Robust provisioning of multicast sessions in cognitive radio networks

Today\u27s wireless networks use fixed spectrum over long term and fixed geographical regions. However, spectrum utilization varies by time and location, which leads to temporal and special spectrum underutilization. Therefore, new ways to improve spectrum utilization are needed. Cognitive radio is an emerging technology that enables dynamic sharing of the spectrum in order to overcome spectrum underutilization problem. Users in cognitive radio networks are either primary or secondary users. A primary user is the user who is licensed to use a channel, and has priority to use it over any other user. The secondary user uses a licensed spectrum channel opportunistically when a primary user is idle. Hence, it has to vacate the channel within a certain tolerable interference time when the primary user appears. As a result of this, the secondary user needs to find backup channels to protect the links it is using from primary user\u27s interruption. In this thesis, we concentrate on supporting the multicast service mode using cognitive radio networks. Moreover, we are concerned with supporting this mode of service such that it is robust in the face of failures. The type of failures we are interested in is channel disappearance due to the resumption of activities by primary users. We develop three algorithms which provide robust multicasting in such networks. Our three proposed algorithms are: 1) multicast sessions protection without link-sharing, 2) multicast sessions protection with link-sharing and 3) multicast sessions protection using rings. These algorithms provision multiple multicast sessions, and protect them against single primary user interruption at a time. They also take into account that the activities of a primary user may disrupt communication in several groups, of secondary users, which are referred to as Shared Primary User Risk Group (SPURG). The objective of the proposed algorithms is to increase the number of sessions that can be accommodated in the network and minimize the cost of provisioning the sessions. Multicast sessions protection with/without link-sharing algorithms generate a primary tree for each multicast session, and protect each link of it using a backup tree. Multicast sessions protection with link-sharing allows backup trees to share some links of the primary tree within the same session, and share some links within backup trees for any session. In the third algorithm, a ring is generated where it starts and ends at the source node, and passes through all destination nodes. Also, we compare the performances of our three proposed algorithms. Simulation results show that the number of accommodated sessions in the network increases and the cost of multicast sessions decreases when the number of available channels increases or the session size decreases. Also, multicast sessions protection with link-sharing algorithm outperforms the other two algorithms in terms of the number of sessions in the network. On the other hand, multicast sessions protection using rings achieves the lowest cost for multicast sessions compared with the other two proposed algorithms

Multicast broadcast services support in OFDMA-based WiMAX systems [Advances in mobile multimedia]

Multimedia stream service provided by broadband wireless networks has emerged as an important technology and has attracted much attention. An all-IP network architecture with reliable high-throughput air interface makes orthogonal frequency division multiplexing access (OFDMA)-based mobile worldwide interoperability for microwave access (mobile WiMAX) a viable technology for wireless multimedia services, such as voice over IP (VoIP), mobile TV, and so on. One of the main features in a WiMAX MAC layer is that it can provide'differentiated services among different traffic categories with individual QoS requirements. In this article, we first give an overview of the key aspects of WiMAX and describe multimedia broadcast multicast service (MBMS) architecture of the 3GPP. Then, we propose a multicast and broadcast service (MBS) architecture for WiMAX that is based on MBMS. Moreover, we enhance the MBS architecture for mobile WiMAX to overcome the shortcoming of limited video broadcast performance over the baseline MBS model. We also give examples to demonstrate that the proposed architecture can support better mobility and offer higher power efficiency

Na neizrazitoj logici zasnovano upravljanje frekvencijom za ODMRP u mobilnim ad hoc mrežama

On Demand Multicast Routing Protocol (ODMRP) is a popular solution designed for ad hoc networks with mobile hosts. Its efficiency, simplicity, and robustness to mobility render it one of the most widely used multicast routing protocols in Mobile Ad hoc NETworks (MANET). In ODMRP, there is no input rate control for upper layer traffic. So, it’s possible that high dense traffic flow causes congestion in networks. In this work, an enhancement to ODMRP is proposed referred to as fuzzy logic based Rate Control ODMRP (FRC-ODMRP). FRC-ODMRP attempts to adapt the arrival rate from upper layers to the state in the network by using feedback information from receivers of the multicast group. Accordingly, source comes up with a decision whether to increase or decrease its transmission rate based on information collected from the receivers. In this research, delay and packet delivery ratio reconsidered as indicators of congestion in addition to number of received packets. Simulation results demonstrate that FRC-ODMRP achieves significant performance improvements in comparison to conventional ODMRP and QoS-ODMRP. Indeed, it efficiently handles simultaneous traffic flows such that no one could dominate available bandwidth of networks.On Demand Multicast Routing Protocol (ODMRP) popularno je rješenje namijenjeno ad hoc mrežama s mobilnim domaćinima. Efikasnost, jednostavnost i robusnost u smislu mobilnosti učini su ovu metodu jednom od najraširenijih multicast protokola u ad hoc mobilnim mrežam (eng. MANET). Kod ODMRP-a nema upravljanja ulaznom frekvencijom za promet višeg sloja. Zbog toga je moguće da gusti promet uzrokuje zagušenje u mrežama. U ovome je radu predstavljeno poboljšanje ODMRP-a nazvano ODMRP zasnovan na fuzzy logici (FRC-ODRMP). FRC-ODRMP pokušava prilagoditi dolazne signale iz viših slojeva stanju u mreži koristeći povratnu informaciju od primatelja iz multicast grupe. Prilikom istraživanja dodatno je uzet omjer kašnjenja i dostavljenih paketa kao pokazatelj zagušenosti mreže uz broj dostavljenih paketa. Simulacijski rezultati pokazuju kako FRC-ODMRP značajno poboljšava performanse u odnosu na konvencionalni ODMRP i Qos-ODMRP. Dodatno, simultani promet efikasno je upravljan tako da nitko ne može dominirati dostupnom propusnošću mreže

Software Defined Networks based Smart Grid Communication: A Comprehensive Survey

The current power grid is no longer a feasible solution due to ever-increasing user demand of electricity, old infrastructure, and reliability issues and thus require transformation to a better grid a.k.a., smart grid (SG). The key features that distinguish SG from the conventional electrical power grid are its capability to perform two-way communication, demand side management, and real time pricing. Despite all these advantages that SG will bring, there are certain issues which are specific to SG communication system. For instance, network management of current SG systems is complex, time consuming, and done manually. Moreover, SG communication (SGC) system is built on different vendor specific devices and protocols. Therefore, the current SG systems are not protocol independent, thus leading to interoperability issue. Software defined network (SDN) has been proposed to monitor and manage the communication networks globally. This article serves as a comprehensive survey on SDN-based SGC. In this article, we first discuss taxonomy of advantages of SDNbased SGC.We then discuss SDN-based SGC architectures, along with case studies. Our article provides an in-depth discussion on routing schemes for SDN-based SGC. We also provide detailed survey of security and privacy schemes applied to SDN-based SGC. We furthermore present challenges, open issues, and future research directions related to SDN-based SGC.Comment: Accepte

Mobile Ad-Hoc Networks

Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of-the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: quality-of-service and video communication, routing protocol and cross-layer design. A few interesting problems about security and delay-tolerant networks are also discussed. This book is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks