Time-series prediction has drawn considerable attention during the past decades fueled by the emerging advances of deep learning methods. However, most neural network based methods fail in extracting the hidden mechanism of the targeted physical system. To overcome these shortcomings, an interpretable sparse system identification method without any prior knowledge is proposed in this study. This method adopts the Fourier transform to reduces the irrelevant items in the dictionary matrix, instead of indiscriminate usage of polynomial functions in most system identification methods. It shows an visible system representation and greatly reduces computing cost. With the adoption of$l_{1}$norm in regularizing the parameter matrix, a sparse description of the system model can be achieved. Moreover, three data sets including the water conservancy data, global temperature data and financial data are used to test the performance of the proposed method. Although no prior knowledge was known about the physical background, experimental results show that our method can achieve long-term prediction regardless of the noise and incompleteness in the original data more accurately than the widely-used baseline data-driven methods. This study may provide some insight into time-series prediction investigations, and suggests that a white-box system identification method may extract the easily overlooked yet inherent periodical features and may beat neural-network based black-box methods on long-term prediction tasks.

Multiobjective shortest path problem (MSPP) is one of the most critical issues in network optimization, aimed at identifying all efficient paths across conflicting objectives. Nowadays, existing methods face substantial bottlenecks in addressing the diverse preferences of decision makers and high spatiotemporal overhead caused by the calculation process, particularly in cases with large-scale networks. To overcome these obstacles, a generalized MSPP in large-scale networks is investigated with the aim of solving it with diverse preferences of decision makers satisfied and low spatiotemporal overhead. Toward this end, with a novel concept, the generalized dominance relation is introduced, and the generalized multiobjective shortest path algorithm via the generalized dynamic programming approach is developed. Moreover, the H-reducible technique is further employed to accelerate the convergence of the proposed algorithm. Additionally, several rigorous proofs are provided for the conclusions that all efficient paths could be found within a tolerable time by the developed algorithm and the algorithm could be implemented in a distributed manner under mild assumptions. Finally, numerous routing experiments are conducted on large-scale communication networks for demonstrating the effectiveness and competitiveness of our approach.

Root cause analysis (RCA) is a crucial technique in network systems for uncovering the abnormal nodes that lead to the network alarm flood. Within private cloud network systems, the calling chains and topologies among entities, such as hosts, routes, and services, are always incomplete due to nonstandardized management. Existing topology-free RCA techniques, which rely on the casual discovery, are inapplicable when the scale of the network system is extremely large or the number of triggered alarms is sparse. This article proposes NetEventCause (NEC), an event-driven, unsupervised, and nonintrusive RCA algorithm for large network systems, where the network topology is unknown. NEC learns from historical alarm events to model the occurrences of various alarm types using a multivariate neural temporal point process (TPP). Based on the conditional intensity predicted by the learned TPP, NEC can identify the root alarms from a cascade of alarm events and locate the causal alarms of derivative alarms using the attribution method. The experimental section evaluates the NEC using both a synthetic event dataset and a large real-world dataset. The real-world dataset is exported from the Huawei Shennong Intelligent Maintenance and Operation Center (IMOC), a platform deployed at one of China's largest airports and manages over 200000 entities. Results obtained from the two datasets demonstrate that NEC outperforms most state of the art (SOTA) TPP models in modeling alarm events and surpasses general RCA methods in terms of identifying root alarms and recovering transmission chains of anomalies.

