IMPROVING STFBC MIMO OFDMA WITH CHANNEL ESTIMATION USING DFT AND DCT TECHNIQUE

Higher demand in rapid data transmission makes the wireless technology become more popular in this new modern era. However due to the many users that want to have access in the same time, it can cause congested traffic and affect the data rate. OFDMA modulation scheme with combination of MIMO will support high data signal and become one of the best solutions that can fulfil everybody’s dream. These MIMO OFDMA system is based on the diversity coding and appropriate channel estimation in order to achieve maximum diversity order for each user and minimize the interference that have been generated during the transmission. Thus, in this paper in order to boost the overall system performances, Space Time Frequency Block Code (STFBC) and channel estimation technique involving Discrete Fourier Transform (DFT) and Discrete Cosine Transform (DCT) are going to be tested to compare their performance. The result states that when using STF block code, it will gain better performance in MIMO OFDMA system by producing lower bit error rate compare to existence DCT and DFT.

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Enhanced NOMA System Using Adaptive Coding and Modulation Based on LSTM Neural Network Channel Estimation

Applied Sciences ◽

10.3390/app9153022 ◽

2019 ◽

Vol 9 (15) ◽

pp. 3022 ◽

Cited By ~ 2

Author(s):

AbdelMoniem ◽

Gasser ◽

El-Mahallawy ◽

Fakhr ◽

Soliman

Keyword(s):

Neural Network ◽

Channel Estimation ◽

Multiple Access ◽

Short Term Memory ◽

Power Coefficient ◽

Modulation Scheme ◽

Channel Fading ◽

Adaptive Coding ◽

Time Frequency ◽

Shift Keying

Non-orthogonal multiple access (NOMA) is the technique proposed for multiple access in the fifth generation (5G) cellular network. In NOMA, different users are allocated different power levels and are served using the same time/frequency resource blocks (RBs). The main challenges in existing NOMA systems are the limited channel feedback and the difficulty of merging it with advanced adaptive coding and modulation schemes. Unlike formerly proposed solutions, in this paper, we propose an effective channel estimation (CE) algorithm based on the long-short term memory (LSTM) neural network. The LSTM has the advantage of adapting dynamically to the behavior of the fluctuating channel state. On average, the use of LSTM results in a 10% lower outage probability and a 37% increase in the user sum rate as well as a maximal reduction in the bit error rate (BER) of 50% in comparison to the conventional NOMA system. Furthermore, we propose a novel power coefficient allocation algorithm based on binomial distribution and Pascal’s triangle. This algorithm is used to divide power among N users according to each user’s channel condition. In addition, we introduce adaptive code rates and rotated constellations with cyclic Q-delay in the quadri-phase shift keying (QPSK) and quadrature amplitude modulation (QAM) modulators. This modified modulation scheme overcomes channel fading effects and helps to restore the transmitted sequences with fewer errors. In addition to the initial LSTM stage, the added adaptive coding and modulation stages result in a 73% improvement in the BER in comparison to the conventional NOMA system.

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HIGH DATA RATE OF A NOVEL MODULATION SCHEME BASED ON ORTHOGONAL CHAOTIC SIGNALS

Telecommunications and Radio Engineering ◽

10.1615/telecomradeng.v75.i18.50 ◽

2016 ◽

Vol 75 (18) ◽

pp. 1657-1663 ◽

Cited By ~ 1

Author(s):

Abbas Salman Hameed

Keyword(s):

Data Rate ◽

High Data Rate ◽

Modulation Scheme ◽

High Data ◽

Chaotic Signals

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Improving Space-Time-Frequency MIMO-OFDM with ICI Self-Cancellation Scheme using Least Square Error Estimator

Scientific Research Journal ◽

10.24191/srj.v12i1.5436 ◽

2015 ◽

Vol 12 (1) ◽

pp. 25

Author(s):

Nur Farahiah Ibrahim ◽

Zahari Abu Bakar ◽

Azlina Idris

Keyword(s):

Channel Estimation ◽

Orthogonal Frequency Division Multiplexing ◽

Symbol Error Rate ◽

Space Time ◽

Least Square ◽

Error Estimator ◽

Frequency Diversity ◽

Time Frequency ◽

Mimo Ofdm ◽

Subcarrier Mapping

Channel estimation techniques for Multiple-input Multiple-output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) based on comb type pilot arrangement with least-square error (LSE) estimator was investigated with space-time-frequency (STF) diversity implementation. The frequency offset in OFDM effected its performance. This was mitigated with the implementation of the presented inter-carrier interference self-cancellation (ICI-SC) techniques and different space-time subcarrier mapping. STF block coding in the system exploits the spatial, temporal and frequency diversity to improve performance. Estimated channel was fed into a decoder which combined the STF decoding together with the estimated channel coefficients using LSE estimator for equalization. The performance of the system was compared by measuring the symbol error rate with a PSK-16 and PSK-32. The results show that subcarrier mapping together with ICI-SC were able to increase the system performance. Introduction of channel estimation was also able to estimate the channel coefficient at only 5dB difference with a perfectly known channel.

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Blind mimo channel estimation using space time block code

Proceedings. 2005 International Conference on Wireless Communications, Networking and Mobile Computing, 2005. ◽

10.1109/wcnm.2005.1543997 ◽

2005 ◽

Author(s):

Bin Lu ◽

Gang Wei

Keyword(s):

Channel Estimation ◽

Block Code ◽

Space Time ◽

Mimo Channel ◽

Time Block ◽

Space Time Block Code

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Performance of LED for line-of-sight (LoS) underwater wireless optical communication system

Journal of Optical Communications ◽

10.1515/joc-2020-0132 ◽

2020 ◽

Vol 0 (0) ◽

Cited By ~ 1

Author(s):

Alaa G. Nasser ◽

Mazin Ali A. Ali

Keyword(s):

Optical Communication ◽

Link Quality ◽

Line Of Sight ◽

Modulation Scheme ◽

Underwater Communication ◽

Optical Communication System ◽

High Data ◽

Wireless Optical Communication ◽

Noise Rate ◽

Wireless Optical Communications

AbstractUnderwater wireless optical communications (UWOC) recently emerge as a solution to the problem of underwater communication for link with a high data rate, low delay, safety, and high immunity. In this study, the line of sight (LoS) method based on LED used for UWOC with different modulation schemes. The bit error rate (BER), signal-to-noise rate, and quality factor are used for assessing system performance and link quality. Besides the effect of transmitting angle, distance link (d), and transmitting power (PT) are analysed. Results show that 8-pulse position modulation (PPM) is the best modulation scheme for achieving a good link in the LoS method.

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An FPGA Implementation of TCM Cascade Space Time Block Code

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.195-196.901 ◽

2012 ◽

Vol 195-196 ◽

pp. 901-903

Author(s):

Jun Wu ◽

Xiao Bo Wu

Keyword(s):

Block Code ◽

Space Time ◽

Coded Modulation ◽

Diversity Gain ◽

Modulation Scheme ◽

Time Block ◽

Coding Gain ◽

Space Time Block Code ◽

Concatenated Code ◽

Trellis Coded

Trellis coded (TCM) modulation can obtain the coding gain without increase the transmission power and the bandwidth but it can not obtain diversity gain, and space-time block code (STBC) can provide diversity gain in a simple encoding and decoding way, though its coding gain is not very satisfied. This article will achieve a STBC-class networking trellis coded modulation scheme based on FPGA to further study the performance of the concatenated code.

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