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• A study on the possibility of avoiding the HEVC intra-frame drift effect. • Theoretically computing a mask multiplicative matrix cancelling the intra-frame drift effect. • Experimental illustrations and benchmarking over state-of-the-art methods. • Future work on the applicative integration under the watermarking framework. • Paving the way towards studying the intra-drift for the HEVC extensions. This paper investigates the possibility of avoiding the HEVC intra-frame drift effect induced by additive modifications of the luma DCT/DST coefficients. The main novelty consists in solving the intra-drift problem in its general form: starting from the equations defining the 35 intra-prediction modes and the DCT/DST computation, a mask multiplicative matrix cancelling the intra-frame drift effect is computed. The relevance of the advanced method with respect to the state of the art studies is illustrated, discussed and quantitatively assessed. [ABSTRACT FROM AUTHOR]

In this paper, we derive the throughput and Bit Error Probability of incremental relaying for cognitive radio networks. Relaying in the secondary network is performed only when the SNR of the direct link is lower than a predefined threshold β . Also, all relays must verify interference constraints: the generated interference to primary receiver must be below a chosen threshold (T) so that the primary throughput is larger than a predefined value. The analysis is valid for different relay selection techniques: Opportunistic amplify and forward, opportunistic decode and forward, partial and reactive AF relay selection. We also consider multihop relaying with single and multiple branches. For multiple branches, two scenarios are considered: all branches are maximum ratio combined or the best branch is activated. We also take into account the interference from primary to secondary nodes. The parameter β of incremental relaying is also numerically optimized to achieve the highest secondary throughput. [ABSTRACT FROM AUTHOR]

In this paper, we address the problem of action detection in unconstrained video clips. Our approach starts from action detection on object proposals at each frame, then aggregates the frame-level detection results belonging to the same actor across the whole video via linking, associating, and tracking to generate action tubes that are spatially compact and temporally continuous. To achieve the target, a novel action detection model with two-stream architecture is firstly proposed, which utilizes the fused feature from both appearance and motion cues and can be trained end-to-end. Then, the association of the action paths is formulated as a maximum set coverage problem with the results of action detection as a priori. We utilize an incremental search algorithm to obtain all the action proposals at one-pass operation with great efficiency, especially while dealing with the video of long duration or with multiple action instances. Finally, a tracking-by-detection scheme is designed to further refine the generated action paths. Extensive experiments on three validation datasets, UCF-Sports, UCF-101 and J-HMDB, show that the proposed approach advances state-of-the-art action detection performance in terms of both accuracy and proposal quality. [ABSTRACT FROM AUTHOR]

Abstract Packet delivery delay minimization is a critical issue in Wireless Sensor Networks. In mission-critical applications, the sensed information is highly delay-sensitive, and should be transmitted to the sink within a required delay. In this paper, we propose a new mixed integer linear programming model (MILP) to address the problem of end-to-end delay minimization of data transmission in delay-sensitive applications such as healthcare monitoring. The proposed model simultaneously guarantees (1) timely delivery data packets, (2) network reliability, (3) connectivity, and (4) flow preservation. We verify by computational experiments that the developed mixed integer linear model, using Cplex, is able to provide an optimal solution for timely data packet delivery of all our small and medium size problems. [ABSTRACT FROM AUTHOR]

In this paper, the performance of non-orthogonal multiple access (NOMA) dual-hop (DH) amplify-and-forward (AF) relaying networks is investigated, where Nakagami-m fading channel is considered. In order to cover more details, in our analysis, the transceiver hardware impairments at source, relay and destination nodes are comprehensively considered. To characterize the effects of hardware impairments brought in NOMA DH AF relaying networks, the analytical closed-form expressions for the exact outage probability and approximate ergodic sum rate are derived. In addition, the asymptotic analysis of the outage probability and ergodic sum rate at high signal-to-noise ratio (SNR) regime are carried out in order to further reveal the insights of the parameters for hardware impairments on the network performance. Simulation results indicate the performance of asymptotic ergodic sum rate are limited by levels of distortion noise. [ABSTRACT FROM AUTHOR]

