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The bidirectional broadcast channel denotes a broadcast channel with two receivers where each receiver knows the message intended for the other. We consider streaming sources where messages of each user arrive as bit-stream to the encoder. Thus our main quantity of interest is the bit error probability. By extending Sahai's argument to bidirectional broadcast channel, we show that under maximum-likelihood decoding the bit error probability decays exponentially in delay with positive exponent for all the rate pairs inside the capacity region. We also show existence of deterministic codes which achieve exponentially decaying bit error probability with delay., QC 20111216

In this and a companion paper a dynamic programming (DP) approach to solve a smart home appliances scheduling problem is considered. The challenge with solving the scheduling problem is the coupling of decision variables due to some time precedence constraints. In general, the system of precedence constraints may contain redundant constraints that offer opportunities for simplification. This simplification is desirable for reducing the computation effort of the nonserial DP procedure presented in the companion paper (i.e., Part II). The current paper establishes the uniqueness of the maximum set of redundant constraints and its polynomial-time solvability with optimality guarantee, under the sufficient and necessary condition that the precedence graph (a graph representation of the precedence constraints system) does not contain any cycle with nonnegative weight. A numerical case study indicates the efficiency of the proposed simplification algorithm versus the brute-force enumerative search. Besides helping to reduce the computation effort in the DP procedure described in the companion paper, the algorithm in the current paper solves a generalization of a precedence graph simplification problem arising from application areas such as parallel computing., QC 20150408

In this paper, we investigate the reachability analysis and safety controller synthesis problem for linear discrete-time systems under additive bounded disturbances. We consider the following problem; design a state feedback controller such that any state trajectories starting from an initial set can be robustly controlled towards a target one in finite time, while at the same time avoiding any prohibited regions. One of the potential disadvantages of existing reachability algorithms when external disturbances are taken into account, may be that the solution to guarantee reachability becomes conservative. Motivated by this, this paper provides a new controller synthesis framework based on the notion of tube-based control strategy, in which a suitable sequence of polytopes is generated according to a convex feasibility problem. An illustrative simulation validates the effectiveness of our proposed method., QC 20180306

It is known that the problem of verifying the infinite-step opacity of nondeterministic finite transition systems (NFTSs)is PSPACE-hard. In this paper, we investigate whether it is possible to use classical bisimulation relation to come up with abstract NFTSs and verify the infinite-step opacity of original NFTSs over their abstractions. First, we show that generally bisimulation relation does not preserve infinitestep opacity. Second, by adding some additional conditions to bisimulation relation, we prove that a stronger version of bisimulation relation, called here opacity-preserving bisimulation relation, preserves infinite-step opacity. Therefore, if one can find an abstract NFTS for a large NFTS under an opacity-preserving bisimulation relation, then the infinite-step opacity of the original NFTS can be verified by investigating that over the abstract NFTS. Finally, we show that under some mild assumptions, the quotient relation between an NFTS and its quotient system becomes opacity-preserving bisimulation relation which provides a scheme for constructing opacity-preserving abstractions of large- scale NFTSs. We show the effectiveness of the results using several examples throughout the paper., QC 20180305

This paper investigates the online motion coordination problem for a group of mobile robots moving in a shared workspace. Based on the realistic assumptions that each robot is subject to both velocity and input constraints and can have only local view and local information, a fully distributed multi-robot motion coordination strategy is proposed. Building on top of a cell decomposition, a conflict detection algorithm is presented first. Then, a rule is proposed to assign dynamically a planning order to each pair of neighboring robots, which is deadlock-free. Finally, a two-step motion planning process that combines fixed-path planning and trajectory planning is designed. The effectiveness of the resulting solution is verified by a simulation example., QC 20210412

This paper studies the construction of symbolic abstractions for periodic event-triggered systems. To construct symbolic abstractions, the original event-triggered mechanism is over- and under-approximated, and thus the abstract event-triggered mechanisms are different from the original one, which leads to the asynchronous phenomenon between the original system and the constructed symbolic abstractions. To deal with this issue, an interface is proposed to guarantee the synchronization between the original and abstract event-triggering mechanisms and the equivalence relations between the original system and the constructed symbolic model. Furthermore, we study the controller refinement based on these two constructed symbolic models. Finally, the obtained results are illustrated via a numerical example., QC 20210414

