Blockchain, the foundation of Bitcoin, has received extensive attentions recently. Blockchain serves as an immutable ledger which allows transactions take place in a decentralized manner. Blockchain-based applications are springing up, covering numerous fields including financial services, reputation system and Internet of Things (IoT), and so on. However, there are still many challenges of blockchain technology such as scalability and security problems waiting to be overcome. This paper presents a comprehensive overview on blockchain technology. We provide an overview of blockchain architechture firstly and compare some typical consensus algorithms used in different blockchains. Furthermore, technical challenges and recent advances are briefly listed. We also lay out possible future trends for blockchain.

An Overview of Blockchain Technology: Architecture, Consensus, and Future Trends

Blockchain has numerous benefits such as decentralisation, persistency, anonymity and auditability. There is a wide spectrum of blockchain applications ranging from cryptocurrency, financial services, risk management, internet of things (IoT) to public and social services. Although a number of studies focus on using the blockchain technology in various application aspects, there is no comprehensive survey on the blockchain technology in both technological and application perspectives. To fill this gap, we conduct a comprehensive survey on the blockchain technology. In particular, this paper gives the blockchain taxonomy, introduces typical blockchain consensus algorithms, reviews blockchain applications and discusses technical challenges as well as recent advances in tackling the challenges. Moreover, this paper also points out the future directions in the blockchain technology.

Blockchain challenges and opportunities: a survey

IoT security: Review, blockchain solutions, and open challenges

Blockchain is a decentralized transaction and data management technology developed first for Bitcoin cryptocurrency. The interest in Blockchain technology has been increasing since the idea was coined in 2008. The reason for the interest in Blockchain is its central attributes that provide security, anonymity and data integrity without any third party organization in control of the transactions, and therefore it creates interesting research areas, especially from the perspective of technical challenges and limitations. In this research, we have conducted a systematic mapping study with the goal of collecting all relevant research on Blockchain technology. Our objective is to understand the current research topics, challenges and future directions regarding Blockchain technology from the technical perspective. We have extracted 41 primary papers from scientific databases. The results show that focus in over 80% of the papers is on Bitcoin system and less than 20% deals with other Blockchain applications including e.g. smart contracts and licensing. The majority of research is focusing on revealing and improving limitations of Blockchain from privacy and security perspectives, but many of the proposed solutions lack concrete evaluation on their effectiveness. Many other Blockchain scalability related challenges including throughput and latency have been left unstudied. On the basis of this study, recommendations on future research directions are provided for researchers.

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Where Is Current Research on Blockchain Technology?-A Systematic Review.

A systematic literature review of blockchain-based applications: Current status, classification and open issues

Nowadays, the development of traditional business models become more and more mature that people use them to guide various kinds of E-business activities. Internet of things (IoT), being an innovative revolution over the Internet, becomes a new platform for E-business. However, old business models could hardly fit for the E-business on the IoT. In this article, we 1) propose an IoT E-business model, which is specially designed for the IoT E-business; 2) redesign many elements in traditional E-business models; 3) realize the transaction of smart property and paid data on the IoT with the help of P2P trade based on the Blockchain and smart contract. We also experiment our design and make a comprehensive discuss.

The IoT electric business model: Using blockchain technology for the internet of things

Nowadays, the development of traditional business models become more and more mature that people use them to guide various kinds of E-business activities. Internet of things(IoT), being an innovative revolution over the Internet, becomes a new platform for E-business. However, old business models could hardly fit for the E-business on the IoT. In this article, we 1) propose an IoT E-business model, which is specially designed for the IoT E-business; 2) redesign many elements in traditional E-business models; 3) realize the transaction of smart property and paid data on the IoT with the help of P2P trade based on the Blockchain and smart contract. We also experiment our design and make a comprehensive discuss.

An IoT electric business model based on the protocol of bitcoin

The ever widening application of virtual reality requires the ultra high resolution omnidirectional videos (OVs) to be transmitted over the wired and wireless Internet at low cost (i.e. bitrate). Various solutions have been proposed to intelligently reduce the bitrate, e.g. adapting the spatial resolution of the video for different directions of the panorama with regard to current direction that the viewer is looking at and the distribution of the probability of each direction to be watched according to the video content. Due to various reasons, spatial resolution adaptation may often cause perceivable quality degradation to user experience. In this paper, we proposed two adaptive encoding techniques to reduce the bitrate of OVs after compression. The first is a content adaptive temporal resolution adaptation scheme for OVs using cube map projection. The second is a quantization and rate-distortion optimization scheme for equirectangular projection. Experiments implementing the proposed algorithms in the open source HEVC encoder x265 show that the proposed algorithms can save 14.69% and 13.01% in BD-rate on average for the cube map and equirectangular projected OVs respectively, while no degradation to the visual experience was reported in subjective tests. The proposed algorithms are compatible with and therefore can collaborate with the currently used adaptive spatial resolution scheme for further bitrate reduction.

Optimized video coding for omnidirectional videos

The number of IoT (Internet of things) connected devices increases rapidly. These devices have different operation systems and therefore cannot communicate with each other. As a result, the data they collected is limited within their own platform. Besides, IoT devices have very constrained resources like weak MCU (micro control unit) and limited storage. Therefore, they need direct communication method to cooperate with each other, or with the help of nearby devices with rich resources. In this paper, we propose a secure method to exchange resources (SMER) between heterogeneous IoT devices. In order to exchange resources among devices, SMER adopts a compensable mechanism for resource exchange and a series of security mechanisms to ensure the security of resource exchanges. Besides, SMER uses a smart contract based scheme to supervise resource exchange, which guarantees the safety and benefits of IoT devices. We also introduce a prototype system and make a comprehensive discussion.

SMER: a secure method of exchanging resources in heterogeneous internet of things

With the rapid development of the Internet application technology, especially Web2.0 and cloud computing, the data content people produced on the network grew in the geometric progression. And one of the fastest growing and the most likely to challenge the technical architecture things is the large number of small files. Traditional file system processes these mass small files is very toughly, In addition, high frequency creating and writing operations on small files may bring many problems under high concurrency requests, such as high disk IO, backup difficulty and poor scalability. This paper describes BerryStore, a distributed object storage system designed for cloud service especially for the massive small files storing, It provides a simple solution to handle a large number of small files. With a distributed coordinate controller introduced, our system is able to provide scalability, concurrency, fault tolerant function.

Yu Zhang

Papers

The IoT electric business model: Using blockchain technology for the internet of things

An IoT electric business model based on the protocol of bitcoin

Optimized video coding for omnidirectional videos

SMER: a secure method of exchanging resources in heterogeneous internet of things

A Novel Solution of Distributed File Storage for Cloud Service