Research On Turbo Equalization Of Short-wave Communication

In recent years, the development of military wireless communication requires higher data transmission speed and better real-time performance. This means that the intersymbol interference caused by channel aberration and multipath becomes more serious. However, blind equalization can not be used because of the large delay, adaptive equalization with better performance and little delay is needed. This dissertation has researches the Turbo equalization technique which is the hotspot in channel equalization field. The technique, processing the equalization and decoding jointly at the receiver, that is, equalizing and decoding repeatedly to the same data block using an iterative algorithm, is Turbo equalization. Several Turbo equalization algorithms are given and compared from complexity and performance .The algorithm with MMSE equalization and SOVA decoding is fit for short-wave channel when considered synthetically. After that, the effect to Turbo equalization system, caused by several parameters such as different decoding algorithms, number of iteration, data frame, is analyzed and conclusions are made. This thesis puts forward an improved joint estimation, equalization and decoding algorithm for short-wave channel ,replacing the MAP algorithm with bidirectional SOVA, classical RLS channel estimation algorithm is meliorated to incorporate soft information from decoder, line MMSE equalization algorithm is mended to incorporate the time-varying CIR, then, system performance can be improved by iterating estimation, equalization and decoding when reducing the complexity,which is seriously meaningful to engineering application.