scholarly journals Upgrading Physical Layer of Multi-Carrier OGFDM Waveform for Improving Wireless Channel Capacity of 5G Mobile Networks and Beyond

Information ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 35
Author(s):  
Mohammad R. Kadhum
Keyword(s):  
Channel Capacity ◽  
Transmission Rate ◽  
Wireless Channel ◽  
Mobile Technologies ◽  
Frequency Division Multiplexing ◽  
Interference Avoidance ◽  
Frequency Division ◽  
Bit Rate ◽  
Bit Loading ◽  
The Future

On the brink of sophisticated generations of mobile starting with the fifth-generation (5G) and moving on to the future mobile technologies, the necessity for developing the wireless telecommunications waveform is extremely required. The main reason beyond this is to support the future digital lifestyle that tends principally to maximize wireless channel capacity and number of connected users. In this paper, the upgraded design of the multi-carrier orthogonal generalized frequency division multiplexing (OGFDM) that aims to enlarge the number of mobile subscribers yet sustaining each one with a high transmission capacity is presented, explored, and evaluated. The expanded multi-carrier OGFDM can improve the performance of the future wireless network that targets equally the broad sharing operation (scalability) and elevated transmission rate. From a spectrum perspective, the upgraded OGFDM can manipulate the side effect of the increased number of network subscribers on the transmission bit-rate for each frequency subcarrier. This primarily can be achieved by utilizing the developed OGFDM features, like acceleration ability, filter orthogonality, interference avoidance, subcarrier scalability, and flexible bit loading. Consequently, the introduced OGFDM can supply lower latency, better BW efficiency, higher robustness, wider sharing, and more resilient bit loading than the current waveform. To highlight the main advantages of the proposed OGFDM, the system performance is compared with the initial design of the multicarrier OGFDM side by side with the 5G waveform generalized frequency division multiplexing (GFDM). The experimented results show that by moving from both the conventional OGFDM and GFDM with 4 GHz to the advanced OGFDM with 6 GHz, the gained channel capacity is improved. Because of the efficient use of Hilbert filters and improved rate of sampling acceleration, the upgraded system can gain about 3 dB and 1.5 dB increments in relative to the OGFDM and GFDM respectively. This, as a result, can maximize mainly the overall channel capacity of the enhanced OGFDM, which in turn can raise the bit-rate of each user in the mobile network. In addition, by employing the OGFDM with the dual oversampling, the achieved channel capacity in worst transmission condition is increased to around six and twelve times relative to the OGFDM and GFDM with the normal oversampling. Furthermore, applying the promoted OGFDM with the adaptive modulation comes up with maximizing the overall channel capacity up to around 1.66 dB and 3.32 dB compared to the initial OGFDM and GFDM respectively. A MATLAB simulation is applied to evaluate the transmission performance in terms of the channel capacity and the bit error rate (BER) in an electrical back-to-back wireless transmission system.

scholarly journals KINERJA ORTHOGONAL FREQUENCY DIVISION MULTIPLE ACCESS (OFDMA) PADA TEKNOLOGI RADIO OVER FIBER (ROF)

2019 ◽  
Vol 20 (3) ◽  
pp. 68
Author(s):  
Amalia Eka Rakhmania ◽  
Sholeh Hadi Pramono ◽  
Dwi Fadila Kurniawan
Keyword(s):  
Optical Fiber ◽  
Channel Capacity ◽  
Fiber Length ◽  
Multiple Access ◽  
Channel Model ◽  
Wireless Channel ◽  
Radio Over Fiber ◽  
Mobile Wimax ◽  
Frequency Division ◽  
Bit Rate