With the continuous advancement of neural network methodologies, time series prediction has attracted substantial interest over the past decades. Nonetheless, the interpretability of neural networks is insufficient and the utilization of deep learning techniques for prediction necessitates significant computational expenditures, rendering its application arduous in numerous scenarios. In order to tackle this challenge, an interpretable sparse system identification method which does not require a time-consuming training through back-propagation is proposed in this study. This method integrates advantages from both knowledge-based and data-driven approaches, and constructs dictionary functions by leveraging Fourier basis and taking into account both the long-term trends and the short-term fluctuations behind data. By using the $l_1$ norm for sparse optimization, prediction results can be gained with an explicit sparse expression function and an extremely high accuracy. The performance evaluation of the proposed method is conducted on comprehensive benchmark datasets, including ETT, Exchange, and ILI. Results reveal that our proposed method attains a significant overall improvement of more than 20\% in accordance with the most recent state-of-the-art deep learning methodologies. Additionally, our method demonstrates the efficient training capability on only CPUs. Therefore, this study may shed some light onto the realm of time series reconstruction and prediction.

Now it is still a challenge to compress high-throughput hyperspectral tensor image data on lightweight air-carried/spaceborne remote sensing systems, primarily due to insufficient computational resources and limited transmission bandwidth. To address this challenge, we propose a bit-level tensor data compression network (BTC-Net) that provides higher compression performance by leveraging a data-driven lightweight quantized neural encoder with two-stage bit compression. The BTC-Net achieves semantic near-lossless high reconstruction quality at low compression bit rates thanks to its optimized decoder, which uses a channel-wise attention-based enhancement module to recover hyperspectral tensor data. Experimental results on different hyperspectral datasets show that the BTC-Net could achieve an extremely low compression bit rate of fewer than 0.04 bits per pixel per band (bpppb) with state-of-the-art reconstruction performances. The demo of BTC-Net will be publicly available online at: https://github.com/zx20173646/BTCNet.

Cloud storage systems have commonly used erasure coding that encodes data in stripes of blocks as a low-cost redundancy method for data reliability. Relative to traditional erasure coding, wide-stripe erasure coding that increases the stripe size has been recently proposed and explored to achieve lower redundancy. We observe that wide-stripe erasure coding makes multi-block failures occur much more frequently than traditional erasure coding in cloud storage systems.However, how to efficiently repair multiple blocks in wide-stripe erasure-coded storage systems remains unexplored. The conventional multi-block repair method sends available blocks from surviving nodes to one single new node to repair all failed blocks in a centralized way, which may cause the new node to be the bottleneck; recent multi-block repair methods follow pipelined single-block repair methods and the former are simply built on the latter in an independent way, which may cause the surviving nodes with limited bandwidth to be bottlenecks.In this paper, we first analyze the effects of both centralized and independent ways on the multi-block repair and then propose HMBR, a hybrid multi-block repair mechanism that combines centralized and independent multi-block repairs to tradeoff the bandwidth bottlenecks caused by the new and surviving nodes, thus optimizing the multi-block repair performance. We further extend HMBR for hierarchical network topology and multi-node failures. We prototype HMBR and show via Amazon EC2 that the repair time of a multi-block failure can be reduced by up to 64.8% over state-of-the-art schemes.

The sparse regression method is known for its ability to unmix hyperspectral data, but it can be computationally expensive and accurately insufficient due to the large scale and high coherence of the spectral library. To address this issue, a new approach called layered sparse regression unmixing (termed LSU) has been proposed in this paper. This method involves breaking down the sparse unmixing process into multilayers, each of which interactively learns a row-sparsity-promoting abundance matrix and fine-tunes active library atoms based on measured activeness. By doing so, LSU outputs both a learned abundance matrix and an optimal library that can best model each mixed pixel in the scene. The proposed LSU can be efficiently solved by the alternating direction method of the multipliers framework. Experimental results obtained from simulated and real hyperspectral images demonstrate the effectiveness of LSU. The demo of the proposed LSU will be publicly available at https://github.com/XiangfeiShen/Layered_Sparse_Regression_Unmixing.

