Buffer management and delivery latency in various networks have been extensively studied. However, little work has considered the condition in which the traffic exhibits interpacket dependency, a common occurrence with many applications. Furthermore, the existing work related to such traffic mainly focuses on maximizing goodput and little attention has been paid to delivery latency. This paper concentrates on the delivery latency minimization problem for streaming data with packet dependencies. A novel optimization model is proposed to describe the aforementioned problem and the theoretical lower bound for delivery latency is deduced. Based on this model, a plain buffer management (PBM) algorithm is applied to the implementation of the buffer scheduling process. Afterwards, we improve the PBM algorithm under the guidance of a heuristic idea and put forward an optimal buffer management greedy (OBMG) algorithm. Experiments demonstrate that the OBMG algorithm outperforms the currently best known online (BKO) algorithm as it decreases the average delivery latency by 35.6%. In some cases, delivery latency obtained from the OBMG algorithm can be quite close to the theoretical lower bound. In addition, the OBMG algorithm can reduce CPU computational overhead by more than 12% in comparison to the BKO algorithm.

This paper investigates a frame aggregation (FA) technique in the medium access control (MAC) layer for downlink multi-user multiple input multiple output (MU-MIMO) channels in wireless local area networks (WLANs), and proposes a high-efficient FA scheme that ehances system performance: transmission performance and fairness in communication between mobile terminals (MTs). The proposed FA scheme employs novel criteria for selecting receiving MTs and wireless frame setting with a frame size adaptation mechanism for MU-MIMO transmissions. The proposed receiving MT selection gives higher priority to the MTs expecting higher throughput in the next MU-MIMO transmission and having large amount transmission data while reducing signaling overhead, leading to improvements in system throughput and fairness in communication. The proposed wireless frame setting, which employs hybrid A-MSDU/A-MPDU FA, achieves frame error rate (FER) better than the requirement from communication services by using A-MSDU frame size adaptation. Through system-level simulation, the effectiveness of the proposed scheme is validated for downlink MU-MIMO channels in WLANs.

The reputation-based majority-voting approach is a promising solution for detecting malicious workers in a cloud system. However, this approach has a drawback in that it can detect malicious workers only when the number of colluders make up no more than half of all workers. In this paper, we simulate the behavior of a reputation-based method and mathematically analyze its accuracy. Through the analysis, we observe that, regardless of the number of colluders and their collusion probability, if the reputation value of a group is significantly different from those of other groups, it is a completely honest group. Based on the analysis result, we propose a new method for distinguishing honest workers from colluders even when the colluders make up the majority group. The proposed method constructs groups based on their reputations. A group with the significantly highest or lowest reputation value is considered a completely honest group. Otherwise, honest workers are mixed together with colluders in a group. The proposed method accurately identifies honest workers even in a mixed group by comparing each voting result one by one. The results of a security analysis and an experiment show that our method can identify honest workers much more accurately than a traditional reputation-based approach with little additional computational overhead.

In the development of inter-vehicle communication systems for a prevention of car crashes, it is important to know path loss characteristics at blind intersections in urban area. Thus field experiments and numerical simulations have been performed. By the way, transparent waves from building walls are not considered in many cases. The reason why is that it is the worst case in terms of the path loss at blind intersection surrounded by buildings in urban area. However, it would be important to know the effect of transparent wave on the path loss in actual environments. On the other hand, path loss models have been proposed to estimate easily the path loss in urban environment. In these models, the effect of transparent wave is not clear. In this paper, the effect of transparent wave from building walls on path loss characteristics at blind intersection in urban area is investigated by using the FDTD method. Additionally, the relationship between transparent wave and path loss models is also investigated.

In most existing centralized lighting control systems, the lighting control problem (LCP) is reformulated as a constrained minimization problem and solved by linear programming (LP). However, in real-world applications, LCP is actually discrete and non-linear, which means that more accurate algorithm may be applied to achieve improvements in energy saving. In this paper, particle swarm optimization (PSO) is successfully applied for office lighting control and a linear programming guided particle swarm optimization (LPPSO) algorithm is developed to achieve considerable energy saving while satisfying users' lighting preference. Simulations in DIALux office models (one with small number of lamps and one with large number of lamps) are made and analyzed using the proposed control algorithms. Comparison with other widely used methods including LP shows that LPPSO can always achieve higher energy saving than other lighting control methods.

