Phase for Face saving-a multicarrier Stego

Abstract High speed and low latency have become the development trend of mobile communication network. Orthogonal frequency division multiplexing (OFDM) technology has become the key technology of mobile communication network due to its efficient transmission method. Space time block coding (STBC) introduces time and space correlation in the signals sent by different antennas, so that diversity gains and coding gains are obtained for the multiple input multiple output-OFDM (MIMO-OFDM) receiver without sacrificing bandwidth. STBC is a signal coding technology that combines higher transmission rates and it is a combination of space and time transmission signals. STBC uses the spatial diversity of multiple transmitters and multiple receivers in space to improve the capacity and information rate of the OFDM system. It proceeds parallel multiplex transmission in the transmission channel, which effectively improves spectrum utilization. For obtaining diversity gains and spectrum efficiency, this paper introduces a variable pilot assisted channel estimation method with different modulation modes. In this paper, the new type pilot sequences with different modulation orders are proposed for improving spectrum efficiency. The proposed variable pilot assisted channel estimation method in MIMO-OFDM systems is adopted with different low and high order modulations. Simulation results show that the proposed variable pilot assisted channel estimation method has 1–2 dB signal-to-noise ratio (SNR) gains for bit error rate (BER) performance of MIMO-OFDM systems. 

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Variable pilot assisted channel estimation in MIMO-OFDM system with STBC and different modulation modes

In this paper, second order response surface designs which in parts are useful to estimate responses and slopes with spherical variance functions are obtained. Specifically a model on augmenting second order rotatable designs (SORD) with additional axial and central points to form second order slope rotatable designs, four and six level second order response surface designs using balanced incomplete block designs.

International journal of advances in computing and information technology

The increasing demand for multimedia data transmission in mobile wireless communication poses a challenge to reliable signal reception. In order to have good signal quality, a robust digital modulation scheme is required at the transmitter. However, the conventional M-ary Phase Shift Keying (MPSK) commonly used in multiple-input multiple-output (MIMO) communication systems with non-linear radio frequency (RF) power amplifiers causes a relative increase in intercarrier interference (ICI). This paper presents a development of offset-MPSK (O-MPSK) modulation scheme in MIMO spatial multiplexing over the Rayleigh fading channel. The O-MPSK modulation schemes were developed for 4, 8, 16, 32 and 64 constellation sizes. The development of the O-MPSK was done by shifting the phase of the conventional QPSK, 8-PSK, 16-PSK, 32-PSK and 64-PSK by an odd multiple of pi (π) to give -QPSK, -8PSK, -16PSK, -32PSK and -64PSK, respectively, with a view to reducing the spectral spreading in the power amplifiers at the receiver of a MIMO system. The MIMO techniques used was MIMO Spatial Multiplexing (MIMO–SM). The system models were developed around these schemes and later simulated using MATLAB application toolkit. The performances of the O-MPSK schemes were evaluated using bit error rate (BER) at signal-to-noise ratio (SNR) range of 0 to 20 dB and compared with the conventional MPSK schemes. The results obtained for all the SNRs in MIMO-SM showed that mean BER of 0.0024, 0.0040, 0.0085, 0.0183 and 0.036 were obtained for -QPSK, -8PSK, -16PSK, -32PSK and -64PSK respectively as against mean BER of 0.0025, 0.0044, 0.0088, 0.0178 and 0.0358 obtained for conventional QPSK, 8PSK, 16PSK, 32PSK and 64PSK respectively. The mean BER values obtained reveal that the developed O-MPSK outperforms the conventional MPSK due to the relatively lower BER of O-MPSK schemes compared with the MPSK schemes. This is as a result of the reduction in the amplitude variations and spectral spreading at the receiver of the MIMO system.

/pdf/offset-phase-shift-keying-modulation-in-multiple-input-1kwr2ruh9j.pdf

Offset Phase Shift Keying Modulation in Multiple-Input Multiple-Output Spatial Multiplexing

Error detection is the important process to test the quality of the channel transmission. This design proposes a program which is based on pseu- do-random m-sequence as the core of the error detection. By using m-sequence and cyclic prefix, an equivalent one-way OFDM channel transmissi- on model is constructed, and using Matlab and the Quartus II software, simulation gives the result. Using Altera EP2C8Q208 chip to completing the function, achieve the purpose of the channel error detection. Simulation results show that, m-sequence as the test sequence could achieve the channel symbol error detection

OFDM channel error detection and FPGA implementation

With the rapid growth of digital communication in recent years, the need for high speed data transmission is increased. OFDM is a promising solution for achieving high data rates in mobile environment, due to its resistance to ISI, which is a common problem found in high speed data communication. A multiple-input multiple-output (MIMO) communication System combined with the orthogonal frequency division multiplexing (OFDM) modulation technique can achieve reliable high data rate transmission over broadband wireless channels. In this paper we will investigate the estimation of channel at high frequencies with conventional Least Square (LS) and Minimum Mean Square (MMSE) estimation algorithms which is carried out through Matlab simulation. The bit-error rate (BER) of multilevel quadrature amplitude modulation (M-QAM) in flat Rayleigh fading channel is also analyzed. The performance of MIMO OFDM is evaluated on the basis of Bit Error Rate (BER) and Mean Square Error (MSE) level.

A. Shanmugam

Papers

BER analysis of MIMO OFDM system using M-QAM over Rayleigh fading channel