Efficient Protection in MPλS Networks Using Backup Trees: Part Two—Simulations

In Part One of this study [1], we presented three approaches for organizing backup tree (BT) protection, where a BT was used to protect a group of working paths (WPs) against single failures. Shared BT protection uses less capacity compared to d edicated (path) protection (DP), while having the same fast recovery. Using shared BT protection is particularly suitable for multi-protocol lambda switching (MPS) networks and can save about 15% capacity resources compared to DP. In this paper, we present a simulation study in which we apply the approaches presented in Part One for several network topologies with different demand scenarios. The effects of network and demand characteristics on the capacity gain obtained with these approaches are analyzed. In addition, the comparison between BTs and 1 : N protection is made.     

MEM-DnP—A Novel Energy Efficient Approach for Memory Integrity Detection and Protection in Embedded Systems

The pervasiveness of modern day embedded systems has led to the storing of huge amounts of sensitive information in them. These embedded devices often have to operate under insecure environments and are hence susceptible to software and physical attacks. Thus, security has been and will remain one of the prime concerns in the embedded systems. Although a lot of hardware and software techniques have been proposed to provide high levels of security, they are hampered by the trade-offs created by the design constraints in embedded systems. This paper presents a novel energy efficient approach for MEMory integrity Detection and Protection (MEM-DnP). The key feature of the proposed MEM-DnP is that it can be adaptively tuned to a memory integrity verification module by using a sensor module. This significantly reduces the energy overheads imposed on an embedded system as compared to the conventional memory integrity verification mechanisms. The simulation results show that the average energy saved in the combined detection and protection mechanism ranges from 85.5 % to 99.998 %. This is substantially higher compared to the results achieved in basecase simulations with traditional memory integrity verification techniques.     

Cooperative MAC Design in Multi-Hop Wireless Networks—Part II: When Source and Destination are Two-Hops Away from Each Other

Ubiquitous and pervasive computing and networking are envisaged as part of the future 5G wireless communication landscape where devices which are multi-hops away from each other are connected in a cooperative way. In this paper, we investigate a challenging case in cooperative communications where source and destination are two-hops away from each other. From the perspective of MAC design, we propose a novel MAC protocol which enables two-hop cooperative communications by involving one or more one-hop neighbors of both source and destination as the relays for cooperative communication. To do so, a concept referred to as Multiple Relay Points (MRPs) has been introduced and the MRPs are selected by jointly considering the link quality of both hops. In addition to employing a static scheme which always uses a fixed number of relays for cooperative communication, we have also proposed an adaptive scheme which can optimally adjust the number of relays flexibly according to channel conditions. Through performance evaluation and comparison with the original IEEE 802.11 based scheme, we demonstrate that more reliable communications, reduced transmission power and significant throughput improvement can be achieved by using our two-hop cooperative MAC protocol, especially when operated in the adaptive mode.     

Electric and magnetic optical polaron in quantum dot——Part 1: strong coupling

We investigated the influence of electric field and magnetic field on the ground state energy of polaron in spherical semiconductor quantum dot (QD) using a modified Lee Low Pines (LLP) method. The numerical results show the increase of the ground state energy with the increase of the electric field and the decreasing with the magnetic field. The modulation of the electric field, magnetic field and the confinement lengths lead to the control of the decoherence of the system.     

On the Effects of Frequency Scaling Over Capacity Scaling in Underwater Networks—Part I: Extended Network Model

In this two-part paper, information-theoretic capacity scaling laws are analyzed in an underwater acoustic network with n regularly located nodes on a square, in which both bandwidth and received signal power can be limited significantly. Parts I and II deal with an extended network of unit node density and a dense network of unit area, respectively. In both cases, a narrow-band model is assumed where the carrier frequency is allowed to scale as a function of n, which is shown to be crucial for achieving the order optimality in multi-hop (MH) mechanisms. We first characterize an attenuation parameter that depends on the frequency scaling as well as the transmission distance. Upper and lower bounds on the capacity scaling are then derived. In Part I, we show that the upper bound on capacity for extended networks is inversely proportional to the attenuation parameter, thus resulting in a highly power-limited network. Interestingly, it is shown that the upper bound is intrinsically related to the attenuation parameter but not the spreading factor. Furthermore, we propose an achievable communication scheme based on the nearest-neighbor MH transmission, which is suitable due to the low propagation speed of acoustic channel, and show that it is order-optimal for all operating regimes of extended networks. Finally, these scaling results are extended to the case of random node deployments providing fundamental limits to more complex scenarios of extended underwater networks.     

On the Effects of Frequency Scaling Over Capacity Scaling in Underwater Networks—Part II: Dense Network Model

This is the second in a two-part series of papers on information-theoretic capacity scaling laws for an underwater acoustic network. Part II focuses on a dense network scenario, where nodes are deployed in a unit area. By deriving a cut-set upper bound on the capacity scaling, we first show that there exists either a bandwidth or power limitation, or both, according to the operating regimes (i.e., path-loss attenuation regimes), thus yielding the upper bound that follows three fundamentally different information transfer arguments. In addition, an achievability result based on the multi-hop (MH) transmission is presented for dense networks. MH is shown to guarantee the order optimality under certain operating regimes. More specifically, it turns out that scaling the carrier frequency faster than or as $n^{1/4}$ is instrumental towards achieving the order optimality of the MH protocol.     

Correction to: Attack Resilient and Efficient Protocol Based on Greedy Perimeter Coordinator Routing—Mobility Awareness for Preventing the Attack in the VANET

Wireless Personal Communications -     

Optimum antireflection coatings for heteroface AlGaAs/GaAs solar cells—Part II: The influence of uncertainties in the parameters of window and antireflection coatings

This paper details both theoretical and experimental results of an enhanced model to design MgF₂/ZnS double-layer antireflection coatings for AlGaAs/GaAs heteroface solar cells. The main contribution of this work is that a method for taking technological tolerances or uncertainties into account in the optically relevant parameters for antireflection coating design is presented. This is done by the calculation of contours of quasi-optimum performance for a certain range of variation of the uncertain parameters. A number of experiments testing different aspects of the predictions made by the model are commented on, showing good agreement with the calculated performance. Unwanted window oxidation, described in Part I of this work, has proven to be the key factor influencing quasi-optimum contours.