Tian Cao

Performance Analysis for Relay-Aided Multihop BPPM FSO Communication System Over Exponentiated Weibull Fading Channels With Pointing Error Impairments

The performances of the decode-and-forward (DF) multihop free-space optical communication system with exponentiated Weibull distribution considering the fading induced by pointing error have been studied. With Meijers G-function, the probability density function (PDF) of the aggregated channel model and the closed-form expression for the average bit error rate (ABER) of binary pulse position modulation are derived. The average bit-error-rate performance is then investigated with different hop numbers H, turbulence strength values, receiver aperture sizes, beamwidths, and jitter variances. Compared with the case without pointing error, the mitigation effect of aperture averaging for fading is more significant over the aggregated channel, regardless of the selected H, and it is less effective for the degradation induced by the increase in H, which can be restrained by larger beamwidth and lower jitter. The outage probability is also investigated, and the results show that aperture averaging has less of an effect on the outage probability under moderate turbulence than that under the weak turbulence condition at a given value of H, which is different from the scenario without pointing error. After this, the end-to-end average capacity is analyzed. Monte Carlo simulation is provided to confirm the validity of the proposed ABER expression.

Performance Analysis of Multihop Parallel Free-Space Optical Systems Over Exponentiated Weibull Fading Channels

The performances of multihop parallel free-space optical (FSO) cooperative communication systems with decode-and-forward protocol under exponentiated Weibull (EW) fading channels have been investigated systematically. With the max-min criterion as the best path selection scheme, the probability density function and the cumulative distribution function of the max-min EW random variable are derived. The analytical expressions for the average bit error rate (ABER) and outage probability with identically and independently distributed (i.i.d.) links are then obtained, respectively. Based on it, the ABER for a non-identically and independently distributed (non-i.i.d.) FSO system is also deduced with the help of the Gauss-Laguerre quadrature rule. The ABER performance of the considered system are further analyzed, in detail, under different turbulence conditions, receiver aperture sizes, and structure parameters (R and C). The comparison between i.i.d. and non-i.i.d. FSO systems over EW fading channels shows that the performances of both systems could be improved with large aperture diameters adopted for the structure parameters R and C selected. Monte Carlo simulation is also provided to confirm the correctness of the analytical ABER expressions. This work presents a generalized system model, and it can be used to analyze and design FSO communication systems.

Multihop FSO Over Exponentiated Weibull Fading Channels With Nonzero Boresight Pointing Errors

The end-to-end (EE) average bit error rate (ABER) performance of a decode-and-forward-based multihop free-space optical communication system is investigated over composite exponentiated Weibull fading channels with nonzero boresight pointing errors considered. In particular, the cumulative distribution function of the aggregated fading channel for non-identically and independently distributed multihop system is derived. Then, the analytical expression of EE ABER with

Impact of nonzero boresight pointing errors on the performance of a relay-assisted free-space optical communication system over exponentiated Weibull fading channels

M

Performance analysis of a PPM-FSO communication system with an avalanche photodiode receiver over atmospheric turbulence channels with aperture averaging

-ary phase shift keying subcarrier intensity modulation is achieved in terms of Gauss–Laguerre quadrature rule considering aperture averaging effect. The results show that the ABER performance is mainly limited by nonzero boresight pointing errors for larger receiver aperture size. The comparison with Monte Carlo simulation verifies the validity of the proposed ABER model.

On the performances of relay-aided FSO system over M distribution with pointing errors in presence of various weather conditions

The impact of nonzero boresight pointing errors on the system performance of decode-and-forward protocol-based multihop parallel optical wireless communication systems is studied. For the aggregated fading channel, the atmospheric turbulence is simulated by an exponentiated Weibull model, and pointing errors are described by one recently proposed statistical model including both boresight and jitter. The binary phase-shift keying subcarrier intensity modulation-based analytical average bit error rate (ABER) and outage probability expressions are achieved for a nonidentically and independently distributed system. The ABER and outage probability are then analyzed with different turbulence strengths, receiving aperture sizes, structure parameters (P and Q), jitter variances, and boresight displacements. The results show that aperture averaging offers almost the same system performance improvement with boresight included or not, despite the values of P and Q. The performance enhancement owing to the increase of cooperative path (P) is more evident with nonzero boresight than that with zero boresight (jitter only), whereas the performance deterioration because of the increasing hops (Q) with nonzero boresight is almost the same as that with zero boresight. Monte Carlo simulation is offered to verify the validity of ABER and outage probability expressions.

Average bit error rate performance analysis of subcarrier intensity modulated MRC and EGC FSO systems with dual branches over M distribution turbulence channels

The average bit error rate (ABER) performance of an avalanche-photodiode (APD)-based pulse-position modulation (PPM) free-space optical (FSO) communication system is investigated considering the aperture averaging effect. The approximate ABER expression is theoretically derived in terms of M and exponentiated Weibull (EW) distributions under weak-to-strong turbulent atmosphere conditions with a binary PPM (BPPM) scheme. Union-bound and Hermite polynomials are then considered to estimate the performance of M-ary PPM FSO systems. The system performance is analyzed with the aperture sizes, turbulence strengths, receiver temperatures, and average photon counts taken into account. The results show that an optimal average APD gain, which is affected by receiver temperature, can be chosen to minimize the ABER value. And the impact of aperture averaging on the system performance over M distribution is not so apparent as that over EW distribution for different temperatures, turbulent strengths, and average photon counts. In addition, the present APD-based system can offer better ABER performance than that of a P-i-N-based PPM system over both EW and M fading channels at 300 and 500 K. This work is beneficial to the FSO system design.