Delay spread
Encyclopedia
In telecommunications, the delay spread is a measure of the multipath richness of a communications channel.
In general, it can be interpreted as the difference between the time of arrival of the earliest significant multipath component (typically the line-of-sight component) and the time of arrival of the latest multipath component.
The delay spread is mostly used in the characterization of wireless channels, but it also applies to any other multipath channel (e.g. multipath in optical fibers).
Delay spread can be quantified through different metrics, although the most common one is the root mean square (rms
) delay spread, which is defined as follows:
According to Goldsmith , let
be the power delay profile
of a channel. Then, the mean delay of the channel is
Thus, the rms delay spread is
In general, it can be interpreted as the difference between the time of arrival of the earliest significant multipath component (typically the line-of-sight component) and the time of arrival of the latest multipath component.
The delay spread is mostly used in the characterization of wireless channels, but it also applies to any other multipath channel (e.g. multipath in optical fibers).
Delay spread can be quantified through different metrics, although the most common one is the root mean square (rms
Root mean square
In mathematics, the root mean square , also known as the quadratic mean, is a statistical measure of the magnitude of a varying quantity. It is especially useful when variates are positive and negative, e.g., sinusoids...
) delay spread, which is defined as follows:
According to Goldsmith , let
be the power delay profilePower delay profile
The power delay profile gives the intensity of a signal received through a multipath channel as a function of time delay. The time delay is the difference in travel time between multipath arrivals...
of a channel. Then, the mean delay of the channel is
Thus, the rms delay spread is