Multicarrier Methods Research Articles

Compensating Chromatic Dispersion and Phase Noise using Parallel AFB-MBPS For FBMC-OQAM Optical Communication System

Filter Bank Multi-Carrier Offset-QAM (FBMC-OQAM) is one of the hottest topics in research for 5G multi-carrier methods because of its high efficiency in the spectrum, minimal leakage in the side lobes, zero cyclic prefix (CP), and multiphase filter design. Large-scale subcarrier configurations in optical fiber networks need the use of FBMC-OQAM. Chromatic dispersion is critical in optical fiber transmission because it causes different spectral waves (color beams) to travel at different rates. Laser phase noise, which arises when the phase of the laser output drifts with time, is a major barrier that lowers throughput in fiber-optic communication systems. This deterioration may be closely related among channels that share lasers in multichannel fiber-optic systems using methods like wavelength-division multiplexing with frequency combs or space-division multiplexing. In this research, we use parallel Analysis Filter Bank (AFB) equalizers in the receiver part of the FBMC OQAM Optical Communication system to compensate for chromatic dispersion (CD) and phase noise (PN). Following the equalization of CD compensation, the phase of the carriers in the received signal is tracked and compensated using Modified Blind Phase Search (MBPS). The CD and PN compensation techniques are simulated and analyzed numerically and graphically to determine their efficacy. To evaluate the FBMC's efficiency across various equalizers, 16-OQAM is taken into account. Bit Error Rate (BER), Optical Signal-to-Noise Ratio (OSNR), Q-Factor, and Mean Square Error (MSE) were the primary metrics we utilized to evaluate performance. Single-tap equalizer, multi-tap equalizer (N=3), ISDF equalizer with suggested Parallel Analysis Filter Banks (AFBs) (K=3), and MBPS were all set aside for comparison. When compared to other forms of Nonlinear compensation (NLC), the CD and PN tolerance attained by Parallel AFB equalization with MBPS is the greatest.

Constrained Message Length Coding for Low Peak to Average Power Ratio in FBMC: OQAM Systems

The FBMC generation techniques are found to surmount the disadvantages of the IFFT/FFT based OFDM system. The minimization of PAPR is a much sought after solution by all multi-carrier methods. This paper investigates the possibility of a unified approach for error control coding and PAPR minimization in an FBMC-OQAM system. A new coding procedure called Constrained Message Length (CML) coding is presented in this paper. A new perspective on PAPR and an analytical framework for estimating the PAPR is also presented. Hybrid techniques using coding and companding are tested for different channel models, and their BER performance is on par with the BCH system. The proposed system is of low complexity and has a PAPR of only 3.81 dB, which is better than or comparable with the existing systems that are using complex methods. This paper has uniquely investigated the dependence of PAPR on the input data variation for a different set of random data loads. The CML coding proposed here can minimize the input data dependent PAPR deviation to a low variance of 0.045 dB, which provides an increased linear region of operation to the power amplifier in the RF section.

Evaluation of single- and multicarrier methods for underwater communication using data-driven simulations.

Unlike in radio communications, there is no standard statistical model for the channel impulse response in underwater acoustic communications. To compare the performance of different communications strategies requires data collected under common environmental conditions. In the present paper, a data-driven simulator is developed for comparing single- and multicarrier communications algorithms. Models for the time-varying channel impulse response over a particular bandwidth are first constructed using archival experimental data. The models are then driven with novel communications sequences of lesser bandwidth. The output is synthetic received data that can then be demodulated to evaluate communications performance. By applying reciprocity to the single-input, multiple-output archival data, both multiple receive arrays and multiple transmit arrays can be simulated. Communications performance for the synthetic data is compared to actual experimental results. [Work partially supported by the ONR.]

Signal processing for underwater acoustic communications

The performance and complexity of signal processing systems for underwater acoustic communications has dramatically increased over the last two decades. With its origins in noncoherent modulation and detection for communication at rates under 100 b/s, phase-coherent digital communication systems employing multichannel adaptive equalization with explicit symbol-timing and phase tracking are being deployed in commercial and military systems, enabling rates in excess of 10 kb/s. Research systems have been shown to further dramatically increase performance through the use of spatial multiplexing. Iterative equalization and decoding has also proven to be an enabling technology for dramatically enhancing the robustness of such systems. This article provides a brief overview of signal processing methods and advances in underwater acoustic communications, discussing both single carrier and emerging multicarrier methods, along with iterative decoding and spatial multiplexing methods.