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Orthogonal frequency division multiplexing (OFDM) systems require orthogonality among subcarriers. Unfortunately, the conditions, such as, residual carrier frequency offset, time variations because of Doppler shift or phase noise, which thus destroys the orthogonality at the receiver, hence results in intercarrier interference (ICI) and degrades the bit error rate (BER) performance. In this paper,...
Based on the orthogonality of space-time (ST) code, this paper concentrates on ST code transmission combined with intercarrier interference (ICI) parallel cancellation (PC) scheme to form STPC systems. With known channel state information (CSI) and orthogonal frequency division multiplexing (OFDM), we further develop this STPC-OFDM system with code rates 1 and 0.5 without increasing in power, bandwidth,...
Underwater speech communication plays an important role in many marine missions, such as oceanographic investigation, environmental monitoring, underwater rescuing and sightseeing. However, the difficulties of underwater acoustic channels such as multipath, time varying and Doppler shifting pose significant challenges to the design of high performance underwater acoustic speech communication. In this...
Fed up of slow speed networks, sharing your hotspot, then here's a solution which involves the use of LEDs at your place because of which speed of the networks get increased with a secured connection. Light has been a source of life and many more stuff, so here comes a new concept Li-Fi, as it is dubbed i.e., Light Fidelity. Chairperson of mobile communication at University of Edinburgh, Herald Haas,...
The increasing capacity requirements for IP traffic in recent innovations are optical communication systems. In this paper, a new framework to handle the problem in which the sequence of the customer demands are fixed while trying to find the path for each demand in order to obtain more reasonable solution. Genetic algorithm (GA) is a search heuristic that minimizes the process of selection. Genetic...
Due to the exploding evolution of wireless communication systems, energy efficiency (EE) becomes the concern of many researches. In this context, we examine this metric into multiband orthogonal frequency division multiplexing ultra wideband (MB-OFDM UWB) systems. Indeed, the focus is about investigating a cross-layer design based on the joint combination between data link layer through the hybrid...
This paper focuses utilization of I/Q-modulation technique for radio channel orthogonal frequency division multiplexing. Particularly, quasi harmonic piece-wise linear functions (QLF) are introduced to construct orthogonal functional basis due to solely phase modulation of radio channel carrier. In contrast to conventional OFDM coding, the QLF basis confines peak-to-average power ratio and provides...
In this paper, we propose a frequency coding waveform with a nonlinear frequency modulation (NLFM) signal for the multiple-input multiple-output (MIMO) radar. The transmitted signal of each transmitting antenna is a pulse train, of which, the sub-pulses are NLFM signals with different carrier frequencies. The frequency sequence and the parameter of the nonlinear frequency function are optimized to...
In this paper, the problem of jointly allocating bits, subcarriers and power to maximize the total transmit bit rate in an OFDM based cognitive radio (CR) is studied. Moreover, different service requirements of SUs are also considered. Since “underlay“ is adopted as the spectrum shared model, secondary users (SU) in the CR system are allowed to utilize any part of frequency band as long as the interference...
Future generation of wireless networks, i.e. 5G, is envisioned to support several new use-cases demanding transmission reliability and latency that cannot be achieved by the current cellular networks such as long-term evolution (LTE). This paper looks at different design aspects of the control channel(s) to support ultra-reliable low-latency communication considering factory automation as an example...
Undersea acoustic links are highly complex due to the various propagation effects like the spreading, multipath, intersymbol interference, fading, etc.. Orthogonal frequency division multiplexing is found to be a good choice to combat intersymbol interference. It enables simpler equalization as well. Coding can be used in conjunction with OFDM to achieve error correction, improved security as well...
Numerous studies have shown that a generic communication system is prone to substantial performance loss in the context of strong impulse noise, which is generally not time invariant and is hard to model accurately. A turbo coded orthogonal frequency division multiplexing system in memory impulse channels is investigated in this work. Upon reception of the transmitted data, each of the two proposed...
In order to transmit the signals by multirays connection channels the method of Orthogonal Frequency Division Multiplexing — OFDM is used. The main advantages of this technology are high resistance concerning selective fades and high frequency effectiveness. While constructing radio connection systems (RCS) with OFDM great attention is paid to the questions of creation the signal and code constructions...
Direct application of spatial modulation (SM) for orthogonal frequency division multiplexing (OFDM) systems does not realize the inherent frequency diversity gain since information symbols are not spread over independently-faded subcarriers. This paper investigates a new transmission scheme that employs spatial modulation (SM) for each group of subcarriers in OFDM. Specifically, OFDM symbols in each...
We propose an indoor visible light communication system model in the paper. By researching several kinds of commonly used modulation methods through the analysis of two channels: diffuse and LOS channels, we established a general indoor visible light communication transmission model and the corresponding modulation communication mode under the condition. A solution to improve intersymbol interference...
A joint modulation and coding scheme is proposed based on Rateless Codes and Vector OFDM systems to combat fading over doubly selective channels. A rateless encoder can generate potentially unlimited coded symbol. Vector OFDM is a general transmission scheme, where OFDM and Single-Carrier systems can be seen as two extreme cases. The main focus of this paper is to design and analyze a Rateless Coded...
This work investigates a technique of high data transmission rate over wireless communication system. Now a day's higher bandwidth demand has been increased and with the minimum tolerance of error. To enhance available bandwidth and improve the quality of transmission convolution codes are used on the OFDM (Orthogonal frequency division multiplexing) wireless communication system over AWGN channel...
Car-to-car (C2C) communications requires reliable connectivity at moderate data rates. This is essential for safety-related applications. The development of such communication systems needs to cope with time-variant propagation channels and rich multipath environments. Moreover, the choice of the antennas and their position in/on the car highly influences the overall propagation channel. This paper...
We propose an orthogonal and full rate MIMO space-time coding technique for OFDM/OQAM, called ‘make-it-real-and-anticirculating’ (MIRAAC), to perform energy efficient wireless data transmission. The equivalent MIMO channel (after space-time coding, propagation and decoding) is made real and anticirculating, so that the receiver can suppress all interference very simply: just by extracting the real...
The increased demand of low-latency and spectrally efficient wireless transmissions requires accurate performance prediction mechanisms. A widely used performance prediction method for coded multicarrier transmissions applying iteratively decoded error correction codes is based on the employment of the mean mutual information of the coded bit. A precise knowledge at the transmitter site of the log...
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