This paper proposes a reliable data aggregation scheduling that uses caching and re-transmission based on track topology. In the proposed scheme, a node detects packet losses by overhearing messages that includes error indications of the child nodes, from its neighbor nodes. If packet losses are detected, as a backup parent, the node retransmits the lost packet. A retransmission strategy is added into the adaptive timeout scheduling scheme, which adaptively configures both the timeout and the collection period according to the potential level of an event occurrence. The retransmission steps cause an additional delay and power consumption of the sensor nodes, but dramatically increase the data accuracy of the aggregation results. An extensive simulation under various workloads shows that the proposed scheme outperforms other schemes in terms of data accuracy and energy consumption.

This paper proposes a compact three-mode H-shaped resonator bandpass filter fed by antiparallel coupled input/output lines. To investigate the resonant behavior of the H-shaped resonator, even/odd-mode resonance conditions of the resonator are first derived analytically. The multimode resonances of the H-shaped resonator filter are modeled by a multipath circuit formed with resonance paths. Moreover, a direct source/load coupling path is connected in parallel, of which the value shows a frequency dependency because of the antiparallel coupled feeding lines, thereby generating four transmission zeros (TZs) greater than the number of a theoretical limitation. The H-shaped resonator bandpass filter is synthesized, developed, and tested, showing a third-order passband response with four TZs located near the passband, and a wide stopband property.

In this paper, the function expansion based topology optimization is employed to the automatic optimization of the waveguide dispersion property, and the optimum design of low-dispersion slow-light photonic crystal waveguides is demonstrated. In order to realize low-dispersion and large group index, an objective function to be optimized is expressed by the weighted sum of the objective functions for the desired group index and the low-dispersion property, and weighting coefficients are updated through the optimization process.

This paper presents a 12-bit interpolated pipeline analog to digital converter (ADC) using body voltage controlled amplifier for current biasing and common mode feedback (CMFB). The proposed body voltage control method allows the amplifier to achieve small power consumption and large output swing. The proposed amplifier has a power consumption lower than 15.6mW, almost half of the folded cascode amplifier satisfying 12-bit, 400MS/s ADC operation. Moreover, the proposed amplifier secures 600mV output swing, which is one drain source voltage (VDS) wider compared with the telescopic amplifier. The 12-bit interpolated pipeline ADC using the proposed amplifier is fabricated in a 1P9M 90nm CMOS technology with a 1.2V supply voltage. The ADC achieves an effective number of bit (ENOB) of about 10-bit at 300MS/s and an figure of merit (FoM) of 0.2pJ/conv. when the frequency of the input signal is sufficiently low.

The relationship between different brain areas is characterized by functional networks through correlations of time series obtained from neuroimaging experiments. Due to its high spatial resolution, functional MRI data is commonly used for generating functional networks of the entire brain. These networks are comprised of the measurement points/channels as nodes and links are established if there is a correlation in the measured time series of these nodes. However, since the evaluation of correlation becomes more accurate with the length of the underlying time series, we construct in this paper functional networks from MEG data, which has a much higher time resolution than fMRI. We study in particular how the network topologies change in an experiment on ambiguity of words, where the subject first receives a priming word before being presented with an ambiguous or unambiguous target word.

Application-Specific Network-on-Chips (ASNoCs) have been proposed as a more promising solution than regular NoCs to the global communication challenges for particular applications in nanoscale System-on-Chip (SoC) designs. In ASNoC Design, one of the key challenges is to generate the most suitable and power efficient NoC topology under the constraints of the application specification. In this work, we present a two-step floorplanning (TSF) algorithm, integrating topology synthesis into floorplanning phase, to automate the synthesis of such ASNoC topologies. At the first-step floorplanning, during the simulated annealing, we explore the optimal positions and clustering of cores and implement an incremental path allocation algorithm to predictively evaluate the power consumption of the generated NoC topology. At the second-step floorplanning, we explore the optimal positions of switches and network interfaces on the floorplan. A power and timing aware path allocation algorithm is also integrated into this step to determine the connectivity across different switches. Experimental results on a variety of benchmarks show that our algorithm can produce greatly improved solutions over the latest works.

This paper describes the design of an interpolated pipeline analog-to-digital converter (ADC). By introducing the interpolation technique into the conventional pipeline topology, it becomes possible to realize a more than 10-bits resolution and several hundred MS/s ADC using low-gain open-loop amplifiers without any multiplying digital-to-analog converter (MDAC) calibration. In this paper, linearity requirement of the amplifier is analyzed with the relation of reference range and stage resolution first. Noise characteristic is also discussed with amplifier's noise bandwidth and load capacitance. After that, sampling speed and SNR characteristic are examined with various amplifier currents. Next, the resolution optimization of the pipeline stage is discussed based on the power consumption. Through the analysis, reasonable parameters for the amplifier can be defined, such as transconductance, source degeneration resistance and load capacitance. Also, optimized operating speed and stage resolution for interpolated pipelined ADC is shown. The analysis in this paper is valuable to both the design of interpolated pipeline ADCs and other circuits which incorporate interpolation and amplifiers.

