A Simple Multicarrier Transmission Technique Combining Transmit Diversity and Data Multiplexing for Non-Orthogonal Multiple Access

2021 ◽  
pp. 1-1
Author(s):  
Dehuan Wan ◽  
Ronglan Huang ◽  
Miaowen Wen ◽  
Gaojie Chen ◽  
Fei Ji ◽  
...  
Keyword(s):  
Multiple Access ◽  
Transmit Diversity ◽  
Multicarrier Transmission ◽  
Transmission Technique ◽  
Data Multiplexing

CO-OFDM and DP-QPSK Based DWDM Optical Wireless Communication System

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Jagana Bihari Padhy ◽  
Bijayananda Patnaik
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Channel Model ◽  
Spectrum Efficiency ◽  
Optical Wireless ◽  
Multicarrier Transmission ◽  
Transmission Technique ◽  
Turbulence Regime ◽  
Dual Polarized ◽  
Dwdm System ◽  
Clear Weather

Abstract The 5 G technology provides a promising solution for future broadband networks. It requires access to high-speed wireless services for systems at anytime and anywhere. For adapting the 5 G services, this paper proposes an optical wireless system with hybrid scheme of dual polarized Gbps dense wavelength division multiplexed (DWDM) system. The multi-carrier transmission technique such as coherent optical orthogonal frequency division multiplexing (CO-OFDM) has also been incorporated into the system. The frequency spacing for the DWDM system is taken 25, 50 and 100 GHz according to the ITU-T standard. Here the subcarriers of each channel are modulated with the dual polarized-quadrature phase shift keying (DP-QPSK) sequence. The information is transmitted with an overall data rate of 0.32 Tbps. The system is successfully demonstrated at different turbulence regime from clear weather to severe turbulence weather under Gamma-Gamma atmospheric turbulence channel model. Due to the high optical signal-to-noise ratio (OSNR) tolerance and high spectrum efficiency of the dual polarized multi-channel and multicarrier transmission technique, the link distance achieved is 2.9 km in clear weather, 2.6 km in moderate turbulence regime, 2.3 km in high turbulence regime and 0.9 km in severe turbulence regime. A comparison study with related works has been carried out. Mathematical modeling is also incorporated for detail analysis of the proposed system.

scholarly journals A Modified SLM Scheme for PAPR Reduction of UFMC Systems

2021 ◽  
Vol 2128 (1) ◽  
pp. 012004
Author(s):  
Sahar M. Alrabeiy ◽  
Sameh A. Fathy ◽  
Safa M. Gasser ◽  
Mohamed S. El-Mahallawy
Keyword(s):  
Spectral Efficiency ◽  
Average Power ◽  
Low Complexity ◽  
Papr Reduction ◽  
Low Latency ◽  
Power Ratio ◽  
Multicarrier Transmission ◽  
Multicarrier System ◽  
Transmission Technique ◽  
Conventional Scheme

Abstract One of the most promising 5G waveform candidates is the universal-filtered multicarrier system (UFMC). The UFMC system reduces the out-of-band (OoB) emission, bringing about higher spectral efficiency. This is assumed to reach robustness against frequency offset and low latency. Although, as aforementioned, the UFMC system offers many advantages, it lacks high peak-to-average power ratio (PAPR) as a multicarrier transmission technique. This research paper tackles two approaches; firstly, RCS, by developing a simulated conventional SLM system, with modifications to generate the same number of waveforms, while using fewer UFMC modulators. Secondly, by developing a simulated conventional SLM system, with modifications using the same number of modulators to generate more waveforms that would be generated in the conventional scheme. The two sets of results from the proposed M-SLM scheme are compared to each other, and to other PAPR reduction schemes using OFDM and UFMC. To reduce PAPR in UFMC systems, (M-SLM) scheme with low complexity is proposed. The essence of the proposed M-SLM scheme is represented in making use of the cyclically shifting process and FMC modulator’s linearity property. The proposed M-SLM scheme uses Um UFMC modulators to produce Uw alternative UFMC waveforms, where Uw = Um (2Um − 1). As a result, drawing a comparison with existing SLM based PAPR reduction schemes for UFMC systems; the proposed M-SLM scheme's computational complexity is reduced. Finally, there is a comparison between the proposed M-SLM scheme and the schemes there in the literature according to PAPR reduction ability.

OFDM Transmission Technique

2009 ◽  
pp. 3561-3587
Author(s):  
Hermann Rohling
Keyword(s):  
Communication Networks ◽  
Mobile Communications ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Access ◽  
Fourth Generation ◽  
Frequency Division ◽  
Carrier Synchronization ◽  
Radio Channels ◽  
Transmission Technique ◽  
Cellular Environment

The orthogonal frequency division multiplexing (OFDM) transmission technique can efficiently deal with multi-path propagation effects especially in broadband radio channels. It also has a high degree of system flexibility in multiple access schemes by combining the conventional TDMA; FDMA; and CDMA approaches with the OFDM modulation procedure; which is especially important in the uplink of a multi-user system. In OFDM-FDMA schemes carrier synchronization and the resulting sub-carrier orthogonality plays an important role to avoid any multiple access interferences (MAI) in the base station receiver. An additional technical challenge in system design is the required amplifier linearity to avoid any non-linear effects caused by a large peak-to-average ratio (PAR) of an OFDM signal. The OFDM transmission technique is used for the time being in some broadcast applications (DVB-T; DAB; DRM) and wireless local loop (WLL) standards (HIPERLAN/2; IEEE 802.11a) but OFDM has not been used so far in cellular communication networks. The general idea of the OFDM scheme is to split the total bandwidth into many narrowband sub-channels which are equidistantly distributed on the frequency axis. The sub-channel spectra overlap each other but the sub-carriers are still orthogonal in the receiver and can therefore be separated by a Fourier transformation. The system flexibility and use of sub-carrier specific adaptive modulation schemes in frequency selective radio channels are some advantages which make the OFDM transmission technique a strong and technically attractive candidate for the next generation of mobile communications. The objective of this chapter is to describe an OFDM-based system concept for the fourth generation (4G) of mobile communications and to discuss all technical details when establishing a cellular network which requires synchronization in time and frequency domain with sufficient accuracy. In this cellular environment a flexible frequency division multiple access scheme based on OFDM-FDMA is developed and a radio resource management (RRM) employing dynamic channel allocation (DCA) techniques is used. A purely decentralized and self-organized synchronization technique using specific test signals and RRM techniques based on co-channel interference (CCI) measurements has been developed and will be described in this chapter.

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