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Abstract Reconfigurable intelligent surface (RIS) has great potential in securing wireless transmission, and it can flexibly change the wireless communication environment. However, the employment of RIS increases the difficulty in beamforming of base station (BS), and existing schemes cannot be directly utilized to enhance the security of system. Therefore, a reinforcement learning framework to jointly control BS and RIS for the purpose of enhancing the secure performance is proposed. Specifically, the beamforming ia transformed with artificial noise and reflection control as a Markov decision problem (MDP) in complex domain. Then, we develop the deep deterministic policy gradient based on complex‐valued neural networks (CV‐DDPG) to imitate the rules of complex computation. Additionally, the CV‐DDPG is performed as the agent of reinforcement learning to control the BS and RIS, which enables better utilization of the implied phase information of complex values in the system. The simulation results show that the proposed model promotes the performance of the control and greatly improves the secrecy rate of the legitimate user.

Abstract This paper is concerned with tele‐presence and tele‐operation of autonomous vehicles over the Additive White Gaussian Noise (AWGN) channel. This wireless communication channel is subject to transmission noise and transmission power constraint. An encoder, decoder and controller are proposed by implementing a novel linearization method for linearizing the nonlinear dynamic systems at operating points. For the linearized systems, the encoder, decoder and controller are implemented that were previously proposed for output tracking as well as stability of linear dynamic systems. Two novel linearization methods are proposed and their satisfactory performances are proved for output tracking as well as stability of nonlinear dynamic system. The first method is based on the fixed linearization rate and the second one is based on the variable (optimal) linearization rate. The decoder that is based on the second method is in fact the extended Kalman filter with the optimal linearization rate. The performances of these two methods are compared with each other and the other proposed methods by implementing them to the problems of the tele‐presence and tele‐operation of autonomous vehicles over the AWGN channel. Their satisfactory performances are illustrated. It is illustrated that the second method has higher computational complexity with slightly better performance and is applicable to a larger class of reference trajectories.

Reconfigurable intelligent surface (RIS) has great potential in securing wireless transmission, and it can flexibly change the wireless communication environment. However, the employment of RIS increases the difficulty in beamforming of base station (BS), and existing schemes cannot be directly utilized to enhance the security of system. Therefore, a reinforcement learning framework to jointly control BS and RIS for the purpose of enhancing the secure performance is proposed. Specifically, the beamforming ia transformed with artificial noise and reflection control as a Markov decision problem (MDP) in complex domain. Then, we develop the deep deterministic policy gradient based on complex‐valued neural networks (CV‐DDPG) to imitate the rules of complex computation. Additionally, the CV‐DDPG is performed as the agent of reinforcement learning to control the BS and RIS, which enables better utilization of the implied phase information of complex values in the system. The simulation results show that the proposed model promotes the performance of the control and greatly improves the secrecy rate of the legitimate user. [ABSTRACT FROM AUTHOR]

This paper is concerned with tele‐presence and tele‐operation of autonomous vehicles over the Additive White Gaussian Noise (AWGN) channel. This wireless communication channel is subject to transmission noise and transmission power constraint. An encoder, decoder and controller are proposed by implementing a novel linearization method for linearizing the nonlinear dynamic systems at operating points. For the linearized systems, the encoder, decoder and controller are implemented that were previously proposed for output tracking as well as stability of linear dynamic systems. Two novel linearization methods are proposed and their satisfactory performances are proved for output tracking as well as stability of nonlinear dynamic system. The first method is based on the fixed linearization rate and the second one is based on the variable (optimal) linearization rate. The decoder that is based on the second method is in fact the extended Kalman filter with the optimal linearization rate. The performances of these two methods are compared with each other and the other proposed methods by implementing them to the problems of the tele‐presence and tele‐operation of autonomous vehicles over the AWGN channel. Their satisfactory performances are illustrated. It is illustrated that the second method has higher computational complexity with slightly better performance and is applicable to a larger class of reference trajectories. [ABSTRACT FROM AUTHOR]

Networked control systems (NCSs) are control systems closed through communication network and applied to remote control of robots, tele-surgery and numerous industrial applications. In NCS, data have to coarsely quantised when the communication network is restricted due to the traffic limit. Under the traffic limitation, the design of an appropriate quantiser is highly important in realising a desired control performance. Further, the coordination of quantisation and control input also plays a decisive role. Towards an optimal balance between the traffic capacity of network and the control performance, this study proposes an MPC based approach for quantised state feedback control systems with dynamic quantisers. In the proposed approach, the control input and the quantisation interval of the quantiser are optimised online. The proposed method can explicitly treat input/state constraints, the parameter of quantiser and other physical restriction. The effectiveness of the proposed method is demonstrated by simulations and experiments.

