Optimizing Delivery Approaches

nltiniedia communications is otic of tlic most challcnging rescarch areas cmcrging rcccntly, due to tlic advance M of multimedia compression atid coding technologics. With the rcccnt siiccesses in the establishtneiit ofsomc multimedia coiiimunicatioiis standards as well as the rapid proliferation of the Liscs and demands, wc can predict thc crcation of a vast nunibcr of applications destined to offcr users iicw, eficient, and sophisticated services in the near fittitre. The word “multimedia,” in general, is considercd to incan simultaneous considcration of a mixture of signal types, such as spccch/audio, image/vidco, graphics/aiiitnatioii, atid text. In particular, video confcrcncing, multimedia mail, video-on-dcinand, HDTV broadcast, and many other multimedia applications tlirougli thc Internet-cithcr hy wircliiie such as asyrnnietric digital subscriber linc (ADSL), ISDN, or by wireless network-post new problems with a distinctivc tiattire, malting multimedia communications onc ofthe most interesting and challcnging rescarch fields. In this tutorial, wc study thc prohlem of reliahle and yet efficicnt multimedia coinmunications ovcr ADSL tlirough joint considcration of coinprcssiori/coding and channcl transmission techniques. ADSL will bc delivcring multimcdia services to inillions ofuscrs. Thc traiisinissioii ofdigita1 inultiincdia data rcquircs the existing systcms to be angmciitcd with functions that can handle not only ordinary (nonmultimedia) data. In addition, the high volume of multiinedia data can he liaiidlcd efficicntly only if all availablc systcni resourccs are carcfully optimizcd. Here wc consider thc spccial charactcristics ofADSL channels to formulatc optimization criteria. Wc prcscut a system where thc cncoder consists of a laycr coder that divides and compresses the sourcc data into codcd layers of inultiincdia data with different performance arid qnality-of-service requircmcnts. The encoded bit streams arc tlicn transmitted over a noisy chaniicl, wherc channel noise inay distort the data. Thc decoder uiidocs all thc coding and conivression auulicd