In this paper, a multiple-object tracking approach in large-scale scene is proposed based on visual sensor network. Firstly, the object detection is carried out by extracting the HOG features. Then, object tracking is performed based on an improved particle filter method. On the one hand, a kind of temporal and spatial dynamic model is designed to improve the tracking precision. On the other hand, the cumulative error generated from evaluating particles is eliminated through an appearance model. In addition, losses of the tracking will be incurred for several reasons, such as occlusion, scene switching and leaving. When the object is in the scene under monitoring by visual sensor network again, object tracking will continue through object re-identification. Finally, continuous multiple-object tracking in large-scale scene is implemented. A database is established by collecting data through the visual sensor network. Then the performances of object tracking and object re-identification are tested. The effectiveness of the proposed multiple-object tracking approach is verified.

SDN (Software-Defined Networking) enables software applications to program individual network devices dynamically and therefore control the behavior of the network as a whole. Incomplete programming and/or inconsistency with the network policy of SDN software applications may lead to verification issues. The objective of this paper is to describe the formal modeling that uses the process algebra called pACSR and then suggest a method to verify the firewall application running on top of the SDN controller. The firewall rules are translated into a pACSR process which acts as the specification, and packet's behaviors in SDN are also translated to a pACSR process which is a role as the implementation. Then we prove the correctness by checking whether the parallel composition of two pACSR processes is deadlock-free. Moreover, in the case of network topology changes, our verification can be directly applied to check whether any mismatches or inconsistencies will occur.

Digital phase shifters are widely used to achieve space scanning in phased array antenna, and beam pointing accuracy depends on the bit number and resolution of the digital phase shifter. This paper proposes a novel phase feeding method to reduce the phase quantization error effects. A linear formula for the beam pointing deviation of a linear uniform array in condition of phase quantization error is derived, and the linear programming algorithm is introduced to achieve the minimum beam pointing deviation. Simulations are based on the pattern of the phased array, which gives each element a certain quantization phase error to find the beam pointing deviation. The novel method is then compared with previous methods. Examples show that a 32-element uniform linear array with 5-bit phase shifters using the proposed method can achieve a higher beam-steering accuracy than the same array with 11-bit phase shifters.

In order to tackle a process-variation problem, we can define several scenarios, each of which corresponds to a particular LSI behavior, such as a typical-case scenario and a worst-case scenario. By designing a single LSI chip which realizes multiple scenarios simultaneously, we can have a process-variation-tolerant LSI chip. In this paper, we propose a multi-scenario high-level synthesis algorithm for variation-tolerant floorplan-driven design targeting new distributed-register architectures, called HDR architectures. We assume two scenarios, a typical-case scenario and a worst-case scenario, and realize them onto a single chip. We first schedule/bind each of the scenarios independently. After that, we commonize the scheduling/binding results for the typical-case and worst-case scenarios and thus generate a commonized area-minimized floorplan result. At that time, we can explicitly take into account interconnection delays by using distributed-register architectures. Experimental results show that our algorithm reduces the latency of the typical-case scenario by up to 50% without increasing the latency of the worst-case scenario, compared with several existing methods.

Visual tracking has been studied for several decades but continues to draw significant attention because of its critical role in many applications. Recent years have seen greater interest in the use of correlation filters in visual tracking systems, owing to their extremely compelling results in different competitions and benchmarks. However, there is still a need to improve the overall tracking capability to counter various tracking issues, including large scale variation, occlusion, and deformation. This paper presents an appealing tracker with robust scale estimation, which can handle the problem of fixed template size in Kernelized Correlation Filter (KCF) tracker with no significant decrease in the speed. We apply the discriminative correlation filter for scale estimation as an independent part after finding the optimal translation based on the KCF tracker. Compared to an exhaustive scale space search scheme, our approach provides improved performance while being computationally efficient. In order to reveal the effectiveness of our approach, we use benchmark sequences annotated with 11 attributes to evaluate how well the tracker handles different attributes. Numerous experiments demonstrate that the proposed algorithm performs favorably against several state-of-the-art algorithms. Appealing results both in accuracy and robustness are also achieved on all 51 benchmark sequences, which proves the efficiency of our tracker.