This study isrelevant to the topic of a robust event‐triggered mechanism for the Takagi–Sugeno (T–S) fuzzy system with successive time‐delay (STD) signals and its application, where the uncertainties satisfy the randomly occurring form. Firstly, an event‐triggered communication scheme is introduced, which can adaptively adjust the communication threshold to save limited communication resource. The primary aim of this study is to model an event‐triggered mechanism with STD, which ensures that the suggested T–S fuzzy system achieves extended dissipative with permissible uncertainties. Secondly, by using the relaxed integral inequality technique, single and double auxillary function‐based integral inequalities to evaluate the derivative of the designed Lyapunov–Krasovskii functional, quadratically stable condition is established for the delayed fuzzy system in terms of linear matrix inequalities and analyse the H∞,L2−L∞, passivity, mixed H∞ and passivity, (Q,S,R)‐dissipativity execution by choosing the weighting matrices can be solved simultaneously in a standard framework based on the idea of extended dissipative. Finally, simulation studies are given to verify the effectiveness of the derived results, among them one example was supported by the real‐life application of the benchmark problem in the sense of STD signals. [ABSTRACT FROM AUTHOR]

This study is concerned with the design of active queue management (AQM) subjected to quantisation errors. First, the authors will show here that quantisation errors exist when AQM experiences transmission control protocol (TCP) during the congestion. Second, a TCP/AQM model that takes into account quantisation errors is proposed – the considered quantisers are dynamic and have a scale parameter. Based on this model, stabilisation will be analysed in which the controller and the scaling parameters are obtained using the Lyapunov–Krassovskii functional method. Finally, Matlab simulation results are displayed to show the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

With the rapid emergence of the Internet of Things (IoT), the development of IoT architecture that facilitates network control and remote management is not only an interesting but also challenging research direction. Designing a systematic framework allowing to remotely (re)reprogram heterogeneous IoT devices requires stringent technical challenges on the interoperability, the scalability and the adaptability. Recently, software defined network (SDN)‐based technologies have been considered as a dominant solution for the IoT network architecture. In this study, the authors firstly review current state‐of‐the‐art approaches of SDN solutions and existing efforts on remote (re)programming IoT systems. The literature review figures out current leading‐edge technologies on SDN‐based solutions and over‐the‐air (OTA) reprogramming approaches in IoT systems as well as indicates the existing challenges that encourage conducting more and more appropriate solutions to fulfil the requirements of the future Internet. Then, a framework called SD‐IoTR (software defined IoT reprogramming) is proposed. The proposed SD‐IoTR framework is based on the SDN architecture and intensively focuses on OTA programming IoT systems. This framework is designed to deal with high demands for dynamic adaptability and scalability. Finally, two case studies are also presented as proofs‐of‐concept that convince the feasibility of applying the proposed framework to real‐world deployments. [ABSTRACT FROM AUTHOR]

In the last couple of decades, the industry saw an increase in the number of wireless sensor networks (WSNs) in replacement of the old cabled technology due to lower deployment and maintenance costs. To keep this momentum, those industrial WSN (IWSN) must assure robustness, scalability, low power, and low maintenance, and the network protocol stack is an important piece of this puzzle. One great dilemma faced by IWSN protocols is how to sustain reliable radio links while avoiding draining too much energy from the battery. In this context, Wireless HART (WH) and ISA SP100.11a, for example require the hardware of the nodes to provide multiple power levels for transmission. Unfortunately, those protocols do not provide a standard procedure to choose between those levels. A simple but inefficient solution often employed simply chooses the highest level available. Seeking a better solution, this proposal presents a transmission power control (TPC) methodology that allows energy saving while sustaining the quality of the communication link employing a simple proportional–integral (PI) controller plus anti‐windup. The proposed approach does not rely on special TPC‐related packets, which is advantageous in comparison with other approaches from the literature by allowing this work to be fully compliant with existing IWSN protocols. [ABSTRACT FROM AUTHOR]

Laser-based wireless power transmission (LWPT) systems are one of the most promising systems in the long-range wireless power transfer field. However, few studies have focused on the efficiency characteristics of LWPT systems. Therefore, most LWPT systems are open-loop systems, making it difficult to best utilise their lasers and photovoltaic cells, thus preventing the system efficiency from being further improved. In this study, a closed-loop power control method is proposed for LWPT systems to explore the best performance conditions for such systems. To this end, the efficiency characteristics of a system are investigated by means of theoretical analysis and experimental measurements. The results show that the duty cycle of the laser input current is one of the key factors for improving the system efficiency. Then, a dual closed-loop controller, which includes an optimal duty cycle search algorithm, is proposed based on the obtained system characteristics. Finally, a small-scale prototype is fabricated and tested in the laboratory to verify the effectiveness of the proposed power control method. [ABSTRACT FROM AUTHOR]

