Abstract

An important and yet unsolved problem is a reliable, simple and accurate estimation of the bit-error rate (BER) in differential phase-shift keying (DPSK) systems. The goal of this paper is to assess the limits of the application of the existing Q-factor models for the return-to-zero (RZ) DPSK data format - conventional Q of the received electrical signal (Q_el = |μ₁ – μ₀|/(σ₁ + σ₀) where μ_1,0 and σ_1,0 ago are the mean and standard deviation of the marks/spaces rail), amplitude $Q(Q_A=〈|f_n|〉/{\sigma }_{\left|f_n\right|}$ where |f_n| is the field amplitude before demodulation) [1], differential phase Q (Q_Δϕ = π/(σ_Δϕ,0 + σ_Δϕ,π) where σ_Δϕ,0 and σ_Δϕ,π are the standard deviations of the 0/π rails) [1], and modified differential phase Q (Q_Δϕ,_mod = 0.87Q_Δϕ) [2] - in the performance analysis of 40 Gbit/s RZ-DPSK systems.

© 2007 IEEE