Toward Packet-Loss Resilient Cell-Free mMIMO: Multi-Criterion Based AP Association and Robust Coordinated Time Synchronization

An overview is presented of compression and packet loss effects in speech biometrics. These new problems appear particularly in recent applications of biometrics over mobile or Internet networks. The influence of speech compression on speaker recognition performance in mobile networks is investigated. In a first experiment, it is found that the use of GSM coding degrades the performance. In a second experiment, the features for the speaker recognition system are calculated directly from the information available in the encoded bit stream. It is found that a low LPC order in GSM coding is responsible for most performance degradations. A speaker recognition system was obtained which is equivalent in performance to the original one which decodes and reanalyses speech before performing recognition. The joint packet loss and compression effects over IP networks are also studied. It is experimentally demonstrated that the adverse effects of packet loss alone are negligible, while the encoding of speech, particularly at a low bit rate, coupled with packet loss, can reduce the verification accuracy considerably.

The high mobility of trains and complex line environment will lead to poor communication quality, which will seriously affect the stability of the virtually coupled train set (VCTS). Packet loss is one of the important indexes to evaluate communication quality. In this paper, a numerical method is proposed to analyze the influence of random packet loss on the stability of the homogeneous VCTS. Firstly, combining with the characteristics of packet loss design probability model. Based on the longitudinal dynamics model and the constraints of the train interval distance, a train operation control model is formulated with considering random packet loss. Secondly, the stability conditions of the homogeneous VCTS expressed by packet loss probability are derived from the perspective of frequency domain. Finally, the effects of random packet loss on the stability of the homogeneous VCTS are analyzed and the validity of the theoretical results is confirmed via numerical simulations.

In this paper, the consensus problem is studied for a class of multi-agent systems with sampled data and packet losses, where random and deterministic packet losses are considered, respectively. For random packet losses, a Bernoulli-distributed white sequence is used to describe packet dropouts among agents in a stochastic way. For deterministic packet losses, a switched system with stable and unstable subsystems is employed to model packet dropouts in a deterministic way. The purpose of this paper is to derive consensus criteria, such that linear multi-agent systems with sampled-data and packet losses can reach consensus. By means of the Lyapunov function approach and the decomposition method, the design problem of a distributed controller is solved in terms of convex optimization. The interplay among the allowable bound of the sampling interval, the probability of random packet losses, and the rate of deterministic packet losses are explicitly derived to characterize consensus conditions. The obtained criteria are closely related to the maximum eigenvalue of the Laplacian matrix versus the second minimum eigenvalue of the Laplacian matrix, which reveals the intrinsic effect of communication topologies on consensus performance. Finally, simulations are given to show the effectiveness of the proposed results.In this paper, the consensus problem is studied for a class of multi-agent systems with sampled data and packet losses, where random and deterministic packet losses are considered, respectively. For random packet losses, a Bernoulli-distributed white sequence is used to describe packet dropouts among agents in a stochastic way. For deterministic packet losses, a switched system with stable and unstable subsystems is employed to model packet dropouts in a deterministic way. The purpose of this paper is to derive consensus criteria, such that linear multi-agent systems with sampled-data and packet losses can reach consensus. By means of the Lyapunov function approach and the decomposition method, the design problem of a distributed controller is solved in terms of convex optimization. The interplay among the allowable bound of the sampling interval, the probability of random packet losses, and the rate of deterministic packet losses are explicitly derived to characterize consensus conditions. The obtained criteria are closely related to the maximum eigenvalue of the Laplacian matrix versus the second minimum eigenvalue of the Laplacian matrix, which reveals the intrinsic effect of communication topologies on consensus performance. Finally, simulations are given to show the effectiveness of the proposed results.

Using proxies to enhance TCP performance over hybrid fiber coaxial networks

In wireless sensor networks, efficient usage of energy helps in improving the network lifetime. Many power saving MAC schemes based on TDMA have been proposed in recent years, but none of them particularly discuss the problem of time synchronization. As there are many time synchronization algorithms have been proposed, but they can't be applied to these TDMA MAC schemes directly. In this paper, a lightweight and energy efficient time synchronization (LEETS) scheme that can be applied to all kinds of TDMA power saving MAC schemes was proposed. In the scheme, nodes compete the first slot of each time frame to broadcast local time information, which can be used to realize whole network synchronization. And guard interval is inserted in two consecutive slots to avoid collision may be caused by synchronization errors. The scheme has been simulated and the results show LEETS needs less message exchanges to realize synchronization than other time synchronization schemes. So, It is lightweight and energy efficient.

The subject of research in the article is the processes of fast rerouting with the protection of the Quality of Service level in infocommunication networks. The aim of the work is the development of a mathematical model of Fast ReRouting with the protection of the Quality of Service level by the bandwidth and probability of packet loss for data traffic. The following tasks are solved in the article: development and research of a fast rerouting flow-based model with the protection of the Quality of Service level of data traffic in the infocommunication network. The following methods are used: the graph theory, the teletraffic theory, the queuing theory, and mathematical programming methods. The following results were obtained: the fast rerouting flow-based model was developed and investigated, which, due to the introduced protection conditions on indicators of bandwidth and packet loss probability, allows providing the Quality of Service along both the primary and backup multipath. Conclusions: Within the framework of the proposed flow-based model, the fast rerouting technological task was formulated as an optimization problem with the constraints of the conditions of implementation of the multipath routing strategy, conditions of flow conservation, and conditions of protection of the link, node, and level of Quality of Service in terms of bandwidth and packet loss probability. The application of this solution contributes to the optimal use of the available network resource while providing the specified level of Quality of Service in terms of bandwidth and probability of packet loss along both the primary and backup routes in the case of a failure of the infocommunication network elements. The proposed flow-based model can be used as the basis of the algorithmic software of existing routers and/or controllers of Software-Defined Networks, which are responsible for the calculation of the primary and backup paths in the fast rerouting of data traffic sensitive to such Quality of Service indicators as bandwidth and packet loss probability.

