For flexibility in supporting mobility and multihoming in edge networks and scalability of the backbone routing system, future Internet is expected to be based on the concept of ID/locator split. Heterogeneity Inclusion and Mobility Adaptation through Locator ID Separation (HIMALIS) has been designed as a generic future network architecture based on ID/locator split concept. It can natively support mobility, multihoming, scalable backbone routing and heterogeneous protocols in the network layer of the new generation network or future Internet. However, HIMALIS still lacks security functions to protect itself from various attacks during the procedures of storing, updating, and retrieving of ID/locator mappings, such as impersonation attacks. Therefore, in this paper, we address the issues of security functions design and implementation for the HIMALIS architecture. We present an integrated security scheme consisting of mapping registration and retrieval security, network access security, communication session security, and mobility security. Through the proposed scheme, the hostname to ID and locator mapping records can be securely stored and updated in two types of name registries, domain name registry and host name registry. Meanwhile, the mapping records retrieved securely from these registries are utilized for securing the network access process, communication sessions, and mobility management functions. The proposed scheme provides comprehensive protection of both control and data packets as well as the network infrastructure through an effective combination of asymmetric and symmetric cryptographic functions.

This paper presents an efficient approach for logarithmic and anti-logarithmic converters which can be used in the arithmetic unit of hybrid number system processors and logarithm/exponent function generators in DSP applications. By employing the novel quasi-symmetrical difference method with only the simple shift-add logic and the look-up table, the proposed approach can reduce the hardware area and improve the conversion speed significantly while achieve similar accuracy compared with the previous methods. The implementation results in both FPGA and 0.18-µm CMOS technology are also presented and discussed.

In this paper, we propose a high-speed full-duplex optical wireless communication system using a single channel imaging receiver for personal area network applications. This receiver is composed of an imaging lens, a small sensitive-area photodiode, and a 2-aixs actuator and it can reject most of the background light. Compared with the previously proposed system with single wide field-of-view (FOV) non-imaging receiver, the coverage area at 12.5 Gb/s is extended by > 20%. Furthermore, since the rough location information of the user is available in our proposed system, instead of searching for the focused light spot over a large area on the focal plane of the lens, only a small possible area needs to be scanned. In addition, by pre-setting a proper comparison threshold when searching for the focused light spot, the time needed for searching can be further reduced. Proof-of-concept experiments have been carried out and the results show that with this partial searching algorithm and pre-set threshold, better performance is achieved.

The traditional selection cooperation scheme selects the relay with best instantaneous receive signal-to-noise ratio to forward the message and achieves good outage performance, which may however cause poor fairness among relays. In this letter, we propose two practical selection cooperation schemes in Decode-and-Forward (DF) fashion to improve the fairness of relay selection. Numerical results suggest that both of the proposed schemes can achieve fairness close to the strict fairness scheme without outage performance deterioration. It is also validated that these schemes have lower complexities than traditional ones and therefore are practical for real networks.

Multi-sensory communications with haptics attract a number of researchers in recent years. To provide services of the communications with high realistic sensations, the researchers focus on the quality of service (QoS) control, which keeps as high quality as possible, and the quality of experience (QoE) assessment, which is carried out to investigate the influence on user perception and to verify the effectiveness of QoS control. In this paper, we report the present status of studies on multi-sensory communications with haptics. Then, we divide applications of the communications into applications in virtual environments and those in real environments, and we mainly describe collaborative work and competitive work in each of the virtual and real environments. We also explain QoS control which is applied to the applications and QoE assessment carried out in them. Furthermore, we discuss the future directions of studies on multi-sensory communications.

IEEE 802.11ac uses DL MU-MIMO and channelization for very high throughput. We propose a new algorithm for adaptive channelization in DL MU-MIMO WLANs. The proposed scheme can enhance the throughput efficiency for DL MU-MIMO transmission by adaptively applying the channelization scheme according to data size and MCS. Moreover, our proposal can reduce the overhead due to the exchange of control frames for DL MU-MIMO transmission in WLANs. A performance evaluation shows that the proposed scheme is superior to IEEE 802.11ac WLAN.

