The Research On The Problems Of QoS Guarantee In Multimedia Sensor Networks

With the complexity and variation of monitoring environment, it is urgent to introduce rich media (i.e. audio, image and video) into environment monitoring activities on the basis of sensor networks, thus perform a complete and accurate environment monitoring. Recently, multimedia sensor networks (MSNs) has been paid wide attention. Due to the variety of services provided by MSNs, their QoS criterions are different. How to guarantee different QoS while maximizing network utilization is becoming a hot topic in this research field. We study the corresponding guarantee mechanisms and algorithms of QoS in different layers of MSNs. This thesis focuses on service model, service-aware traffic scheduling scheme, service-aware routing algorithm and self-adaptive QoS guarantee mechanism. The main contributions of this thesis are as follows:(1) Considering the characteristic of MSNs, based on the cluster-based architecture of MSNs, we improve the DAVIC model to establish a service model suitable for MSNs. Furthermore, we design the protocol flows of this service model. This architecture and service model make MSNs focus on service and provide multimedia services to meet the QoS requirements of users and upper applications.(2) For two kinds of basic service modes (event-driven and query-driven) in MSNs, we propose a traffic scheduling model which can provide differentiated service. Based on the queuing model with non-preemptive priority, we design a service-aware traffic scheduling scheme, which can ensure delay-constrained requirements of two kinds of services to satisfy different QoS of multimedia applications.(3) For three types of MSNs services: event-driven service, data query service and stream query service, we analyze different QoS requirements, thus abstract a QoS routing model for MSNs. Moreover, we propose a QoS routing model for MSNs. By differentiating three types of typical services, we satisfy with diverse QoS requirements of all these services. Moreover, we improve the traditional ant-based algorithm and quantify pheromones value to speed up the convergence of our algorithm. In particular, we propose a novel ant-based service-aware routing algorithm (ASAR). According to different QoS requirements of all types of media data, this ASAR algorithm can select the optimal paths to satisfy with their individual QoS requirements, thus optimize network utilization.(4) There exist two kinds of streams in MSNs: end-to-end stream and event-to-sink stream. Combined with transport control protocol and generating approach of capturing task, we present a self-adaptive QoS guarantee scheme based on two-layer feedback. We partition the network into 10 typical states according to the network QoS level and network congestion status. MSNs perform the state transfer to the optimal one in the transport layer by means of adjusting delivery ratios of two streams in the transport control protocol. Moreover, application layer evaluates the optimal scheme of capturing multimedia according to the multimedia packet delivery ratio calculated by the transport layer. Our method is fit to the hybrid transport model for MSNs, and it can ensure the QoS of two kinds of basic services.(5) According to the cluster-based architecture of sensor networks, we design and develop a prototype system for MSNs. To guarantee QoS in multimedia sensor networks, we also present a flexible, distributed middleware named as AuViM. Moreover, we detail the functions of different components in AuViM and the flows of two service modes. In particular, the QoS description structure is introduced to help users to customize individual QoS requirements.In all, this thesis studies the key problems of QoS guarantee from MAC layer, network layer, transport layer and application layer in MSNs, and designs a middleware suitable for MSNs. At present, the technologies of QoS guarantee in MSNs are immature. The coexistence of all kinds of services makes QoS in MSNs difficult to handle. Therefore, the research on QoS has a significant meaning for the development of MSNs.