Study of Correlation Coefficients of Complex Envelope and Phase in a Domain with Time and Frequency Axes in Narrowband Multipath Channel

摘要

As a basic multipath property required to allocate the pilot signal in orthogonal frequency division multiplexing (OFDM) and compose antennas in the multiple-input multiple-output (MIMO) technique, correlation coefficients of the complex envelope in the received signal level and phase in multipath channels were studied theoretically and by computer simulation in a domain with time, frequency, and space axes. First, correlation coefficient ρ_e(Δx) of the envelope was derived in the domain with a variable Δx= f_mT_s + Δfσ, where f_mT_s is on the time axis (f_mT_s: normalized maximum fading frequency) and Δfσ is on the frequency and space axes (Δf: frequency separation, σ: delay spread). Bird's-eye views of ρ_e(Δx) and ρ_p(Δx) of the phase in multipath channels are shown in the domains to give a good overall grasp of them. The theoretical values of ρ_e(Δx) and ρ_p(Δx) agree with the simulated ones. Furthermore, it is shown that the cumulative distributions influenced on bit error rate performance depended strongly on Δx and spread as Δx increased.