Networked control systems (NCSs) are control systems closed through communication network and applied to remote control of robots, tele-surgery and numerous industrial applications. In NCS, data have to coarsely quantised when the communication network is restricted due to the traffic limit. Under the traffic limitation, the design of an appropriate quantiser is highly important in realising a desired control performance. Further, the coordination of quantisation and control input also plays a decisive role. Towards an optimal balance between the traffic capacity of network and the control performance, this study proposes an MPC based approach for quantised state feedback control systems with dynamic quantisers. In the proposed approach, the control input and the quantisation interval of the quantiser are optimised online. The proposed method can explicitly treat input/state constraints, the parameter of quantiser and other physical restriction. The effectiveness of the proposed method is demonstrated by simulations and experiments. [ABSTRACT FROM AUTHOR]

The distributed control plane is the alternate solution to reliability and scalability like potential issues in the software‐defined wide area network (SDWAN), but the static mapping between controller and switches might cause an uneven load distribution among controllers. Migration of switches from one controller to another under‐loaded controller is a solution to handle the peak traffic. However, the switch migration process is a complex process that may affect the end‐user quality of service (QoS), as a result, the response time of the control messages are also affected. To address this issue, the authors present RTSM, a novel strategy, that optimises the response time of the control messages during switch migration. Further, an SDWAN architecture was proposed, in which the introduction of the layer‐2 controller reduces the dependency on WAN communication of the forwarding devices. The Karush–Kuhn–Tucker conditions have been applied for target controller selection, which ensures improved response time. A switch selection method was also introduced, which minimally affects the end‐user QoS during device migration in SDWAN scenario. To evaluate the performance of the RTSM, Mininet simulator with the Floodlight controller has been used, and the result shows that the proposed algorithm outperforms the other existing works during load balancing. [ABSTRACT FROM AUTHOR]

The authors investigate secure resource allocation for an orthogonal frequency division multiple access two‐way relay network, which has several pairs of mobile users (MUs) and one energy harvesting (EH) relay. In this network, the relay is untrusted and each MU pair may also overhear the other MU pairs' confidential information. In particular, to forward information for each MU, the relay adopts power splitting technique to harvest energy from radio frequency signals emitted by each MU. For this scenario, which has hardly been considered, the joint problem of subcarrier allocation, power control, and power splitting ratio selection is formulated, with the aim to maximise the total secrecy rate of all MUs. A suboptimal algorithm with low complexity and satisfactory performance is proposed to solve the formulated non‐convex problem. [ABSTRACT FROM AUTHOR]

Cooperative vehicular cyber physical systems build a group of entities that can accomplish a cooperative task using the distributed control approaches. To this end, such a cooperative task can be coordinated and managed by a distributed control plane that will be able to encapsulate all the required functionality in a layered architecture providing the required interoperability. Here, the authors propose such a distributed control plane that consists of the cooperative awareness layer, the communication layer and the distributed control layer. Wireless communications play an important role for the mobility provision, taking into account different constraints in order to provide high reliability and low latency. A simulation environment is considered with a leader–follower control format, where the reliability is evaluated. Further, a distributed safety monitoring approach is devised, given a control diagram and mapping of the events to the different components. The event monitoring relies on the self-triggered approach, where a use case is evaluated to highlight the impact of the input and output delays to the model predictive control component of the overall distributed control diagram including the calculation of the number of triggered events.

The hybrid cognitive radio (CR) system which combines the two classical interweave and underlay approaches has an improved spectrum efficiency compared to conventional CR systems. In this study, the authors apply the joint spectrum access and power control in a hybrid CR system in the presence of threshold estimation errors. They first formulate the performance metrics of the hybrid CR system under the optimal joint spectrum access and power control strategies by taking into account the threshold estimation errors. Then they show that the threshold estimation error decreases the probability of detecting the primary user (PU) while it increases the false‐alarm probability. Next, they show that the threshold estimation error degrades the performance of the hybrid CR system in terms of outage probability, average achievable data rate and the average interference introduced to the PU. To overcome these performance degradations, they propose a modified spectrum access formulation based on the probabilistic spectrum access scheme, which reduces the impact of threshold estimation uncertainty on the performance of the hybrid CR system. Simulation results indicate that the proposed spectrum access can compensate the performance degradation of a CR system up to 65% for a detection probability of 0.7. [ABSTRACT FROM AUTHOR]

In this study, a modified fluid model is proposed to understand the design of controlled delay (CoDel) algorithm for active queue management (AQM) and analyse its sensitivity to parameter settings. CoDel significantly differs from other AQM algorithms because it operates at the head of the queue and adopts a deterministic packet drop strategy, unlike other algorithms that operate at the tail and adopt a probabilistic packet drop strategy. The correctness of the proposed fluid model is verified by comparing its results with those obtained from ns ‐2. Subsequently, using the model developed in this study, the authors analyse the performance of CoDel algorithm by changing its internal parameters and modifying its control law. They highlight the role of the internal parameters and control law on the ability of the CoDel algorithm to control queue delay. Their analysis shows that the CoDel algorithm is sensitive to its parameter settings and that its control law requires minor modifications to gain a better control over the queue delay. [ABSTRACT FROM AUTHOR]

