Distributed Algorithms for Location Based Services

Real-time localization services are some of the most challenging and interesting mobile broadband applications in the Location Based Services (LBS) world. They are gaining more and more importance for a broad range of applications, such as road/highway monitoring, emergency management, social networking, and advertising. This Ph.D. thesis focuses on the problem of defining a new category of decentralized peer-to-peer (P2P) algorithms for LBS. We aim at defining a P2P overlay where each participant can efficiently retrieve node and resource information (data or services) located near any chosen geographic position. The idea is that the responsibility and the required resources for maintaining information about position of active users are properly distributed among nodes, for which a change in the set of participants causes only a minimal amount of disruption without reducing the quality of provided services. In this thesis we will assess the validity of the proposed model through a formal analysis of the routing protocol and a detailed simulative investigation of the designed overlay. We will depict a complete picture of involved parameters, how they affect the performance and how they can be configured to adapt the protocol to the requirements of several location based applications. Furthermore we will present two application scenarios (a smartphone based Traffic Information System and a large information management system for a SmartCity) where the designed protocol has been simulated and evaluated, as well as the first prototype of a real implementation of the overlay using both traditional PC nodes and Android mobile devices

Decentralized Resource Availability Prediction in Peer-to-Peer Desktop Grids

Grid computing is a form of distributed computing which is used by an organiza­ tion to handle its long-running computational tasks. Volunteer computing (desktop grid) is a type of grid computing that uses idle CPU cycles donated voluntarily by users, to run its tasks. In a desktop grid model, the resources are not dedicated. The job (computational task) is submitted for execution in the resource only when the resource is idle. There is no guarantee that the job which has started to execute in a resource will complete its execution without any disruption from user activity (such as keyboard click or mouse move). This problem becomes more challenging in a Peer-to-Peer (P2P) model of desktop grids where there is no central server which takes the decision on whether to allocate a job to a resource. In this thesis we propose and implement a P2P desktop grid framework which does resource availability prediction. We try to improve the predictability of the system, by submitting the jobs on machines which have a higher probability of being available at a given time. We benchmark our framework and provide an analysis of our results

An Efficient Holistic Data Distribution and Storage Solution for Online Social Networks

