Improving MIMO-OFDM Performance with Convolutional Coding and Discrete Wavelet Transform

In this paper, we analyze the Bit Error Rate (BER) performance of Golden coded Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) system over Rician multipath fading channel. We also compare the performance of the MIMO-OFDM system using Golden code in Rayleigh and Rician multipath fading channels. We discuss the effects of the presence of line-of-sight (LoS) component in the multipath fading environment which renders the improvement in the overall performance of the Golden coded MIMO-OFDM. This paper discusses the performance of Golden codes in a frequency selective Rician fading channel. To deal with the frequency selective fading channel, we use the OFDM (Orthogonal Frequency Division Multiplexing) modulation. The BER performance of the Golden coded MIMO-OFDM system under several propagation conditions has been evaluated. Keywords—MIMO, OFDM, Golden STBC, Rayleigh fading, Rician fading.

Wireless network is one of the most important things in the development of telecommunication. However, the existing wireless technology has not been able to efficiently create a very high data rate because it was very sensitive to fading. Therefore, Orthogonal Frequency Division Multiplexing (OFDM) technology combined with MIMO (Multiple Input Multiple Output) transceiver system was used to gain more diversity and bandwidth efficiency. The propagation performed on the OFDM MIMO system was multipath propagation. To reduce Intersymbol Interference (ISI) was used Zero Forcing (ZF) equalizer which works by combining channel response and equalizer response itself to eliminate ISI. This study aims to determine the effect of Zero Forcing Equalizer on OFDM MIMO system using rayleigh fading channel and compared the result with OFDM MIMO STBC system. The research method used was simulation using MatLab R2015a. The simulation results showed that the performance of OFDM MIMO ZF system was worse than OFDM MIMO STBC system i.e BER vs EbNo simulation, eye diagram simulation, and constellation diagram simulation. The OFDM MIMO ZF system was required an Eb / No value more than 25 dB to achieve BER 10-4 while the OFDM MIMO STBC system only required an Eb / No value of 10.5 dB to achieve BER 10-4. The eye pattern generated by the OFDM MIMO ZF system was more closed and the dispersion of constellation signals away from the ideal point while OFDM MIMO STBC system displayed a more open eye pattern and the dispersion of its constellation signal closer to the ideal point. It indicated more ISI occurs in the OFDM MIMO ZF system than that in OFDM MIMO STBC system.

In this new information age, high data rate and strong reliability features our wireless communication systems and is becoming the dominant factor for a successful deployment of commercial networks. MIMO-OFDM (multiple input multiple output-orthogonal frequency division multiplexing), a new wireless broadband technology, has gained great popularity for its capability of high rate transmission and its robustness against multi-path fading and other channel impairments. A major challenge to MIMO-OFDM systems is how to obtain the channel state information accurately and promptly for coherent detection of information symbols and channel synchronization. In the first part, this dissertation formulates the channel estimation problem for MIMO-OFDM systems and proposes a pilot-tone based estimation algorithm. A complex equivalent base-band MIMO-OFDM signal model is presented by matrix representation. By choosing equally-spaced and equally-powered pilot tones from sub-carriers in one OFDM symbol, a down-sampled version of the original signal model is obtained. Furthermore, this signal model is transformed into a linear form solvable for the LS (least-square) estimation algorithm. Based on the resultant model, a simple pilot-tone design is proposed in the form of a unitary matrix, whose rows stand for different pilot-tone sets in the frequency domain and whose columns represent distinct transmit antennas in the spatial domain. From the analysis and synthesis of the pilot-tone design in this dissertation, our estimation algorithm can reduce the computational complexity inherited in MIMO systems by the fact that the pilot-tone matrix is essentially a unitary matrix, and is proven an optimal channel estimator in the sense of achieving the minimum MSE (mean squared error) of channel estimation for a fixed power of pilot tones. In the second part, this dissertation addresses the wireless location problem in WiMax (worldwide interoperability for microwave access) networks, which is mainly based on the MIMO-OFDM technology. From the measurement data of TDOA (time difference of arrival), AOA (angle of arrival) or a combination of those two, a quasi-linear form is formulated for an LS-type solution. It is assumed that the observation data is corrupted by a zero-mean AWGN (additive white Gaussian noise) with a very small variance. Under this assumption, the noise term in the quasi-liner form is proved to hold a normal distribution approximately. Hence the ML (maximum-likelihood) estimation and the LS-type solution are equivalent. But the ML estimation technique is not feasible here due to its computational complexity and the possible nonexistence of the optimal solution. Our proposed method is capable

Multiple-input multiple-output (MIMO) systems can significantly improve the network capacity and the quality of service (QoS). We propose a novel beamforming method for MIMO orthogonal frequency division multiplexing (OFDM) systems in this work. The presented method is based on the Rayleigh Quotient (RQ) of the Fourier transform of the channel matrix. Two RQ analysis algorithms, simple steepest descent and Luo's algorithms, are used to obtain the new beamforming method. It is demonstrated that the proposed method can considerably reduce the complexity and needs only (2K+1)L complex multiplications and 2KL-1 complex additions for a single run, where K and L are the number of antennas at the transmitter and the receiver, respectively. We evaluate the performance of the presented method in AWGN and Rayleigh fading channels. Simulation results show that the new method reduces the bit error rate (BER) significantly while having low computational complexity. It is also shown that the presented method has a very fast convergence rate.

