When humans talk with humans, they are able to use implicit situational information, or context, to increase the conversational bandwidth. Unfortunately, this ability to convey ideas does not transfer well to humans interacting with computers. In traditional interactive computing, users have an impoverished mechanism for providing input to computers. By improving the computer’s access to context, we increase the richness of communication in human-computer interaction and make it possible to produce more useful computational services. The use of context is increasingly important in the fields of handheld and ubiquitous computing, where the user?s context is changing rapidly. In this panel, we want to discuss some of the research challenges in understanding context and in developing context-aware applications

Abowd, Gregory D.

Brown, Peter J.

Davies, Nigel

Dey, Anind K.

Smith, Mark E.

Steggles, Pete

Kent Academic Repository

Towards a Better Understanding of Context and Context-Awareness

In this paper a reconfigurable systems-architecture in combination with a QoS driven operating system is introduced that can deal with the inherent dynamics of future mobile systems. We claim that a radical new approach has to be taken in order to fulfill the requirements - in terms of processing power and energy consumption - of future mobile applications

Smit, Gerard J. M.

Bos, Ties

Havinga, Paul J.M.

Mullender, Sape J.

Smit, Jaap

Gellersen, Hans-W.

NARCIS 

Chameleon - reconfigurability in hand-held multimedia computers

University of Twente Research Information

Chameleon − Reconfigurabilityin Hand-Held Multimedia ComputersGerard J.M. Smit, Ties Bos, Paul J.M. Havinga, Sape J. Mullender, Jaap SmitUniversity of Twente, Dept. Computer Science, Enschede, The Netherlands,e-mail: smit@cs.utwente.nlAbstract. In this paper a reconfigurable systems-architecture in combination witha QoS driven operating system is introduced that can deal with the inherent dy-namics of future mobile systems. We claim that a radical new approach has to betaken in order to fulfill the requirements - in terms of processing power and energyconsumption - of future mobile applications.1 IntroductionIn the next decade two trends will definitively play a significant role in driving technol-ogy: the development and deployment of personal mobile computing devices and thecontinuing advances in integrated circuit technology. The development of personal hand-held devices is quite challenging, because these devices have a very small energy budget,are small in size, but require a performance which exceeds the levels of current desktopcomputers. On the other hand they should have the flexibility to handle a variety of mul-timedia services and standards (like different video decompression schemes and securitymechanisms) and the adaptability to accommodate to the nomadic environment, requiredlevel of security, and available resources. We believe that state-of-the-art system-architectures cannot provide the wealth of services required by a fully operational mobilecomputer given the increasing levels of energy consumption. Without significant energyreduction techniques and energy saving architectures, battery life constraints limit thecapabilities of these devices. This paper discusses reconfigurability issues in low-powerhand-held multimedia systems, with particular emphasis on energy reduction.2 Energy EfficiencyIn the area of mobile computing it will be an enormous challenge to work with a minimalpower budget. Yet, the architecture must provide the performance for functions likespeech recognition, audio/video compression/decompression and data encryption. Powerbudgets close to current high-performance microprocessors, are unacceptable for portable,battery operated devices. We think progress has to be made in two areas in particular:H.-W. Gellersen (Ed.): HUC’99, LNCS 1707, pp. 340-342, 1999. Springer-Verlag Berlin Heidelberg 1999• Reconfigurable system architecturesReconfigurable architectures are flexible and adaptive, use the chip area effectivelyand are relatively easy to design.• Energy-aware operating systemsMobile systems should be flexible and adaptive to the inherent unpredictability of themobile environment, and should be able to control the multimedia streams throughthe reconfigurable architecture. The operating system has to be Quality of Servicedriven to be able to adhere to these requirements efficiently. Here QoS not only in-volves network performance parameters, but also energy cost and infrastructure cost.These parameters are ‘vertical’ controls: they have impact on all layers of the proto-col stack, from applications down to the physical layer. Therefore our approach isbased on an extensive use of power reduction techniques at all levels of system de-sign.3 Reconfigurable Systems ArchitectureThe strength of a reconfigurable systems architecture is its flexibility. Reconfigurationcan be applied at several layers in the system and in various levels of granularity, forexample: a) reconfigurable processing modules b) reconfigurable media streams, and c)system decomposition. In addition to