The contradictions created by the differences in mass P2P data and transfer capability of wireless networks, and mismatch of overlay network topology and physical network topology are the main barriers hindering the implementation of P2P resource sharing in wireless multi-hop networks. This paper investigates the problem of enabling P2P resource sharing in WMNs with two-tier architecture. SpiralChord, the DHT approach implemented through routers in the upper tier, is proposed to address the major problems of wireless resource sharing – how to efficiently find resources currently available and reduce redundant messages as much as possible. SpiralChord uses an ID assignment technique to integrate location awareness with cross-layering. Location awareness aims at alleviating mismatch in physical network topology and overlay network topology, and it is designed to map neighboring routers to close-by IDs in the logical ring. Cross-layering aims at speeding up resource lookup operations in the application layer by exploiting the information that is available at the MAC layer, and it tends to be more effective when physically neighboring routers have faraway IDs in the logical ring. An ID assignment strategy based on spiral curve is proposed to meet the contradictory requirements of location awareness and cross-layering, mapping a peer's neighbors in the overlay network to peers which are its physical neighbors and distributing the remaining physical neighbors as widely as possible in the overlay network. In addition, a mobility management mechanism is proposed to address the adverse effect of the movements of clients in lower tier on resource sharing. A client is assigned a managing router to take the responsibility for the location of the client. Simulations show SpiralChord is more effective in reducing message overhead and increasing lookup performance than Chord, and mobility management for mobile clients performs well at reducing message overhead caused by mobile clients in SpiralChord.

To accurately evaluate and manage future distributed wireless networks, it is indispensable to fully understand cooperative propagation channels. In this contribution, we propose cascaded multi-keyhole channel models for analyzing cooperative diversity wireless communications. The cascaded Wishart distribution is adopted to investigate the eigenvalue distribution of the multi-keyhole MIMO (multiple input multiple output) channel matrix, and the capacity performance is also presented for the wireless systems over such channels. A diversity order approximation method is proposed for better evaluating the eigenvalue and capacity distributions. The good match of analytical derivations and numerical simulations validates the proposed models and analysis methods. The proposed models can provide an important reference for the optimization and management of cooperative diversity wireless networks.

In this paper we propose MR-MAC, a new multiple reservation MAC protocol for asynchronous duty cycling wireless sensor networks. In MR-MAC, the receiver transmits a collection packet to the senders when it wakes up that asks for the number of packets each sender wants to send. Then each sender replies to the receiver according to the scheduled sequence with a short report packet. After getting the number of packets from each sender, the receiver assigns multiple batch transmission (MBT) for the senders and begins to initiate the transmissions. The senders then transmit packets to the receiver in a batch style as scheduled so that packets can be delivered to the receiver as fast as possible. Experiments on a Tmote-sky testbed show that our protocol outperforms other protocols in diverse performance metrics such as throughput, latency and energy efficiency.

A novel conjugate unitary ESPRIT (CU-ESPRIT) algorithm for the joint direction of departure (DOD), and direction of arrival (DOA), estimation in a bistatic MIMO radar is proposed. A new virtual array is formed by using the properties of noncircular signals, and the properties of the centro-Hermitian matrix are employed to convert the complex-valued data matrix into a real-valued data matrix. Then the real-valued rotational invariance properties of the new virtual array are determined to estimate DODs and DOAs, which are paired automatically. The proposed method provides better angle estimation performance and detects more targets owing to double number of MIMO virtual array elements. Simulation results are presented to verify the effectiveness of the proposed algorithm.

Clock network synthesis is one of the most important and limiting factors in VLSI designs. Hence, the clock skew variation reduction is one of the most important objectives in clock distribution methodology. Cross-link insertion is proposed in [1], however, it is based on empirical methods and does not use variation information for link insertion location choice. [17] considers the delay variation, but it is slow even for small clock trees. In this paper, we propose a fast link insertion algorithm that considers the delay variation information directly during link selection process. Experimental results show that our algorithm is very fast and achieves better skew variability reduction while utilizing considerably lesser routing resources compared with existing methods.

This paper discusses hybrid state saving for applications in which processes should create checkpoints at constant intervals and can hold a finite number of checkpoints. We propose a reclamation technique for checkpoint space, that provides effective checkpoint time arrangements for a rollback distance distribution. Numerical examples show that when we cannot use the optimal checkpoint interval due to the system requirements, the proposed technique can achieve lower expected overhead compared to the conventional technique without considering the form of the rollback distance distribution.

The Linking Open Data (LOD) cloud is a collection of linked Resource Description Framework (RDF) data with over 31 billion RDF triples. Accessing linked data is a challenging task because each data set in the LOD cloud has a specific ontology schema, and familiarity with the ontology schema used is required in order to query various linked data sets. However, manually checking each data set is time-consuming, especially when many data sets from various domains are used. This difficulty can be overcome without user interaction by using an automatic method that integrates different ontology schema. In this paper, we propose a Mid-Ontology learning approach that can automatically construct a simple ontology, linking related ontology predicates (class or property) in different data sets. Our Mid-Ontology learning approach consists of three main phases: data collection, predicate grouping, and Mid-Ontology construction. Experiments show that our Mid-Ontology learning approach successfully integrates diverse ontology schema with a high quality, and effectively retrieves related information with the constructed Mid-Ontology.

