Journal of High Speed Networks - Volume 20, issue 3

Authors: Meroufel, Bakhta | Belalem, Ghalem

Article Type: Research Article

Abstract: Fault tolerance is actually an essential issue in cloud computing to face failures and minimize their damages. The checkpointing is a powerful fault tolerance technique that consists of saving the transient state of a computation system on a persistent storage from which the execution state can be restarted in case of failure. The coordinated checkpointing is an efficient checkpointing strategy because it is domino effect-free and it needs only the last stored checkpoint to ensure a consistent state. In this paper we propose a lightweight coordinated checkpointing for cloud computing that minimizes the overload of classical coordinated checkpointing by minimizing …the number of the participating virtual machines (VMs) in each checkpointing interval. The experimental results prove that our proposal reduces the overload and improves the system performances. Show more

Keywords: Cloud computing, fault tolerance, checkpoints, rollback, data center, virtual machine, overload, Input/Output, distributed system, performances

DOI: 10.3233/JHS-140492

Citation: Journal of High Speed Networks, vol. 20, no. 3, pp. 131-143, 2014

Authors: Salvo Rossi, Pierluigi | Ciuonzo, Domenico

Article Type: Research Article

Abstract: In this paper we explore the possibility of using Energy-Division Multiple Access (EDMA) scheme for uplink communications in a cognitive radio context in order to allow transmission to unlicensed users overlapping with the primary user in both time and frequency domains. The proposed solution is energy consuming for unlicensed users, thus represents a viable solution when spectral efficiency and/or latency are more crucial than energy constraints. Simulation results in scenarios with Orthogonal Frequency Division Multiplexing (OFDM) transmissions, both uncoded and coded cases, are presented.

Keywords: Cognitive radio, interference management, multiple access, multiuser detection, successive decoding

DOI: 10.3233/JHS-140493

Citation: Journal of High Speed Networks, vol. 20, no. 3, pp. 145-152, 2014

Authors: Elgohary, Ashraf | Sobh, Tarek S. | Nouh, Sayed A. | Zaki, M.

Article Type: Research Article

Abstract: Critical MANET environments such as military battlefields and disaster recovery operations impose a number of requirements such as the need for robustness and performance within high mobility scenarios; also, they impose some constraints such as Hostile attacks, RF range and cost, battery limitations. We studied the core-based routing protocol PUMA, in addition to two ant-based routing protocols MANHSI and AAMRP to identify their drawbacks while working in critical MANETs. Finally, we propose a novel routing protocol named Adaptive Secure Headship Following Induction Keeping (ASHFIK) to work ideally in critical MANETs scenarios. In this paper, we discuss the structure …of ASHFIK, which uses a new mechanism called the Headship Mechanism, which provides always a standby core to work if the original core is down. After studying performance analysis of ASHFIK compared to PUMA, we can conclude that ASHFIK is particular suitable for most critical MANETs scenarios. Show more

Keywords: Critical MANET, core based routing, PUMA, MANHSI, AAMRP, ASHFIK, mesh based multicasting, ACO, trust and reputation models

DOI: 10.3233/JHS-140494

Citation: Journal of High Speed Networks, vol. 20, no. 3, pp. 153-168, 2014

Authors: Chao, I-Fen | Chiou, Chuei-Sheng

Article Type: Research Article

Abstract: OFDMA-based networks have been considered to be a promising solution to wireless networks especially for broadband multimedia mobile services. The major challenges pertaining to such OFDMA-based networks are to design a medium access control scheme that is expected to exploit multi-channel multi-rate diversity and with QoS provision. The previous existing scheduling algorithms either target at maximizing system throughput while starving the low-rate users, or focus on throughput fairness but seriously decreasing the system throughput. While proportional fair (PF) has emerged as a prominent candidate in wireless networks, as it achieves a good tradeoff between system throughput and fairness, PF still …leads to low throughput of bad channel users, resulting in limiting the attainable QoS throughput for the entire system. In this paper, we propose a QoS-enhanced proportional fair (QEPF) scheduling algorithm, which aims at maximizing QoS throughput while still retaining fairness as well as maximizing system throughput in downlink OFDMA networks. QEPF proposes a QoS-enhanced PF-based utility function, which supports QoS and is a low-complexity algorithm for multi-channel OFDMA networks. We demonstrate via extensive simulation results, that QEPF outperforms PF in terms of system throughput and mean delay. The results illustrate that QEPF surprisingly attains great performance for poor channel users, while not sacrifices the performance of good channel users. Furthermore, the results show that QEPF well accommodates nearly twice the amount of high priority data than PF does. Show more

Keywords: Orthogonal Frequency Division Multiple Access (OFDMA), proportional fairness (PF), Quality of Service (QoS)

DOI: 10.3233/JHS-140495

Citation: Journal of High Speed Networks, vol. 20, no. 3, pp. 169-177, 2014

Authors: Chen, Chin-Ling | Kuo, Tsung-Min | Shih, Tzay-Farn

Article Type: Research Article

Abstract: Vehicular communications have become an increasingly important communication technique worldwide. The current limitations of vehicular communications are not determined by capability or authentication but by security infrastructure. In 2005, a proposal for vehicular network security was discussed by Raya and Hubaux. However, such protocol is not practical and is unsafe for use in VANETs. In addition, handoff has become a relevant issue for vehicles moving from one region to another. For these reasons, we propose a secure communication and handoff protocol. In our protocol, a vehicle can enjoy seamless service between heterogeneous vehicular networks. Furthermore, vehicular communication is made more …secure and ubiquitous. Show more

Keywords: Authentication, handoff, VANET, confidentiality, non-repudiation

DOI: 10.3233/JHS-140496

Citation: Journal of High Speed Networks, vol. 20, no. 3, pp. 179-192, 2014