The goal of software testing should go beyond simply finding defects. Ultimately, testing should be focused on increasing customer satisfaction. Defects that are detected in areas of the software that the customers are especially interested in can cause more customer dissatisfaction. If these defects accumulate, they can cause the software to be shunned in the marketplace. Therefore, it is important to focus on reducing defects in areas that customers consider valuable. This article proposes a value-driven V-model (V2 model) that deals with customer values and reflects them in the test design for increasing customer satisfaction and raising test efficiency.

SSDs consist of non-mechanical components (host interface, control core, DRAM, flash memory, etc.) whose integrated behavior is not well-known. This makes an SSD seem like a black-box to users. We analyzed power consumption of four SSDs with standard I/O operations. We find the following: (a) the power consumption of SSDs is not significantly lower than that of HDDs, (b) all SSDs we tested had similar power consumption patterns which, we assume, is a result of their internal parallelism. SSDs have a parallel architecture that connects flash memories by channel or by way. This parallel architecture improves performance of SSDs if the information is known to the file system. This paper proposes three SSD characterization algorithms to infer the characteristics of SSD, such as internal parallelism, I/O unit, and page allocation scheme, by measuring its power consumption with various sized workloads. These algorithms are applied to four real SSDs to find: (i) the internal parallelism to decide whether to perform I/Os in a concurrent or an interleaved manner, (ii) the I/O unit size that determines the maximum size that can be assigned to a flash memory, and (iii) a page allocation method to map the logical address of write operations, which are requested from the host to the physical address of flash memory. We developed a data sampling method to provide consistency in collecting power consumption patterns of each SSD. When we applied three algorithms to four real SSDs, we found flash memory configurations, I/O unit sizes, and page allocation schemes. We show that the performance of SSD can be improved by aligning the record size of file system with I/O unit of SSD, which we found by using our algorithm. We found that Q Pro has I/O unit of 32 KB, and by aligning the file system record size to 32 KB, the performance increased by 201% and energy consumption decreased by 85%, which compared to the record size of 4 KB.

This paper proposes a static application mapping technique, based on integer linear programming, for non-hierarchical manycore embedded systems. Unlike previous work which was designed for hierarchical manycore SoCs, this work allows more flexible application mapping to achieve higher performance. The experimental results show the effectiveness of this work.

Ternary content addressable memory (TCAM), which can store 0, 1, or X in its cells, is widely used to store routing tables in network routers. Negative bias temperature instability (NBTI) and positive bias temperature instability (PBTI), which increase Vth and degrade transistor switching speed, have become major reliability challenges. This study analyzes the signal probability of routing tables. The results show that many cells retain static stress and suffer significant degradation caused by NBTI and PBTI effects. The bit flipping technique is improved and proactive power gating recovery is proposed to mitigate NBTI and PBTI effects. In order to maintain the functionality of TCAM after bit flipping, a novel TCAM cell design is proposed. Simulation results show that compared to the original architecture, the bit flipping technique improves read static noise margin (SNM) for data and mask cells by 16.84% and 29.94%, respectively, and reduces search time degradation by 12.95%. The power gating technique improves read SNM for data and mask cells by 12.31% and 20.92%, respectively, and reduces search time degradation by 17.57%. When both techniques are used, read SNM for data and mask cells is improved by 17.74% and 30.53%, respectively, and search time degradation is reduced by 21.01%.

