System Architecture Design

pSHIELDSystem Architecture DesignPU• Physical Architecture: The physical architecture further defines the technical solution at a detailedlevel. Some design decisions, such as the selection of content storage product, can berepresented in this layer• Implementation Architecture: The implementation architecture specifies system composition andinterconnectionspSHILED Functional Architecture (pSFA) is composed by four functional layers: node, network,middleware and overlay, which represent a set of four functional sub-systems that are specified by its setof elements, functional entities and interfaces.Node Layer (NoL) of pSFA: node layer is composed of Intelligent ES HW/SW Platform and havedifferent kinds of Intelligent ES Nodes: nano node, micro/personal node, power node, and DependableSelf-X Crypto Technologies. This layer is composed of standalone and/or connected NoL elements likesensors and actuators, which perform smart transmission.The NoL is a layer composed by physical nodes (i.e. hardware). Each node is a generic EmbeddedSystem (for example a sensor, an actuator, a transmitter etc.).Network Layer (NeL) of pSFA is a heterogeneous layer composed by a common set of protocols,procedures, algorithms and communication technologies that allow the communication between two ormore nodes.Middleware Layer (ML) of pSFA is the software layer that provides the basic functionalities to use theunderlying networks of embedded systems (like service discovery and composition) as well as somesecurity functionalities (like accounting or access control). This layer, being software, is installed on thenodes.Overlay Layer (OL) of pSFA is a logical vertical layer that collects (directly or indirectly) semanticinformation coming from the Node, Network and Middleware layers and uses them to compute theadequate actions (if any) that ensure the desired level of SPD. It is a software routine running atmiddleware and/or application level.3.1 Cross-Layer / Cross-Overlay Architecture Definitions3.1.1 IntroductionThe purpose of this chapter is to give an overview on the cross-layer architectures (CLAs) proposedrecently by the research community and to address in details SPD issues for overall pSHIELD SystemArchitecture (pSSA).In wireless and mobile networking envisioned for pSHIELD System Architecture (pSSA), difficultenvironmental conditions are a permanent challenge, resulting in a demand for cross-layer optimizations.There is also a need to further increase flexibility of the network. Therefore, we believe cross-layerarchitectures should adapt themselves to these changing conditions, just as they adapt the network stack,devices, and applications.The network protocol stacks are logically organized in layers. These layers are strictly separated and thecross-layer functionality between them is restricted by determined interfaces, which in effect only allowpassing packets up and down the stack. In principle, all these layers have been designed to fulfil theirfunctionality without interaction across the layers. History shows that this works well in wired and staticPUD2.3.2Issue 5 Page 17 of 122