In the past few years, Online Social Networks (OSNs) have dramatically spread over the world. Facebook [4], one of the largest worldwide OSNs, has 1.35 billion users, 82.2% of whom are outside the US [36]. The browsing and posting interactions (text content) between OSN users lead to user data reads (visits) and writes (updates) in OSN datacenters, and Facebook now serves a billion reads and tens of millions of writes per second [37]. Besides that, Facebook has become one of the top Internet traffic sources [36] by sharing tremendous number of large multimedia files including photos and videos. The servers in datacenters have limited resources (e.g. bandwidth) to supply latency efficient service for multimedia file sharing among the rapid growing users worldwide. Most online applications operate under soft real-time constraints (e.g., ≤ 300 ms latency) for good user experience, and its service latency is negatively proportional to its income. Thus, the service latency is a very important requirement for Quality of Service (QoS) to the OSN as a web service, since it is relevant to the OSN’s revenue and user experience. Also, to increase OSN revenue, OSN service providers need to constrain capital investment, operation costs, and the resource (bandwidth) usage costs. Therefore, it is critical for the OSN to supply a guaranteed QoS for both text and multimedia contents to users while minimizing its costs. To achieve this goal, in this dissertation, we address three problems. i) Data distribution among datacenters: how to allocate data (text contents) among data servers with low service latency and minimized inter-datacenter network load; ii) Efficient multimedia file sharing: how to facilitate the servers in datacenters to efficiently share multimedia files among users; iii) Cost minimized data allocation among cloud storages: how to save the infrastructure (datacenters) capital investment and operation costs by leveraging commercial cloud storage services. Data distribution among datacenters. To serve the text content, the new OSN model, which deploys datacenters globally, helps reduce service latency to worldwide distributed users and release the load of the existing datacenters. However, it causes higher inter-datacenter communica-tion load. In the OSN, each datacenter has a full copy of all data, and the master datacenter updates all other datacenters, generating tremendous load in this new model. The distributed data storage, which only stores a user’s data to his/her geographically closest datacenters, simply mitigates the problem. However, frequent interactions between distant users lead to frequent inter-datacenter com-munication and hence long service latencies. Therefore, the OSNs need a data allocation algorithm among datacenters with minimized network load and low service latency. Efficient multimedia file sharing. To serve multimedia file sharing with rapid growing user population, the file distribution method should be scalable and cost efficient, e.g. minimiza-tion of bandwidth usage of the centralized servers. The P2P networks have been widely used for file sharing among a large amount of users [58, 131], and meet both scalable and cost efficient re-quirements. However, without fully utilizing the altruism and trust among friends in the OSNs, current P2P assisted file sharing systems depend on strangers or anonymous users to distribute files that degrades their performance due to user selfish and malicious behaviors. Therefore, the OSNs need a cost efficient and trustworthy P2P-assisted file sharing system to serve multimedia content distribution. Cost minimized data allocation among cloud storages. The new trend of OSNs needs to build worldwide datacenters, which introduce a large amount of capital investment and maintenance costs. In order to save the capital expenditures to build and maintain the hardware infrastructures, the OSNs can leverage the storage services from multiple Cloud Service Providers (CSPs) with existing worldwide distributed datacenters [30, 125, 126]. These datacenters provide different Get/Put latencies and unit prices for resource utilization and reservation. Thus, when se-lecting different CSPs’ datacenters, an OSN as a cloud customer of a globally distributed application faces two challenges: i) how to allocate data to worldwide datacenters to satisfy application SLA (service level agreement) requirements including both data retrieval latency and availability, and ii) how to allocate data and reserve resources in datacenters belonging to different CSPs to minimize the payment cost. Therefore, the OSNs need a data allocation system distributing data among CSPs’ datacenters with cost minimization and SLA guarantee. In all, the OSN needs an efficient holistic data distribution and storage solution to minimize its network load and cost to supply a guaranteed QoS for both text and multimedia contents. In this dissertation, we propose methods to solve each of the aforementioned challenges in OSNs. Firstly, we verify the benefits of the new trend of OSNs and present OSN typical properties that lay the basis of our design. We then propose Selective Data replication mechanism in Distributed Datacenters (SD3) to allocate user data among geographical distributed datacenters. In SD3,a datacenter jointly considers update rate and visit rate to select user data for replication, and further atomizes a user’s different types of data (e.g., status update, friend post) for replication, making sure that a replica always reduces inter-datacenter communication. Secondly, we analyze a BitTorrent file sharing trace, which proves the necessity of proximity-and interest-aware clustering. Based on the trace study and OSN properties, to address the second problem, we propose a SoCial Network integrated P2P file sharing system for enhanced Efficiency and Trustworthiness (SOCNET) to fully and cooperatively leverage the common-interest, geographically-close and trust properties of OSN friends. SOCNET uses a hierarchical distributed hash table (DHT) to cluster common-interest nodes, and then further clusters geographically close nodes into a subcluster, and connects the nodes in a subcluster with social links. Thus, when queries travel along trustable social links, they also gain higher probability of being successfully resolved by proximity-close nodes, simultaneously enhancing efficiency and trustworthiness. Thirdly, to handle the third problem, we model the cost minimization problem under the SLA constraints using integer programming. According to the system model, we propose an Eco-nomical and SLA-guaranteed cloud Storage Service (ES3), which finds a data allocation and resource reservation schedule with cost minimization and SLA guarantee. ES3 incorporates (1) a data al-location and reservation algorithm, which allocates each data item to a datacenter and determines the reservation amount on datacenters by leveraging all the pricing policies; (2) a genetic algorithm based data allocation adjustment approach, which makes data Get/Put rates stable in each data-center to maximize the reservation benefit; and (3) a dynamic request redirection algorithm, which dynamically redirects a data request from an over-utilized datacenter to an under-utilized datacenter with sufficient reserved resource when the request rate varies greatly to further reduce the payment. Finally, we conducted trace driven experiments on a distributed testbed, PlanetLab, and real commercial cloud storage (Amazon S3, Windows Azure Storage and Google Cloud Storage) to demonstrate the efficiency and effectiveness of our proposed systems in comparison with other systems. The results show that our systems outperform others in the network savings and data distribution efficiency

Emerging business models in local energy markets: A systematic review of peer-to-peer, community self-consumption, and transactive energy models

