HANDOFF ARCHITECTURES AND PROTOCOLS FOR TRANSMITTING COMPRESSED MULTIMEDIA INFORMATION IN MOBILE PCSS

A multimedia presentation always (1) has some realtime requirements to keep the video/audio continuity, and (2) delivers compressed media un its to reduce the network bandwidth requirement. In multimedia mobile systems, e.g., mobile personal communication systems-s(PCSs), (1) the re-transmission policy for recovering the lost information, which occu rs during handoff, cannot be adopted because it cannot meet the real-t ime requirement, and (2) if some inter-unit-based compression techniqu es are adopted, the characteristic of losing information during handof f results in losing a number of media units, which causes very serious discontinuity in video/audio presentations, Additionally, a multimedi a system always allocates a lot of buffers at client site to smooth th e random network delays. However, the client devices in mobile systems , i.e., the mobile PCS handset-s are not always associated with larger buffers in order to reduce the cost, physical size, etc. These issues should be resolved to have smooth multimedia presentations in a mobil e PCS environment. In this paper, we present a mobile PCS network arch itecture to achieve smooth multimedia presentations, and propose a neu , concept, which is called give-point, in the design of handoff protoc ols to keep the continuity property in video/audio presentations. Base d on the give-point concept, several handoff protocols that can achiev e smooth multimedia presentations in a mobile PCS environment are pres ented.