5,121 research outputs found
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
Minimum power multicasting with delay bound constraints in Ad Hoc wireless networks
In this paper, we design a new heuristic for an important extension of the minimum power multicasting problem in ad hoc wireless networks. Assuming that each transmission takes a fixed amount of time, we impose constraints on the number of hops allowed to reach the destination nodes in the multicasting application. This setting would be applicable in time critical or real time applications, and the relative importance of the nodes may be indicated by these delay bounds. We design a filtered beam search procedure for solving this problem. The performance of our algorithm is demonstrated on numerous test cases by benchmarking it against an optimal algorithm in small problem instances, and against a modified version of the well-known Broadcast Incremental Power (BIP) algorithm 20 for relatively large problems
Exploiting AWG Free Spectral Range Periodicity in Distributed Multicast Architectures
Modular optical switch architectures combining wavelength routing based on
arrayed waveguide grating (AWG) devices and multicasting based on star couplers
hold promise for flexibly addressing the exponentially growing traffic demands
in a cost- and power-efficient fashion. In a default switching scenario, an
input port of the AWG is connected to an output port via a single wavelength.
This can severely limit the capacity between broadcast domains, resulting in
interdomain traffic switching bottlenecks. In this paper, we examine the
possibility of resolving capacity bottlenecks by exploiting multiple AWG free
spectral ranges (FSRs), i.e., setting up multiple parallel connections between
each pair of broadcast domains. To this end, we introduce a multi-FSR
scheduling algorithm for interconnecting broadcast domains by fairly
distributing the wavelength resources among them. We develop a general-purpose
analytical framework to study the blocking probabilities in a multistage
switching scenario and compare our results with Monte Carlo simulations. Our
study points to significant improvements with a moderate increase in the number
of FSRs. We show that an FSR count beyond four results in diminishing returns.
Furthermore, to investigate the trade-offs between the network- and
physical-layer effects, we conduct a cross-layer analysis, taking into account
pulse amplitude modulation (PAM) and rate-adaptive forward error correction
(FEC). We illustrate how the effective bit rate per port increases with an
increase in the number of FSRs. %We also look at the advantages of an
impairment-aware scheduling strategy in a multi-FSR switching scenario
Algorithmic Aspects of Energy-Delay Tradeoff in Multihop Cooperative Wireless Networks
We consider the problem of energy-efficient transmission in delay constrained
cooperative multihop wireless networks. The combinatorial nature of cooperative
multihop schemes makes it difficult to design efficient polynomial-time
algorithms for deciding which nodes should take part in cooperation, and when
and with what power they should transmit. In this work, we tackle this problem
in memoryless networks with or without delay constraints, i.e., quality of
service guarantee. We analyze a wide class of setups, including unicast,
multicast, and broadcast, and two main cooperative approaches, namely: energy
accumulation (EA) and mutual information accumulation (MIA). We provide a
generalized algorithmic formulation of the problem that encompasses all those
cases. We investigate the similarities and differences of EA and MIA in our
generalized formulation. We prove that the broadcast and multicast problems
are, in general, not only NP hard but also o(log(n)) inapproximable. We break
these problems into three parts: ordering, scheduling and power control, and
propose a novel algorithm that, given an ordering, can optimally solve the
joint power allocation and scheduling problems simultaneously in polynomial
time. We further show empirically that this algorithm used in conjunction with
an ordering derived heuristically using the Dijkstra's shortest path algorithm
yields near-optimal performance in typical settings. For the unicast case, we
prove that although the problem remains NP hard with MIA, it can be solved
optimally and in polynomial time when EA is used. We further use our algorithm
to study numerically the trade-off between delay and power-efficiency in
cooperative broadcast and compare the performance of EA vs MIA as well as the
performance of our cooperative algorithm with a smart noncooperative algorithm
in a broadcast setting.Comment: 12 pages, 9 figure
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