We have already proposed a regional PC communication network system that provides a LAN environment and group communication services to the customers. A Low-end Card (LECard) is set up in the subscriber's household and provides the popular Ethernet interface (10Base-T). A multiplex-port brouter (MBR) was developed to accommodate a lot of customers in a cost-effective manner. Ethernet packets are transferred through each subscriber channel between the LECard and the MBR using the HDLC protocol. The LECard and the MBR are controlled by the group management server (GMS) to realize the group communication system. The performance of an experimental system in ordinary use must be evaluated before bringing the system into practical use. However, it is difficult to prepare a number of PCs and to use them at the same time to evaluate the performance degradation seen in multiple-access. This paper presents a newly developed multiple-access simulator for evaluating MBR performance. The simulator connects to the MBR under test through a multiplexed signal interface. It simulates the conditions in which many LECards and PCs are connected to an MBR and they access the network at the same time. The basic function of the LECard, passing the MAC addresses of subordinate PCs to GMS, and the packet generating function of the PCs are implemented in the simulator. Ethernet packets are transmitted to all ports of the multiplexed interface. MBR throughput in the experimental system was evaluated by transmitting Ethernet packets from/to the simulator. The results show that the MBR package has a processing speed of about 4000 PPS. They also show that the degradation in user port performance is slight up to approximately 20% of the active ratio, i. e. 20% of the users access at the same time.

The transmission of HDTV signals on digital networks requires adoption of sophisticated compression techniques to limit the bit-rate requirements and to provide a high-quality and reliable services to customers. This paper describes system design and transmission characteristics of an adaptive subband DCT codec that can encode original 1.2Gb/s HDTV signals at 156Mb/s. The performance of the codec was evaluated using motion picture signals. The characteristics obtained with the codec was found to maintain good picture quality.

High Definition Television (HDTV) is likely to be one of the major services in the Broadband Integrated Services Digital Network (B-ISDN). The transmission of HDTV signals on digital networks requires the adoption of sophisticated compression techniques to limit the bit-rate requirements and to provide high-quality and cost-effective network services. A flexible coding scheme that supports various bit-rates is needed to support the various services expected which will have different requirements. This paper describes the design of an HDTV codec based on a subband DCT coding algorithm that can encode original 1.2 Gb/s HDTV signals to less than 50Mb/s. A configuration that efficiently bridges HDTV and standard TV signals is also proposed. Computer simulation results show that the degradation caused by the bridging function is insignificant. In the coder, first stage quadrature mirror filters (QMFs) decompose the input signal into two bands in the horizontal direction, while the second stage filters decompose the two bands into four bands in the vertical direction. Adaptive DCT (Discrete Cosine Transform) is adopted for horizontal-low and vertical-low (LL) signal coding. High-band signals are coded by adaptive DPCM and PCM. To maximize bit-rate reduction efficiency, DCT coding is adaptively applied to either the intra-field signals, the inter-field signals, or the motion compensated inter-frame signals. Bi-directional inter-frame prediction is applied to the adaptive DCT coding to improve coding performance at low bit rates. The same prediction mode as for LL signal is applied to adaptive DPCM coding of LH and HL signals. Compatibility is realized by a configuration in which both the TV signal components and the residual signal, derived by subtracting the TV signal from the LL signal, are encoded.

This paper describes research on a cost-effective regional Personal-Computer (PC) communication network system based on Fiber-to-the-Home (FTTH) systems and examines its realization. A small scale prototype experimental system was developed and tested in a home-use trial. This paper specifically discusses a sophisticated system architecture with a newly developed miutiplex-port brouter (bridging router) based on the experimental system. The system provides a LAN environment and group communication services to the customers. The Low-end Card (LEC), which provides the popular Ethernet interface (10Base-T), is set up in the subscriber household. The leased circuits are connected between the LEC and the brouter. The LEC and the brouter are controlled by the management server to function as a group communication system. The brouter, which has a multiplex subscriber-port interface, must accommodate many customers in a cost effective manner. This paper presents the system design of a multiplex-port brouter with an SDH/SONET interface. Two types of interface cards at 150 Mbit/s and 50 Mbit/s are prepared making the system scalable. The brouter can accommodate up to 2,700 subscribers. The subscriber channel rate can be set from 64 Kbit/s to 1.5 Mbit/s. Ethernet packets from the PCs are transferred through each subscriber channel between the LEC and the brouter using the High-level Data Link Control (HDLC) protocol.