In this paper, we consider a secure distributed filtering problem for linear time-invariant systems with bounded noises and unstable dynamics under compromised observations. A malicious attacker is able to compromise a subset of the agents and manipulate the observations arbitrarily. We first propose a recursive distributed filter consisting of two parts at each time. The first part employs a saturation like scheme, which gives a small gain if the innovation is too large. The second part is a consensus operation of state estimates among neighboring agents. A sufficient condition is then established for the boundedness of estimation error, which is with respect to network topology, system structure, and the maximal compromised agent subset. We further provide an equivalent statement, which connects to 2s-sparse observability in the centralized framework in certain scenarios, such that the sufficient condition is feasible. Numerical simulations are finally provided to illustrate the developed results., QC 20201007

In this paper, we present a unified framework based on integral quadratic constraints for analyzing the convergence of distributed push-pull based optimization algorithms for directed graphs. Our framework provides numerical upper bounds on linear convergence rates of existing distributed push-pull based algorithms when local objective functions are strongly convex and smooth and directed graphs are strongly connected. Moreover, we propose a new distributed optimization algorithm for directed graphs and show that the proposed framework can also be applied to establish its linear convergence rate. The theoretical results are illustrated and validated via numerical examples., Part of proceedings: ISBN 978-1-7281-1164-3QC 20211014

This paper deals with the solution bounds for discrete-time Networked Control Systems (NCSs) via delay-dependent Lyapunov-Krasovskii methods. Solution bounds are widely used for systems with input saturation caused by actuator saturation or by the quantizers with saturation. A time-delay approach was introduced recently for continuous-time NCS under a weighted Try-Once-Discard (TOD) protocol in [12], where actuator saturation was not taken into account. In the present paper, we develop the time-delay approach for linear (probably, uncertain) discrete-time NCS under the weighted TOD protocol in the presence of actuator saturation. A novel Lyapunov-based method is presented for finding the domain of attraction. Polytopic uncertainties in the system model can be easily included in our analysis. The efficiency of the time-delay approach is illustrated on the example of a cart-pendulum system., QC 20131216

In this paper a dynamic programming (DP) solution approach to a nonconvex resource allocation problem (RAP) is presented. The problem in this paper generalizes the smart home appliances scheduling problem introduced in the companion paper (i.e., Part I). The computation difficulty with solving the RAP depends on the decision variable coupling, which can be described by an interaction graph. This paper proposes a DP algorithm to solve the RAP in the special setting where the interaction graph is a tree. This extends the applicability result of DP to RAP beyond the standard serial case where the interaction graph is a line. The extension of the result is achieved by establishing that even in the tree case DP computation effort is polynomial in the number of decision variables. For RAP in its general form, this paper proposes a modification to the nonserial DP procedure originally introduced by Bertele and Brioschi. Contrary to that of the previous method, the computation effort of the proposed method can be characterized by a well-known minimum feedback vertex set problem. Case studies on known examples indicate that both nonserial DP methods are similarly efficient., QC 20150408

This paper deals with the solution bounds for discrete-time Networked Control Systems (NCSs) via delay-dependent Lyapunov-Krasovskii methods. Solution bounds are widely used for systems with input saturation caused by actuator saturation or by the quantizers with saturation. A time-delay approach was introduced recently for continuous-time NCS under a weighted Try-Once-Discard (TOD) protocol in [12], where actuator saturation was not taken into account. In the present paper, we develop the time-delay approach for linear (probably, uncertain) discrete-time NCS under the weighted TOD protocol in the presence of actuator saturation. A novel Lyapunov-based method is presented for finding the domain of attraction. Polytopic uncertainties in the system model can be easily included in our analysis. The efficiency of the time-delay approach is illustrated on the example of a cart-pendulum system., QC 20131216

This paper deals with the solution bounds for discrete-time Networked Control Systems (NCSs) via delay-dependent Lyapunov-Krasovskii methods. Solution bounds are widely used for systems with input saturation caused by actuator saturation or by the quantizers with saturation. A time-delay approach was introduced recently for continuous-time NCS under a weighted Try-Once-Discard (TOD) protocol in [12], where actuator saturation was not taken into account. In the present paper, we develop the time-delay approach for linear (probably, uncertain) discrete-time NCS under the weighted TOD protocol in the presence of actuator saturation. A novel Lyapunov-based method is presented for finding the domain of attraction. Polytopic uncertainties in the system model can be easily included in our analysis. The efficiency of the time-delay approach is illustrated on the example of a cart-pendulum system., QC 20131216