The tremendous proliferation of smart phones and other smart devices has spurred the explosive growth of delay-sensitive high-rate multimedia services, which significantly increases energy consumption in wireless cellular networks. Therefore, it is an important yet challenging issue to carry out resource allocation for cellular networks to meet the quality of service requirement in terms of high data rate and, at the same time, achieve high energy efficiency. In this paper, two resource allocation approaches are proposed, where user selection and power allocation are jointly considered, to maximize effective capacity (EC) and effective energy efficiency (EEE), respectively, for a relay-assisted downlink of cellular networks. Channel estimation errors are taken into account to make the proposed approaches more practical. Moreover, to solve the EC maximization problem efficiently, we develop an optimal algorithm based on Lagrange method and Karush–Kuhn–Tucker conditions, and derive closed-form optimal solutions for user selection and power allocation at both the base station and relays. For the EEE maximization problem, an iterative algorithm based on the Dinkelbach method is developed to find the optimal solutions. Theoretical analysis and simulation results are presented to demonstrate the performance of the proposed approaches in terms of EC, EEE, and delay bound violation probability. [ABSTRACT FROM PUBLISHER]

Device-to-device communications have attracted much more attention recently in the realization of smart cities. In this paper, we propose a network coding (NC) scheme based on device-to-device communication for centralized wireless local area network (WLAN). In centralized WLAN scenarios, users’ communication can be implemented through multiple interaction of access points acted as relay nodes, which are similar to direct link session (DLS) protocol in IEEE 802.11 standard and we named the proposed protocol as advanced DLS scheme, where analytical performance results of the proposed two-way communication system using NC, with and without AP selection, are obtained in multi-AP cases, as well as the asymptotic results in high transmitting power. In addition, the performance comparisons of throughput, delay and collision probability of proposed scheme with IEEE 802.11 are provided in simulation, which present the advantages of centralized WLAN. By the analysis, it is found that the proposed advanced DLS scheme can achieve almost exactly the same bit error ratio performance as the optimal selection at all signal to noise ratio ranges. It is also shown that the proposed transmission scheme significantly outperform the current mode in two-way communication Nakagami channels owing to the diversity order and array gains. The proposed scheme only need little frame modification and can be compatible with the current standard. Finally, simulation results validate the theoretical analysis. [ABSTRACT FROM AUTHOR]

In the midst of low cost and easy-to-use multimedia editing software, which make it exceedingly simple to tamper with digital content, the domain of digital multimedia forensics has attained considerable significance. This research domain deals with production of tools and techniques that enable authentication of digital evidence prior to its use in various critical and consequential matters, such as politics, criminal investigations, defense planning. This paper presents a forensic scheme for detection of frame-based tampering in digital videos, especially those captured by surveillance cameras. Frame-based tampering, which involves insertion, removal or duplication of frames into or from video sequences, is usually very difficult to detect via simple visual inspection. Such forgeries, however, disturb the temporal correlation among successive frames of the tampered video. These disturbances, when analyzed in an appropriate manner, help reveal the evidence of forgery. The forensic technique presented in this paper relies on objective analysis of prediction residual and optical flow gradients for the detection of frame-based tampering in MPEG-2 and H.264 encoded videos. The proposed technique is also capable of determining the exact location of the forgery in the given video sequence. Results of extensive experimentation in diverse and realistic forensic set-ups show that the proposed technique can detect and locate tampering with an average accuracy of 83% and 80% respectively, regardless of the number of frames inserted, removed or duplicated. [ABSTRACT FROM AUTHOR]

Terminal relaying is expected to offer an effective means for realizing machine-type communications (MTC) in wireless cellular networks. In the absence of channel quality indicators, the effective utilization of relaying terminals (RTs) requires a mechanism by which RTs can autonomously assign available resource blocks (RBs) to potentially large numbers of uncoordinated MTC devices with minimal conflicts. Unlike random RB assignments, which do not offer performance guarantees, using prescribed RB assignment sequences provides an opportunity for obtaining performance gains. However, realizing these gains requires optimizing RB assignments over a large set of lengthy sequences. One technique for selecting assignment sequences is based on an exhaustive search of exponential complexity over sequences generated by multiplicative cyclic groups. This technique restricts the number of RBs to be prime minus one and does not consider sequences generated using other group operations. In this paper, we use group isomorphism to eliminate the constraint on the number of RBs and to show that the optimal assignment sequences generated by a specific cyclic group are globally optimal over the set of all cyclically generated sequences. We develop a greedy algorithm with polynomial complexity for the sequential selection of RB assignment sequences in systems with large numbers of RTs and arbitrary device distributions. This algorithm is further simplified by invoking the graphical representation of cyclic groups. The resulting algorithm is more efficient and thus suitable for generating assignment sequences for relay-assisted massive multiple access Internet-of-Things systems. Numerical results show that the performance of the sequences generated by the greedy algorithms is comparable to that of those generated by exhaustive search, but with much less computational cost. [ABSTRACT FROM PUBLISHER]