A new model for malicious file propagation and transmission in a computer network is formulated. This model introduced a cure rate ξ (E ‐cure rate) which is calculated after the regular running of anti‐virus in the systems of the computer network. This will result in monitoring the anti‐virus efficiency in fighting not only a local malicious file but also the global spreading of such a file. The file has to go through different scenarios including many other states. Therefore, a vertical transmission concept is introduced in the proposed model. The threshold conditions for the stability of the proposed model are determined. Numerous methods are used to prove that the viral equilibrium points of our model are globally and locally stable. The behaviour of the compartment nodes in the computer network has been analysed. In addition, the optimal control theory is used to study immunisation strategies against Malware in order to control the economic losses of security investments and keep infection loss at the lowest possible level. The existence and uniqueness of results related to the system are confirmed. Finally, the simulation shows that the spread of malware can be effectively controlled by choosing the appropriate control strategy of specific parameters. [ABSTRACT FROM AUTHOR]

Here, the problem of non‐cooperative game‐theoretic distributed power control is studied in a radar network system based on low probability of intercept (LPI) subject to the signal‐to‐interference‐plus‐noise ratio (SINR) constraint and the transmit power constraint of each radar, where all the radars in the network share the same frequency band. The objective is to improve the LPI performance by reducing the transmit power caused by some radars' SINRs over the specified threshold. First, a novel LPI performance‐oriented utility function is defined as a metric to evaluate power control. Then, consider that radars in the network are self‐interested to maximise their own utilities, the distributed power control problem is formulated as a non‐cooperative game, and an iterative power control algorithm is proposed that converges quickly to the Nash equilibrium (NE) of the non‐cooperative game. Finally, the existence and uniqueness of NE are proved analytically. Numerical simulation results are provided to demonstrate that, compared with other methods, the presented algorithm not only guarantees the minimum SINR requirements of all radars but also improves the LPI performance for radar network. [ABSTRACT FROM AUTHOR]

In an unreliable cluster‐based, broadcast vehicular network setting, the authors investigate the transmission reliability and throughput performance of random network coding (RNC) as a function of the percentage of packet generation rate and transmit power‐to‐noise ratio. In this study, a novel scheme called reliable and efficient cooperative cross‐layer medium access control (RECMAC) is proposed. The proposed scheme consists of a source vehicle broadcasting packets to a set of receivers (i.e. one‐to‐many) over independent broadcast erasure channels. The source vehicle performs RNC on N packets and broadcasts the encoded message to a set of receivers. In each hop, several vehicles form a cluster and cooperatively transmit the encoded or re‐encoded packet. The combination of the RNC, cluster based, and cooperative communications enables RECMAC to optimally minimise data redundancy, which means less overhead, and improve reliability as opposed to coding‐based solutions. Theoretical analyses and simulation results show that under the same conditions RECMAC scheme can achieve improved performance in terms of transmission reliability and throughput. [ABSTRACT FROM AUTHOR]

Transmission power control is an effective method to reduce energy consumption for wireless sensor networks. However, the current algorithms of power control have relatively low accuracy. At the same time, the parameters cannot be adjusted dynamically. In order to improve the energy utilisation as well as data transmission efficiency and balance the load, therefore, a fuzzy power‐optimised clustering routing algorithm is proposed in this study. The algorithm optimises the iteration radius and classifies the sensor nodes into different categories according to their node degree. Then select the cluster head by multi‐parameter iteration adaptively among the same category, and optimise the cluster structure with a comprehensive consideration of parameters such as degree of centralisation, distance between node and base station and so on. Finally, fuzzy control is used to adjust the transmission power of cluster nodes dynamically to minimise the energy consumption. Simulation results show that when the average cluster radius RL=60, weight of election parameters α=0.2, adjustment parameter of cluster radius η=0.7, compared with other similar algorithms, the proposed algorithm prolongs the lifetime by at least 42.2% and increases the amount of data packets by at least 40.1%. [ABSTRACT FROM AUTHOR]

Recently, the visible light communication (VLC) is considered as a future emerging technology in the telecommunication and lighting industry, as defined in the IEEE 802.15.7 standard. In the meantime, the ANSI E1.45 standard was made to provide VLC data transmissions from a VLC data server to a lighting device that is equipped with a VLC transmitter in lighting control networks. However, the ANSI E1.45 scheme cannot provide reliable transmissions of VLC data, and thus a lost data, if any, cannot be recovered. To overcome such limitation, timer‐based VLC data transmission schemes have been studied by applying the retransmission scheme of Internet. However, these schemes still have limitation that the lost VLC data cannot be recovered immediately. Hence, in this study, the authors propose new reliable transmission schemes for VLC data over lighting control networks. The proposed schemes are classified into the packet‐based (PRVS) and fragment‐based (FRVS) schemes. From performance analysis by simulation, the authors see that the FRVS gives the best transmission throughput among the four candidate schemes. In addition, it is shown that the proposed reliable transmission scheme can effectively perform the error recovery operation in the networks with packet losses, compared to the ANSI E1.45 scheme. [ABSTRACT FROM AUTHOR]