This paper deals with the solution bounds for discrete-time Networked Control Systems (NCSs) via delay-dependent Lyapunov-Krasovskii methods. Solution bounds are widely used for systems with input saturation caused by actuator saturation or by the quantizers with saturation. A time-delay approach was introduced recently for continuous-time NCS under a weighted Try-Once-Discard (TOD) protocol in [12], where actuator saturation was not taken into account. In the present paper, we develop the time-delay approach for linear (probably, uncertain) discrete-time NCS under the weighted TOD protocol in the presence of actuator saturation. A novel Lyapunov-based method is presented for finding the domain of attraction. Polytopic uncertainties in the system model can be easily included in our analysis. The efficiency of the time-delay approach is illustrated on the example of a cart-pendulum system., QC 20131216

This paper deals with the solution bounds for discrete-time Networked Control Systems (NCSs) via delay-dependent Lyapunov-Krasovskii methods. Solution bounds are widely used for systems with input saturation caused by actuator saturation or by the quantizers with saturation. A time-delay approach was introduced recently for continuous-time NCS under a weighted Try-Once-Discard (TOD) protocol in [12], where actuator saturation was not taken into account. In the present paper, we develop the time-delay approach for linear (probably, uncertain) discrete-time NCS under the weighted TOD protocol in the presence of actuator saturation. A novel Lyapunov-based method is presented for finding the domain of attraction. Polytopic uncertainties in the system model can be easily included in our analysis. The efficiency of the time-delay approach is illustrated on the example of a cart-pendulum system., QC 20131216

Queue overflow of a dynamic queue system gives rise to the information loss (or packet loss) in the communication buffer or the decrease of throughput in the transportation network. This paper investigates a stochastic optimal control problem for dynamic queue systems when imposing probability constraints on queue overflows. We reformulate this problem as a Markov decision process (MDP) with safety constraints. We prove that both finite-horizon and infinite-horizon stochastic optimal control for MDP with such constraints can be transformed as a linear program (LP), respectively. Feasibility conditions are provided for the finite-horizon constrained control problem. Two implementation algorithms are designed under the assumption that only the state (not the state distribution) can be observed at each time instant. Simulation results compare optimal cost and state distribution among different scenarios, and show the probability constraint satisfaction by the proposed algorithms., QC 20190319

This paper presents the formulation and analysis of a fully distributed dynamic event-triggered communication based robust dynamic average consensus algorithm. Dynamic average consensus problem involves a networked set of agents estimating the time-varying average of dynamic reference signals locally available to individual agents. We propose an asymptotically stable solution to the dynamic average consensus problem that is robust to network disruptions. Since this robust algorithm requires continuous communication among agents, we introduce a novel dynamic event-triggered communication scheme to reduce the overall inter-agent communications. It is shown that the event-triggered algorithm is asymptotically stable and free of Zeno behavior. Numerical simulations are provided to illustrate the effectiveness of the proposed algorithm., QC 20190305

In this paper, we consider the distributed optimization problem, whose objective is to minimize the global objective function, which is the sum of local convex objective functions, by using local information exchange. To avoid continuous communication among the agents, we propose a distributed algorithm with a dynamic event-triggered communication mechanism. We show that the distributed algorithm with the dynamic event-triggered communication scheme converges to the global minimizer exponentially, if the underlying communication graph is undirected and connected. Moreover, we show that the event-triggered algorithm is free of Zeno behavior. For a particular case, we also explicitly characterize the lower bound for inter-event times. The theoretical results are illustrated by numerical simulations., QC 20190305

The indirect approach to continuous-time system identification consists in estimating continuous-time models by first determining an appropriate discrete-time model. For a zero-order hold sampling mechanism, this approach usually leads to a transfer function estimate with relative degree 1, independent of the relative degree of the strictly proper real system. In this paper, a refinement of these methods is developed. Inspired by the indirect prediction error method, we propose an estimator that enforces a fixed relative degree in the continuous-time transfer function estimate, and show that the estimator is consistent and asymptotically efficient. Extensive numerical simulations are put forward to show the performance of this estimator when contrasted with other indirect and direct methods for continuous-time system identification., QC 20190305

We consider a lossless multi-terminal source coding problem with one transmitter, two receivers and side information. The achievable rate region of the problem is not well understood. In this paper, we characterise the rate region when the side information at one receiver is conditionally less noisy than the side information at the other, given this other receiver's desired source. The conditionally less noisy definition includes degraded side information and a common message as special cases, and it is motivated by the concept of less noisy broadcast channels. The key contribution of the paper is a new converse theorem employing a telescoping identity and the Csiszár sum identity., QC 20130219