Amalia Eka Rakhmania, Sholeh Hadi Pramono, Dwi Fadila Kurniawan, in this paper explain that radio over Fiber (RoF) is a technology that integrates wireless and wireline transmission system to transmit radio signal through optical fibre cable. This paper evaluates the performance of Orthogonal Frequency Division Multiple Access (OFDMA) implemented in RoF system for mobile WiMAX network. RoF channel model includes both optical fiber with Relative Intensity Noise, shot noise, thermal noise, and chromatic dispersion, and also wireless channel with Additive White Gaussian Noise (AWGN). Through simulation, signal to noise ratio (SNR), channel capacity, bit rate, and bit error rate (BER) with the influence of optical fiber length and wavelength. Result shows that optical fiber length is proportional to SNR, channel capacity, and bit rate but inversely proportional to BER. 1550 nm wavelength has better channel capacity but lesser bit rate than 1310 nm.

scholarly journals Frequency Division Multiplexing of Terahertz Waves Realized by Diffractive Optical Elements

2021 ◽  
Vol 11 (14) ◽  
pp. 6246
Author(s):  
Paweł Komorowski ◽  
Patrycja Czerwińska ◽  
Mateusz Kaluza ◽  
Mateusz Surma ◽  
Przemysław Zagrajek ◽  
...  
Keyword(s):  
Frequency Division Multiplexing ◽  
Diffractive Optical Elements ◽  
Frequency Division ◽  
Terahertz Waves ◽  
Optical Elements ◽  
Telecommunication Systems ◽  
Wide Range ◽  
The Future ◽  
Wireless Telecommunication ◽  
Finite Distance

Recently, one of the most commonly discussed applications of terahertz radiation is wireless telecommunication. It is believed that the future 6G systems will utilize this frequency range. Although the exact technology of future telecommunication systems is not yet known, it is certain that methods for increasing their bandwidth should be investigated in advance. In this paper, we present the diffractive optical elements for the frequency division multiplexing of terahertz waves. The structures have been designed as a combination of a binary phase grating and a converging diffractive lens. The grating allows for differentiating the frequencies, while the lens assures separation and focusing at the finite distance. Designed structures have been manufactured from polyamide PA12 using the SLS 3D printer and verified experimentally. Simulations and experimental results are shown for different focal lengths. Moreover, parallel data transmission is shown for two channels of different carrier frequencies propagating in the same optical path. The designed structure allowed for detecting both signals independently without observable crosstalk. The proposed diffractive elements can work in a wide range of terahertz and sub-terahertz frequencies, depending on the design assumptions. Therefore, they can be considered as an appealing solution, regardless of the band finally used by the future telecommunication systems.

scholarly journals Iterative Channel Estimation for the Chinese Digital Television Terrestrial Broadcasting Systems with the Multiple-Antenna Receivers

2012 ◽  
Vol 6-7 ◽  
pp. 439-444
Author(s):  
Zi Wei Zheng
Keyword(s):  
Fourier Transform ◽  
Channel Estimation ◽  
Fast Fourier Transform ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multipath Fading ◽  
Wireless Channel ◽  
Digital Television ◽  
Frequency Division Multiplexing ◽  
Multiple Antenna ◽  
Frequency Division

Orthogonal frequency division multiplexing is an effective against multipath fading and high data throughput wireless channel transmission technology. Assistance with the inverse fast Fourier transform and fast Fourier transform operation, orthogonal frequency division multiplexing modulation and demodulation operations of the system convenient and convenient hardware implementation, orthogonal frequency division multiplexing, so in the modern digital television terrestrial broadcasting the system is widely used to support high performance bandwidth-efficient multimedia services. Broadband multi-carrier orthogonal frequency division multiplexing with multi-antenna and multi-antenna receiving system, to increase the diversity gain and improve the capacity of the system in different multipath fading channel. Accurate channel estimation in a simple channel equalization and decoding of broadband multi-carrier orthogonal frequency division multiple-antenna receiver and channel estimation accuracy and multiplexing system is very important, is the key to the performance of the overall broadband multi-carrier orthogonal frequency division multiplexing system in the multi-antenna receiver bit error rate. In this paper, iterative channel estimation to plan for digital terrestrial television broadcasting broadband multi-carrier orthogonal frequency division multiple antenna receiver multiplexing system proposal.