The emergence of peer-to-peer, collective or community self-consumption, and transactive energy concepts gives rise to new configurations of business models for local energy trading among a variety of actors. Much attention has been paid in the academic literature to the transition of the underlying energy system with its macroeconomic market framework. However, fewer contributions focus on the microeconomic aspects of the broad set of involved actors. Even though specific case studies highlight single business models, a comprehensive analysis of emerging business models for the entire set of actors is missing. Following this research gap, this paper conducts a systematic literature review of 135 peer-reviewed journal articles to examine business models of actors operating in local energy markets. From 221 businesses in the reviewed literature, nine macro-actor categories are identified. For each type of market actor, a business model archetype is determined and characterised using the business model canvas. The key elements of each business model archetype are discussed, and areas are highlighted where further research is needed. Finally, this paper outlines the differences of business models for their presence in the three local energy market models. Focusing on the identified customers and partner relationships, this study highlights the key actors per market model and the character of the interactions between market participants

Trajectory Privacy Preservation and Lightweight Blockchain Techniques for Mobility-Centric IoT

Various research efforts have been undertaken to solve the problem of trajectory privacy preservation in the Internet of Things (IoT) of resource-constrained mobile devices. Most attempts at resolving the problem have focused on the centralized model of IoT, which either impose high delay or fail against a privacy-invading attack with long-term trajectory observation. These proposed solutions also fail to guarantee location privacy for trajectories with both geo-tagged and non-geo-tagged data, since they are designed for geo-tagged trajectories only. While a few blockchain-based techniques have been suggested for preserving trajectory privacy in decentralized model of IoT, they require large storage capacity on resource-constrained devices and can only provide conditional privacy when a set of authorities governs the blockchain. This dissertation addresses these challenges to develop efficient trajectory privacy-preservation and lightweight blockchain techniques for mobility-centric IoT. We develop a pruning-based technique by quantifying the relationship between trajectory privacy and delay for real-time geo-tagged queries. This technique yields higher trajectory privacy with a reduced delay than contemporary techniques while preventing a long-term observation attack. We extend our study with the consideration of the presence of non-geo-tagged data in a trajectory. We design an attack model to show the spatiotemporal correlation between the geo-tagged and non-geo-tagged data which undermines the privacy guarantee of existing techniques. In response, we propose a methodology that considers the spatial distribution of the data in trajectory privacy-preservation and improves existing solutions, in privacy and usability. With respect to blockchain, we design and implement one of the first blockchain storage management techniques utilizing the mobility of the devices. This technique reduces the required storage space of a blockchain and makes it lightweight for resource-constrained mobile devices. To address the trajectory privacy challenges in an authority-based blockchain under the short-range communication constraints of the devices, we introduce a silence-based one of the first technique to establish a balance between trajectory privacy and blockchain utility. The designed trajectory privacy- preservation techniques we established are light- weight and do not require an intermediary to guarantee trajectory privacy, thereby providing practical and efficient solution for different mobility-centric IoT, such as mobile crowdsensing and Internet of Vehicles