This study addresses the robust consensus problem of a network of Lur'e systems coordinating over uncertain communication channels. The authors model each communication channel of the network as an ideal transmission system with the unitary transfer function perturbed by a norm‐bounded uncertainty, which is particularly susceptible to describe quantisation errors and communication noises. Based on the uncertain relative state information among neighbouring agents, a distributed consensus protocol is proposed and designed in terms of linear matrix inequalities to ensure robust consensus for both undirected connected graphs and leader‐follower graphs containing a directed spanning tree. [ABSTRACT FROM AUTHOR]

This study investigates the coverage control problems for the mobile sensor network in a given domain, in which the density function characterising the distribution of the information of interest is unknown. To approximate the density function, we develop an adaptive spatial estimation algorithm for the mobile sensor network. Then, a distributed coverage control strategy is proposed to drive the sensors to the optimal locations. To further improve the efficiency of the coverage process, the authors apply the consensus mechanism into the spatial estimation algorithm and propose an improved control strategy such that the coverage system can converge to the optimal deployment effectively. The convergences of the proposed coverage systems are proved through Lyapunov stability theorem. Moreover, the authors show that the convergence rate of the consensus‐based spatial estimation algorithm is faster than the distributed case. Finally, numerical simulations are provided to illustrate the proposed approaches. [ABSTRACT FROM AUTHOR]

In this Letter, a general space–time line code (STLC)‐based two‐way relay (TWR) method is proposed to enable a power control for individual data streams transmitted to source nodes. Optimal power control factors are derived to ensure fairness between two source nodes under per‐antenna power constraints. When the two‐way channels are unbalanced, numerical results verify that the proposed method outperforms the existing TWR methods, an STLC TWR method without power control, and a space division multiple‐access‐based TWR method. [ABSTRACT FROM AUTHOR]

This study addresses the event‐triggered output tracking control under wireless network environments. First, an improved event‐triggered communication scheme and a sampled‐state‐error dependent tracking model for wireless networked control systems is presented. In this scheme and model, (a) the sensor takes samples in a periodic manner; (b) an improved event‐triggering condition is applied in the communications to determine whether the sampled data is transmitted to the controller or not; and (c) the closed‐loop tracking system with a networked state‐dependent controller is modelled as an augmented time‐delay system. Second, by constructing a novel Lyapunov–Krasovskii functional, two theorems are derived with guaranteed H∞ tracking performance subject to imperfect wireless communications. The tracking performance is based on two permissible limits on the signal transmission. That is, the maximum allowable communication delay bound and maximum allowable number of successive data dropouts. Finally, a satellite tracking example is given to show the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This study investigates the pinning control issue for group consensus of large‐scale systems (LSSs) with communication topology changes and network disturbances. A node selection principle is firstly designed to choose appropriate control nodes, and a centralised pinning control protocol is proposed to drive LSSs achieving group consensus. For reducing control command updates, an event‐trigger is employed to determine whether control signal need be changed. Since the node receives compound exogenous disturbances from its communication neighbours, an improved point‐to‐area H∞ index is advocated as a system robustness performance. Considering communication topology changes, an event‐triggered H∞ Markovian switching pinning control law is finally established and a sufficient controller and event‐trigger co‐design method is presented. Under this strategy, the group consensus of LSSs with a pre‐scheduled H∞ performance can be simultaneously achieved while the Markovian switching topologies are tolerated, moreover, only fewer nodes are controlled and seldom control commands are updated. Finally, illustrative examples are given to demonstrate the effectiveness of the proposed theoretical result. [ABSTRACT FROM AUTHOR]

Orthogonal frequency division multiplexing (OFDM) is an emerging technology in recent wireless communication standards where high data rate is required at low latency and better spectral efficiency. OFDM signals have a generic problem of high peak‐to‐average power ratio (PAPR) due to the superimposition of the data‐modulated subcarriers. This high peak signals may result in amplifier non‐linearity which creates many problems such as performance degradation and out‐of‐band distortion. Hence, the authors addressed this problem by designing and implementing four new PAPR reduction schemes such as phase modulation, rail clipping, sample and hold approach and threshold methods based on amplitude clipping to reduce PAPR and improve the band gap between spectral sidelobes to main lobe significantly. For practical proof of the suggested concepts, they have chosen software‐defined radio as an experimental setup in which universal software radio peripheral N210 employed as hardware and GNU radio as software. Experimental results are analysed in terms of significant PAPR reduction and out‐of‐band spectral leakage control. Besides these, motivation, background and relevant mathematical analysis with rigid justification are presented in this study. [ABSTRACT FROM AUTHOR]

