The Systems research group studies the system aspects of communication networks. These networks have a hierarchical structure of interconnected layers. All levels in the network are covered by COBRA, from the global and national networks (“wide-area networks”) over regional networks (“metropolitan-area networks”) to local networks (“access networks” and “networks in buildings”).

All levels of the network interact closely, and some may cause problems or bottlenecks in others. Thus, knowledge of all levels of the network may help to solve specific issues or to circumvent them altogether.

This means that we cover every aspect in the communication network chain: from the physical layer – involving cables and electromagnetic signals – via data link layers – researching data and clock-generation and recovery – to the switching and routing layer, which controls the sending, receiving, and redirecting of data packets.

COBRA’s research is especially focussed on three main bottlenecks in the network chain. First, linking the end user to the optical network. Currently, the huge capacity of the wide-area and metropolitan-area networks does not reach end users, due to the limited capacity of copper-based “last mile” connections. Also, wireless technologies for in-home use are far slower than optical fibers.

Second, we focus on the nodes in the network. As data rates go up, more and more data packets have to be routed. Hence, the nodes consume more energy at an alarming rate. We look into optical technologies to improve the capacity of network nodes while reducing power consumption. Application areas include both telecommunication network nodes as well as nodes in data (center) communication networks.

Third, we investigate transmission systems. Here we focus on long-haul and metropolitan networks. The challenge is to increase the reach and the capacity of optical fiber transmission systems, and improve the spectrum efficiency to carry more and more data within a limited spectrum.

COBRA has also played an important role in the Dutch national research program “Freeband”. The program aimed at creating a leading position for the Netherlands in the area of ambient, intelligent communication networks. Within the project “Broadband Photonics Access,” COBRA’s design for a dynamically reconfigurable optical-access network linked to the home has been tested successfully in the field.

With a view to the deployment of high-speed networks within homes, offices, hospitals, and so forth, experiments with polymer optical fiber (POF) have been carried out. This fiber is easy to install, at low costs, and COBRA has shown that connection speeds of several gigabits per second (Gbps) are possible. New “radio-over-fiber” technologies have been developed to connect wireless end users to the network at unmatched data rates.

On a European level, the Systems research group participated in the FP7 “ALPHA” research project. The project investigated innovative network architecture and transmission solutions for access and in-building networks based on many different sorts of optical fibers (single-mode, multi-mode, glass or polymer), including the transport of wireless services. With respect to optical switching, the group participated in the European projects ‘’STOLAS”, “LASAGNE”, “HISTORIC”, “LIGHTNESS”, and the recently funded integrated project “COSIGN”. The aim of these projects is to support both wired and wireless services in converged network infrastructures. Furthermore, the group has played an important role in several bit rate European Networks of Excellence (e.g. “ePhoton-ONe”, “BONE”, and “EuroFOS”).

The Telecommunications Systems (ECO) group (Eindhoven University of Technology, Faculty of Electrical Engineering) has broad experience with high bit rate optical communication systems, both on WDM and on OTDM. It is equipped with test and measurement facilities up to 40 Gb/s ETDM and 640 Gb/s OTDM, as well as facilities for small-scale fiber-chip coupling and packaging development, and prototyping of multi-fiber optical devices and sub-systems. The ECO group was involved in the first demonstration of error-free 160 Gb/s OTDM transmission over 550-km field-installed fiber and 160 Gb/s add-drop multiplexing and clock recovery using semiconductor optical amplifiers. The ECO group packaged the world’s smallest WDM cross-connect, and produced the world’s smallest optical flip-flop. Furthermore, the group is leading in systems research using multimode fibers and polymer optical fibers for access, local area and indoor networks. Recently, the ECO group has obtained some world records in switching optical data packets of sub-Tb/s using only one semiconductor optical amplifier. Completed and on-going European projects with COBRA involvement include: RACE-MUNDI, ACTS-TOBASCO, ACTS-PRISMA, ACTS-BLISS, ACTS-UPGRADE, ACTS-APEX, ESPRIT-LOCOM, IST-HARMONICS, IST-METEOR, IST-OBANET, IST-STOLAS, IST-FASHION, IST-LASAGNE, IST-MUFINS, IST-POFALL, IST-MODEGAP, IST-LIGHTNESS, IST-COSIGN.