| The most common model of Data Conference Standard T.120, defined by International Telecommunication Union (ITU-T), is center-controlling model. In computer data conference on wide-area network, all the signals and data must be processed by the T.120 MCU(Multipoint Control Unit), which is the Server reside in the conference center. As the participants dispersed geographically increases, the T.120 MCU will become the performance bottleneck. It may also cause the re-transmission of the same data packets which further leads to a low utilization of the wide-area network resources.Aimed at those weaknesses caused by the center-controlling system model, we designed and developed a prototype of T.120 Distributed Data Conference System. In this distributed model, data relaying and processing are carried out by MP (Multipoint Process) systems on local-area network, while the signals controlling function is still carried out by the T.120 MCU on wide-area network. By extended interfaces, MCU and MP can carry out the signal and data processing function in a distributed mode. This can significantly improve the performance of the whole system and also eliminate the redundant re-transmission for cross-area data transmission hence to save scarce wide-area network resources.As common practices, data conferences usually include video/audio conferences. So we have also studied how to prevent huge bandwidth consumption during peak times through flow-control function. This can prevent the real-time demanding video/audio transmission applications being affected by T.120 huge volume data transmission.Finally this study has successfully conducted the function and performance test of the T.120 Distributed Data Conference System. It is proved by the test result that the T.120 Distributed Data Conference System is capable of handling conference signal processing in a coordinated way, relaying local data transmission and effectively implementing flow-control of the data transmission. |
PDF Full Text Request