Developments in mobile devices and wireless networking provide the technical platform for video streaming over mobile ad hoc networks (MANETs). However, efforts to realize video streaming over MANETs have met many challenges, which are addressed by several different techniques. Examples include cross-layer optimization, caching and replication, and packet prioritization. Cross-layer optimization typically leverages multiple description video coding and multipath routing to provide the receiver(s) sufficient video quality. Caching and replication add tolerance to disruptions and partitioning. In this paper, we identify the challenges of realizing video streaming over MANETs, and analyze and classify the proposed techniques. Since 65 % of the identified involve cross-layering design, we study the distribution of joint optimization and parameter exchanges. Due to the importance and complexity of evaluating the techniques, we analyze the common methods, indicating that the research domain suffers from a problem of comparability.

Due to the technical developments in electronics the amount of digital content is continuously increasing. In order to make digital content respectively multimedia content available to potentially large and geographically distributed consumer populations, Content Distribution Networks (CDNs) are used. The main task of current CDNs is the efficient delivery and increased availability of content to the consumer. This area has been subject to research for several years. Modern CDN solutions aim to additionally automate the CDN management. Furthermore, modern applications do not just perform retrieval or access operations on content, but also create content, modify content, actively place content at appropriate locations of the infrastructure, etc. If these operations are also supported by the distribution infrastructure, we call the infrastructure Content Networks (CN) instead of CDN. In order to solve the major challenges of future CNs, researchers from different communities have to collaborate, based on a common terminology. It is the aim of this paper, to contribute to such a terminology, to summarize the state-of-the-art, and to highlight and discuss some grand challenges for CNs that we have identified. Our conception of these challenges is supported by the answers to a questionnaire we received from many leading European research groups in the field. q

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Middleware technologies suchus CORBA or Juvu RMI huve proved their suitubility for "stundurd" clientserver applications. However, challenges fiom existing and new types of upplicutions, including support for multimediu, reul-time requirements und mobility seems to indicute the need for defining U new urchitecture for open distributed systems. The new urchitecture should be designed Ji-om the beginning with flexibility und uduptubility in mind. This can be achieved by defining un open engineering middleware plutjorm thut is run time conjguruble und ullows inspection und uduptution of the underlying components. This puper proposes U next generution middlewure urchitecture thut conforms to requirements us indicated ubove. This urchitecture is churucterised by being open, and uduptuble bused on the principle of reflection. The puper ulso reports on some existing reseurch prototypes with U focus towurds their suitubility us next generution middle wure.

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The overall goal of this work is to improve video delivery in emergency and rescue scenarios using sparse MANETs that might be prone to frequent link breaks and network partitions. The core idea of our approach is to reduce the number of MAC layer retransmissions that are likely to fail. We do not drop packets that could not be sent after the final retransmission. Instead we handle them in an overlay for storecarry-forwarding. The design of the overlay protocol takes the instability of the network into account, in such a way that each overlay entity works autonomously and keeps a minimum amount of state. Our experimental results show that we reduce packet loss seen on broken links, while at the same time significantly reducing overhead in terms of the total amount of packets transmitted at the physical layer.

Using Mobile Ad-hoc Networks (MANETs) for audio and video transmission is very promising for application domains such as emergency and rescue. However, audio/video streaming services are not designed for such dynamic and unstable networks. The problems are even more important in so-called sparse MANETs where the node density is relatively low so that disconnections and network partitions are common. We have designed an architecture that combines MANET routing with caching and delay tolerant store-carry-forward operations in an overlay network to improve the quality of audio/video transmission over sparse MANETs. We have implemented a prototype to evaluate the architecture. The results from the experiments demonstrate that our system clearly outperforms simple client-server solutions when the network has temporal disconnections.

One important class of applications for the Internet of Things is related to the need to gain timely and continuous situational awareness, like smart cities, automated traffic control, or emergency and rescue operations. Events happening in the real-world need to be detected in real-time based on sensor data and other data sources. Complex Event Processing (CEP) is a technology to detect complex (or composite) events in data streams and has been successfully applied in high volume and high velocity applications like stock market analysis. However, these application domains faced only the challenge of high performance, while the Internet of Things and Mobile Big Data introduce a new set of challenges caused by mobility. This chapter aims to explain these challenges and to give an overview on how they are solved respectively how far state-of-the-art research has advanced to be useful to solve Mobile Big Data problems. At the infrastructure level the main challenge is to trade performance against resource consumption and energy efficiency and operator placement is the most dominant mechanism to address these problems. At the application and consumer level, mobile queries pose a new set of challenges for CEP related to continuously changing positions of consumers and data sources, and the need to adapt the query processing to these changes. Finally, proper methods and tools for systematical testing and reproducible performance evaluation for mobile distributed CEP are needed but not yet available.