| 摘要 |
A local networking system, offers integrated communication services to multiple local voice stations and data terminals via a common transmission medium. This system, utilizing Frequency Division Multiplexing (FDM) signals as carrier, transports information with CSMA/CD protocol. Voice transmissions are organized in traditional TDMA format with fixed frame length and dynamically assigned time slots to avoid interference caused by other devices in the system. Data services operate in traditional CSMA/CD format, but restricted to specified blocks of time intervals. The voice service quality is guaranteed because the required channels and bandwidths, up to the designed maximum, are always available when needed. The grade of data service may be impacted by voice traffic volume which is automatically managed by data terminal's inherent design with CSMA/CD protocol. This unified digital multiplexing system is applicable to transmission media with restricted channels. For example, even with very limited transmission bandwidth, a Dual Area Network (DAN) for integrated voice and data transmissions still can be set up on power or telephone line. On the other hand, this technique can maximize channel utilization of any given bandwidth in a wide band transmission facility, such as radio wave, coaxial cable or infrared system.
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