Enhanced Multimedia Exchanges over the Internet

Although the Internet was not originally designed for exchanging multimedia streams, consumers heavily depend on it for audiovisual data delivery. The intermittent nature of multimedia traffic, the unguaranteed underlying communication infrastructure, and dynamic user behavior collectively result in the degradation of Quality-of-Service (QoS) and Quality-of-Experience (QoE) perceived by end-users. Consequently, the volume of signalling messages is inevitably increased to compensate for the degradation of the desired service qualities. Improved multimedia services could leverage adaptive streaming as well as blockchain-based solutions to enhance media-rich experiences over the Internet at the cost of increased signalling volume. Many recent studies in the literature provide signalling reduction and blockchain-based methods for authenticated media access over the Internet while utilizing resources quasi-efficiently. To further increase the efficiency of multimedia communications, novel signalling overhead and content access latency reduction solutions are investigated in this dissertation including: (1) the first two research topics utilize steganography to reduce signalling bandwidth utilization while increasing the capacity of the multimedia network; and (2) the third research topic utilizes multimedia content access request management schemes to guarantee throughput values for servicing users, end-devices, and the network. Signalling of multimedia streaming is generated at every layer of the communication protocol stack; At the highest layer, segment requests are generated, and at the lower layers, byte tracking messages are exchanged. Through leveraging steganography, essential signalling information is encoded within multimedia payloads to reduce the amount of resources consumed by non-payload data. The first steganographic solution hides signalling messages within multimedia payloads, thereby freeing intermediate node buffers from queuing non-payload packets. Consequently, source nodes are capable of delivering control information to receiving nodes at no additional network overhead. A utility function is designed to minimize the volume of overhead exchanged while minimizing visual artifacts. Therefore, the proposed scheme is designed to leverage the fidelity of the multimedia stream to reduce the largest amount of control overhead with the lowest negative visual impact. The second steganographic solution enables protocol translation through embedding packet header information within payload data to alternatively utilize lightweight headers. The protocol translator leverages a proposed utility function to enable the maximum number of translations while maintaining QoS and QoE requirements in terms of packet throughput and playback bit-rate. As the number of multimedia users and sources increases, decentralized content access and management over a blockchain-based system is inevitable. Blockchain technologies suffer from large processing latencies; consequently reducing the throughput of a multimedia network. Reducing blockchain-based access latencies is therefore essential to maintaining a decentralized scalable model with seamless functionality and efficient utilization of resources. Adapting blockchains to feeless applications will then port the utility of ledger-based networks to audiovisual applications in a faultless manner. The proposed transaction processing scheme will enable ledger maintainers in sustaining desired throughputs necessary for delivering expected QoS and QoE values for decentralized audiovisual platforms. A block slicing algorithm is designed to ensure that the ledger maintenance strategy is benefiting the operations of the blockchain-based multimedia network. Using the proposed algorithm, the throughput and latency of operations within the multimedia network are then maintained at a desired level

Designing peer-to-peer overlays:a small-world perspective

The Small-World phenomenon, well known under the phrase "six degrees of separation", has been for a long time under the spotlight of investigation. The fact that our social network is closely-knitted and that any two people are linked by a short chain of acquaintances was confirmed by the experimental psychologist Stanley Milgram in the sixties. However, it was only after the seminal work of Jon Kleinberg in 2000 that it was understood not only why such networks exist, but also why it is possible to efficiently navigate in these networks. This proved to be a highly relevant discovery for peer-to-peer systems, since they share many fundamental similarities with the social networks; in particular the fact that the peer-to-peer routing solely relies on local decisions, without the possibility to invoke global knowledge. In this thesis we show how peer-to-peer system designs that are inspired by Small-World principles can address and solve many important problems, such as balancing the peer load, reducing high maintenance cost, or efficiently disseminating data in large-scale systems. We present three peer-to-peer approaches, namely Oscar, Gravity, and Fuzzynet, whose concepts stem from the design of navigable Small-World networks. Firstly, we introduce a novel theoretical model for building peer-to-peer systems which supports skewed node distributions and still preserves all desired properties of Kleinberg's Small-World networks. With such a model we set a reference base for the design of data-oriented peer-to-peer systems which are characterized by non-uniform distribution of keys as well as skewed query or access patterns. Based on this theoretical model we introduce Oscar, an overlay which uses a novel scalable network sampling technique for network construction, for which we provide a rigorous theoretical analysis. The simulations of our system validate the developed theory and evaluate Oscar's performance under typical conditions encountered in real-life large-scale networked systems, including participant heterogeneity, faults, as well as skewed and dynamic load-distributions. Furthermore, we show how by utilizing Small-World properties it is possible to reduce the maintenance cost of most structured overlays by discarding a core network connectivity element – the ring invariant. We argue that reliance on the ring structure is a serious impediment for real life deployment and scalability of structured overlays. We propose an overlay called Fuzzynet, which does not rely on the ring invariant, yet has all the functionalities of structured overlays. Fuzzynet takes the idea of lazy overlay maintenance further by eliminating the need for any explicit connectivity and data maintenance operations, relying merely on the actions performed when new Fuzzynet peers join the network. We show that with a sufficient amount of neighbors, even under high churn, data can be retrieved in Fuzzynet with high probability. Finally, we show how peer-to-peer systems based on the Small-World design and with the capability of supporting non-uniform key distributions can be successfully employed for large-scale data dissemination tasks. We introduce Gravity, a publish/subscribe system capable of building efficient dissemination structures, inducing only minimal dissemination relay overhead. This is achieved through Gravity's property to permit non-uniform peer key distributions which allows the subscribers to be clustered close to each other in the key space where data dissemination is cheap. An extensive experimental study confirms the effectiveness of our system under realistic subscription patterns and shows that Gravity surpasses existing approaches in efficiency by a large margin. With the peer-to-peer systems presented in this thesis we fill an important gap in the family of structured overlays, bringing into life practical systems, which can play a crucial role in enabling data-oriented applications distributed over wide-area networks

