KEYWORDS: Antennas, Orthogonal frequency division multiplexing, Radio optics, Free space, Free space optics, Radio over Fiber, Modulation, Signal attenuation, Interference (communication), Optical amplifiers
The integration of photonic antennas with radio over fiber (RoF) systems can serve high dense populated areas such as airports,
shopping centers, dead-zone areas and tunnels. In this paper, we present an optical wireless communication downlink with a photonic
antenna. Our proposed radio over fiber (RoF) system is to carry modulated orthogonal frequency division multiplexing (OFDM)
signals with a 2.4 GHz radio frequency over a cost effective optical link. A comparison of using a photonic antenna as a passive and
an active in the RoF system is presented. The active photonic antenna (APHA) is mounted at the end of the optical link to the
photodiode as a package of a band-pass filter (BPF) and a radio frequency power amplifier. The photonic antenna scattering
parameters are implemented into the optical system simulation tools with various fiber length and free space loss (FSL). The wireless
link is implemented for a transmission distance up to 100 meters. The transmitted signal is fully carried over a radio frequency signal
and then optically carried over a standard single mode fiber (SSMF). The measurements of the EIPR and SNR were done with 0 dBm
RF input into the directly modulated laser (DML) for all the simulations. The results show that the analog optical wireless link is very
suitable to carry the OFDM signals. Moreover, the active photonic antenna provides sufficient service for more than 30 meters
compared to the passive antenna.
KEYWORDS: Orthogonal frequency division multiplexing, Wireless communications, Data conversion, Optical communications, Data communications, Signal processing, Receivers, Transmitters, MATLAB, Nonlinear optics
OFDM has been adopted in many high systems due to its high data rates and to its robust performance in fading channel.
OFDM distributes the data among number of carriers which are called subcarriers. The subcarriers must be orthogonal to
prevent the carrier from interfering to each other. Features such overcoming ISI (inter-symbol interference) and the
complexity of Designing both receiver and transmitter made it ideal technique for both wired and wireless
communication as long as optical communications. However, OFDM suffers from a defect called Peak Average power
ratio (PAPR). APARP is crucial drawback that limits the way that OFDM functions and reducing or mitigating this
factor in wireless and optical environment will help overcome and enhance the OFDM date rate. PAPR is the main cause
of inter-carrier interference and high out-of-band power, and consequently Bit error rate BER. We investigate some of
the techniques that mitigate the effect of PAPR. These techniques are merged together to provide a better PAPR
reduction with the existing techniques. In this paper, we are proposing a new reduction algorithm to minimize the effect
of the PAPR. The results and simulation are done in Optisystem V-11 and Matlab environment. These approaches will
be applied on WiMAX application and the performances between the different techniques are examined.
The Orthogonal Frequency Division Multiplexing Ultra-Wideband (OFDM-UWB) technique that widely used for the new emerging networks requires further investigation in terms of fiber length and UWB signal degradation. Simulations are used in this work to estimate the system performance which consists of two main links: wireless and optical, where the channel is considered as point to point between the UWB transmitter and the UWB receiver. In this paper, we demonstrate the use of UWB signals of carrying data to the end users within a campus area through an optical fiber link. A cost effective optical components are used in the system. The UWB signals are transmitted over a channel bandwidth of 528 MHz via low bit rate OFDM-subcarriers. Then, the accumulated data from each OFDM subcarrier is transmitted over an optical channel. Finally, UWB signals are wirelessly distributed to the end user over a short distance depending on the data rate being used. For this point to point system, using simulations, the performance of the system in terms of the bit error rate (BER) is examined. The results show that the wireless channel effects have the larger impact on the overall system performance compared with the fiber length effect.
KEYWORDS: Orthogonal frequency division multiplexing, Telecommunications, Data conversion, Modulation, Data communications, Nonlinear optics, Optical amplifiers, Signal attenuation, Computer engineering, Analog electronics
Orthogonal Frequency Division Multiplex (OFDM) is one form of a multicarrier modulation technique. It is
implemented in high date communication systems. The data in OFDM is divided into groups of sub- streams. Each supstream is mapped into orthogonal subcarrier. Consequently, the period of symbol will be long enough and is not affected by multipath channel fading. OFDM provides high spectral efficiency as long as robustness to the fading channel which makes it desirable for any communication system but there are some drawbacks of the OFDM. One main defect of OFDM is the PAPR which causes inter-carrier interference and high out-of-band power which degrades the performance of OFDM such as BER and ISI. The mitigation of the PAPR’s impact is the goal of this paper in the case of WiMAX.
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