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xxii Preface
is widely known that wireless channels vary quickly and drastically. It is a challenge
to instantly make an accurate estimation of channel conditions. In addition, digital
systems cannot support image and video multicasts well. Although analog systems
have been discarded by academia and the industry, the processing still has its own
advantages especially in channel adaptation and multicast.
Recently, I have become interested in looking for a communications system be-
tween digital and analog systems, where images and video are not compressed com-
pletely and still have some redundancy. Such redundancy can be used for resisting
channel noise, finding external correlated images and video, and introducing signal
processing in the