Providing security and fault tolerance in P2P connections between clouds for mHealth services

[EN] The mobile health (mHealth) and electronic health (eHealth) systems are useful to maintain a correct administration of health information and services. However, it is mandatory to ensure a secure data transmission and in case of a node failure, the system should not fall down. This fact is important because several vital systems could depend on this infrastructure. On the other hand, a cloud does not have infinite computational and storage resources in its infrastructure or would not provide all type of services. For this reason, it is important to establish an interrelation between clouds using communication protocols in order to provide scalability, efficiency, higher service availability and flexibility which allow the use of services, computing and storage resources of other clouds. In this paper, we propose the architecture and its secure protocol that allows exchanging information, data, services, computing and storage resources between all interconnected mHealth clouds. The system is based on a hierarchic architecture of two layers composed by nodes with different roles. The routing algorithm used to establish the connectivity between the nodes is the shortest path first (SPF), but it can be easily changed by any other one. Our architecture is highly scalable and allows adding new nodes and mHealth clouds easily, while it tries to maintain the load of the cloud balanced. Our protocol design includes node discovery, authentication and fault tolerance. We show the protocol operation and the secure system design. Finally we provide the performance results in a controlled test bench.Lloret, J.; Sendra, S.; Jimenez, JM.; Parra-Boronat, L. (2016). Providing security and fault tolerance in P2P connections between clouds for mHealth services. Peer-to-Peer Networking and Applications. 9(5):876-893. doi:10.1007/s12083-015-0378-3S87689395The Fifty-eighth World Health Assembly, Resolutions and Decisions. Document: A58/21. Available at: http://www.who.int/healthacademy/media/WHA58-28-en.pdf . [Last access: Dec. 30, 2014]World Health organization. Topics of eHealth. In WHO website. Available at: http://www.who.int/topics/eHealth/en/ . [Last access: Dec. 30, 2014]Pickup JC, Freeman SC, Sutton AJ (2011) Glycaemic control in type 1 diabetes during real time continuous glucose monitoring compared with self monitoring of blood glucose: meta-analysis of randomised controlled trials using individual patient data. BMJ 343:d3805Promotional Material Digital health: working in partnership. Department of Health. UK. (2014) Available at: https://www.gov.uk/government/publications/digital-health-working-in-partnership/digital-health-working-in-partnerships#digital-health---harnessing-technology-for-patient-benefit . [Last access: Dec. 30, 2014]eHealth for a Healthier Europe!– opportunities for a better use of healthcare resources. Available at: https://joinup.ec.europa.eu/sites/default/files/files_epractice/sites/eHealth%20for%20a%20Healthier%20Europe %20-%20Opportunities%20for%20a%20better%20use%20of%20healthcare%20resources.pdf. [Last access: Dec. 30, 2014]Adibi S (2012) Link technologies and BlackBerry mobile health (mHealth) solutions: a review. IEEE Trans Inf Technol Biomed 16(4):586–597Chiarini G, Ray P, Akter S, Masella C, Ganz A (2013) mHealth technologies for chronic diseases and elders: a systematic review. IEEE J Sel Areas Commun 31(9):6–18Lopes IM, Silva BM, Rodrigues JJ, Lloret J, Proenca ML (2011) A mobile health monitoring solution for weight control. In proceedings of the 2011 International Conference on Wireless Communications and Signal Processing (WCSP 2011), Nanjing, pp 1–5Lopes IM, Silva BM, Rodrigues JJPC, Lloret J (2012) Performance evaluation of cooperation mechanisms for m-health applications. In proceedings