System Development

A prototype system has been developed in this research to demonstrate the practicality of the generic design conceptual framework, using a case study.

5.2.1. Development Methodology

The system development methodology used in this research is a combination of both an iterative design method and an incremental build model approach. This choice is based on the need to sustain the large development effort required because of the multiple design concepts integration, justifying the relationship between iterations and increments. This effort emphasizes the importance of what has been learned from integrating different design

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concepts, discovering new functional requirements and understanding the impact of non-functional requirements, and testing the different system functions segmented into partitions.

This approach enables the modifications easier to make as the iterations progress, and the different modules are logically segmented.

The discovery of new functional requirements results from the sensor and WSN data fusion process which describes the different steps of integration of sensors and WSN data and knowledge from several sources.

These steps are:

 Data Input,

 Data processing,

 Data level fusion,

 Signal classification and

 State classification.

The sensor and WSN data fusion functional diagram is shown below in figure 5.1.

Figure 5.1: Sensor and data fusion integration process

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This data fusion process which is illustrated in the data management architecture shown in Figure 3.4, is part of a context aware information fusion that includes support capabilities for on-line transactional and analytical processing, based on a panoply of theory, techniques and tools for exploiting the synergy in the information acquired from multiple sources and produce knowledge supported by fusion functions. The integrated WSN-RFID plays a preponderant role in enhancing sensing, monitoring and tracking, observing and analysing the environment to instantly identify situations that require taking immediate actions. This results in updating knowledge and models stored in databases, about previous behaviour, simulations predicting future behaviour.

5.2.2. Case Study

The case study presented in this work consists of the design of an integrated WSN-RFID based on the use of a virtual building layout to support:

 Emergency preparedness and fire simulation,

 Sensor data collection and communication of this data to a centralized data repository, and

 Building control access and evacuation simulation.

In this case study, we have considered a building made of three rooms attended by people, and containing some objects that can be used to support people-object proximity and collision detection while people will be evacuating the building. This support is based on the development of the software HIDSS which fully integrates the different steps of the decision making process when designing, configuring and deploying the integrated WSN-RFID. The following sensitive issues are considered:

 Organising the scheduling for o the in-networking, o the sleep sensor and o the passive sensor node,

 Data compression,

 Energy-efficient monitoring of sensor nodes extreme values

 Selective reporting and collision search,

 Performance analysis of devices and routers,

 Extreme value finding in a sensor node cluster,

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 Eliminating or reducing a data bottleneck when sending and receiving in the network,

 Implementing an effective sensor node reconfiguration policy to reduce the limitation of communication bandwidth,

 Eliminating redundancy among data values from neighbouring sensors, and

 Reducing energy consumption by implementing in-networking and reducing the large amount of data communicated within the network.

5.2.3. Physical Entities

The data description of the physical entities is essential to the implementation of the different system functional units. This description is illustrated in the entity relation model shown in Figure 5.2, representing the different devices performing a wide range of sensing, monitoring, tracking and communication. These devices are:

 Sensors,

 RFID Tags,

 Homogeneous devices (Sensing, monitoring and tracking devices),

 Heterogeneous devices that enhance the deployment of the homogeneous devices, and

 Gateways and routers.

5.2.4. Devices Support

Of great importance in the support of the data and information fusion is the device assessment functionality supported by the data fusion model which includes several fusion levels, illustrating the sensor network signal processing tasks, and corresponding to the following functions:

 Signal or feature assessment involving data extraction, analysis and event detection,

 Entity assessment that includes the parametric and attributive states of devices during their configuration and deployment,

 Situation assessment regarding the nature of influence of between the different devices,

 Impact assessment concerning predicted impacts on other devices, and

 Performance assessment in terms of measures of effectiveness.

This device support, which is organised in a distributive architecture system, integrates data fusion and mining to produce optimal decision fusion by considering a set of finite of

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decision alternatives at each data fusion level. This process integrates low level decisions, and can be decomposed into two functional components:

 Real time detection of known or expected patterns as the heart of the information fusion process to filter known patterns, and

 Off-line discovery of new patterns supported by data analytics and aggregation as the data mining process.

5.2.5. WSN Database

The design of the WSN database which takes into account of the need of supporting online transactional and analytical processing illustrated in Figure 3.4, and data storage (data identification, mapping, management and measurement) shown in Figure 5.1, is based on the use of the sensor domain model shown in Figure 4.8, insisting on the importance of the selection of the support for the grouping of sensor capabilities which depends greatly on the mobility of the domain entities to be sensed and/or monitored and tracked. Fixed and mobile sensing, or detecting devices, and attached RFID tags to people, sensor nodes and objects are used in the design of the generic or universal sensor node supporting the integration of RFID and WSN as a hybrid embedded system wirelessly connected to the WSN.

5.2.6. Link between the HIDSS architecture and the case study

The framework proposed in this research illustrated in the HIDSS system architecture shown in Section 4.3.2.1, establishes the conceptual link between:

a) Data, Information and knowledge using the Data Mining, and the Knowledge Discovery and Extraction, and

b) Knowledge, decisions and Explanations using Hybrid Decision Models.

These two conceptual links are reflected in the case study proposed in this research, at the following functional levels:

 Sensors and sensing knowledge discovery (b),

 Creation of the building layout (a,b),

 Design and configuration of detection and tracking devices (b),

 Allocate detection devices for optimal sensing coverage (b),

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 Allocate heterogeneous to enhance the detection devices functionality (a),

 Deployment and configuration of the integrated RFID-WSN (a,b),

 Adjustment of the sensing context and devices selection (b),

 WSN generation (a,b),

 Data capture and processing (a,b), and

 Event simulation (a,b).