In this paper we extend the notion of approximate dual to fusion frames and present some approaches to obtain alternate dual and approximate alternate dual fusion frames. We also study the stability of alternate dual and approximate alternate dual fusion frames. [ABSTRACT FROM AUTHOR]

This paper proposes Lossy-Forwarding Hybrid Automatic Repeat reQuest (LF-HARQ) schemes to improve bit-error-rate, packet-error-rate and throughput performances of dual-hop wireless parallel relaying systems. In contrast to the conventional lossless decode-and-forward schemes, where erroneous packets are always discarded at the relay, we introduce Lossy-Forwarding concept to HARQ technique that allows the relay nodes to forward them to the next hop, referred to as Fully LF-HARQ (FLF-HARQ) scheme. We then propose Partially LF-HARQ (PLF-HARQ) scheme, where the relaying nodes select either forwarding the erroneous packets or requesting retransmission. The mode selection is based on the confidence indicator (CI) expressing the reliability of the received packets. Since the channels are assumed to suffer from block Rayleigh fading, the CI is calculated via online measurement of mutual information, block-by-block. Results of computer simulations to verify the superiority of the proposed techniques are presented. [ABSTRACT FROM AUTHOR]

Faked deauthentication and disassociation frames introduce serious denial of service (DoS) attacks on wireless local area networks (WLANs), and these attacks include deauthentication flooding (DeauthF) and disassociation flooding (DisassF). IEEE 802.11w standard was introduced to extend 802.11i functionalities for preventing DeauthF and DisassF, and so far there has been no detailed theoretical and experimental study on the performance of 802.11w for resolving these attacks. We implemented a prototype at the lab to perform detailed study on the performance of 802.11w for preventing rogue AP based DoS attacks, and the study shows that the current IEEE 802.11w standard cannot resolve DeauthF and DisassF at high attacking rates. Then, based on 802.11 wireless station (STA) modules, a STA-based queuing model is developed to derive a mathematical model for explaining 802.11w performance variations under DeauthF and DisassF attacks. Furthermore, using frame sequence checking and frame queuing, we propose a traffic shaping (TS) scheme to enhance the current IEEE 802.11w standard, and experimental results show that the proposed approach of 802.11w-TS is effective in preventing low-rate and high-rate DeauthF and DisassF attacks under various attacking scenarios. [ABSTRACT FROM AUTHOR]

In this paper, we investigate an incremental semi-blind opportunistic amplify-and-forward (AF) protocol in two-way relaying communication. This protocol is analyzed in terms of the average sum-rate and average symbol error rate considering independent Rayleigh fading channels. Bounds of these performance criteria are provided in closed-form expressions for the semi-blind and channel state information (CSI)-assisted relaying. The performance of the incremental semi-blind opportunistic AF relaying is compared to the performance of incremental CSI-assisted opportunistic AF relaying in order to prove the validity of the proposed analysis. We illustrate that the incremental semi-blind opportunistic AF relaying reduces significantly the system complexity for the cost of a slight decrease in the system performance. [ABSTRACT FROM AUTHOR]

Frequency synchronization of a distributed measurement system requires the transfer of an accurate frequency reference to all nodes. The use of a general-purpose packet-based network for this aim is analyzed in this paper, where oversampling is considered as a means to counter the effects of packet delay variation on time accuracy. A comprehensive analysis that includes the stability of the local clock is presented and shows that frequency transfer through a packet network of this kind is feasible, with an accuracy level that can be of interest to a number of distributed measurement applications. [ABSTRACT FROM PUBLISHER]