This paper considers the precoder designs for successive zero-forcing dirty paper coding (SZF-DPC), a suboptimal transmission technique for MIMO broadcast channels (MIMO BCs). Existing precoder designs for SZF-DPC often consider a sum power constraint. In this paper, we address the precoder design for SZF-DPC with per-antenna power constraints (PAPCs), which has not been well studied. First, we formulate the precoder design as a rank-constrained optimization problem, which is generally difficult to handle. To solve this problem, we follow a relaxation approach, and prove that the optimal solution of the relaxed problem is also optimal for the original problem. Considering the relaxed problem, we propose a numerically efficient algorithm to find the optimal solution, which exhibits a fast convergence rate. Suboptimal precoder designs, with lower computational complexity, are also presented, and compared with the optimal ones in terms of achievable sum rate and computational complexity., QC 20130118

This paper deals with the problem of adaptive robust parallel simultaneous stabilization(ARPSS) of two uncertain nonlinear port-controlled Hamiltonian systems subject to input saturation, and proposes a number of results on the control design. Firstly, an adaptive H∞ control design approach is presented by using both the dissipative Hamiltonian structural and saturated actuator properties for the case that there are both parametric uncertainties and external disturbances in the systems. Secondly, the results obtained for Hamiltonian systems are applied to ARPSS problem for two uncertain nonlinear affine systems subject to input saturation, and several interesting results are obtained. Finally, study of an example with simulations shows that the adaptive controller proposed in this paper is effective., QC 20130218

This paper investigates the adaptive parallel simultaneous stabilization (APSS) of two multi-input nonlinear Port-Controlled Hamiltonian (PCH) systems subject to actuator saturation, and proposes a number of results on the design of the APSS controllers. Using both the dissipative Hamiltonian structural and saturated actuator properties, the two systems are combined to generate an augmented PCH system subject to actuator saturation, with which some results on the control designs are then obtained. Study of an illustrative example with simulations shows that the APSS controller obtained in this paper is effective., QC 20130130

We consider a lossless multi-terminal source coding problem with one transmitter, two receivers and side information. The achievable rate region of the problem is not well understood. In this paper, we characterise the rate region when the side information at one receiver is conditionally less noisy than the side information at the other, given this other receiver's desired source. The conditionally less noisy definition includes degraded side information and a common message as special cases, and it is motivated by the concept of less noisy broadcast channels. The key contribution of the paper is a new converse theorem employing a telescoping identity and the Csiszár sum identity., QC 20130219

Dynamic decode-and-forward (DDF) is an improved decode-and-forward (DF) protocol under which the relay decides based on its received channel-state information (CSI) when to switch from listening mode to transmission mode without knowing the CSI of other links. In this paper we propose to apply rate-compatible LDPC convolutional (RC-LDPCC) codes to the DDF relay channel. The RC-LDPCC codes are constructed by successive graph extensions, and they have been proved analytically to be capacity achieving over the binary erasure channel. In this paper we show that the RC-LDPCC codes fit well with the DDF relaying, and the regularity of degree distributions simplifies the code optimization. Numerical results in terms of bit erasure rate and achievable rate are provided to evaluate the performance of the system. The results show that the RC-LDPCC codes are able to provide high achievable rates for the DDF relay channel., QC 20120831

We consider a lossless multi-terminal source coding problem with one transmitter, two receivers and side information. The achievable rate region of the problem is not well understood. In this paper, we characterise the rate region when the side information at one receiver is conditionally less noisy than the side information at the other, given this other receiver's desired source. The conditionally less noisy definition includes degraded side information and a common message as special cases, and it is motivated by the concept of less noisy broadcast channels. The key contribution of the paper is a new converse theorem employing a telescoping identity and the Csiszár sum identity., QC 20130219

This paper studies minimum-energy packet forwarding policies for communicating sensor measurements from plant to controller over an unreliable multi-hop wireless network so as to guarantee that the optimal controller achieves a prespecified closed-loop performance. For fixed sampling interval, we demonstrate that the minimal linear-quadratic control loss is monotonically decreasing in the reliability of the sensor-to-controller communication. This allows us to decompose the overall design problem into two separate tasks: finding the minimum end-to-end reliability that allows to achieve a prespecified linear-quadratic loss, and developing minimum-energy packet forwarding policies under a deadline-constrained reliability requirement. We develop optimal solutions for both subproblems and show how the co-designed system with minimum forwarding energy cost and guaranteed LQG control performance can be found by a one-dimensional search over admissible sampling periods. The paper ends with a numerical example which demonstrates the effectiveness of the proposed framework., QC 20121116