In this paper, we propose an optimal power allocation scheme for joint pilot placement and space frequency (SF) code design for multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM) wireless channels. OFDM is combined with multiple antennas to increase data diversity gain on a time varying multipath fading channel, resulting in a MIMO-OFDM system. A set of fast time-varying and frequency-selective fading channels is considered. The proposed pilot assisted transmission scheme multiplexes known symbols with information bearing data to estimate the channel in the presence of inter symbol interference (ISI). The channel is assumed to be unchanged for the duration of one OFDM block and change independently from one OFDM block to the other. The number of pilot symbols for each OFDM block is held constant and the symbols are dispersed throughout the block for efficient channel estimation. However, equally distributing the total power between the data and pilots doesn't optimize the transmission over a frequency-selective fading channel. We propose an optimal power allocation scheme for the joint pilot placement and space frequency code design scheme based on the channel response and the bit error rate (BER) values. This leads to substantial improvement in performance for a 2 times 2 MIMO-OFDM system. The results can be extended to MIMO-OFDM systems with any number of transmit and receive antennas.

The paper analyses the performance of a dual-signal receiver in a Rician fading channel. The receiver is designed for simultaneous reception of two narrowband binary phase shift keying (BPSK) modulated co-channel signals, e.g. two desired signals, of different strength. The dual signal receiver consists of two demodulators. The principle of operation is based on separation of both signals using the data signal of the large signal which is estimated by the first demodulator. After cancellation of the large signal, the small signal is demodulated. The bit error rate (BER) and receiver outage performance in the Rician fading channel with additive white gaussian noise are derived for both signals. Numerical results are presented for two receiver structures with different second demodulator: (i) the coherent BPSK demodulator; (ii) the differentially coherent (DPSK) demodulator. It is shown that the dual-signal receiver outperforms the conventional receiver significantly, especially in the interference limited channel with high signal-to-noise ratio.

The channel estimation techniques based on comb-type pilot arrangement, which is used in multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) system, is investigated in this paper. In view of the contradiction of the time-domain least squares (LS) channel estimation bit error rate (BER) performance and the practical realization complexity, a novel optimal pilots design method for multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) is proposed. By using this approach no large matrix pseudo-inverse is required, which greatly reduces the complexity of algorithms. Simulation results show that the proposed method provides better BER performance and lower complexity. And it is easy to implement in practical systems.

This paper presents an energy-efficient wireless communication framework utilizing MIMO-OFDM (Multiple Input Multiple Output - Orthogonal Frequency Division Multiplexing) tailored for IoT-enabled healthcare systems. By combining advanced modulation techniques, such as BPSK, QPSK, and QAM, with the robust Alamouti scheme, the framework optimizes energy consumption while ensuring reliable data transmission. Evaluation in an IoT-enabled healthcare environment demonstrates significant improvements in energy efficiency and data accuracy. Simulation results show reduced Bit Error Rates (BER) at varying Signal-to-Noise Ratios (SNR), with BPSK offering the best performance in low SNR conditions and QAM excelling at high data rates. Compared to traditional methods, the framework achieves superior energy efficiency and robust communication, supporting the seamless operation of IoT healthcare devices. These findings underline the potential of MIMO-OFDM technology in advancing scalable, energy-efficient, and reliable healthcare solutions

This paper proposes a way of turning the equalisation of multiple- input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) signals simpler through the employment of low complexity iterative frequency domain equalisation (FDE) receivers based on equal gain combining (EGC) and maximum ratio combining (MRC) concepts, that do not require computing the inverses of high dimensional channel matrices. Performance results show that MIMO- OFDM schemes employing this type of techniques can achieve excellent bit error rate (BER) performances over severe time- dispersive channels and, therefore, approach or even outperform receivers that require inverting channel matrices, such as zero forcing (ZF) and minimum mean squared error (MMSE), after a few iterations.

