Performance Of Pulse Position Modulation Research Articles

Performance Analysis of Total Attenuation Effects and Different Values of Transmitter Power on Bit Error Rate and Signal-To-Noise Ratio for Free Space Optical Communication

Objective: In this paper, the performance of pulse position modulation (PPM), nonreturn zero modulation (NRZ), and return zero modulation (RZ) at signal-to-noise ratio and bit error rate in free space optical communication is compared. This comparison is performed to obtain the most effective modulation in atmospheric attenuations. Also, the effect of increasing transmitter power on the bit error rate and signal-to-noise ratio is investigated. Methods: Utilizing a light source with a wavelength of 1550 nm, the system is simulated in MATLAB by choosing the Kim data transmission link model with different visibility values of 0- 10 km. The analytical equations of free space optical communications are implemented by selecting appropriate parameters. The effects of weak, moderate, and strong atmospheric attenuation, geometric loss, and different transmitter powers (1-5 mW) on bit error rate and signal-to-noise ratio are investigated for all three modulations. Results: The results show that PPM is the most effective modulation compared to other modulations used in this study and shows a better performance in the mentioned atmospheric attenuation conditions within the given values of bit error rate and signal-to-noise ratio. Conclusion: Modulations with lower average power will perform better than other modulations in bit error rate and signal-to-noise ratio under the same atmospheric attenuation conditions. In PPM modulation, increasing the transmitter power causes more reduction in the bit error rate than other modulations used in this paper. Therefore, using this modulation to optimize the power budget in free space optical communications will be appropriate.

M-ary pulse position modulation performance with adaptive optics corrections in atmospheric turbulence

ABSTRACTThe performance of M-ary pulse position modulated (PPM) optical wireless communication (OWC) systems in atmospheric weak turbulence medium is evaluated by using adaptive optics corrections. Piston, tilt, defocus and coma components of adaptive optics corrections are applied to the avalanche photodetector (APD) type of receiver and the results are obtained depending on various turbulence and receiver parameters. The lognormal channel distribution is used to model the weak atmospheric turbulence conditions. Adaptive optics correction increases the bit-error-rate (BER) performance of an OWC system operating in atmospheric turbulence conditions. Piston component yields the highest BER performance, followed by the tilt, defocus and coma adaptive optics correction components respectively.

Experimental Evaluation of Modulation Formats’ Performance in Diffuse UV Channels

The fundamental properties of free space optical channels in the ultraviolet (UV) spectral range between 200 and 280 nm are the enhanced scattering and the solar blind operation. Exploiting these properties, point-to-point links in a non-line-of-sight (NLOS) regime were experimentally tested and the performance of pulse position modulation of fourth order (4-PPM) and flip–orthogonal frequency division multiplexing (Flip-OFDM) modulation formats was evaluated. At the transmitting side, light-emitting diodes (LEDs) emitting at 265 nm were used. At the receiving side, a photo-multiplier tube was combined with an optical filter. Distances up to 20 m were covered and kilobits/s rates were applied. The performance was also evaluated after modifying artificially the atmospheric conditions by the operation of a fog machine. In short, 4-PPM outperformed Flip-OFDM, whereas a medium that offers enriched scattering due to fog may boost the performance of short-range NLOS links in the UV spectral range.

Novel results on pulse-position modulation performance for terrestrial free-space optical links impaired by turbulent atmosphere and pointing errors

In a recent study, the error performance of pulse-position modulation (PPM) schemes has been investigated for a terrestrial free-space optical (FSO) link, which was assumed to be impaired by both turbulent atmosphere and pointing errors. Only for the binary case a closed-form solution was achievable, whereas for non-binary conditions just an approximate relationship could be given. The key point in this respect was the approximation of the complementary error function so that the two-fold integral, otherwise required in this context, ended up in a closed form. In the current contribution, the problem is tackled by an additive combination of exponentials whose coefficients are optimised in the least-square sense. It turns out that second-order approximations are a good compromise between accuracy and computational complexity.

Performance of pulse-position modulation on measured non-directed indoor infrared channels

We examine the performance of pulse-position modulation (PPM) on measured channels with intersymbol interference (ISI). We summarize the bit-error-rate performance of unequalized systems and review the performance of maximum-likelihood sequence detection (MLSD) for PPM over ISI channels with additive white Gaussian noise. We evaluate the performance of PPM links over 46 experimentally measured indoor infrared channels. Detailed results are presented for 2, 4, 8, and 16-PPM at bit rates of 10 Mb/s and 30 Mb/s, and these techniques are compared to on-off keying. Our results show that when MLSD is employed, 16-PPM provides the best average-power efficiency among the modulation techniques considered in this study.