Despite the tremendous research effort spent on MIMO systems - very few papers address the impact of hardware imperfections. In this paper we analyze the distortion noise of the transmitter branches of a MIMO transmitter. In particular we analyze the cross-correlation of the distortion noises for the case that the transmitted signals are correlated. This case arises when there is just a single stream being transmitted with beamforming or in the case of multiple streams and linear precoding. We analyze the problem in two ways: using analytical derivations and using measurements on our testbed. In the analytical case we assume a transmitter impaired by a 3rd order non-linearity. For this scenario we find that the absolute correlation coefficient of the distortion noises is given by the absolute value of the correlation coefficients of the input signals to the power of three, while the phase is the same as that of the input signal. Our measurements also show good agreement between measurements and analytical results. It seems to suggest that the distortion noises can be regarded as practically independent whenever there are two or more modulation streams being transmitted (spatial multiplexing). In a single-stream scenario, the distortion noise will tend to have the same spatial distribution as the desired signal., QC 20130118

We consider a lossless multi-terminal source coding problem with one transmitter, two receivers and side information. The achievable rate region of the problem is not well understood. In this paper, we characterise the rate region when the side information at one receiver is conditionally less noisy than the side information at the other, given this other receiver's desired source. The conditionally less noisy definition includes degraded side information and a common message as special cases, and it is motivated by the concept of less noisy broadcast channels. The key contribution of the paper is a new converse theorem employing a telescoping identity and the Csiszár sum identity., QC 20130219

We consider a lossless multi-terminal source coding problem with one transmitter, two receivers and side information. The achievable rate region of the problem is not well understood. In this paper, we characterise the rate region when the side information at one receiver is conditionally less noisy than the side information at the other, given this other receiver's desired source. The conditionally less noisy definition includes degraded side information and a common message as special cases, and it is motivated by the concept of less noisy broadcast channels. The key contribution of the paper is a new converse theorem employing a telescoping identity and the Csiszár sum identity., QC 20130219

This paper studies minimum-energy packet forwarding policies for communicating sensor measurements from plant to controller over an unreliable multi-hop wireless network so as to guarantee that the optimal controller achieves a prespecified closed-loop performance. For fixed sampling interval, we demonstrate that the minimal linear-quadratic control loss is monotonically decreasing in the reliability of the sensor-to-controller communication. This allows us to decompose the overall design problem into two separate tasks: finding the minimum end-to-end reliability that allows to achieve a prespecified linear-quadratic loss, and developing minimum-energy packet forwarding policies under a deadline-constrained reliability requirement. We develop optimal solutions for both subproblems and show how the co-designed system with minimum forwarding energy cost and guaranteed LQG control performance can be found by a one-dimensional search over admissible sampling periods. The paper ends with a numerical example which demonstrates the effectiveness of the proposed framework., QC 20121116

This paper studies minimum-energy packet forwarding policies for communicating sensor measurements from plant to controller over an unreliable multi-hop wireless network so as to guarantee that the optimal controller achieves a prespecified closed-loop performance. For fixed sampling interval, we demonstrate that the minimal linear-quadratic control loss is monotonically decreasing in the reliability of the sensor-to-controller communication. This allows us to decompose the overall design problem into two separate tasks: finding the minimum end-to-end reliability that allows to achieve a prespecified linear-quadratic loss, and developing minimum-energy packet forwarding policies under a deadline-constrained reliability requirement. We develop optimal solutions for both subproblems and show how the co-designed system with minimum forwarding energy cost and guaranteed LQG control performance can be found by a one-dimensional search over admissible sampling periods. The paper ends with a numerical example which demonstrates the effectiveness of the proposed framework., QC 20121116

This paper studies minimum-energy packet forwarding policies for communicating sensor measurements from plant to controller over an unreliable multi-hop wireless network so as to guarantee that the optimal controller achieves a prespecified closed-loop performance. For fixed sampling interval, we demonstrate that the minimal linear-quadratic control loss is monotonically decreasing in the reliability of the sensor-to-controller communication. This allows us to decompose the overall design problem into two separate tasks: finding the minimum end-to-end reliability that allows to achieve a prespecified linear-quadratic loss, and developing minimum-energy packet forwarding policies under a deadline-constrained reliability requirement. We develop optimal solutions for both subproblems and show how the co-designed system with minimum forwarding energy cost and guaranteed LQG control performance can be found by a one-dimensional search over admissible sampling periods. The paper ends with a numerical example which demonstrates the effectiveness of the proposed framework., QC 20121116