In this paper, we perform a system-level feasibility analysis of full-duplex (FD) relay-aided cellular networks that are equipped with multiple antennas at the base stations (BSs) and the relay nodes (RNs). The aim is to understand whether FD relaying is capable of enhancing the rate of cellular networks. With the aid of tools from stochastic geometry, we develop a tractable approach for computing the percentile rate, which allows us to gain insights on the impact of FD relaying for both the cell-edge and the cell-median mobile terminals subject to network interference. Contrary to previous works that do not consider the network interference, the framework reveals that even in the absence of self-interference at the FD RNs, a network with half-duplex (HD) RNs can outperform its FD counterpart for a moderate number of antennas at the BSs and RNs. On the other hand, the FD-based network can substantially outperform both the HD-based one and the one without RNs for a sufficiently large number of antennas at the BSs and RNs and substantially small self-interference power effect at the RNs. Finally, the aforementioned analytical insights are validated by means of Monte Carlo simulations. [ABSTRACT FROM PUBLISHER]

Cellular wireless systems rely on frame-based transmissions. The frame design is conventionally based on heuristics, consisting of a frame header and a data part. The frame header contains control information that provides pointers to the messages within the data part. In this paper, we revisit the principles of frame design and show the impact of the new design in scenarios that feature short data packets, which are central to various 5G and Internet of Things applications. We treat framing for downlink transmission in an AWGN broadcast channel with $K$ users, where the sizes of the messages to the users are random variables. Using approximations from finite blocklength information theory, we establish a framework in which a message to a given user is not necessarily encoded as a single packet, but may be grouped with messages to other users and benefit from the improved efficiency of longer codes. This requires changes in the way control information is sent, and it requires that the users need to spend power decoding other messages, thereby increasing the average power consumption. We show that the common heuristic design is only one point on a curve that represents the tradeoff between latency and power consumption. [ABSTRACT FROM PUBLISHER]

This paper reports an outdoor experiment to optimize the timeout of wireless network coding (WNC) and frame aggregation (FA), which are implemented to carrier sense multiple access with collision avoidance (CSMA/CA)-based wireless two-hop relay prototype. The system throughput is improved. In the prototype, FA is implemented at the terminal nodes. Timeout function for WNC is available at the relay node and that for FA is available at the terminal nodes. Our outdoor experiment shows that optimizing the timeout values of WNC and FA can improve system throughput by 2.04-fold compared to the conventional relay without WNC or FA. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

Video registration is a difficult task especially when spurious frame intensity differences and spatial variations between the two frames are present. To robust Video registration algorithms to such spurious variations it can be useful to employ a video registration matching criteria on higher dimensional feature spaces. This paper will present an overview of our recent work on Video registration using high dimensional Video features and Scale Invariant Feature Vector (SIFT) Feature Vector matching criteria. New approach estimates of information divergence measures will be presented. We will demonstrate the advantage of our approach for Video registration. [ABSTRACT FROM AUTHOR]

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In this paper, we design and evaluate the proposed geographic-based spray-and-relay (GSaR) routing scheme in delay/disruption-tolerant networks. To the best of our knowledge, GSaR is the first spray-based geographic routing scheme using historical geographic information for making a routing decision. Here, the term spray means that only a limited number of message copies are allowed for replication in the network. By estimating a movement range of destination via the historical geographic information, GSaR expedites the message being sprayed toward this range, meanwhile prevents that away from and postpones that out of this range. As such, the combination of them intends to fast and efficiently spray the limited number of message copies toward this range and effectively spray them within range, to reduce the delivery delay and increase the delivery ratio. Furthermore, GSaR exploits delegation forwarding to enhance the reliability of the routing decision and handle the local maximum problem, which is considered to be the challenges for applying the geographic routing scheme in sparse networks. We evaluate GSaR under three city scenarios abstracted from real world, with other routing schemes for comparison. Results show that GSaR is reliable for delivering messages before the expiration deadline and efficient for achieving low routing overhead ratio. Further observation indicates that GSaR is also efficient in terms of a low and fair energy consumption over the nodes in the network. [ABSTRACT FROM PUBLISHER]

