phase shift key. These systems are employed by Matlab simulation to show significant results in terms of enhancing the Rayleigh fading channel capacity, bit error rate (BER) and security as well as in recovering the transmitting audio signals. Each system has advantages than the others in one performance term respect to the other terms. The simulation results have provided to prove and discuss our analysis.

- by Indonesian Journal of Electrical Engineering and Computer Science and +1
- •
- BPSK, Capacity, Interleaving, QPSK

Quadrature Phase-Shift Keying (QPSK) modulation technique is one of the most widely used modulation scheme in modern digital communication system as it provides high bandwidth efficiency. In this paper, the model of QPSK modulator and... more

- by Rawan Ayyoub
- •
- Distributed Computing, BER, Modulator, QPSK

- by Varun Jeoti
- •
- QPSK