Search

This paper proposes a variant of the recently reported pool mining approach and provides a reduction in the energy that is consumed by the blockchain consensus protocol. The novelty of the proposed architecture lies in the employment of an innovative cryptographic puzzle that is based on stream ciphering. This enables flexibility in setting the difficulty parameter of the protocol, and allows for the separation of the energy and memory resources that are required for the puzzle solving. The proposed approach provides high resistance against the following malicious activities of miners in public blockchain systems: (i) the submission of fake work and fictitious computation results; and (ii) some well-known attacks that target the blockchain incentive mechanism. We experimentally evaluate the power consumption of the proposed consensus protocol and compare it with the traditional proof-of-work protocol based on hashing. The obtained results point out the gain that the proposed pool mining provides compared with the traditional types.

Blockchains (BCs) are distributed database systems, popular for their innovative, unsupervised maintenance process. They use a so-called consensus protocol to prevent inference by any third party of absolute trust. Security, privacy, consistency, and energy consumption have been identified as the main issues involved in BC maintenance. According to the recent literature, some of these issues can be formulated as combinatorial optimization (CO) problems, and this fact motivated us to consider incorporating CO approaches into a BC. In this paper, we propose the new combinatorial optimization consensus protocol (COCP) based on the proof-of-useful-work (PoUW) concept that assumes solving instances of real-life CO problems. Due to the complexity of the underlying CO problems, we have developed various types of heuristic methods, which are utilized in the COCP. Most of these methods are problem-dependent stochastic heuristic or metaheuristic methods. As is the case with the majority of consensus protocols, PoUW exhibits the property of asymmetry. It is difficult to find a solution for the considered CO problem; however, once a solution is found, its verification is straightforward. We present here a BC framework combining the two above-mentioned fields of research: BC and CO. This framework consists of improvements aiming towards developing the COCP of the PoUW type. The main advantage of this consensus protocol is the efficient utilization of computing resources (by exploring them for finding solutions of real-life CO problem instances), and the provision of a broad range of incentives for the various BC participants. We enumerate the potential benefits of the COCP with respect to its practical impacts and savings in power consumption, describing in detail an illustrative example based on part of the real-life BC network. In addition, we identify several challenges that should be resolved in order to implement a useful, secure, and efficient PoUW consensus protocol.

This paper proposes an approach for pool mining in public blockchain systems based on the employment of a recently reported consensus protocol with the puzzle based on a symmetric encryption that provides an energy–space trade-off and reduces energy consumption. The proposed architecture employs a pseudo-symmetric allocation of the resources for the blockchain consensus protocol and provides protection against certain malicious actions of the pool members, as well as a miner’s opportunity for selecting the resources required for participation in the consensus protocol. Given that the considered consensus protocol employs two resources, the proposed architecture uses this two-dimensional nature to provide resistance against block withholding and selfish mining attacks, as well as a reduction in energy spending as a trade-off with the employment of certain memory resources. The high resistance of the proposed pool mining approach against the considered attacks appears to be a consequence of the success probability of the pool in comparison with the success probability of malicious miners. Assuming appropriate selection of the puzzle hardness, the probability that malicious miners can solve the puzzle without the support of the pool manager can be arbitrarily small. Implementation of the proposed approach on a modified Ethereum platform and experimental evaluation issues have also been reported. The conceptual novelty of the proposed pool mining approach is the following: Instead of separation of the blockchain consensus protocol and control of pool miners honest work, this paper proposes an approach where honest work of miners and pool managers is provided by a dedicated application of the considered consensus protocol. Advantages of the proposal in comparison with the previously reported ones include the following: (i) high resistance against block withholding and selfish mining attacks without an additional security procedure; (ii) reduction in the energy required, and at the same time preservationthe security of the consensus protocol; (iii) flexibility of the pool miners regarding selection of the resources that should be employed providing a trade-off between required energy and memory resources. The proposed architecture was implemented employing a dedicated modification of the Ethereum platform and the performed experiments confirmed the feasibility and effectiveness of the proposal.

