The Octopus switch

This chapter1 discusses the interconnection architecture of the Mobile Digital Companion. The approach to build a low-power handheld multimedia computer presented here is to have autonomous, reconfigurable modules such as network, video and audio devices, interconnected by a switch rather than by a bus, and to offload as much as work as possible from the CPU to programmable modules placed in the data streams. Thus, communication between components is not broadcast over a bus but delivered exactly where it is needed, work is carried out where the data passes through, bypassing the memory. The amount of buffering is minimised, and if it is required at all, it is placed right on the data path, where it is needed. A reconfigurable internal communication network switch called Octopus exploits locality of reference and eliminates wasteful data copies. The switch is implemented as a simplified ATM switch and provides Quality of Service guarantees and enough bandwidth for multimedia applications. We have built a testbed of the architecture, of which we will present performance and energy consumption characteristics

The Design of a System Architecture for Mobile Multimedia Computers

This chapter discusses the system architecture of a portable computer, called Mobile Digital Companion, which provides support for handling multimedia applications energy efficiently. Because battery life is limited and battery weight is an important factor for the size and the weight of the Mobile Digital Companion, energy management plays a crucial role in the architecture. As the Companion must remain usable in a variety of environments, it has to be flexible and adaptable to various operating conditions. The Mobile Digital Companion has an unconventional architecture that saves energy by using system decomposition at different levels of the architecture and exploits locality of reference with dedicated, optimised modules. The approach is based on dedicated functionality and the extensive use of energy reduction techniques at all levels of system design. The system has an architecture with a general-purpose processor accompanied by a set of heterogeneous autonomous programmable modules, each providing an energy efficient implementation of dedicated tasks. A reconfigurable internal communication network switch exploits locality of reference and eliminates wasteful data copies

Energy-efficient wireless communication

In this chapter we present an energy-efficient highly adaptive network interface architecture and a novel data link layer protocol for wireless networks that provides Quality of Service (QoS) support for diverse traffic types. Due to the dynamic nature of wireless networks, adaptations in bandwidth scheduling and error control are necessary to achieve energy efficiency and an acceptable quality of service. In our approach we apply adaptability through all layers of the protocol stack, and provide feedback to the applications. In this way the applications can adapt the data streams, and the network protocols can adapt the communication parameters

Het onzichtbare zichtbaar

Computers worden steeds kleiner, en ze worden steeds meer met elkaar verbonden via netwerken. Aangezien de computers ingebed worden in zowat alles, in lampen en in kleren, in auto’s en in wegen, voor gebruik ter land, ter zee, en in de lucht, is het ontwerpen van slimme systemen hiervoor zowel uitdagend als veelbelovend

Mobile Multimedia Systems

Recent advances in wireless networking technology and the exponential development of semiconductor technology have engendered a new paradigm of computing, called personal mobile computing. In this paradigm, the basic personal computing and communication device will be an integrated, battery-operated device, small enough to carry with you all the time. This device will be used as a replacement of many items the modern human-being carries around. However, the technological challenges to establishing this paradigm are non-trivial. In particular, these devices have limited battery resources, will handle diverse data types, and will operate in environments that are insecure, time varying, and unplanned. As the mobiles must remain usable in a wide variety of environments, they must be flexible enough to accommodate a variety of multimedia services and communication capabilities and adapt to various operating conditions in an (energy) efficient way. The opportunities given by the continuous miniaturisation of micro-electronics are employed in the architecture of the Mobile Digital Companion to solve some of the problems that mobile multimedia computers encounter. We have shown that it is not sufficient to simply continue advancing our chip architectures and technologies as just more of the same: building microprocessors and devices that are simply more complicated versions of the kind built today