This study discusses wireless data flow controller design accounting for input signal saturation and an unknown delay. A main focus is to maintain a low real‐time computational complexity. This is motivated by a need to run a very large number of controllers in a single network node, e.g. in wireless 5G data flow control applications. Linear quadratic Gaussian design is therefore first applied to compute feedback and feedforward gains, for assumed nominal delays without accounting for the saturation that is caused by the one‐directional data flow. Gridding of design penalties, system parameters and delays are then used to pre‐compute and tabulate a subset of the ℒ2 stability region by repeated evaluation of the Popov criterion. This step secures a second requirement of robust stability with respect to the uncertain feedback delay. The design is validated with simulation using a detailed model of a networked wireless data flow controller used in cellular communications. [ABSTRACT FROM AUTHOR]

In this study, the problem of robust adaptive power control (PC) in an underlay cognitive radio network with multiple secondary users (SUs) and primary users (PUs) is considered. Due to the effects of uncertainties (i.e. estimation errors, delays), the optimal PC (resource allocation) cannot guarantee the quality of service of SUs and PUs under imperfect channel state information and interference power of PUs. A robust resource allocation problem is formulated to maximise sum throughput of SUs under individual power constraints and signal‐to‐interference‐and‐noise ratio constraints of SUs as well as interference temperature constraints of PUs, whereas channel uncertainties and interference uncertainties induced into the secondary system are modelled by multiplicative uncertainties. Under the worst‐case approach, the problem is transformed into a geometric programming problem solved by Lagrange dual methods. The performance of the different algorithms and the impact of uncertainties are discussed according to several simulation results. [ABSTRACT FROM AUTHOR]

The future wireless communication systems require an intelligent and service adaptive network selection to perform vertical handover (HO) in heterogeneous environments. Since multiple parameters are considered to select the best suitable network, reducing the complexity in multi‐attribute decision making algorithm becomes apparent. In the proposed scheme, fuzzy logic controllers are used to estimate the necessity of HO and to determine the user satisfaction degree based on the critical parameters, such as mobile terminal speed, network load and service cost. Fuzzy analytic hierarchy process is used to calculate the weights of each attribute according to the traffic. Since it handles the uncertainty and vagueness in mapping the user preference to the priority scales, consistency level of network selection can be improved. Quality of service factor is calculated for each network by processing the weighted decision matrix using principal component analysis. Simulation results show that proposed scheme can ensure the best network selection by providing trade‐off between complexity and consistency. [ABSTRACT FROM AUTHOR]

In wireless sensor networks, the necessity of reprogramming becomes more and more important for variety of purposes. However, the reprogramming produces a large amount of data and causes large energy consumption and interference. In this Letter, we propose an energy-efficient reprogramming scheme with Raptor code by using transmission power control. By selecting proper relay nodes, relay nodes’ transmission power and Raptor code overhead, the proposed scheme minimises energy consumption while guaranteeing reliable transmission. This is verified by comparing it with conventional schemes.

The aim of this study is to develop a new feedback stabilisation strategy involving a non‐linear potential feedback control (PFC) for scalar discrete‐time systems with disturbances by using Lyapunov functions. The main interest of the PFC is to achieve the stabilisation with a constraint on the state space. The authors apply this strategy for the uplink power control in a real wireless sensor network and compare with the adaptive transmission power control (ATPC) usually used in telecommunications. A study of the energy saving is also provided. [ABSTRACT FROM AUTHOR]

Healthcare facilities with intelligent wireless devices can reduce the workload of the paramedic staff. These devices include low-power wireless sensors, personal wireless hub (PWH), and receivers. The PWH can act as a relay in the hospital network. To help the wireless sensor devices, we use multiple PWHs to transfer sensor data to the main central controller. The use of multiple PWHs can increase the performance of the wireless network in the hospital. It also adds reliability to the coverage of the wireless network. In this paper, we propose a framework and low-complexity algorithm for interference aware joint power control and multiple PWH assignment (IAJPCPA) in a hospital building with cognitive radio capability. In the proposed framework, any wireless sensor device can send and receive data from multiple PWHs. The proposed IAJPCPA is a nonconvex mixed integer nonlinear optimization problem, which is generally NP-hard. The main objective of IAJPCPA is to maximize the total transmission data rate by assigning PWHs to the wireless sensor devices under the constraint of acceptable interference to the licensed wireless devices. To this end, we present an efficient PWH assignment and power control scheme for IAJPCPA problem by employing an upper bound on the IAJPCPA that converts the nonconvex problem into a convex optimization problem. Finally, we examine the effect of different system parameters on the performance of the proposed algorithm. [ABSTRACT FROM PUBLISHER]

