In a duplex radio link wherein
digital data information from a
data interface is transmitted from a local terminal to a remote terminal over
fading dispersive channels, a method and
transceiver are described that provide for transmission at an adaptive
data rate. The transmission is at a constant
symbol rate so that the
signal bandwidth can be fixed and at the remote terminal
receiver the input sampling rate can be fixed. The
digital data information is transmitted over a constant
data rate interval in accordance with a selected
data rate mode that is a function of direct sequence spreading
gain, error
correction code rate, and
signal constellation type. The data rate is adapted by selecting a data rate mode that is a function of the arrival rate of data packets from the
data interface and a link quality measure fed back from the remote terminal. The data
packet arrival rate is controlled as a function of the link quality measure and the current data
packet arrival rate. In systems with multiple
transmit diversity channels,
independent data is sent over each of the
transmit diversity channels. The adaptive data rate technique utilizes both orthogonal transmit diversities such as frequency and troposcatter
polarization diversity as well as nonorthogonal transmit diversities in a Multiple-input Multiple-Output (
MIMO) configuration. A single antenna troposcatter link using angle diversity and
adaptation of data rate by feedback communications is described. In an idealized feedback communication example, the single antenna
system in a Ku-band application is shown to have 15.5 times the data rate capability of a conventional two-antenna
system at S-band.