Three dimensional integration using Through-Silicon Vias (TSVs) offers short inter-layer interconnects and higher packing density. In order to take advantage of these attributes, a novel hybrid 3D NoC-Bus architecture is proposed in the paper. For vertical link, a Fake Token Bus architecture is elaborated, which utilizes the bandwidth efficiently by updating token synchronously. Based on this bus architecture, a methodology of hybrid 3D NoC-Bus design is introduced. The network hybridizes with the bus in vertical link and distributes long links of the full connected network into different layers, which achieves a network with a diameter of only 3 hops and limited radix. In addition, a congestion-aware routing algorithm applied to the hybrid network is proposed. The algorithm routes packets in horizontal firstly when the bus is busy, which balances the communication and reduces the possibility of congestion. Experimental results show that our network can achieve a 34.4% reduction in latency and a 43% reduction in power consumption under uniform random traffic and a 36.9% reduction in latency and a 48% reduction in power consumption under hotspot traffic over regular 3D mesh implementations on average.

We evaluate the rich-club property of the Internet topology at the autonomous system (AS) level by comparing the Internet AS graphs of traceroute and BGP, and the synthetic graphs of PFP model. The results indicate that, for rich-club coefficient, PFP model can exactly match traceroute AS graphs in the early years around 2002, but it has significantly deviated from the grown AS graphs since about 2010.

Network topology significantly affects network cost, path length, link load distribution, and reliability, so we need to consider multiple criteria with different units simultaneously when designing a network's topology. The analytic hierarchy process (AHP) is a technique of balancing multiple criteria in order to reach a rational decision. Using AHP, we can reflect the relative importance of each criterion on the evaluation result; therefore, we have applied it to network topology evaluation in past research. When evaluating network topologies using AHP, we need to construct the set of topology candidates prior to the evaluation. However, the time required to construct this set greatly increases as the network size grows. In this paper, we propose applying a binary partition approach for constructing a topology candidate set with dramatically reduced calculation time. To reduce the calculation time, we introduce an upper limit for the total link length. Although the results of AHP are affected by introducing the upper limit of the total link length, we show that desirable topologies are still selected in AHP.

In this letter, we propose a Cooperation-aware topology control scheme with Opportunistic Interference Cancellation (COIC) to improve network capacity in wireless ad hoc networks by jointly considering both upper layer network capacity and physical layer cooperative communications with interference cancellation. We show that the benefits brought by cooperative communications are opportunistic and rely on network structures and channel conditions. Such opportunistic advantages have significant impacts on network capacity, and our proposed COIC can effectively capture these opportunities to substantially improve network capacity.

Internet behavior is becoming more complex due to ever-changing networking technologies and applications. Thus, understanding and controlling the complex behavior of the Internet are important for designing future networks. One of the complex behaviors of the Internet is traffic dynamics. Previous studies revealed that flow control in the transport layer affects the traffic dynamics of the Internet. However, it is not clear how the topological structure impacts traffic dynamics. In this paper, we investigate packet delay dynamics and traffic fluctuation in ISP router-level topologies where the degree distribution exhibits a power-law nature, and the nodes interact via end-to-end feedback control functionality. We show the packet delay dynamics of the BA topologies generated by the Barabasi-Albert (BA) model and the ISP router-level topologies. Simulation results show that the end-to-end delay distributions exhibit a heavy tail in the TCP model. Moreover, the number of links with highly fluctuating queue length increases dramatically compared to that in the stop-and-wait model. Even in this case, the high-modularity structures of the ISP topologies reduce the number of highly fluctuating links compared with the BA topologies.

Topology control is one of the key issues in wireless networks. In this letter, we propose a simple topology control algorithm based on Connected Dominant Set (CDS) theory. The proposed algorithm uses less memory and less overhead cost than other existing schemes, and is therefore appropriate for implementation in wireless sensor networks. We will prove that the algorithm can form a CDS and guarantee network connectivity. The performance of our algorithm is demonstrated by simulation results.

