We present a design and implementation of a QoS control mechanism in an Adaptive Multimedia Communication System (AMCS) using multiagent-based computing technology. In this paper, we first define functional requirements for AMCS. Subsequently we describe the design and implementation of AMCS with a knowledge-based multiagent framework to fulfill the functional requirements. Moreover we evaluate the adaptability of the prototype systems of AMCS with the operational situations observed in its experiments. From the result of the experiments, we conclude that the multiagent-based design and implementation is reasonable for construction of AMCS.

In this study, we analyze the system which simultaneously transmits spread-spectrum signals with different processing gains. The main purpose of this study is to give an analytical framework that describes the influence of the interfering signals with different processing gains. For this purpose, we define a crosscorrelation function between the spreading sequences with different code lengths, and discuss the effects of interaction between the signals. As the results, we show that the power of the interference component after despreading procedure, the power ratio of the desired to undesired components, and thus the bit error rate are not constant but vary symbol by symbol.

Time-critical-communication, which should guarantee a time limit of a communication service is getting important in multimedia and factory automation fields. This paper proposes an IP-based protocol, Network Protocol with Performance (NPP) to provide the advanced best-effort service which takes a time constraint into account for real-time applications on the Internet. NPP uses the packet-scheduling function to make an effort to guarantee time constraints. Packet-scheduling algorithm chooses a packet in a NPP queue by a precedent level and a time constraint of each packet. We also discuss an application of NPP to multimedia communication system, and investigate performance of NPP by simulation.