This paper deals with a characteristic of the so-called effective boundary condition for a plane wave scattering from periodic surfaces with perfect conductivity. The perturbation solution with all orders is explicitly given under the effective boundary condition. It is newly found that such a perturbation solution satisfies the optical theorem under the exact boundary condition. A comparison between such a perturbation solution and a reference solution for the exact boundary condition by other methods is performed. Then, the validity of such a perturbation solution is concretely discussed.

This paper describes a simulation platform for use in the quantitative assessment of different respiratory motion correction techniques in Coronary MR angiography (CMRA). The simulator incorporates acquisition of motion parameters from heart motion tracking and applies it to a deformable heart model. To simulate respiratory motion, a high-resolution 3-D coronary heart reference image is deformed using the estimated linear transformation from a series of volunteer coronal scout scans. The deformed and motion-affected 3-D coronary images are used to generate segmented k-space data to represent MR data acquisition affected by respiratory motion. The acquired k-space data are then corrected using different respiratory motion correction methods and converted back to image data. The resulting images are quantitatively compared with each other using image-quality measures. Simulation experiment results are validated by acquiring CMRA scans using the correction methods used in the simulation.

The cooperative orthogonal frequency-division multiplexing (OFDM) relaying system is widely regarded as a key design for future broadband mobile cellular systems. This paper focuses on channel estimation in such a system that uses amplify-and-forward (AF) as the relaying strategy. In the cooperative AF relaying, the destination requires the individual (disintegrated) channel state information (CSI) of the source-relay (S-R) and relay-destination (R-D) links for optimum combination of the signals received from source and relay. Traditionally, the disintegrated CSIs are obtained with two channel estimators: one at the relay and the other at the destination. That is, the CSI of the S-R link is estimated at relay and passed to destination, and the CSI of the R-D link is estimated at destination with the help of pilot symbols transmitted by relay. In this paper, a new disintegrated channel estimator is proposed; based on an expectation-maximization (EM) algorithm, the disintegrated CSIs can be estimated solely by the estimator at destination. Therefore, the new method requires neither signaling overhead for passing the CSI of the S-R link to destination nor pilot symbols for the estimation of the R-D link. Computer simulations show that the proposed estimator works well under the signal-to-noise ratios of interest.

Testbeds play a key role in the advancement of network science and the exploration of new network architectures. Because the scale and scope of any individual testbed is necessarily limited, federation is a useful technique for constructing testbeds that serve a wide range of experimenter needs. In a federated testbed, individual facilities maintain local autonomy while cooperating to provide a unified set of abstractions and interfaces to users. Forming an international federation is particularly challenging, because issues of trust, user access policy, and local laws and regulations are of greater concern that they are for federations within a single country. In this paper, we describe an architecture, based on the US National Science Foundation's GENI project, that is capable of supporting the needs of an international federation.

In this note we suggest a new parallelizable mode of operation for message authentication codes (MACs). The new MAC algorithm iterates a pseudo-random function (PRF) FK:{0,1}m → {0,1}n, where K is a key and m,n are positive integers such that m ≥ 2n. The new construction is an improvement over a sequential MAC algorithm presented at FSE2008, solving positively an open problem posed in the paper – the new mode is capable of fully parallel execution while achieving rate-1 efficiency and “full n-bit” security. Interestingly enough, PMAC-like parallel structure, rather than CBC-like serial iteration, has beneficial side effects on security. That is, the new construction is provided with a more straightforward security proof and with an even better (“-free”) security bound than the FSE 2008 construction.

In this letter, we analyze the outage performance of cognitive spectrum sharing in two-way relaying systems. We derive expressions of outage probability for the primary and secondary network over independent but not necessarily identically distributed (i.n.i.d.) Rayleigh fading channels. Monte Carlo simulations are presented to verify the theoretical analyses.

Existing salient object detection methods either simply use a threshold to detect desired salient objects from saliency map or search the most promising rectangular window covering salient objects on the saliency map. There are two problems in the existing methods: 1) The performance of threshold-dependent methods depends on a threshold selection and it is difficult to select an appropriate threshold value. 2) The rectangular window not only covers the salient object but also contains background pixels, which leads to imprecise salient object detection. For solving these problems, a novel saliency threshold-free method for detecting the salient object with a well-defined boundary is proposed in this paper. We propose a novel window search algorithm to locate a rectangular window on our saliency map, which contains as many as possible pixels belonging the salient object and as few as possible background pixels. Once the window is determined, GrabCut is applied to extract salient object with a well-defined boundary. Compared with existing methods, our approach doesn't need any threshold to binarize the saliency map and additional operations. Experimental results show that our approach outperforms 4 state-of-the-art salient object detection methods, yielding higher precision and better F-Measure.