of the 2012 I.E. Global Communications Conference (GLOBECOM 2012), AnaheimKyriacou EC, Pattichis CS, Pattichis MS (2009) An overview of recent health care support systems for eEmergency and mHealth applications. In proceedings of the 31st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2009), Hilton Minneapolis, pp 1246–1249Nkosi MT, Mekuria F (2010) Cloud computing for enhanced mobile health applications. In proceedings of the 2010 I.E. Second International Conference on Cloud Computing Technology and Science (CloudCom 2010), Indianapolis, pp 629–633Sultan N (2014) Making use of cloud computing for healthcare provision: opportunities and challenges. Int J Inf Manag 34(2):177–184Pandey S, Voorsluys W, Niu S, Khandoker A, Buyya R (2012) An autonomic cloud environment for hosting ECG data analysis services. Futur Gener Comput Syst 28(1):147–154Xia H, Asif I, Zhao X (2013) Cloud-ECG for real time ECG monitoring and analysis. Comput Methods Prog Biomed 110(3):253–259Bourouis A, Feham M, Bouchachia A (2012) A new architecture of a ubiquitous health monitoring system: a prototype of cloud mobile health monitoring system. arXiv preprint. Reference: arXiv:1205.6910Chen KR, Lin YL, Huang MS (2011) A mobile biomedical device by novel antenna technology for cloud computing resource toward pervasive healthcare. In proceedings of the 11th International Conference on Bioinformatics and Bioengineering (BIBE 2011), Taichung, pp 133–136Lacuesta R, Lloret J, Sendra S, Peñalver L (2014), Spontaneous ad hoc mobile cloud computing network. Sci World J (Article ID 232419): 1–19Ghafoor KZ, Bakar KA, Mohammed MA, Lloret J (2013) Vehicular cloud computing: trends and challenges (Chapter 14). In Mobile Networks and Cloud computing Convergence for Progressive Services and Applications. IGI Global. pp. 262–274. DOI: 10.4018/978-1-4666-4781-7.ch014Wan J, Zhang D, Zhao S, Yang LT, Lloret J (2014) Context-aware vehicular cyber-physical systems with cloud support: architecture, challenges and solutions. IEEE Commun Mag 52(8):106–113. doi: 10.1109/MCOM.2014.6871677Rodrigues JJPC, Zhou L, Mendes LDP, Lin K, Lloret J (2012) Distributed media-aware flow scheduling in cloud computing environment. Comput Commun 35(15):1819–1827Dutta R, Annappa B (2014) Protection of data in unsecured public cloud environment with open, vulnerable networks using threshold-based secret sharing. Netw Protoc Algoritm 6(1):58–75Modares H, Lloret J, Moravejosharieh A, Salleh R (2013) Security in mobile cloud computing (Chapter 5). In Mobile Networks and Cloud computing Convergence for Progressive Services and Applications. IGI Global. pp. 79–91Mehmood A, Song H, Lloret J (2014) Multi-agent based framework for secure and reliable communication among open clouds. Netw Protoc Algoritm 6(4):60–76Mendes LDP, Rodrigues JJPC, Lloret J, Sendra S (2014) Cross-layer dynamic admission control for cloud-based multimedia sensor networks. IEEE Syst J 8(1):235–246Xiong J, Li F, Ma J, Liu X, Yao Z, Chen PS (2014) A full lifecycle privacy protection scheme for sensitive data in cloud computing. Peer-to-Peer Netw Appl 1–13Yang H, Kim H, Mtonga K (2014) An efficient privacy-preserving authentication scheme with adaptive key evolution in remote health monitoring system. Peer-to-Peer Netw Appl 1–11Silva BM, Rodrigues JJ, Canelo F, Lopes IM, Lloret J (2014) Towards a cooperative security system for mobile-health applications. Electron Commer Re 1–27Flynn D, Gregory P, Makki H, Gabbay M (2009) Expectations and experiences of eHealth in primary care: a qualitative practice-based investigation. Int J Med Inform 78(9):588–604Thampi SM (2010) Survey of search and replication schemes in unstructured P2P networks. Netw Protoc Algoritm 2(1):93–131Khan SM, Mallesh N, Nambiar A, Wright M (2010) The dynamics of salsa: a robust structured P2P system. Netw Protoc Algoritm 2(4):40–60Garcia