Many modern communication networks suffer significantly from the unreliable characteristic of their nodes and links. To deal with failures, traditionally, centralized erasure codes have been extensively used to improve reliability by introducing data redundancy. In this thesis, we address several issues in implementing erasure codes in a decentralized way such that coding operations are spread to multiple nodes. Our solutions are based on fountain codes and randomized network coding, because of their capability of being amenable to decentralized implementation originated from their simplicity and randomization properties. Our contributions consist of four parts. First, we propose a novel decentralized implementation of fountain codes utilizing random walks. Our solution does not require node location information and enjoys a small local routing table with a size in proportion to the number of neighbors. Second, we introduce priority random linear codes to achieve partial data recovery by partition and encoding data into non-overlapping or overlapping subsets. Third, we present geometric random linear codes to decrease communication costs in decoding significantly, by introducing modest data redundancy in a hierarchical fashion. Finally, we study the application of network coding in disruption tolerant networks. We show that network coding achieves shorter data transmission time than replication, especially when data buffers are limited. We also propose an efficient variant of network coding based protocol, which attains similar transmission delay, but with much lower transmission costs, as compared to a protocol based on epidemic routing.

Video streaming applications over wireless networks have turned out to be immensely popular recently. In this thesis, we first study the buffering schemes for the VBR video streaming in heterogeneous wireless networks. An analytical framework is presented to derive the expected number of jitters and average buffering delay. Through experimenting with a wide range of buffering schemes, we quantify the bene¯t of incorporating user location information in streaming over heterogeneous wireless networks. Second, we consider the delivery of scalable VBR video streams over wireless channels. We propose adaptive rate control algorithms to improve the combined system performance of video frame quality and playout smoothness based on the feedback information of wireless network estimation, buffer content and playback situation. The proposed adaptive rate control algorithms provide significantly improved streaming quality compared with the non-control policy.

Recent studies show that network coding improves multicast session throughput. In this thesis, we demonstrate how random linear network coding can be incorporated to provide security and network diagnosis for peer-to-peer systems. First, we seek to design a security scheme for network coding architectures which are highly susceptible to jamming attacks. We evaluate Null Keys, a novel and computationally efficient security algorithm, by studying its application in real-world topologies. Null Keys is a cooperative security based on the subspace properties of network coding. We then present a new trace collection protocol that allows operators to diagnose peer-to-peer networks. Existing solutions are not scalable and fail to collect measurements from departed peers. We use progressive random linear network coding to disseminate the traces in the network, from which the server pulls data in a delayed fashion. We leverage the power of progressive encoding to increase block diversity and tolerate block losses.

Video streaming applications over wireless networks have turned out to be immensely popular recently. In this thesis, we first study the buffering schemes for the VBR video streaming in heterogeneous wireless networks. An analytical framework is presented to derive the expected number of jitters and average buffering delay. Through experimenting with a wide range of buffering schemes, we quantify the bene¯t of incorporating user location information in streaming over heterogeneous wireless networks. Second, we consider the delivery of scalable VBR video streams over wireless channels. We propose adaptive rate control algorithms to improve the combined system performance of video frame quality and playout smoothness based on the feedback information of wireless network estimation, buffer content and playback situation. The proposed adaptive rate control algorithms provide significantly improved streaming quality compared with the non-control policy.

Recent studies show that network coding improves multicast session throughput. In this thesis, we demonstrate how random linear network coding can be incorporated to provide security and network diagnosis for peer-to-peer systems. First, we seek to design a security scheme for network coding architectures which are highly susceptible to jamming attacks. We evaluate Null Keys, a novel and computationally efficient security algorithm, by studying its application in real-world topologies. Null Keys is a cooperative security based on the subspace properties of network coding. We then present a new trace collection protocol that allows operators to diagnose peer-to-peer networks. Existing solutions are not scalable and fail to collect measurements from departed peers. We use progressive random linear network coding to disseminate the traces in the network, from which the server pulls data in a delayed fashion. We leverage the power of progressive encoding to increase block diversity and tolerate block losses.

Many modern communication networks suffer significantly from the unreliable characteristic of their nodes and links. To deal with failures, traditionally, centralized erasure codes have been extensively used to improve reliability by introducing data redundancy. In this thesis, we address several issues in implementing erasure codes in a decentralized way such that coding operations are spread to multiple nodes. Our solutions are based on fountain codes and randomized network coding, because of their capability of being amenable to decentralized implementation originated from their simplicity and randomization properties. Our contributions consist of four parts. First, we propose a novel decentralized implementation of fountain codes utilizing random walks. Our solution does not require node location information and enjoys a small local routing table with a size in proportion to the number of neighbors. Second, we introduce priority random linear codes to achieve partial data recovery by partition and encoding data into non-overlapping or overlapping subsets. Third, we present geometric random linear codes to decrease communication costs in decoding significantly, by introducing modest data redundancy in a hierarchical fashion. Finally, we study the application of network coding in disruption tolerant networks. We show that network coding achieves shorter data transmission time than replication, especially when data buffers are limited. We also propose an efficient variant of network coding based protocol, which attains similar transmission delay, but with much lower transmission costs, as compared to a protocol based on epidemic routing.