The WiMax (Worldwide Interoperability for Microwave Access) is a technology in<strong> </strong>broadband wireless access, which employs OFDM (Orthogonal Frequency Division Multiplexing) as an alternative transmission to enable high speed data in communication system. This research aim is to analyze the performance system of the OFDM-Based WiMAX, which used the cyclic prefix. The model was designed in four schemes of simulation method, the BPSK (Binary Phase Shift Keying, QPSK (Quadrature Phase Shift Keying), 16 QAM (Quadrature Amplitude Modulation) and 64 QAM. Each scheme was investigated BER (Bit Error Rate) on AWGN (Additive White Gaussian Noise) channel and multipath Rayleigh fading channel, which had applied the cyclic prefix. By simulation of the cyclic prefix was produced the modulation measurement of the BPSK, QPSK, 16 and 64 QAM. The performance result of Eb/No 15 dB was obtained the BER of BPSK and QPSK of 1.11E-11, the BER of 16 QAM and 64 QAM of 8.69E-06 and 0.00333 respectively. Those results indicated much smaller BER value than EbNo 0 dB which BPSK and QPSK of 1 BER, 1.5 and 1.75 BER for 16 QAM and 64 QAM respectively. In conclusion, a higher value of EbNo, hence the BER value would be lower.

Rapid development of wireless services, leads to ubiquitous personal connectivity in the world. The demand for multimedia interactivity is higher in the world which leads to the requirement of high data transmission rate. Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) is a future wireless service which is used to overcome the existing service problems such as development of subscriber pool and higher throughput per user. Although it overcomes the problems in existing services, resource allocation becomes one of the major issues in the MIMO-OFDM systems. Resource allocation in MIMO-OFDM is the optimization of subcarrier and power allocation for the user. The overall performance of the system can be improved only with the efficient resource allocation approach. The user data rate is increased by efficient allocation of the subcarrier and power allocation for each user at the base station, which is subject to constraints on total power and bit error rate. In this study, the problem of resource allocation in MIMO-OFDM system is tackled using hybrid artificial bee colony optimization algorithm based on a crossover operation along with Poisson-Jensen in equation. The experimental results show that the proposed methodology is better than the existing techniques.

The combination of the channel fading compensation technique and the coded modulation technique is discussed. The system presented is considered to operate under correlated Rayleigh or Rician fading channels. The channel correlation property has been used to carry out channel fading compensation with the aid of periodically inserted pilot symbols. A multidimensional BCM (block coded modulation) scheme was used to improve the system error performances. On decoding, a corresponding trellis is used; therefore, the Viterbi algorithm and channel state information become available. The error performances of the system are investigated through computer simulations. Combined with the fading compensation, the multidimensional BCM scheme gives good error performances under various fading channels. For the Rayleigh fading channel, 7.5-dB coding gain has been achieved at a bit error rate (BER) of 10/sup -3/. For the Rician fading channel with K=10 dB, the coding gain is 3.7 dB at BER=10/sup -4/.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

This Paper is containing the different types of Channel Coding which is used in multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM). To increase the efficiency of MIMO-OFDM there are several channel coding are applied in it.in this paper the aim is to show the discussion about all channel coding which are used as well as using in MIMO-OFDM system. This paper is structured in such way that in section I OFDM System and channel coding is described, in II section there is discussion about block diagram.In III section there is discussion of formula used in FFT and IFFT. In section IV several channel coding are defined which are used in MIMO-OFDM system. Further conclusion is made in section V.

This paper focuses on the issue of achieving transmit diversity for the multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) system working with quadrature index modulation (QIM). Inspired by the ideas of quadrature spatial modulation (QSM) and quadrature space-frequency index modulation (QSF-IM), parts of the space-frequency resource units in each resource block (RB) of the MIMO-OFDM system are activated twice independently to send the in-phase and quadrature components of a space-frequency code, respectively, to achieve the second order transmit diversity. Thus the proposed scheme is called space-frequency coded QIM (SFC-QIM). The SFC-QIM scheme allows for a linear-complexity maximum likelihood (ML) receiver, which benefits from the orthogonality between the real and imaginary parts of the symbols in the SFC codewords. Owing to obtaining higher diversity order, simulation results of bit error rate (BER) performance demonstrate that the new SFC-QIM scheme outperforms some existing IM schemes in both independent and identically distributed (i.i.d.) and correlated Rayleigh fading channels.

This paper shows the study of Bit Error Rate (BER) using differential dual hop relaying system over Alpha-mu fading channel, Generalized- Gamma fading channeland Rician fading channel between Source to Relay/Relay to Destination i.e. (S-R)/(R-D). Here, two modulation techniques; DQPSK and DBPSK are used along with three channel schemes; SR - Slow Fading and RD - Slow Fading, SR- Fast Fading and RD- Slow Fading and SR - Fast Fading and RD - Fast Fading for the analysis of BER. Firstly, the BER is simulated over the combination of Alpha-mu fading channel andRician fading channel. Also, similar analysis has been achieved over the combination of Generalized Gamma fading channel and Rician fading channel. Finally, the results have been verified through the numerical analysis.