This paper studies minimum-energy packet forwarding policies for communicating sensor measurements from plant to controller over an unreliable multi-hop wireless network so as to guarantee that the optimal controller achieves a prespecified closed-loop performance. For fixed sampling interval, we demonstrate that the minimal linear-quadratic control loss is monotonically decreasing in the reliability of the sensor-to-controller communication. This allows us to decompose the overall design problem into two separate tasks: finding the minimum end-to-end reliability that allows to achieve a prespecified linear-quadratic loss, and developing minimum-energy packet forwarding policies under a deadline-constrained reliability requirement. We develop optimal solutions for both subproblems and show how the co-designed system with minimum forwarding energy cost and guaranteed LQG control performance can be found by a one-dimensional search over admissible sampling periods. The paper ends with a numerical example which demonstrates the effectiveness of the proposed framework., QC 20121116

This paper presents a measurement recipe to characterize the out-of-band nonlinear behavior of RF devices when harmonic sampling is used as a digitizing technique. A major challenge to consider when using harmonic sampling is the overlapping of the aliased spectral bins of the digitized waveform. This challenge is more pronounced when using modulated excitation signals. In addition, the excitation signal used should mimic the real behavior of signals used in today's wireless systems. Hence, this paper provides the reader with a tool to select the proper excitation signal, sampling frequency and record length in order to achieve an accurate characterization of the nonlinear behavior of RF devices., QC 20111107

Multicell joint processing has been shown to efficiently suppress inter-cell interference, while providing a high capacity gain due to spatial multiplexing across distributed Base Stations (BSs). However, the complexity of the optimal joint decoder in the multicell uplink channel grows exponentially with the number of users, making it prohibitive to implement in practice. In this direction, this paper investigates the uplink capacity performance of multicell joint linear minimum mean square error (LMMSE) filtering, followed by single-user decoding. The considered cellular multiple-access channel model assumes both Rayleigh and Rician flat fading, path loss, distributed users and correlated multiple antennas at the base station side. The case of Rayleigh fading is tackled using a free probability approach, while the case of Rician fading is addressed through a deterministic equivalent calculated using non-linear programming techniques. In this context, it is shown that LMMSE can provide high spectral efficiencies in practical macrocellular scenarios., Invited Paper. QC 20120209

In this paper, we consider the problem of the joint optimization of encoder-controller for closed-loop control with state feedback over a binary-input Gaussian channel (BGC). The objective is to minimize the expected linear quadratic cost over a finite horizon. Thisencoder-controller optimization problem is hard in general, mostly because of the curse of dimensionality. The result of this paper is a synthesis technique for a computationally feasible suboptimal controller which exploits both the soft and hard information of thechannel outputs. The proposed controller is efficient in the sense that it embraces measurement quantization, error protection and control over a finite-input infinite-output noisy channel. How to effectively implement this controller is also addressed in the paper. In particular, this is done by using Hadamard techniques. Numerical experiments are carried out to verify the promising gain offered by the combined controller, in comparison to the hard-information-based controller., QC 20120124

This paper discusses adaptive spatial wavelets for the class of motion-compensated orthogonal video transforms. Motion-compensated orthogonal transforms (MCOT) are temporal transforms for video sequences that maintain orthonormality while permitting flexible motion compensation. Orthogonality is maintained for arbitrary integer-pixel or sub-pixel motion compensation by cascading a sequence of incremental orthogonal transforms and updating so-called scale counters for each pixel. The energy of the input pictures is accumulated in a temporal low-band while the temporal high-bands are zero if the input pictures are identical after motion compensation. For efficient coding, the temporal subbands should be further spatially decomposed to exploit the spatial correlation within each temporal subband. In this paper, we discuss adaptive spatial wavelets that maintain the orthogonal representation of the temporal transforms. Similar to the temporal transforms, they update scale counters for efficient energy concentration. The type-1 adaptive wavelet is a Haar-like wavelet. The type-2 considers three pixels at a time and achieves better energy compaction than the type-1., QC 20110221

This paper considers the joint design of bit loading, precoding and receive filters for a multiple-input multiple-output (MIMO) digital communication system employing decision feedback (DF) detection at the receiver. Both the transmitter as well as the receiver are assumed to know the channel matrix perfectly. It is well known that, for linear MIMO transceivers, a diagonal transmission (i.e., orthogonalization of the matrix channel) is optimal for some criteria. Surprisingly, it was shown five years ago that for the family of Schur-convex functions an additional rotation of the symbols is necessary. However, if the bit loading is optimized jointly with the linear transceiver, then the rotation is unnecessary. Similarly, for DF MIMO transceivers, a rotation of the symbols is sometimes needed. The main result of this paper shows that for a DF MIMO transceiver where the bit loading is jointly optimized with the transceiver filters, the rotation of the symbols becomes unnecessary and, consequently, also the DF part of the receiver is not required., QC 20110302

