New techniques for adaptive equalisation of multipath propagation on digital radio

The possibilities of improving the performance of the adaptive equaliser operation in microwave radio channels are investigated by exploring the following: (1) deliberately enhancing equalisation content in the transmitted signal which can be readily used for adaptive equalisation at the receiving end; and (2) exploiting any available a priori knowledge of the channel, and incorporating this in the equaliser adaptation process. An example of the first approach, namely data assisted equalisation (DAE), has been suggested by Muthukkumarasamy and Ingram (see Proc. of the Fourth Region 10 Int. Conf.-TENCON ´89, p.916, 1989) for baseband transmission systems. This technique allows introduction of equalisation data by purely digital methods. The use of DAE methods in carrier wave modulated systems is investigated