by A.J. Casaca and M.S. Nunes
The ISDN and B-ISDN research and development activities at INESC-Lisboa are carried out in two groups: "Architecture of Communication Systems", led by Augusto Casaca and "Switching and Terminal Equipment", led by Serafim Nunes. The groups have mainly centered their activities on the development of new ISDN terminal equipment and private ISDN switching systems.
The PCBIT (Personal Computer Based ISDN Terminal) is a card which allows the connection of a PC to the ISDN S0 interface. This card with the applications that run over it, changes a PC into a real multiservice terminal. The PCBIT has the capability to process the ISDN signalling protocol (DSS1) and to transmit data on the B channels using X.25, simultaneously with voice calls. The PCBIT includes also V.110 adapter to connect an external data terminal via a RS-232C interface. The PCBIT-D, a card for data applications only, was also developed.
The CARDIS is a small Integrated Services PABX (ISPBX) to establish and release voice and data ISDN connections between simple or multifunctional terminals with standardised ISDN S0 interfaces. The system also allows the interconnection with other ISPBX for implementation of a private ISDN network or for interconnection with the public ISDN network. The interconnection of the CARDIS with a LAN, e.g. Ethernet, though a gateway with a 2.048 Mbit/s interface is also possible.
LIGA is a PC based LAN - ISDN Gateway for the interconnection of remote LANs through the public ISDN, using a primary rate interface of 2.048 Mbit/s. It can also be used as a terminal server, allowing a user with an ISDN terminal to access different workstations connected in different remote LANs. The LIGA protocols are based on the Ethernet (IEEE 802.3) and TCP/IP for the LAN side and Euro-ISDN on the ISDN side.
A backup unit for digital leased lines up to 64 Kbit/s, named URDIS, was developed. This unit monitors the digital leased line. When a fault is detected, an ISDN call is automatically established through the public ISDN to the remote destination unit. A management interface is defined which permits the configuration of the unit and the locally or remotely reading of fault statistics.
In the area of B-ISDN, an intense activity in the European research project RACE has been carried out by the group.
In the RACE Project 1022 "Technology for ATD", the groups were responsible for the specification and design of a number of ATM Terminal Adapters, namely for N-ISDN, Audio/Video and Multimedia, and participated actively in the large ATM demonstrator set-up in the scope of this project in Basel.
In the RACE Project 2061 "EXPLOIT", the groups were responsible for the specification of an Interworking Unit between ATM and N-ISDN and participate actively in its design and implementation. The main contribution in the design phase is in the signalling interworking between the two networks.
In the RACE Project 2032, COMBINE, the groups are involved in the development of an Interworking Unit between ATM and DQDB. In this project they are responsible for the whole software and more specifically for the development of the global management and layer management in frame mode of the IWU.
In parallel there is a strong collaboration with TLP, the telecommunication operator for Lisbon and Oporto, now merged in the Portugal Telecom. Through this collaboration, elements of the groups contributed to some tasks in the Eurescom projects "European studies for a VP switched ATM network", "B-ISDN signalling" and "European studies for a VC switched ATM network". Also, since 1990 several contributions for the ETSI-NA5 and CCITT-SGXVIII (ITU-T SG13) standard comittees have been prepared and presented in the area of the ATM Adaptation Layer. More recently two R&D projects have been started under contract with TLP, in the area of ATM. One of them consists in the design and implementation of an ATM service multiplexer for the user's premises and the other one aims to the design and implementation of a PC multimedia adaptation board for ATM.