In this paper, a new packet loss control mechanism in congested networks known as dynamic partial buffer sharing (DPBS) is proposed. In contrast to the static partial buffer sharing (SPBS) scheme, the thresholds are dynamically varied in run-time based on packet loss behaviors. A problem with the SPBS scheme is that there is no simple mathematical expression relating the thresholds to the desired packet loss ratios among the different classes of packets, especially in the case of nested thresholds. Also, the variation of packet loss probabilities can be very large. These problems are overcome in the DPBS scheme. The desired packet loss ratios can be achieved by setting the control parameters according to a simple formula. Simulation results show that the mean packet loss probability of DPBS is smaller than that of SPBS by 3% to 47% while the loss variation is improved by 100 times to 1000 times under the same input traffic. It is a benefit, especially for congestion control.

LQG-like control of scalar systems over communication channels: The role of data losses, delays and SNR limitations

Industrial wireless sensor networks (IWSNs) can provide wireless communication for the control system and have therefore received considerable attention. However, network-induced delays or packet losses, among other issues, significantly degrade the performance of IWSNs and can even destabilize an entire system. In this study, a predictive compensator, a modified linear quadratic regulator (LQR) compensator, and a combination of both compensators were proposed to mitigate the effects of unpredictable packet loss in an IWSN. The control system applying the three proposed compensators was simulated under various condition of packet loss using Matlab Simulink and Truetime. An inverted pendulum was used as the object of the controller. Simulation results showed that, among the three compensators, the combined compensator works best in compensating for the packet loss in both forward and backward channels of the control system.

Loss resilient H.263+video over the Internet

Packet loss probability alone does not provide a complete characterization of the quality of a network's real-time packet sessions. Additional performance measures such as the consecutive packet loss (the so called average packet gap) must be considered. The authors propose to improve the packet gap performance of asynchronous transfer mode (ATM) sessions by minimizing the packet gap present in the network's buffers. They introduce a simple packet dropping policy that, in steady state, minimizes: (i) the packet gap, and (ii) the packet buffering delay, when this delay can be reduced without increasing the packet gap, or packet loss probability.

This paper proposes a novel error-resilient packet video coding method which is designed to operate on unreliable IP networks suffering from large bursts of packet losses. The main novelties of the proposed system are: (1) A Bayesian packet loss predictor is employed to dynamically predict the packet loss probabilities; (2) A harmonic frame-expansion is applied to the video stream to add error-resilience. This includes dynamically choosing the size of the expansions. (3) Error-propagation is reduced by filtering out error-prone high-frequency components from reference images. This means that the proposed video codec method does not need to switch between the inter and intra coding modes. (4) Theoretical analysis of the video performance is given. Our preliminary simulations have shown that the frame expansion method can provide excellent resilience to video packet losses. The system has generated high quality videos at low bit-rates (64kbs) on simulated networks with the packet loss probability ranging from 5% to 20%. Visual inspection has shown that under similar PSNRs, the resulting videos have noticeable less visual artifacts as compared with those from the conventional codecs

In recent years, wavelet transforms have been successfully applied to image and video compression. In a distributed, multimedia computing environment, compressed video and image files need to be transmitted to users for real-time replay. Because the network is subject to packet losses, the image packetization scheme should take packet losses into account in their design. In this paper, we present an error concealment algorithm for wavelet-based compressed images over packet-switched networks. Two different packetization schemes, called the intrablock-oriented and interblock-oriented schemes, in conjunction with wavelet coding, are presented. In our approach, adjacent wavelet coefficients are scattered into different packets, so that any packet contains encoded wavelet coefficients at different resolution layers. When a packet is lost due to network congestion or transmission errors, a lost wavelet coefficient is estimated by the receiver through a linear interpolation of its adjacent ones. Our approach is evaluated under two different packet loss models with various packet loss probabilities through simulations driven by actual video sequences.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

System identification with binary-valued output observations under either-or communication and data packet dropout

The performance limitations of multiple-input multiple-output (MIMO) information time delay system (ITDS) with packet loss, codec and white Gaussian noise (WGN) are investigated in this article. By using the spectrum decomposition technique, inner-outer factorization, and partial factorization techniques, the expression of performance limitations is obtained under the two-degree-of-freedom (2DOF) compensator. The theoretical analysis results demonstrate that the system performance is related to the time delay, non-minimum phase (NMP) zeros, unstable zeros and their directions in a given device. In addition, WGN, packet loss and codec also impact the performance. Finally, the theoretical results are verified by simulation examples. Simulation results show that packet loss rate and encoding and decoding have a greater impact on system performance.