As the Internet represents a key social infrastructure, its reliability is essential if we are to survive failures. Physical connectivity of networks is also essential as it characterizes reliability. There are collaboration structures, which are topological structures where two or more nodes are connected to a node, and collaboration structures are observed in transcriptional regulatory networks and the router-level topologies of ISPs. These collaboration structures are related to the reliability of networks. The main objective of this research is to find whether an increase in collaboration structures would improve reliability or not. We first categorize the topology into a three-level hierarchy for this purpose, i.e., top-level, middle-level, and bottom-level layers. We then calculate the reliability of networks. The results indicate that the reliability of most transcriptional regulatory networks is higher than that of one of router-level topologies. We then investigate the number of collaboration structures. It is apparent that there are much fewer collaboration structures between top-level nodes and middle-level nodes in router-level topologies. Finally, we confirm that the reliability of router-level topologies can be improved by rewiring to increase the collaboration structures between top-level and middle-level nodes.

Bittorrent is one of the most popular and successful applications in the current Internet. However, we still have little knowledge about the topology of real Bittorrent swarms, how dynamic the topology is, and how it affects overall behavior. This paper describes an experimental study of the overlay topologies of real-world Bittorrent networks, focusing on the activity of the nodes of its P2P topology and especially their dynamic relationships. Peer Exchange Protocol (PEX) messages are analyzed to infer topologies and their properties, capturing the variations of their behavior. Our measurements, verified using the Kolmogorov-Smirnov goodness of fit test and the likelihood ratio test and confirmed via simulation, show that a power-law with exponential cutoff is a more plausible model than a pure power-law distribution. We also found that the average clustering coefficient is very low, supporting this observation. Bittorrent swarms are far more dynamic than has been recognized previously, potentially impacting attempts to optimize the performance of the system as well as the accuracy of simulations and analyses.

Network structures can be found in almost any kind of natural or artificial systems as transport medium for communication between the respective nodes. In this paper we study certain key topological features of brain functional networks obtained from functional magnetic resonance imaging (fMRI) measurements. We compare complex network measures of the extracted topologies with those from Internet service providers (ISPs). Our goal is to identify important features which will be helpful in designing more robust and adaptive future information network architectures.

Network-on-Chips (NoCs) have been proposed as a solution for addressing the global communication challenges in System-on-Chip (SoC) architectures that are implemented in nanoscale technologies. For the use of NoCs to be feasible in today's industrial designs, a custom-tailored, power- efficient NoC topology that satisfies the application characteristics is required. In this work, we present a design methodology that automates the synthesis of such application-specific NoC topologies. We present a method which integrates partitioning into floorplanning phase to explore optimal clustering of cores during floorplanning with minimized link and switch power consumption. Based on the size of applications, we also present an Integer Linear Programming and a heuristic method to place switches and network interfaces on the floorplan. Then, a power and timing aware path allocation algorithm is carried out to determine the connectivity across different switches. We perform experiments on several SoC benchmarks and present a comparison with the latest work. For small applications, the NoC topologies synthesized by our method show large improvements in power consumption (27.54%), hop-count (4%) and running time (66%) on average. And for large applications, the synthesized topologies result in large power (31.77%), hop-count (29%) and running time (94.18%) on average.

The emergence of new services in the cloud computing era has made smooth service migration an important issue in access networks. However, different types of equipment are typically used for the different services due to differences in service requirements. This leads to an increase in not only capital expenditures but also operational expenditures. Here we propose using a service adaptive approach as a solution to this problem. We analyze the requirements of a future access network in terms of service, network, and node. We discuss available access network technologies including the passive optical network, single star network. Finally, we present a future service adaptive access/aggregation network and its architecture along with a programmable optical line terminal and optical network unit, discuss its benefit, and describe example services that it would support.

When a graph can be decomposed into components of well-connected subgraphs, it is possible to speed up random walks by taking advantage of topology of the graph. In this paper, a modified Metropolis random walk scheme is introduced and conditions are given when it performs better than the original Metropolis algorithm.

The peer-assisted streaming paradigm has been widely employed to distribute live video data on the internet recently. In general, the mesh-based pull approach is more robust and efficient than the tree-based push approach. However, pull protocol brings about longer streaming delay, which is caused by the handshaking process of advertising buffer map message, sending request message and scheduling of the data block. In this paper, we propose a new approach, mesh-push, to address this issue. Different from the traditional pull approach, mesh-push implements block scheduling algorithm at sender side, where the block transmission is initiated by the sender rather than by the receiver. We first formulate the optimal upload bandwidth utilization problem, then present the mesh-push approach, in which a token protocol is designed to avoid block redundancy; a min-cost flow model is employed to derive the optimal scheduling for the push peer; and a push peer selection algorithm is introduced to reduce control overhead. Finally, we evaluate mesh-push through simulation, the results of which show mesh-push outperforms the pull scheduling in streaming delay, and achieves comparable delivery ratio at the same time.