In noise-limited cooperative wireless networks, the diversity order of selection combining (SC) is the same as the diversity order of maximal ratio combining (MRC). The contribution of this paper is to report that the diversity order of SC and MRC may be different in the presence of randomly distributed interferers at the destination. More specifically, an amplify-and-forward (AF) dual-branch dual-hop cooperative relaying protocol in the presence of Nakagami- $m$ fading, additive Gaussian noise at the relay, and additive Gaussian noise and symmetric alpha-stable interference at the destination is investigated. By contrasting the diversity order of SC against recent results on the diversity of MRC, it is shown that both combining schemes provide the same diversity order if the distribution of the interference is unknown to the destination (interference-oblivious design) . They may achieve a different diversity order, on the other hand, if the interference can be estimated at the destination (interference-aware design) . Moreover, it is shown that the achievable diversity order depends on the interference in the broadcast and relaying phases being spatially correlated or independent. [ABSTRACT FROM PUBLISHER]

This paper addresses the area of heterogeneous wireless relaying vehicular clouds. We devise an advanced vehicular relaying technique for enhanced connectivity in densely populated urban areas. We investigate the performance of a transmission scheme over a Long-Term Evolution-Advanced (LTE-A) network where vehicles act as relaying cooperating terminals for a downlink session between a base station and an end-user. The abundance of moving vehicles, operating in an ad hoc fashion, can eliminate the need for establishing a dedicated relaying infrastructure. However, the associated wireless links in vehicular clouds are characterized by a doubly selective fading channel; this causes performance degradation in terms of increased error probability. Hence, we propose a precoded cooperative transmission technique to extract the underlying rich multipath–Doppler-spatial diversity, which is a relay selection scheme to take advantage of the potentially large number of available relaying vehicles. We further contribute by the derivation of a closed-form error rate expression, diversity gain, and outage expressions and introduce our derived performance unconditional expressions as a benchmark to assess our analysis and future research studies of such an approach. Our analytical and simulation results indicate that significant diversity gains and reduced error rates are achievable. In addition, there is a noticeable reduction in the required transmitting power compared with traditional transmission schemes, as well as an increase in distance coverage. [ABSTRACT FROM PUBLISHER]

Many studies have presented the order sense results of information transmission capacity and packet delivery delay in mobile ad hoc networks (MANETs). To achieve the fundamental understanding of MANETs, we focus on deriving the closed-form expressions of the network capacity and end-to-end delay. A MANET with the generalized correlated mobility model is considered in this paper, where the mobility of nodes clustered in one group is confined within a specified area, and multiple groups move uniformly across the network. We also leverage limited packet redundancy to speed up the packet transmission, i.e., each source node is allowed to distribute at most f copies of each packet in its delivery process. Specifically, we first propose an effective multi-hop scheduling-routing scheme under the correlated mobility model, and then develop the closed-form expressions of both per node throughput capacity and expected end-to-end delay. We further explore the tradeoff between throughput capacity and packet delay by using packet redundancy f. The simulation studies validate our theoretical results. [ABSTRACT FROM AUTHOR]

Protocols for sensor networks have traditionally been designed using the best effort delivery model. However, there are many specific applications that need reliable transmissions. In event-driven wireless sensor networks, the occurrence of an event may generate a large amount of data in a very short time. Among them, some critical urgent information needs to be transmitted reliably in a timely manner. In this scenario, congestion is inevitable because of the constraints in available resources. How to control the congestion is very important for the reliable transmission of urgent information. To address this problem, we propose a queue-based congestion detection and a multistage rate control mechanism. In our proposed mechanism, not only the current queue length but also the queue fluctuation are adopted as indications of congestion. Each sensor node evaluates its congestion level locally and determines its congestion state with a state machine. We design a multistage rate adjustment mechanism for nodes to adjust their rates depending on their congestion states. We also distinguish high-priority critical traffic from low-priority non-critical traffic. Extensive simulation results confirm the superior performance of our proposed protocol with respect to throughput, loss probability, and delay.Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we propose to provide throughput guarantees in heterogeneous wireless mesh networks by jointly optimizing routing and Medium Access Control configuration. Our solution is based on the notion of linearized capacity region, which provides a technology-independent way of representing the capacity of a wireless link (thereby hiding the technology specifics to the upper layers). From the available capacity of the underlying links as given by the linearized capacity region, we propose two routing algorithms (based on multipath and single path) that find optimal paths for all the flows in the network given their throughput requirements. The throughput allocation resulting from routing is then provided to each link, which uses this information to optimize its technology-specific Medium Access Control parameters. The proposed approach is evaluated in a heterogeneous scenario comprising Wireless Local Area Networks (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX) technologies and is shown to outperform previous solutions by (at least) a factor of 2.Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]