that, a generalized QoS model that encompassesdifferent levels of granularity of the system is essential to select an efficient configuration.Small grain reconfigurability: Reconfigurable processing modulesMultimedia applications have a high computational complexity with a regular and spa-tially local computation. Communication between modules is significant. State-of-the-artapplication-specific coprocessors have the potential to perform multimedia tasks effi-ciently: both in terms of performance as well as in energy consumption. Such coproces-sors are not attractive though, due to their inflexibility [1].For a wide range of functions that use digital filtering algorithms on parallel data state-of-the-art reconfigurable devices (such as FPGAs), do not posses the required processingpower. We defined a novel architecture called FPFAs (Field-Programmable FunctionArray). These devices have a matrix of ALUs and lookup tables [3]. A broad class ofcompute-intensive algorithms can be implemented on an FPFA efficiently. The instruc-tion set of an FPFA-ALU can be thought of as the set of ordinary ALU instructions, withthe exception that there are no load and store operations which operate on memories.Instead, they operate on the programmable interconnect; that is, the ALU loads its oper-ands from neighboring ALU outputs, or from (input) values stored in lookup tables orlocal registers. A novel aspect in this concept is that chip design is replaced by dynamicreconfiguration and reprogramming for future applications using a highly efficient plat-form. In our opinion, this sheds a new light on the fundamental issues of low-power em-bedded systems.342 G.J.M. Smit et al.Medium grain reconfigurability: Reconfigurable media streamsMuch energy can be saved in multimedia systems by improving the component interac-tion [2]. Autonomous, reconfigurable modules such as network, video and audio devices,interconnected by a switch, offload as much work as possible from the CPU to program-mable modules that are placed in the data streams. Thus, communication between compo-nents is not broadcast over a bus to main memory, but delivered exactly to where it isneeded, work is carried out where the data passes through and, if memory is required atall, it is placed on the data path where it is needed. Modules are autonomously entering anenergy-conservation mode and adapt themselves to the current state of resources, theenvironment and the requirements of the user. To support this, the operating system mustbecome a small, distributed system.Coarse grain reconfigurability: System decompositionIn a system many tradeoffs can be made. A careful analysis of the data flow in the systemand decomposition of the system functions can reduce energy consumption considerably.For example, when we consider the transmission of an image over a wireless network,there is a trade-off between image compression, error control, communication require-ments, and energy consumption. In an architecture with reconfigurable modules and datastreams, functions can be dynamically migrated between functional modules such that anefficient configuration can be obtained.4 ConclusionWithout significant energy reduction techniques and energy saving architectures, batterylife constraints limit the capabilities of future mobile systems. In this paper we claim thata flexible and reconfigurable systems-architecture in combination with a QoS drivenoperating system is needed to deal with the inherent dynamics of future mobile systems.This reconfigurability can be found in the interaction of multimedia devices, in the mediaprocessing and in migration of functionality.References1. Abnous A., Rabaey J., “Ultra-Low-Power Domain-Specific Multimedia Proces-sors,” Proceedings of the IEEE VLSI Signal Processing Workshop, San Francisco,October 1996.2. Smit G.J.M., et al.: “An overview of the Moby Dick project”, 1st Euromicro sum-mer school on mobile computing, pp. 159-168, Oulu, August 1998.3. Smit J., et al, “Low Cost & Fast Turnaround: Reconfigrable Graph-Based Execu-tion Units”, Proceedings Belsign Workshop, 1998.343Chameleon - Reconfigurability in Hand-Held Multimedia Computers

English

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Handheld and Ubiquitous Computing

In this paper a reconfigurable systems-architecture in combination with  a QoS driven operating system is introduced that can deal with the inherent dynamics  of future mobile systems. We claim that a radical new approach has to be  taken in order to fulfill the requirements - in terms of processing power and energy  consumption - of future mobile applications

Gerard J. M. Smit

Ties Bos

Paul J. M. Havinga

Sape J. Mullender

Jaap Smit

CiteSeerX

Chameleon -- Reconfigurability in Hand-Held Multimedia Computers

An overview of the Moby Dick project”, 1 st Euromicro summer school on mobile computing,

Low Cost & Fast Turnaround: Reconfigrable Graph-Based Execution Units”,

Ultra-Low-Power Domain-Specific Multimedia

http://purl.utwente.nl/publications/18922

Towards a Better Understanding of Context and Context-Awareness

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