This bachelor thesis studies the impact of social networking on customer loyalty. Customer loyalty is defined as a commitment to re-buy a specific product or service in the future, despite external influences. There are several influencers of customer loyalty that must be taken care of, e.g. core offering, demographics, elasticity level or share of wallet. The objective of this thesis is to investigate the factors that influence customer loyalty through social networking on Facebook. In order to achieve that, the author has reviewed academic literature on the topic of customer loyalty, as well as on social networking and the ways in which Facebook is used as a marketing tool.

Abstract Due to the advanced development of information technology, society groups generated from internet have been in shear progress. Not only can this phenomenon establish a bridge of emotional connection, it can also provide health information and medical knowledge. Moreover, it certainly can be influential on health policy conducted by governments. Among the present medical society groups, PatientsLikeMe.com (PLM) developed an innovative business model. It built up a platform which allows patients share their own medical history. Through sharing medical history, the patients are able to discover someone else who has similar symptoms and then help to improve clinical outcome. This website may collect patients¡¦ information under patients¡¦ permission. After being clearly filed and analyzed, the data may be sold to medical companies or co-operated institutions for improving clinical therapy. This model has been evaluated by an American consulting institution on business model -- ¡§Board of Innovation¡¨ --as the ¡§Top 10 shocking Business Model of 2010¡¨.Additionally, this model is recognized as a specific research model that may permanently change the methodology of medical research.(J Gospel Net December 2nd,2010) With a view to evaluating the function of websites on helping breast cancer patients to overcome depression and helplessness on diseases, in this study, we would like to introduce the concept of PLM internet society groups. After two interviews on breast cancer patients, we found that the patients are desperately looking for information while the diagnosis is firstly confirmed. These patients are thereby paying deep sympathy to the ones who are also in the same shoes. Under this condition, the patients are willing to share their experience anonymously. At the same time, they only want to solve the problems that already come to the door rather than prepare in advance. Consequently, all the information is collected from the surroundings and lack of proved quality. Therefore, it is important to avoid the fear brought by the overloaded information. From this research, we concluded that (1) during treatment, the breast cancer patients can receive professional assistance and sharing experience from PLM or similar function/ service on websites. (2)Through internet technology, it is possible to provide a platform that surpasses the limitation of both time and space and allows patients to share their personal experience and medical history. (3) PLM system opens a window that allows physicians or nurses to answer patient¡¦s question in one-to-one manner. It is also possible for patients to share their knowledge and some tips that may not be mentioned by medical professionals. However, we also notice that most patients still have problems on using internet society groups because of time limitation, incapability of typing and being unfamiliar on internet skills etc. This research concludes that internet society groups are unlikely to fulfill the requirement of breast cancer patients. Key Word¡GPatientsLikeMe.com (PLM), Case Manager, Social Networking.

Networking Communication has been so popular in recent years and Blog has become one of the newest tools in network media. Diverse users are from all kinds of industries. In general, networking communication researches are often focused on the application in enterprise and industry, but the application in Non-Profit Organization (NPO) should also be considered. There are nearly 26000 institutes from all types of industries that belong to the NPO and the study aims to understand how the Blog application influences the communication. The conclusion can be taken as reference for the NPO to establish a low cost and strong functional network. Method of quality research was carried out in six NPOs and the recording of interview was transferred to manuscripts. After analyzing the manuscripts, the conclusion shows that there¡¦s possibility for Blog designed in low technology and low cost can help the NPO to be seen and heard. The successful operational factors must include rich concept that can be updated promptly at any time and the data of professional knowledge can be easily saved and accumulated. After long term endeavor, competitiveness will be increased and the best efficiency of networking communication for the NPO can then be achieved.

In recent years, network's spreading has already been more valued by everyone. The blog is one of the newly arisen network media tool. The personal user are fast growing and popular to every social field. The Non-profit organization is so called the third section, signing with the government and enterprise together. There are more than 26,000 houses already in the domestic various Non-profit Organization , according to the Ministry of Interior statistics. The research aims at making use of network's dissemination study of influence to carry on a research to the Non-profit Organization to blog. Expect that it can offer some advice to the majority with less of Non-profit Organization, then build up a low cost and a powerful functional blog interaction piping. This research uses a case study method. The research interviewee is the financial group of ¡§Children are us Foundation¡¨. We are currently use it to go on the observation and research. And aim at executive of the result and processing of carry out the statistics and analysis. From the result, the Blog is a low technique part, low cost, and also combining the media, such as network and non- network...etc. to carry on the promotion. In addition to the Blog can become the piping of the Non-profit Organization and get a chance to be famous. It can also collect the money effectively by dissemination behavior. However, the successful component is lying in the blog usage which is familiar with a net friend habit. In order to provide the interaction with net friends and cohere with net friends to become clubs; furthermore; it will create contribution through blog dissemination. To be successful, it needs to take some time. The Blog must be put more effort over a long period of time. Then, it will have opportunity to make good use of blog connection. In the end, it creates the extreme influence of network dissemination for the Non-profit Organization.