Spectrum utilization efficiency in CRNs with hybrid spectrum access and channel reservation: A comprehensive analysis under prioritized traffic

in Future Generation Computer Systems (2021)

The enhancement of spectrum utilization efficiency (SUE) is a critical objective in fifth generation networks-enabled Internet of Things (5G-IoT) for providing communication opportunities to plethora of ... [more ▼]

The enhancement of spectrum utilization efficiency (SUE) is a critical objective in fifth generation networks-enabled Internet of Things (5G-IoT) for providing communication opportunities to plethora of 5G-IoT devices within the already scarce spectrum. Cognitive radio networks (CRNs) with interweave and underlay modes are foreseen to achieve this objective. The interweave mode is adequate for legacy CRNs, while the underlay mode is fitting for resource-constrained CRNs. As 5G-IoT is rapidly evolving into heterogeneous networks, CRNs enabled by hybrid underlay-interweave mode (H-mode) emerge to be the best option for SUE enhancement in 5G-IoT. In this paper, we comprehensively analyze the performance of H-mode enabled CRNs containing heterogeneous users by proposing two H-mode schemes, namely, primary user full priority (FP) and primary user partial priority (PP). The schemes consider secondary users (SUs) with high and low priorities. In FP, primary users (PUs) have absolute priority in channel access while in PP, SUs with certain attributes are immune from interruptions. Additionally, to accommodate interrupted users, a simple yet efficient channel reservation algorithm is proposed, which divides the given channels into reserved and unreserved bands. Using Markov chain modeling, expressions are derived for core SUE related performance metrics including service completion rate (SCR), blocking probability (BP), network serveability (NS), successful service completion probability (SSCP), handoff probability, and throughput, independently for PUs and all types of SUs. Performance of the proposed schemes is analyzed under varying channel failure rates and network traffic loads. Efficacy of the proposed schemes is shown through analytical and simulation results against state-of-the-art. Improvements of up to 67% in BP and 83% in cost efficiency are recorded as compared to the state-of-the-art. Likewise, up to 10% and 84% difference in PUs’ and SUs’ SSCP, respectively, and up to 17% and 93% difference in PUs’ and SUs’ SCR, respectively, are noted. Similarly, up to 85% performance difference in NS is recorded. Moreover, up to 35% improvement in throughput in H-mode is witnessed. Lastly, handoff probability is found to be increased by 5%. [less ▲]

Enhanced Lightning Network (off-chain)-based micropayment in IoT ecosystems

in Future Generation Computer Systems (2020)

Information is being seen as the new “oil” for companies. Trading and negotiating personal data, which includes data generated by owned smart devices, is gaining attention and acceptance in the Internet ... [more ▼]

Information is being seen as the new “oil” for companies. Trading and negotiating personal data, which includes data generated by owned smart devices, is gaining attention and acceptance in the Internet of Things (IoT) era. There is a global trend to move towards open innovation ecosystems that allow data owners to have better control over their data and privacy, choosing if/what and with whom to share/trade specific data streams. Nonetheless, this requires the design of IoT ecosystems that integrate automatic enforcing mechanisms to guarantee the delivery of the negotiated data, or still the capability of making near-instantaneous payments for the data (in the form of micro-units). This paper discusses the requirements that need to be fulfilled to properly support (micro)-payment in IoT, and further the extent to which different blockchain technologies can fulfill those requirements. Based on this analysis, our paper progresses the current state-of-the-art in three-respect: (i) by carrying out a benchmark performance analysis between LN and other-like solutions; (ii) by integrating the Lightning Network (LN) off-chain technology within an existing IoT ecosystem, developed as part of the bIoTope H2020 project, and (iii) by designing a novel algorithm for payment channel fee reduction. Experiments carried out in this paper show that LN outperforms traditional blockchain solutions under IoT-specific constraints and objectives, and that an optimal parameter setting of the proposed algorithm can be identified. [less ▲]

Hopfield neural network for simultaneous job scheduling and data replication in grids

in Future Generation Computer Systems (2013), 29(8), 1885-1900

This paper presents a novel heuristic approach, named JDS-HNN, to simultaneously schedule jobs and replicate data files to different entities of a grid system so that the overall makespan of executing all ... [more ▼]

This paper presents a novel heuristic approach, named JDS-HNN, to simultaneously schedule jobs and replicate data files to different entities of a grid system so that the overall makespan of executing all jobs as well as the overall delivery time of all data files to their dependent jobs is concurrently minimized. JDS-HNN is inspired by a natural distribution of a variety of stones among different jars and utilizes a Hopfield Neural Network in one of its optimization stages to achieve its goals. The performance of JDS-HNN has been measured by using several benchmarks varying from medium- to very-large-sized systems. JDS-HNN’s results are compared against the performance of other algorithms to show its superiority under different working conditions. These results also provide invaluable insights into scheduling and replicating dependent jobs and data files as well as their performance related issues for various grid environments. [less ▲]