This paper presents the Cellular Binary Neural Network (CBNN), which is an efficient deep neural network with binary weights and activations. To address the challenge of performance drop caused by low-precision representation, the CBNN adopts multiple subnets which are connected via learnable global lateral paths. The introduced lateral connections are assumed to be sparse and grouped with respect to different source layers. The inter-network lateral connections and inner-network parameters are simultaneously optimized by the distributional loss, classification loss and the group sparse regularization term. Experiments on the CIFAR-10 and ImageNet datasets showed that, by incorporating optimized group-sparse lateral paths, the CBNN outperformed many state-of-the-art binary neural networks in terms of classification accuracy. Besides, to verify the generalization of the proposed binary model, we extended the CBNN on semantic segmentation task. CBNN takes advantage of the multiple subnets to derive the more informative feature maps which are computed by the parallel aggregation in the last convolution block. Experiments on PASCAL VOC segmentation dataset demonstrated that, under the same segmentation settings, the proposed method achieved the superior performance over other compared networks and even the full-precision counterpart.

Erasure coding is commonly used as a storage-efficient redundancy method for fault tolerance in cold storage. Recent studies have begun to explore the use of erasure coding in hot storage, which requires fast online recovery to preserve read performance. However, existing erasure-coded repair strategies cannot effectively handle frequent and rapidly-changing network congestions in hot storage clusters. In this paper, we present the notion of pivots, which refer to the storage nodes with sufficient available downlink and uplink bandwidths in a congested hot storage network. We propose PivotRepair, a pivot-based pipelined single-chunk repair technique that leverages pivots for enabling the fast construction of a pipelined repair tree that bypasses congested links. We further propose an adaptive scheduling strategy to improve full-node repair performance. We prototype PivotRepair and show that the repair time of a single-chunk repair and a full-node repair can be reduced by up to 71.27% and 16.50%, respectively, over state-of-the-art repair schemes.

360-degree virtual reality videos greatly improve the video experience by providing users with a more immersive and interactive environment than standard streaming video. However, 360-degree videos suffer from bandwidth limits. Existing bandwidth-efficient solutions mainly focus on spatially cutting 360-degree video into tiles, and only provide video content in the Field-of-View (FoV) of users with high quality to reduce bandwidth consumption. Although existing tile-based schemes can reduce the bandwidth consumption, the bandwidth and transmission delay provided by a single-path TCP may still not meet the high requirements of 360-degree videos. Multipath TCP (MPTCP) allows a TCP connection to operate across multiple paths simultaneously and becomes highly attractive to support the mobile devices with various radio interfaces to aggregate multipath bandwidth and improve the throughput. In this paper, by taking the advantage of MPTCP, we propose an MPTCP-based adaptive streaming framework for 360-degree Virtual Reality videos, named MP-VR. MP-VR dynamically selects the appropriate tile bitrate according to the bandwidth and transmission delay of different subflows. Then it schedules the video segments to subflows to improve QoE of users. We conduct experiments on a testbed in our lab and simulations on NS-3. Evaluation results show that MP-VR outperforms existing tile-based strategies when network fluctuations or errors in FoV predictions occur.

As the user demand for data transmission over high-speed and long distance (hereafter abbreviated as HSLD) networks increases significantly, multipath TCP (MPTCP) shows a great potential to further improve the utilization of HSLD network resources than traditional TCP, and provides better quality of service (QoS). It has been reported that TCP causes serious waste of bandwidth in HSLD networks, while MPTCP can transmit data by using multiple network paths simultaneously between two distant hosts, thus provides better resource utilization, higher throughput and smoother failure recovery for applications. However, the existing multipath congestion control algorithms cannot perfectly meet the efficiency requirements of HSLD network, since they mainly emphasize fairness rather than other critical indicators of QoS such as throughput, but still encounter fairness issues when coexist with various TCP variants. To solve these problems, we develop weighted Compound (wCompound), a loss-and-delay-based compound multipath congestion control algorithm which is originated from Compound TCP, and is applicable to HSLD networks. Different from the traditional methods of setting an empirical value as the threshold, wCompound innovatively adopts a dynamic threshold and have the flexibility to adjust the sending window of each subflow based on current network state, so as to effectively couple all subflows and fully utilize the network capacity. Moreover, with the cooperation of delay-based and loss-based methods, wCompound also ensures good fairness to different types of TCP variants. We implement wCompound in the Linux kernel, then carry out sufficient experiments on our testbed. The results show that wCompound achieves higher utilization of network resources and can always maintain an appropriate throughput no matter competing with loss-based or delay-based network traffic.

