Method for the redundancy-reducing error-correcting coding in digital radio relay systems using multi-level modulation

摘要

For using such a FEC method in systems of the most varied type, the invention provides that the serial binary data stream to be transmitted is supplied to a device for rate adaptation and serial/parallel conversion, in which, on the one hand, the data rate is increased to the transmission rate, forming free spaces for accommodating redundancy bits, and, on the other hand, from the serial data stream a corresponding number of parallel data streams is generated, one half of which in each case forms the I and Q channel, respectively. The redundancy spaces in this arrangement are located in the least-significant bits of I and Q channel. The higher-significance bits of I and Q channel directly control the associated inputs of a quadrature modulator, while the least-significant bit is supplied to the relevant input in each case via a multiplexer. In addition, the least-significant bit of I amd Q channel is in each case supplied to a coder, each of which looks at a particular number of incoming bits and from these generates one or several redundancy bits in accordance with the coding rule of a particular basic code. These bits are inserted into the places provided for this purpose in the I and Q channel, respectively, with the aid of the two multiplexers. …IMAGE…