No abstract

The problem of selfishness and misbehaviour in wireless networks is well known, as are the associated solutions that have been proposed for it in IEEE 802.11 Wireless Local Area Network (WLAN) and Wireless Sensory Network (WSN). However, tackling such problem in relation to the Internet of Things (IoT) is relatively new since the IoT is still under development. The central communication infrastructure of IoT is the IEEE 802.15.4 standard which defines low-rate and low energy wireless personal area networks. In order to share the medium fairly and efficiently in a beacon-enabled mode, the standard uses Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) in the Contention Access Period (CAP), and Guarantee Time Slot (GTS) in the Contention Free Period (CFP) of a super-frame. These channel sharing mechanisms are known to be vulnerable to selfishness, misbehaviour and channel capture as a result of nodes disobeying the communication rules. Most of the existing game theoretic solutions were designed for IEEE 802.11 WLAN and WSN. In this work, we present a dynamic game in which nodes can select and adapt their strategies of play according to the 'state of the game' and their energy level in order to increase their utility whenever their utility declined. Our model enables resources constrained nodes to optimised their strategies individually based upon the current state of the game and their available resources. Our analysis and simulation results suggest an improvement in utility, and fairness in channel sharing, as well as efficiency in energy usage in our dynamic model and hence performance and security in our scheme over the default IEEE 802.15.4 access mechanism.

The current trend in developing smart technology for the Internet of Things (IoT) has motivated a lot of research interest in optimising data transmission or minimising energy consumption, but with little evidence of proposals for achieving both objectives in a single model. Using the concept of game theory, we develop a new MAC protocol for IEEE 802.15.4 and IoT networks in which we formulate a novel expression for the players' utility function and establish a stable Nash Equilibrium (NE) for the game. The proposed IEEE 802.15.4 MAC protocol is modelled as a smart game in which analytical expressions are derived for channel access probability, data transmission probability and energy used. These analytical expressions are used in formulating an Optimization Problem (OP) that maximizes data transmission and minimizes energy consumption by nodes. The analysis and simulation results suggest that the proposed scheme is scalable and achieves better performance in terms of data transmission, energy efficiency and longevity, when compared with the default IEEE 802.15.4 access mechanism.

The development of electronic voting applications remains an active area of research and this has led to the proposal and implementation of many models based on blockchains. However, most of the proposed models are partially decentralized solutions, in which the blockchain is used as a storage media for votes while the application is written in programming tools such as HTML, CSS, and JavaScript. This makes them vulnerable to attacks such as Denial of Service (DoS) attacks, Single Point of Failure (SPF), and fraudulent record modification.In this paper, we propose a fully decentralized electronic voting application, SEVA, in which we placed the whole application (code and data) in Ethereum to protect the application from vulnerabilities. Additionally, we propose a new consensus algorithm, Proof of Smart Vote (PoSV) for SEVA, as a viable energy-saving alternative to the energy-intensive Proof of Work (PoW). We implemented and evaluated SEVA with PoSV and compared it with a partially decentralized model of the application.

<div>Abstract—Despite the various advantages inherent in the use of blockchain technology, blockchain application platforms are characterized by bottlenecks, latency, energy inefficiency, time inefficiency, low transaction throughput, vulnerability to 51% attacks, and a lack of fairness in the sharing of mining proceeds. These challenges are currently affecting the performance of this technology, hindering its rapid development and adoption for real-time applications such as Electronic Voting Applications (EVAs). It is well known that the consensus mechanism responsible for the security and consistency features of a blockchain, is also responsible for most of the above challenges.</div><div>In this paper, a new consensus mechanism, Proof of Vote (PoV) is proposed, a lightweight consensus mechanism specifically adapted for EVA, as a replacement for the heavyweight Proof of Work (PoW) consensus algorithm. We use the Ethereum blockchain as a decentralized application platform, in which we develop a decentralized electronic voting application (ADEVA), replacing the Ethereum PoW consensus algorithm with the proposed PoV consensus algorithm. Thus we implemented ADEVA with PoV and compared it to the two major consensus mechanisms: Proof of work (PoW) and Proof of Stake (PoS). We found that PoV enhanced the performance of ADEVA over and above that achieved using PoW and PoS. The low resource utilization and high transaction throughput of ADEVA with PoV makes it a scalable solution for real-world EVAs.</div>