The contribution of this paper is a variance analysis of estimated models of cascade dynamical systems. Models of such systems are important in for example cascade control applications. The model quality is analyzed by means of the asymptotic covariance matrix of the prediction error method parameters estimates. Recent work has shown that identification of two cascaded linear systems, where the transfer functions of the sub-systems are identical, has some fundamental limitations in terms of asymptotic statistical performance. Under this condition, the output from the second sub-system does not influence the quality of the estimated model of the first subsystem. The objective of this paper is to extend this result to the case where the transfer functions of the sub-systems are not completely identical, but do have some common dynamics. We will also study cascaded systems with three sub-systems, and show that a similar variance result also holds for this case. The results are illustrated by some simple FIR examples., © 2008 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20110121

The contribution of this paper is a variance analysis of estimated models of cascade dynamical systems. Models of such systems are important in for example cascade control applications. The model quality is analyzed by means of the asymptotic covariance matrix of the prediction error method parameters estimates. Recent work has shown that identification of two cascaded linear systems, where the transfer functions of the sub-systems are identical, has some fundamental limitations in terms of asymptotic statistical performance. Under this condition, the output from the second sub-system does not influence the quality of the estimated model of the first subsystem. The objective of this paper is to extend this result to the case where the transfer functions of the sub-systems are not completely identical, but do have some common dynamics. We will also study cascaded systems with three sub-systems, and show that a similar variance result also holds for this case. The results are illustrated by some simple FIR examples., © 2008 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20110121

The contribution of this paper is a variance analysis of estimated models of cascade dynamical systems. Models of such systems are important in for example cascade control applications. The model quality is analyzed by means of the asymptotic covariance matrix of the prediction error method parameters estimates. Recent work has shown that identification of two cascaded linear systems, where the transfer functions of the sub-systems are identical, has some fundamental limitations in terms of asymptotic statistical performance. Under this condition, the output from the second sub-system does not influence the quality of the estimated model of the first subsystem. The objective of this paper is to extend this result to the case where the transfer functions of the sub-systems are not completely identical, but do have some common dynamics. We will also study cascaded systems with three sub-systems, and show that a similar variance result also holds for this case. The results are illustrated by some simple FIR examples., © 2008 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20110121

The contribution of this paper is a variance analysis of estimated models of cascade dynamical systems. Models of such systems are important in for example cascade control applications. The model quality is analyzed by means of the asymptotic covariance matrix of the prediction error method parameters estimates. Recent work has shown that identification of two cascaded linear systems, where the transfer functions of the sub-systems are identical, has some fundamental limitations in terms of asymptotic statistical performance. Under this condition, the output from the second sub-system does not influence the quality of the estimated model of the first subsystem. The objective of this paper is to extend this result to the case where the transfer functions of the sub-systems are not completely identical, but do have some common dynamics. We will also study cascaded systems with three sub-systems, and show that a similar variance result also holds for this case. The results are illustrated by some simple FIR examples., © 2008 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20110121

The contribution of this paper is a variance analysis of estimated models of cascade dynamical systems. Models of such systems are important in for example cascade control applications. The model quality is analyzed by means of the asymptotic covariance matrix of the prediction error method parameters estimates. Recent work has shown that identification of two cascaded linear systems, where the transfer functions of the sub-systems are identical, has some fundamental limitations in terms of asymptotic statistical performance. Under this condition, the output from the second sub-system does not influence the quality of the estimated model of the first subsystem. The objective of this paper is to extend this result to the case where the transfer functions of the sub-systems are not completely identical, but do have some common dynamics. We will also study cascaded systems with three sub-systems, and show that a similar variance result also holds for this case. The results are illustrated by some simple FIR examples., © 2008 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20110121

Wireless networked embedded systems are becoming increasingly important in a wide area of technical fields. In this tutorial paper we present recent results on the design of these systems and their use in control applications, that have been developed within the project Reconfigurable Ubiquitous Networked Embedded Systems (RUNES). RUNES is a European Integrated Project with the aim to control complexity in networked embedded systems by developing robust and scalable middleware systems. New components for control under varying network conditions are discussed for the RUNES architecture. The paper highlights how the complexity of the closed-loop system is increased, due to additional disturbances introduced by the communication system: additional delays, jitter, data rate limitations, packet losses, etc. Experimental work on integration test beds that demonstrates these results is presented, together with motivating links to the RUNES disaster relief tunnel scenario., © 2006 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20120216