scholarly journals Relaxation of the Radio-Frequency Linewidth for Coherent-Optical Orthogonal Frequency-Division Multiplexing Schemes by Employing the Improved Extreme Learning Machine

Symmetry ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 632 ◽  
Author(s):  
David Zabala-Blanco ◽  
Marco Mora ◽  
Cesar A. Azurdia-Meza ◽  
Ali Dehghan Firoozabadi ◽  
Pablo Palacios Játiva ◽  
...  
Keyword(s):  
System Performance ◽  
Orthogonal Frequency Division Multiplexing ◽  
Regularization Parameter ◽  
Transmission Rate ◽  
Phase Error ◽  
Activation Function ◽  
The Other ◽  
Frequency Division Multiplexing ◽  
The Novel ◽  
Frequency Division

A coherent optical (CO) orthogonal frequency division multiplexing (OFDM) scheme gives a scalable and flexible solution for increasing the transmission rate, being extremely robust to chromatic dispersion as well as polarization mode dispersion. Nevertheless, as any coherent-detection OFDM system, the overall system performance is limited by laser phase noises. On the other hand, extreme learning machines (ELMs) have gained a lot of attention from the machine learning community owing to good generalization performance, negligible learning speed, and minimum human intervention. In this manuscript, a phase-error mitigation method based on the single-hidden layer feedforward network prone to the improved ELM algorithm for CO-OFDM systems is introduced for the first time. In the training step, two steps are distinguished. Firstly, pilots are used, which is very common in OFDM-based systems, to diminish laser phase noises as well as to correct frequency-selective impairments and, therefore, the bandwidth efficiency can be maximized. Secondly, the regularization parameter is included in the ELM to balance the empirical and structural risks, namely to minimize the root mean square error in the test stage and, consequently, the bit error rate (BER) metric. The operational principle of the real-complex (RC) ELM is analytically explained, and then, its sub-parameters (number of hidden neurons, regularization parameter, and activation function) are numerically found in order to enhance the system performance. For binary and quadrature phase-shift keying modulations, the RC-ELM outperforms the benchmark pilot-assisted equalizer as well as the fully-real ELM, and almost matches the common phase error (CPE) compensation and the ELM defined in the complex domain (C-ELM) in terms of the BER over an additive white Gaussian noise channel and different laser oscillators. However, both techniques are characterized by the following disadvantages: the CPE compensator reduces the transmission rate since an additional preamble is mandatory for channel estimation purposes, while the C-ELM requires a bounded and differentiable activation function in the complex domain and can not follow semi-supervised training. In the same context, the novel ELM algorithm can not compete with the CPE compensator and C-ELM for the 16-ary quadrature amplitude modulation. On the other hand, the novel ELM exposes a negligible computational cost with respect to the C-ELM and PAE methods.

scholarly journals Space Time Trellis Code Frequency Index Modulation with Neuro-LS Channel Estimation in OFDM

2019 ◽  
Vol 5 (9) ◽  
pp. 7
Author(s):  
Sarita Yadav ◽  
Ashish Nema ◽  
Jitendra Mishra
Keyword(s):  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Transmission Rate ◽  
Space Time ◽  
Time Shift ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Error Performance ◽  
Result Analysis ◽  
Index Modulation

In wireless communication, orthogonal frequency division multiplexing (OFDM) plays a major role because of its high transmission rate. In space-time shift keying (STSK), the information is conveyed by both the spatial and time dimensions, which can be used to strike a trade-off between the diversity and multiplexing gains. On the other hand, orthogonal frequency division multiplexing (OFDM) relying on index modulation (IM) conveys information not only by the conventional signal constellations as in classical OFDM, but also by the indices of the subcarriers. In this paper compressed sensing(CS) is studied in order to increase throughput and bit-error performance by transmitting extra information bits in each subcarrier block as well as to decrease the complexity of the detector. In this paper, soft trellis decoding algorithm is implemented with channel estimation using Neuro-LS technique. The result analysis shows the better performance of trellis decoder with respect to BER and Neuro-LS channel estimation with respect to BER.

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