US 5,265,128 A · Method and device for the digital transmission of information in short-wave radio networks

Abstract

For the purpose of channel state estimation at the receiver end, a reference signal (f.sub.q (t)) is added to and is transmitted with the data signal (f.sub.i (t)) containing the actual information. The addition of the reference signal (f.sub.q (t)) to the data signal (f.sub.i (t)) is effected by means of a quadrature modulation with the reference signal on the Q-axis and with the data signal on the I-axis, the envelopes being selected so that the magnitude of the complex envelope is constant. The receiver has a function stage for preprocessing the receive signal, for quadrature detection of the data signal elements and reference signal elements (y.sub.i) and (b.sub.i) respectively, for selection of the data/reference signal and for estimating the channel state. This permits the operation of non-linear final stages of the transmitter and a maximum energy output from the transmitter, and the requirements of the short-wave transmission such as very low signal-to-noise ratio and signal interference ratio, fading, slightly drifting local oscillators and time bases, as well as high noise burst frequency are taken account of in an optimum manner. In addition the send signal has a narrow bandwidth and a low sensitivity to bit slip, which increases the connection probability and the robustness of the transmission.

Claims17

Dependent claims

Method for the digital transmission of information in short-wave radio networks having a plurality of stations with a transmitter and/or a receiver to enable robust, efficient data communications, comprising the steps of:

adding at the transmitter a predetermined reference signal to a data signal containing actual information for estimating channel state at the receiver end, addition of the reference signal to the data signal being effected by a quadrature modulation with the reference signal on a Q-axis and with the data signal on an I-axis, envelopes of the reference signal and the data signal being selected so that the magnitude of a complex envelope of the quadrature modulated signal is constant;
transmitting the added reference and data signals;
and,
processing the quadrature modulated signal as a receiver input signal by detecting a received signal vector element-by-element, each element of said signal vector representing a complex value of a quadrature detection of an ith receiver input signal time interval and the complex value consisting of an ith data signal element and reference signal element, the quadrature detection being realized by correlation, said correlation being implemented by applying fast Fourier transforms (FFT0 of mutually overlapping time intervals of the receiver input signal and by alternatingly associating each FFT-processed interval with the ith data signal element and reference signal element;
and,
processing further said signal vector for channel adaptive data detection.

3 more elements

Dependencies are inferred from the claim text.

Method and device for the digital transmission of information in short-wave radio networks

Life of this patent

Method and device for the digital transmission of information in short-wave radio networks

Life of this patent

Abstract

Claims17