Wireless networked embedded systems are becoming increasingly important in a wide area of technical fields. In this tutorial paper we present recent results on the design of these systems and their use in control applications, that have been developed within the project Reconfigurable Ubiquitous Networked Embedded Systems (RUNES). RUNES is a European Integrated Project with the aim to control complexity in networked embedded systems by developing robust and scalable middleware systems. New components for control under varying network conditions are discussed for the RUNES architecture. The paper highlights how the complexity of the closed-loop system is increased, due to additional disturbances introduced by the communication system: additional delays, jitter, data rate limitations, packet losses, etc. Experimental work on integration test beds that demonstrates these results is presented, together with motivating links to the RUNES disaster relief tunnel scenario., © 2006 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20120216

Wireless networked embedded systems are becoming increasingly important in a wide area of technical fields. In this tutorial paper we present recent results on the design of these systems and their use in control applications, that have been developed within the project Reconfigurable Ubiquitous Networked Embedded Systems (RUNES). RUNES is a European Integrated Project with the aim to control complexity in networked embedded systems by developing robust and scalable middleware systems. New components for control under varying network conditions are discussed for the RUNES architecture. The paper highlights how the complexity of the closed-loop system is increased, due to additional disturbances introduced by the communication system: additional delays, jitter, data rate limitations, packet losses, etc. Experimental work on integration test beds that demonstrates these results is presented, together with motivating links to the RUNES disaster relief tunnel scenario., © 2006 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20120216

Wireless networked embedded systems are becoming increasingly important in a wide area of technical fields. In this tutorial paper we present recent results on the design of these systems and their use in control applications, that have been developed within the project Reconfigurable Ubiquitous Networked Embedded Systems (RUNES). RUNES is a European Integrated Project with the aim to control complexity in networked embedded systems by developing robust and scalable middleware systems. New components for control under varying network conditions are discussed for the RUNES architecture. The paper highlights how the complexity of the closed-loop system is increased, due to additional disturbances introduced by the communication system: additional delays, jitter, data rate limitations, packet losses, etc. Experimental work on integration test beds that demonstrates these results is presented, together with motivating links to the RUNES disaster relief tunnel scenario., © 2006 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20120216

Wireless networked embedded systems are becoming increasingly important in a wide area of technical fields. In this tutorial paper we present recent results on the design of these systems and their use in control applications, that have been developed within the project Reconfigurable Ubiquitous Networked Embedded Systems (RUNES). RUNES is a European Integrated Project with the aim to control complexity in networked embedded systems by developing robust and scalable middleware systems. New components for control under varying network conditions are discussed for the RUNES architecture. The paper highlights how the complexity of the closed-loop system is increased, due to additional disturbances introduced by the communication system: additional delays, jitter, data rate limitations, packet losses, etc. Experimental work on integration test beds that demonstrates these results is presented, together with motivating links to the RUNES disaster relief tunnel scenario., © 2006 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20120216

This paper presents a fully automated procedure for controller synthesis for a general class of multi-agent systems under coupling constraints. Each agent is modeled with dynamics consisting of two terms: the first one models the coupling constraints and the other one is an additional bounded control input. We aim to design these inputs so that each agent meets an individual high-level specification given as a Metric Interval Temporal Logic (MITL). Furthermore, the connectivity of the initially connected agents, is required to be maintained. First, assuming a polyhedral partition of the workspace, a novel decentralized abstraction that provides controllers for each agent that guarantee the transition between different regions is designed. The controllers are the solution of a Decentralized Robust Optimal Control Problem (DROCP) for each agent. Second, by utilizing techniques from formal verification, an algorithm that computes the individual runs which provably satisfy the high-level tasks is provided., QC 20180306

This paper studies a design problem of how a group of wireless sensors are selected and scheduled to transmit data efficiently over a multi-hop network subject to energy-saving consideration, when they are observing multiple independent discrete-time linear systems. Each time instant, some sensors are selected to transmit their measurements to a remote estimator. We formulate an optimization problem, minimizing a linear combination of the averaged estimation error and the averaged transmission energy consumption to obtain suitable network scheduling and estimation algorithms. Necessary conditions for optimality are derived and these conditions help trim the feasible solution space so that the optimal solution can be computed efficiently. A numerical example is provided to demonstrate the theoretical results., QC 20180306