Statistical Analysis and Characterization of Doppler Spectrum in Large Office Environment

Abstract

In recent years, multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems have been assiduously studied because of their attractive frequency utilization efficiency [1]. Spatial division multiplexing (SDM) and spatial division multiple access (SDMA) in particular are techniques that can fully utilize the benefits yielded by efficient frequency utilization, and achieve the maximum performance when the channel state is completely stationary. However, these techniques are greatly affected by mismatching between the estimated and the actual channel state [2]. In an actual environment, the channel state varies over time. Therefore, the channel state information should be updated at appropriate intervals. So, static Doppler spectrum have been analyzed experimentally up to now [3, 4], because the time varying channel is derived from Doppler spectrum. However, these analyses are evaluated by single Doppler spectrum, and there has not yet been any published analysis based on multiple Doppler spectra. In this paper, the Doppler spectrums are measured in a typical large office environment during working hour. And multiple Doppler spectra are statistically evaluated based on a bell-shape spectrum model. The results show that the channel in this measurement environment can considered more quasi-static than described in TGn channel models [5]. Additionally, empirical formulas for Doppler spectrum in large office environments are proposed.