Bandwidth-dependent modelling of small-scale fade depth in wireless channels

Abstract

In this paper, the relation between small-scale fade depth and channel bandwidth in an indoor environment is investigated. The fade depth, a measure of the signal power variability over a local region in space, is evaluated for narrowband, wideband and ultrawide-band channels. The experimental analysis is based on frequency-domain measurements in the 3.1-10.6 GHz microwave band. Physical insight into the fading process is provided, and the effect of increasing bandwidth and temporal resolution is discussed. A dual-slope empirical model is developed, which accurately describes the relationship between fade depth and channel bandwidth. It is demonstrated that the fade depth, considered at the three standard deviation values, converges to about 4 dB at 1 GHz bandwidth, and a further increase in bandwidth yields only a marginal improvement in fade mitigation.

Analytical Approach to Model the Fade Depth and the Fade Margin in UWB Channels

“…The fade depth, denoted by F ns , can be defined as a measure of the channel power variation due to the small-scale fading [8]. In a statistically sense, the fade depth can be calculated as n times, n = 1, 2, 3,¼, the standard deviation, s, of the channel power variations expressed in logarithmic units.…”

“…; {l,k}¹{n,m} represents the condition of summation, l¹n OR k¹m; and the m k,l parameter is calculated using (8) and (9).…”

“…In [6], the dependence of the received signal level distribution on the channel bandwidth is studied by computer simulations, showing that the fade depth has a strong dependence on the equivalent channel bandwidth. In [8], a relationship between the fade depth and the channel bandwidth is derived from a measurements campaign carried out in an indoor scenario. Therefore, the study of the average signal level, the fade depth and the fade margin in wideband transmission systems is a key issue for the development of wireless systems.…”

Modelado en frecuencia del canal UWB y su aplicación en el análisis de técnicas de modulación adaptativa en sistemas MB-OFDM UWB para redes WPAN

“…Igualmente sólo se ha encontrado dos trabajos de investigación que mediante experimentación evalúa el comportamiento de la potencia en función del ancho de banda para un canal UWB [Mal07], [Mal08].…”

“…En canales móviles inalámbricos donde el desvanecimiento a pequeña escala debido a la propagación multicamino es pronunciado, la profundidad del desvanecimiento se define como una medida de la variación de la potencia del canal alrededor de su media [Mal08]. Esta variación se expresa en términos estadísticos, relacionando el fade depth con la desviación estándar, σ, de la potencia en dBm y se representa como F σ .…”