A triplexer is presented by using bandpass filters (BPFs) which consist of two-stage of wideband resonator and additional open-circuited stubs. The resonator is firstly proposed by using a coupled-line and an inductive element loaded transmission line. This resonator produces the wide passband by a dual-mode resonance, high attenuation level at stopbands, and the steepness at the edge of the passband due to the attenuation poles. In order to understand the behavior of the resonator, the conditions for resonances and attenuation poles are especially solved and their current densities are analyzed by an electromagnetic simulation. Secondly, three types of wideband BPFs are constituted and finally a wideband triplexer is composed by using these BPFs. The basic characteristics of the proposed BPFs and the matching methodology enable to realize the triplexer whose desired passbands are around 3.1-5.1 GHz, 5.85-7.85 GHz, and 8.6-10.6 GHz with high isolation performance at the other passbands. The proposed triplexer is predominance in the flexible bandwidth or wide operating frequency range. All the BPFs and the triplexer are implemented on a planar printed circuit board assuming the use of the microstrip line structure.

This paper proposes a new design formula of coupling coefficient between antenna and resonator for an efficient design of filtering antennas consisting of an antenna and resonators. The filtering antenna can be designed by introducing a well-established filter design theory. For such a design approach, an external Q factor at input port, coupling coefficients, and a radiation Q factor of the antenna need to be evaluated. However, conventional design methods have a time-consuming procedure, since there are no effective techniques to evaluate the coupling coefficient between resonator and antenna. To solve the problem, we derive the new design formula using only amplitude property of input reflection responses obtained from a coupled structure of resonator and antenna. As an example, a third-order filtering antenna is synthesized, designed, and tested at 2.45 GHz, which numerically and experimentally validates the effectiveness of the derived equation.

This paper describes a blind frequency offset estimator (FOE) with wide frequency range for coherent quadrature amplitude modulation (QAM) receivers. The FOE combines a spectrum-based frequency offset estimation algorithm as a coarse estimator with a frequency offset estimation algorithm using the periodogram as a fine estimator. To establish our design methodology, each block of the FOE is rigorously analyzed by using formulas and the minimum fast Fourier transform (FFT) size that generates a frequency spectrum for both the coarse and fine estimators is determined. The coarse estimator's main feature is that all estimation processes are carried out in the frequency domain, which yields convergence more than five times faster than that of conventional estimators. The estimation frequency range of the entire FOE is more than 1.8 times wider than that of conventional FOEs. Experiments on coherent optical 64-ary QAM (64-QAM) reveal that frequency offset estimation can be achieved under a frequency offset value greater than the highest value of the conventional estimation range.

In this paper, we analyze two representative tree-based RFID anti-collision algorithms: the Query Tree protocol and the Binary Search algorithm. Based on the advantages and disadvantages of the two algorithms, we propose and evaluate two optimized anti-collision algorithms: the Optimized Binary Search, which performs better than the Query Tree Protocol with the same tag-side overhead, and the Optimized Binary Search with Multiple Collision Bits Resolution algorithm, which performs the best with an acceptable increase in tag-side processing overhead.

This paper considers on-demand WiFi wake-up where a wake-up receiver is installed into each WiFi device. The wake-up receiver detects a wake-up call by finding the predefined length of WiFi frames, which corresponds to a wake-up ID, through envelope detection with limited signal processing. Since each wake-up receiver continuously observes the WiFi channel, an adverse event of False Positive (FP), where a WiFi device is falsely turned on without actual wake-up calls, can occur when the length of non-wake-up, background data frames match with predefined length. In this paper, we suggest using the received signal strength (RSS) of WiFi frames to differentiate the real and false wake-up calls. The proposed scheme exploits the correlation among RSSs of WiFi frames received from a single station located in a fixed position. Using measured RSS data obtained under various settings and different degrees of mobility, we investigate not only the FP reduction rate but also its impact on the probability of detecting real wake-up calls. We also present experimental results obtained with our prototype in which the proposed scheme is implemented.

Recently, due to the development of design and manufacturing technologies for VLSI systems, an embedded system becomes more and more complex. Consequently, not only the performance of chips, but also the flexibility and dynamic adaptation of the implemented systems are required. To achieve these requirements, a partially reconfigurable device is promising. In this paper, we propose an efficient data structure to manage the reconfigurable units. And then, on the assumption that each task utilizes the rectangle shaped resources, a very simple MER enumeration algorithm based on this data structure is proposed. By utilizing the result of MER enumeration, the free space on the reconfigurable device can be used sufficiently. We analyze the complexity of the proposed algorithm and confirm its efficiency by experiments.