M, Hammoumi M, Canovas A, Lloret J (2011) Controlling P2P file-sharing networks’ traffic. Netw Protoc Algoritm 3(4):54–92Lloret J, Garcia M, Tomas J, Rodrigues JJPC (2014) Architecture and protocol for InterCloud communication. Inf Sci 258:434–451Chowdhury CR (2014) A survey of cloud based health care system. Int J Innov Res Comput Commun Eng 2(8):5477–5481Ghosh R, Papapanagiotou I, Boloor KA (2014) Survey on research initiatives for healthcare clouds. Cloud Computing Applications for Quality Health Care Delivery. IGI Global 1–18Donahue S (2010) Can cloud computing help fix health care? Cloudbook J 1(6):1–6Deng M, Petkovic M, Nalin M, Baroni IA (2011) Home healthcare system in the cloud--addressing security and privacy challenges. In proceedings of the 2011 I.E. International Conference on Cloud Computing (CLOUD 2011), Washington, pp 549–556Wang X, Gui Q, Liu B, Chen Y, Jin Z (2013) Leveraging mobile cloud for telemedicine: a performance study in medical monitoring. In proceedings of the 39th Annual Northeast Bioengineering Conference (NEBEC 2013), Syracuse, pp 49–50Alamri A (2012) Cloud-based e-health multimedia framework for heterogeneous network. In proceedings of the 2012 I.E. International Conference on Multimedia and Expo Workshops (ICMEW 2012), Melbourne, pp 447–452Constantinescu L, Kim J, Feng DD (2012) Sparkmed: a framework for dynamic integration of multimedia medical data into distributed m-health systems. IEEE Trans Inf Technol Biomed 16(1):40–52Botts N, Thoms B, Noamani A, Horan TA (2010) Cloud computing architectures for the underserved: public health cyberinfrastructures through a network of healthatms. In proceedings of the 43rd Hawaii International Conference on System Sciences (HICSS 2010), Honolulu, pp 1–10Fan L, Buchanan W, Thummler C, Lo O, Khedim A, Uthmani O, Lawson A, Bell D (2011) DACAR platform for eHealth services cloud. In proceedings of the 2011 I.E. International Conference on Cloud Computing (CLOUD 2011), Washington, pp 219–226Ruiz-Zafra A, Benghazi K, Noguera M, Garrido JL (2013) Zappa: An Open Mobile Platform to Build Cloud-Based m-Health Systems. In proceedings of the 4th International Symposium on Ambient Intelligence (ISAmI 2013), Salamanca, pp 87–94Nijon S, Dickerson RF, Asare P, Li Q, Hong D, Stankovic JA, Hu P, Shen G, Jiang X (2013) Auditeur: a mobile-cloud service platform for acoustic event detection on smartphones. In Proceeding of the 11th annual international conference on Mobile systems, applications, and services. ACM, Taipei, pp 403–416Lloret J, Diaz JR, Boronat F, Jiménez JM (2006) A fault-tolerant P2P-based protocol for logical networks interconnection. In proceedings of the International Conference on Networking and Services (ICNS’06), Silicon ValleyLloret J, Palau C, Boronat F, Tomas J (2008) Improving networks using group-based topologies. Comput Commun 31(14):3438–3450Lloret J, Boronat Segui F, Palau C, Esteve M (2005) Two levels SPF-based system to interconnect partially decentralized P2P file sharing networks. In proceedings of the Joint International Conference on Autonomic and Autonomous Systems and International Conference on Networking and Services.(ICAS-ICNS 2005), Papeete, p 39Cramer C, Kutzner K, Fuhrmann T (2004) Bootstrapping locality-aware P2P networkS. In proceedings of the 12th IEEE International Conference on Networks (ICON 2004), Singapore, pp 357–361FIPS 180-1 - Secure Hash Standard, SHA-1. National Institute of Standards and Technology. http://www.itl.nist.gov/fipspubs/fip180-1.htm [Last access: Dec. 30, 2014]Eastlake D., Jones P., US Secure Hash Algorithm 1 (SHA1),(2001). In IETF website, Available at: http://www.ietf.org/rfc/rfc3174.txt [Last access: March 20, 2015]Lacuesta R, Lloret J, Garcia M, Peñalver L (2011) Two secure and energy-saving spontaneous Ad-Hoc protocol for wireless mesh client networks. J Netw Comput Appl 3(2):492–50