Mobile station localization in mobile networks started with simple methods (e.g. Cell-ID method) which required only slight modifications of network infrastructures. Principally, it was about network localization by which a localization service became available to all types of mobile phones. Due to low precision, the initiated development of more sophisticated methods has not been finished yet. Among the advanced location-based methods are those based on the measurement of location parameters in the time domain. In this paper the general consideration of radio location methods in 3G (UMTS) radio networks is presented. The use of time based measurement methods was analysed in detail. Due to the limited article length, the use of other locating methods in 3G networks (based on power measurements, on radio direction measurement, and on cells identification – Cell ID and global positioning system - GPS) are not described. Introduction Mobile station localization within modern cellular networks increases the level of user security and opens wide opportunities for commercial operators who provide this service. The major obstacle for the implementation of this service, which also prevents its practical usage, is the modification of the existing network infrastructure. In general, depending on the infrastructure used, positioning methods can be divided into two groups: integrated and independent. Integrated methods are primarily created for communication networks. A possibility to locate users represents just an additional service within a radio network. Independent methods are totally detached from the communication network in which the user whose location is being determined is. Radio location methods Determining the location of a mobile radio station is performed by determining the intersection of two or more lines of position. These lines represent the position of the set of points at which the mobile station may be located. These lines can be: (a) direction, if specified by a direction on an object, (b) circle, if determined by measuring the distance of an object, or (c) a hyperbola, if the difference is determined by measuring the distance between two objects. In cellular networks, the location of mobile stations can be estimated roughly by proximity sensing methods and methods based on an evaluation of the characteristics of base stations (fingerprinting). Basic characteristics of the UMTS standard The radio network controller (RNC) has three different roles and is therefore known as: Controlling RNC (CRNC), Serving RNC (SRNC) and Drifting RNC (DRNC). The Local Measurement Unit (LMU) performs radio measurements (measuring the delay of signals from base stations to the LMU) and forwards the data to the CRNC. The main location functions are performed within the Serving RNC which can operate in two modes: RNC central and central SAS (Standalone SMLC). The RNC in the RNC central mode controls the flow of requirements for the localization, chooses the method of localization, provides information as necessary and, finally, estimates the location of the user. The SAS mode performs the procedures based on the requirements of the service radio network controller (SRNC). The SAS executes the global location (Global Navigation Satellite System) and location on the uplink, based on measuring the time difference U-TDoA (Uplink - Time Difference of Arrival). Methods of locating the MS in a UMTS network In the UMTS network, depending on the used network infrastructure, both the station and network-based method can be used, i.e. determining the MS location can be performed on the MS or on the network side. In UMTS networks, the following methods can be used: methods based on measurements in the time domain (time-based), methods based on measurements of a received power level (Received Signal Strength - RSS), methods based on measuring the angle under which the signal arrives to the receiving antenna and methods based on the global location system (Global Navigation Satellite System). The methods based on measuring the values ​​of the parameters of radio signals propagation in the time domain, analyzed in detail in the work, are divided by the type of location parameters used into: RTT, ToA and TDoA methods. Conclusion This paper examines the methods of radio locating in radio networks with a detailed analysis of methods of locating mobile stations in the 3G (UMTS) cellular networks based on station and network measurements of location parameters in the time domain.

This paper presents a scientometric and bibliometric literature review of the research on transitions to autonomous and electric vehicles. We discuss the main characteristics, evolution, and various transitional issues, identifying potential trends for future research. The Scopus and WoS search for relevant research articles generated a corpus of 4693 articles, which we analyzed using VOSviewer visualization software. This result shows that the transition research is interdisciplinary, with 54 scientific areas identified. Analysis requires an understanding of the broader aspects of the automotive industry, trends related to sustainability, environment protection, road safety, public policies, market factors and other business, and legal and management issues. This study highlights the need for more research to address the challenges of this global transition in the automotive industry. Topics for future research are constant improvements in AI algorithms used in AVs, innovations in green energy sources, and storage solutions for EVs. This is leading to new innovative business models and platforms. Further to that, the conclusion is that the impact of the transition to a shared economy, the emergency of mobility as a service, and public acceptance of the technology have to be comprehensively considered. The vehicle of the future is seen as a smart electric car, running on green energy, and utilizing various levels of automation up to full autonomy.