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In this letter, we introduce a detection technique based on differential signaling scheme for outdoor free space optical communications. This method requires no channel state information (CSI) and does not suffer from the computational load compared with the conventional receivers, where adjusting dynamically the detection threshold level (either based on CSI knowledge, or by using pilots) leads to...
Space optical communications is studied at National Institute of Information and Communications Technology, where the Small Optical TrAnsponder (SOTA) was developed and embarked on a 50-kg-class satellite. Atmospheric fluctuation is an issue to be solved in ground-to-satellite optical communication links. The SOTA has error-correcting functions using Reed–Solomon code and low-density generator matrix...
In-band multi bidirectional passive optical network (MPON) based on optical code division multiple access technique was implemented. Up/downstream data carried by wavelengths in C-band with channel spacing 25/50GHz and all the data encoded by modified quadratic congruence code (MQC). The MPON network has been implemented to increase the system capacity by using the same code and same prime number...
In this paper, the enhanced high-speed performance and energy-efficiency of 1.3 µm Short-Cavity VCSEL with buried-tunnel-junction is reported. Error-free data-transmission at 30 Gb/s up to 10 km and at 25 Gb/s up to 25 km is performed at room temperature over single mode fiber. Furthermore, low energy-to-data-distance ratios of 24 fJ/(bit·km) are achieved.
Advances in solid-state lighting have overcome common limitations on optical wireless such as power needs due to light dispersion. It's been recently proposed the modification of lamp's drivers to take advantages of its switching behaviour to include data links maintaining the illumination control they provide. In this paper, a remote access application using visible light communications is presented...
An infrared optical wireless system is presented, consisting on autonomous remote nodes communicating with a central node. The network is designed for telecommand/telemetry purposes, comprising a large number of nodes at a low data rate. Simultaneous access is granted by using CDMA techniques, and an appropriate selection of the code family can also keep power consumption to a minimum.
Optical CDMA systems suffer from multiple access interferences (MAI) originating from other simultaneous users. As the number of simultaneous user increases, the bit error probability becomes higher. Several interference cancellation techniques have been proposed aiming at lowering MAI as Optical Parallel Interference Cancellation (OPIC), this system is complex, and the hardware is increased as the...
In order to further enhance the bandwidth of the data communication system in theodolite, a single channel serial optical transmission system was designed based on the studying of the 10BASE-X Gigabit Ethernet physical layer technology which meets the IEEE standard. The conversion between the 64-bit 156.25MHz TTL signals and the 4 channel 3.125Gbps PCML differential signals is carried out by FPGA;...
Free space optical communications have potential applications in the future global communication network. However, performance of free space optical communication is degraded by atmospheric turbulence. In this paper, we derive closed-form expressions of outage probability for the cases when the scintillation is lognormal probability ditribution over weak atmospheric turbulence channels and gamma-gamma...
We present lightwave modulation techniques for high-speed signal generation in digital and analogue applications. Advanced modulation formats, such as differential quadrature phase-shift-keying, amplitude- and phase-shift-keying, quadrature-amplitude-modulation etc, were investigated to obtain enhanced spectral efficiency, where Mach-Zehnder modulators (MZMs) are commonly used to control optical amplitude...
In this paper, we present optical orthogonal frequency division multiplexing (O-OFDM) systems using direct detection (DD), suitable for cost-effective applications. A scheme based on discrete Hartley transform (DHT) is proposed and compared to standard O-OFDM implementation. Both asymmetrically clipped (AC) and DC-biased solutions are analyzed for intensity-modulated DD systems. We show that AC is...
We present a scalable, low latency optical packet switch sub-system that is capable to switch optical packets with multiple modulation formats. The optical packet switch sub-system employing in-band labeling to allow for transparent routing of packets with multiple data formats and data bit-rates. Packets employing in-band labels can be processed without the need to reconfigure the label processor...
Block transmission with frequency-domain equalization (FDE) has been proven as an attractive alternative to orthogonal frequency division multiplex (OFDM) for radio frequency (RF) communication, especially at 60 GHz. In this paper, we show that FDE can be advantageously applied for optical transmission over dispersive channels as well, and in particular, in direct-detection systems. We review the...
As demands for plastic optical fiber (POF) rise up in optical data communication system, POF are now being applied as base material for passive optical splitter. In order to produce the economical passive device, optical 1??3 splitters have been fabricated four times through handwork fusion. Besides, red LED with wavelength of 650 nm has been transmitted into splitter for the purpose of characterization...
We experimentally demonstrate a flexible electronic compensator for group velocity dispersion induced time skewing in multi-wavelength optical CDMA systems. The compensator uses a distributed transversal filter already proposed in the context of optical communications. Results show improvement in the ability to detect the autocorrelation peak in presence of multi-access interference.
Error performance of a coherent free space optical system with K-distributed turbulence is studied. A closed-form expression of the moment generating function for K-distributed turbulence is derived, and the moment generating function is used to obtain the exact error rates for binary phase shift keying (BPSK), BPSK with spatial diversity, as well as differential phase-shift keying. Based on our analytical...
The use of optical communication links is a growing and promising technology, with its applications spreading over many areas of telecommunication. ESA's involvement in the development of optical communication terminals for high data rate links between satellites already resulted in the successful demonstration of the SILEX programme using optical inter-satellite links, using the ARTEMIS satellite...
In this paper, performance of ideal cross correlated ZCC code is investigated to support different multimedia applications with variable data rates and quality of service requirements in terms of signal to noise ratio and bit error rate. Simplicity in code construction and flexibility in Cross Correlation control has made this code a compelling candidate for future OCDMA applications. Further, various...
One of the challenging aspects in building an efficient underwater wireless sensor network (UWSN) is under-water wireless communication. Radio frequencies are strongly attenuated in water: the available radio modules such as Bluetooth or wireless LAN (IEEE 802.11), which operate in the gigahertz range, around 2.4 GHz, cannot be used underwater where, currently, acoustic communication is mainly employed...
One of the techniques used to mitigate the problem of cross correlation is successive interference cancellation (SIC). This technique has been inspired of multi user detection technique (MUD), and can increase the capacity of optical CDMA system. A detailed analysis of this system is theoretically analyzed, taking into account multiple-access interference (MAI). In addition, the system performance...
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