Wireless body area networks have recently received much attention because of their application to assisted living and remote patient monitoring. For these applications, energy minimisation is a critical issue since, in many cases, batteries cannot be easily replaced or recharged. Reducing energy expenditure by avoiding unnecessary high transmission power and minimising frame retransmissions is therefore crucial. In this study, a transmit power control scheme suitable for IEEE 802.15.6 networks operating in beacon mode with superframe boundaries is proposed. The transmission power is modulated, frame‐by‐frame, according to a run‐time estimation of the channel conditions. Power measurements using the beacon frames are made periodically, providing reverse channel gain and an opportunistic fade margin, set on the basis of prior power fluctuations, is added. This approach allows tracking of the highly variable on‐body to on‐body propagation channel without the need to transmit additional probe frames. An experimental study based on test cases demonstrates the effectiveness of the scheme and compares its performance with alternative solutions presented in the literature. [ABSTRACT FROM AUTHOR]

The fast handover Mobile IPv6 (FMIPv6) offers a handover preparation mechanism for a mobile node (MN) to reduce the handover latency over wireless network. However, FMIPv6 mainly deals with one MN instead of multiple MNs. In the wireless network, a group of MNs may move from the same previous network to the next network. In this paper, a group‐based fast handover (GB‐FH) control scheme is proposed to resolve the aforementioned problem. For the proposed GB‐FH scheme, one MN initiates a handover preparation and other neighboring MNs can join the handover preparation using the "hitch‐and‐ride" concept, which means that when one MN is preparing for a handover, its neighbours can join the on‐going handover preparation. Through the use of the shared invocation of the handover preparation procedure, (1) the handover preparation delay and handover latency can be reduced for about 20% and 8% respectively comparing with FMIPv6, (2) handover control messages can be reduced for about 57% comparing with FMIPv6 and (3) the contention of the wireless channel for multiple MNs can be improved due to the use of fewer control messages. [ABSTRACT FROM AUTHOR]

The growing energy consumption has posed new challenges for the future development of networks. Some earlier work has proposed solutions to improve energy consumption based on the existing control plane, for example, node/links sleeping. This study presents a new possibility to reduce network energy consumption by proposing a new integrated control plane structure utilising Software Defined Networking technologies. The integrated control plane increases the efficiencies of exchanging control information across different network domains, while introducing new possibilities to the routing methods and the control over quality of service (QoS). The structure is defined as an overlay generalised multi‐protocol label switching (GMPLS) control model. With the defined structure, the integrated control plane is able to gather information from different domains (i.e. optical core network and the access networks), and enable energy efficiency networking over a wider area. In the case presented, the integrated control plane collects the network energy related information and the QoS requirements of different types of traffic. This information is used to define the specific group of traffic's (flow's) routing behaviours. With the flexibility of the routing structure, results show that the energy efficiency of the network can be improved without compromising the QoS for delay/blocking sensitive services. [ABSTRACT FROM AUTHOR]

To improve the availability of the software‐defined networking (SDN) under distributed denial of service (DDoS) attacks, a multi‐queue SDN controller scheduling algorithm based on time slice allocation strategy is proposed. The proposed algorithm can take different time slice allocation strategies according to the intensity of DDoS attacks and use SDN controller to schedule processing flow request from different switches (including the switches suffering from different degrees of attacks and normal switches) to ensure better protection to the normal switch in the network under DDoS attacks. Simulation results are presented to show the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

The concept of SDN has emerged as a way to address numerous challenges with traditional network architectures by decoupling network control and forwarding. So far, the use cases for SDN mainly targeted data-center applications. This article considers SDN for network carriers, facing operation of large-scale networks with millions of customers, multiple technologies, and high availability demands. With specific carrier-grade features such as scalability, reliability, flexibility, modularity, and virtualization in mind, the SPARC EU project has developed the SPARC SplitArchitecture concept. The SplitArchitecture control plane allows hierarchical layering of several control plane layers which can be flexibly mapped to data plane layers. Between control layers open interfaces are used. Furthermore, SplitArchitecture proposes an additional split of forwarding and processing functions in data path elements, enabling switch based OAM functionality and handling of tunneling techniques. The SplitArchitecture concept is evaluated in a prototype demonstrating an SDN version of BRAS: the floating BRAS. The floating BRAS allows creation of residential Internet access services with dynamically managed BRAS instances. The demo is based on a controller enabling protected MPLS transport connections spanning SDN-controlled aggregation and IP/MPLS-based core domains. The prototype showcases how SplitArchitecture enables virtualization of service nodes in an SDN-controlled network, leading to increased flexibility in configuration and placement of service creation functions. Overall, the results show that it is technically and economically beneficial to apply SDN, and specifically the SplitArchitecture concept, to the carrier domain. [ABSTRACT FROM AUTHOR]

