Aleksandra S. Panajotovic

Influence of Even Order Dispersion on Soliton Transmission Quality with Coherent Intereference

The transmission speed of optical networks strongly depends on the impact of higher order dispersion. In the presence of coherent interference which can’t be kept under control by optical filtering, the impact of higher order dispersion becomes more serious. In this paper we give general expressions that describe pulse deformation due to even higher order dispersion in a single-mode fiber. The impulsive responses for even order dispersion in the presence of coherent interference are characterized by symmetrical waveforms with long trailing skirts. Individual and joint influence of second and fourth order dispersion on the transmission quality is studied. Pulse shape and eye diagram are obtained.

Average Level Crossing Rate of Dual Selection Diversity in Correlated Rician Fading with Rayleigh Cochannel Interference

We present an infinite-series representation for the average level crossing rate (LCR) of dual selection combining (SC) receivers, operating over correlated Rician fading channels, in the presence of Rayleigh cochannel interference (CCI). Numerical results are presented to illustrate the proposed mathematical analysis and to point out the effect of the branch correlation and fading severity on the average LCR.

Cochannel interference effect on BEP performance of SSC receiver in correlated Rician fading

Abstract We study the performance of dual branch switch and stay combining (SSC) diversity receivers operating over correlated Rician fading channels, in the presence of correlated Rayleigh distributed cochannel interference (CCI). Fast convergent infinite series representations for both the joint probability density function (PDF) of the SSC input signal-to-interference ratios (SIRs) and the PDF of the SSC output SIR are derived. The last one is applied to semi-analytically study the average bit error probability (ABEP) of differential binary phase shift keying (DBPSK). Furthermore, the optimum switching threshold in the sense of minimum ABEP is obtained numerically and the effects of fading severity and branch correlation on both ABEP and optimum switching threshold are investigated. Numerical and simulation results are presented to support the mathematical analysis.

Average Level Crossing Rate of Dual Selection Diversity over Correlated Unbalanced Nakagami-m Fading Channels in the Presence of Cochannel Interference

A dual selection combining (SC) receiver which applies desired signal power algorithm and operates over correlated, but not necessary identically distributed Nakagami-m fading channels in the presence of cochannel interference (CCI) is considered in this letter. Actually, a novel infinite-series expression for the average level crossing rate (LCR) at the output of that SC receiver is obtained. Numerical results are presented to examine the effects of the fading severity, input signal-to-interference ratio (SIR) unbalance and the level of branch correlation on the average LCR, as well as the correctness of proposed analytical formulation.

Performance Analysis of Dual-Branch Selection Combining Over Correlated Rician Fading Channels for Desired Signal and Cochannel Interference

System performances of dual selection combining over fading channels are analyzed. Fading between the diversity branches and between interferences is correlated and Rician distributed. Infinite series expressions for the probability density function, and the cumulative distribution function of the output signal-to-interference ratio are derived, which is the main contribution of this paper. Outage probability and the average bit error probability for noncoherent modulation schemes are also presented. Numerical results, presented in this paper, point out the effects of fading severity and correlation on the system performances.

Average Fade Duration of Dual Selection Diversity over Correlated Unbalanced Nakagami-m Fading Channels in the Presence of Cochannel Interference

Abstract A dual selection combining (SC) receiver with correlated and unbalanced diversity branches operating in interference-limited Nakagami-m fading environment is considered in this paper. Actually, average fade duration (AFD) of SC system applying desired signal decision algorithm is obtained. Numerical results can be used to examine the effects of fading severity, input signal-to-interference ratio (SIR) unbalance and level of branch correlation on the AFD, as well as the correctness of proposed analytical formulation.

The influence of crosstalk signal interference to signal propagation along the nonlinear and dispersive fiber

In this paper, the signal propagation along the fiber, in both absence or presence of the crosstalk signal interference at different places along the fiber, for both dispersive regime cases, is considered. The crosstalk appears at the transmitter output or along the fiber. The pulse shape at the receiver input is determined using Schrodinger equation [1]. The noise sources are the photodetector and resistance in the reciever. The bit error probability of intensity modulation and direct detection (IM-DD) system in the presence of the crosstalk, quantum and thermal noise is determined.

Adaptive Uniform Channel Decomposition in MU-MIMO-OFDM: Application to IEEE 802.11ac

This work considers the design of multiuser MIMO (MU-MIMO) schemes suitable for orthogonal frequency division multiplex (OFDM) systems such as those being currently discussed within IEEE 802.11ac. A general framework is proposed showing that the singular value decomposition (SVD), the geometric mean decomposition (GMD), and the uniform channel decomposition (UCD) are all viable mechanisms on which to lay the design. Nonetheless, some striking differences in terms of performance among these three schemes are uncovered. In particular, a novel adaptive transmission scheme based on the UCD is introduced that enables multiuser MIMO-OFDM gains to be realized, clearly outperforming those obtained using the SVD or GMD counterparts while remaining fully compliant with the latest IEEE 802.11ac specification. Relying on the UCD properties, the proposed technique takes into account the availability of a finite modulation and coding set and restrictions on transmission mode selection defined within the standard, to incorporate an optimisation step in charge of selecting the number of transmitted data streams to each user to maximise the system throughput. Comprehensive simulation results in the context of IEEE 802.11ac confirm the applicability and advantage of the adaptive UCD-based design.

Influence of Even-Order Dispersion on Super-Sech Soliton Transmission Quality under Coherent Crosstalk

The transmission speed of optical network strongly depends on the impact of higher order dispersion. In presence of coherent crosstalk, which cannot be otherwise controlled by optical filtering, the impact of higher order dispersions becomes more pronounced. In this paper, the general expressions, that describe pulse deformation due to second- and fourth-order dispersions in a single-mode fiber, are given. The responses for such even-order dispersions, in presence of coherent crosstalk, are characterized by waveforms with long trailing edges. The transmission quality of optical pulses, due to both individual and combined influence of second- and fourth-order dispersions, is studied in this paper. Finally, the pulse shape and eye diagrams are obtained.

Pulse Deformation due to Fourth Order Dispersion and Inband Interference

Recent research in optical communication have made some important discoveries such as femtosecod laser as well as new methods for neutralization of the second and third order dispersion influence. The fourth order dispersion influence on pulse propagation must not be neglected in case of using these new methods and lasers. The impact of fourth order dispersion on the pulse propagation in the presence of interference is the main subject of this paper. We considered the worst case of interference, i.e. case when phase shift of interference is pi. The resulting pulse shape at the receiver is obtained using analytical expressions that describe propagation along the fiber. Numerical results are presented and compared for various signal-to- interference ratios (SIR).