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Multilevel Amplitude and Phase Shift Keying Optical Transmission
Published in Le Nguyen Binh, Advanced Digital, 2017
Orthogonal frequency division multiplexing (OFDM) is a transmission technology that is primarily known from wireless communications and wired transmission over copper cables [31,32]. It is a special case of the widely known frequency division multiplexing (FDM) technique in which digital or analog data are modulated onto a certain number of carriers and transmitted in parallel over the same transmission medium. The main motivation for using FDM is the fact that due to parallel data transmission in the frequency domain, each channel occupies only a small frequency band. Signal distortions originating from frequency-selective transmission channels, the fiber CD, can be minimized. The special property of OFDM is its very high spectral efficiency. While for conventional FDM, the spectral efficiency is limited by the selectivity of the bandpass filters required for demodulation, OFDM is designed such that the different carriers are pairwise orthogonal. In this way, for the sampling point, the intercarrier interference (ICI) is suppressed, although the channels are allowed to overlap spectrally.
Multi-Carrier OFDM Optical Modulation
Published in Le Nguyen Binh, Optical Modulation, 2017
Orthogonal frequency division multiplexing (OFDM) is a transmission technology that is primarily known from wireless communications and wired transmission over copper cables. It is a special case of the widely known frequency division multiplexing (FDM) technique for which digital or analog data is modulated onto a certain number of carriers and transmitted in parallel over the same transmission medium. The main motivation for using FDM is the fact that, due to parallel data transmission in frequency domain, each channel occupies only a “small” frequency band. Signal distortions originating from frequency-selective transmission channels, the fiber chromatic dispersion, can be minimized. The special property of OFDM is characterized by its very high spectral efficiency. While for conventional FDM, the spectral efficiency is limited by the selectivity of the bandpass filters required for demodulation, OFDM is designed such that the different carriers are pair wise orthogonal. This way, the sampling point the inter-carrier interference (ICI) is suppressed although the channels can overlap spectrally.
Popular Combinational Circuits
Published in Sajjan G. Shiva, Introduction to Logic Design, 2018
Information is commonly multiplexed from many sources onto a single transmission line through Frequency Division Multiplexing (FDM) and Time Division Multiplexing (TDM). In FDM, each signal is modulated up to a specific frequency band and then transmitted. For example, in telephone conversations in which 3 kilohertz (KHz) is the highest frequency to each signal, one signal may be modulated to 3 to 6 KHz and another from 7 to 10 KHz for transmission on the same line. In TDM, a common multiplexing mode in digital circuits, each signal source is allocated a time slot in which it transmits on the common transmission line. Thus, if there are 10 devices, each might transmit for 1 μs during each 10-μs transmission cycle.
A Comprehensive Analysis of PAPR Reduction in Scrambled UFMC and OFDM Using Artificial Bee Colony Algorithm for 5G Communications
Published in IETE Journal of Research, 2023
Krishna Kishore K, Jagan Naveen V, Rajesh Kumar P, Sreenivasa Rao E
UFMC is a multi-carrier transmission technique based on the principle of Frequency Division Multiplexing (FDM). In FDM, the input data stream is subdivided into many sub bands with narrow bandwidth. Hence, by using FDM, a single channel can accommodate many users. In UFMC, bandwidth is divided into sub-bands [13] and it provides each sub-band with a large number of sub-carriers. As a result, it can increase the data rate. The individual sub bands are filtered and added to get the UFMC Symbol as shown in Figure 1.