We consider a wireless network where two nodes (source and destination) aim at exchanging a message that must be kept secret from a third eavesdropper node. Other legitimate nodes relay the message from the source to the destination over multiple hops. Channels are subject to fading and only a partial channel state information at the transmitter is available before transmission. Assuming that each transmission has an entangled cost, e.g., delay or energy, we aim at finding the optimal routing policy that minimizes the cost with a constraint on the average secrecy outage probability. We model the problem as the search for a control policy of a stochastic dynamic system that minimizes a discounted expected cost objective, with a discounted expectation constraint. A Lagrange-multiplier based solution is proposed. Numerical results show the merits of the proposed solution over a multi-hop wireless network. [ABSTRACT FROM PUBLISHER]

This paper aims to realize OpenFlow-controlled revenue-driven advance reservation (AR) provisioning in software-defined elastic optical networks (SD-EONs). We design control plane framework, propose two algorithms for the OpenFlow controller, implement the whole system in a semi-practical SD-EON testbed, and conduct experiments with two payment models. Experimental results indicate the proposed system performs well and can increase total revenue-gain effectively. [ABSTRACT FROM PUBLISHER]

For the requirements of energy saving in wireless sensor networks (WSNs), this study proposes a transmission power control strategy for cluster heads (CHs) based on multi‐packet reception in clustering WSNs. First, this study proposes a new CHs selection algorithm for clustering WSNs. Second, transmission power levels of each CH are determined according to the number of CHs in monitoring area. Third, with restrictions of successive interference cancellation algorithm in sink, transmission power control strategy for CHs are determined by distance from CHs to sink and residual energy of CHs. For whole network, single‐hop communication mode is designed to send data from sensor nodes to CHs, at the same time; it is also applied to send data from CHs to sink. Simulation results show that this power control strategy can reduce the energy consumption of sensor nodes and increase network throughput, which can greatly improve network lifetime. The authors believe that their findings will be useful guidelines for moving forward with successive interference cancellation research in WSNs. [ABSTRACT FROM AUTHOR]

In this study the authors present a novel technique for control of signal power transients caused by signal add/drops in optical communication networks with erbium‐doped fibre amplifiers (EDFAs). The approach utilises the electronic automatic gain control that combines both feedback and feedforward control of EDFA. Feedback control is non‐linear integral control and feedforward control is a steady‐state gain scheduling technique. The feedback non‐linear control requires information about the average inversion level that is obtained via a simple linearised first‐order observer. The scheduling variable used is the nominal pump power needed to keep the average inversion level at the desired value at steady state and the input signal powers given at particular wavelengths. In the simplified gain scheduling version, the scheduling variable is the total input signal power. Simulation examples indicate that the proposed controller completely eliminates at steady state the photon power transients caused by signal add/drops with the steady state being reached within a few milliseconds. [ABSTRACT FROM AUTHOR]

Adaptive flexi-grid optical networks should be able to autonomously decide where and when to dynamically setup, reoptimize, and release elastic optical connections, in reaction to network state changes. A stateful path computation element (PCE) is a key element for the introduction of dynamics and adaptation in generalized multiprotocol label switching (GMPLS)-based distributed control plane for flexi-grid DWDM networks (e.g., global concurrent reoptimization, defragmentation, or elastic inverse-multiplexing), as well as for enabling the standardized deployment of the GMPLS control plane in the software defined network control architecture. First, this paper provides an overview of passive and active stateful PCE architectures for GMPLS-enabled flexi-grid DWDM networks. A passive stateful PCE allows for improved path computation considering not only the network state (TED) but also the global connection state label switched paths database (LSPDB), in comparison with a (stateless) PCE. However, it does not have direct control (modification, rerouting) of path reservations stored in the LSPDB. The lack of control of these label switched paths (LSPs) may result in the suboptimal performance. To this end, an active stateful PCE allows for optimal path computation considering the LSPDB for the control of the state (e.g., increase of LSP bandwidth, LSP rerouting) of the stored LSPs. More recently, an active stateful PCE architecture has also been proposed that exposes the capability of setting up and releasing new LSPs. It is known as active stateful PCE with instantiation capabilities. This paper presents the first prototype implementation and experimental evaluation of an active stateful PCE with instantiation capabilities for the GMPLS-controlled flexi-grid DWDM network of the ADRENALINE testbed. [ABSTRACT FROM PUBLISHER]

High degree of heterogeneity of future optical networks, stemming from provisioning of services with different quality-of-transmission requirements, and transmission links employing mixed modulation formats or switching techniques, will pose a challenge for the control and management of the network. The incorporation of cognitive techniques can help to optimize a network by employing mechanisms that can observe, act, learn and improve network performance, taking into account end-to-end goals. The EU project CHRON: Cognitive Heterogeneous Reconfigurable Optical Network proposes a strategy to efficiently control the network by implementing cognition. In this paper we present a survey of different techniques developed throughout the course of the project to apply cognition in future optical networks. [ABSTRACT FROM PUBLISHER]