Multipath TCP (MPTCP) utilizes multiple paths for simultaneous data transmission to enhance performance. However, existing MPTCP protocols are still far from satisfactory in wireless networks because of their loss-based congestion control and the difficulty of managing multiple subflows. To overcome these problems, we redesign the coupled congestion control algorithm and scheduler to boost MPTCP in wireless heterogeneous networks. The main purpose is to promote transmission rate under lossy networks, while also provide stability when networks suffer physical link changes and asymmetric links. In this paper, inspired by Bottleneck Bandwidth and Round-trip propagation time (BBR), we first propose Coupled BBR that utilizes detected bandwidth to adjust the sending rate within an MPTCP connection. Coupled BBR provides high loss tolerance as well as balanced congestion among MPTCP subflows. Then, to further improve the performance, we propose an Adaptively Redundant and Predictive packet (AR&P) scheduler to improve adaptability and keep in-order packet delivery in highly dynamic network scenarios. Based on Linux kernel implementation and experiments in both testbed and real network scenarios, we show that the proposed scheme not only provides high throughput in wireless networks, but also improves robustness and reduces out-of-order packets in some harsh circumstances.

Named data networking (NDN) is an emerging network paradigm that decouples content from its storage location by providing one or more content copies and distributing them within the whole network. Congestion control is a fundamental and important problem in NDN, but it has not been well solved yet. Existing works can be divided into three main types, receiver driven flow based control, hop-by-hop interest shaping and hybrid control. While they are faced with more or less high computational complexity, multi-content source and multitransmission path problems, we proposed our edge computing aided congestion control scheme (EACC). The main idea is to detect congestion along the transmission path and avoid it by interest forwarding control at edge nodes. We add a new field to data packet to record the congestion status of the transmission path when it returns. After that, we deploy the core computing functions of the solution at edge nodes, and formulate the interest packet forwarding control into a local MDP (Markov Decision Process) problem based on the returned path congestion status and local user request information. Then we use neuro-dynamic programming (NDP) to solve this decision problem and present a practical implementation at edge nodes. The proposed scheme is implemented in ndnSIM simulator and compared to other two methods. Simulation results show the effectiveness of our scheme.

Nowadays, mobile devices are equipped with multiple interfaces connected to various networks, which makes it possible to aggregate bandwidth in actual application. Multipath TCP (MPTCP) is one of the transport protocols that uses multiple interfaces simultaneously and provides robust and efficient data transmission. In practice, MPTCP will interact with various network facilities. Among them, Content Delivery Network (CDN) is a popular one, which is a widely distributed network system deployed across the Internet. Using MPTCP in CDN could provide better performance for users, however, we find that CDN may not give full play to its functions when working with MPTCP. Because the Default Server Selection (DSS) mechanism in CDN only obtains servers optimal in single path connection scenarios, it may not provide the globally optimal server for MPTCP. In this paper, we propose a new algorithm called Server Selection for MPTCP (SSMP), which utilizes all available multi-homed sources to provide the globally optimal performance. SSMP modifies the DNS mechanism to return the optimal server for each available interface by the origin strategy and further selects the globally optimal server for both elephant and mice flows. We compare SSMP with DSS through experiments under video streaming and file download scenarios with both stable and variable environments. Our results show that SSMP consistently utilizes available paths more efficiently than DSS, particularly for servers with a great gap in server quality.

In order to be TCP-friendly, the original Multipath TCP (MPTCP) congestion control algorithm is always restricted to gain no better throughput than a traditional single-path TCP on the best path. However, it is unable to maximize the throughput over all available paths when they do not go through a shared bottleneck. Also, bottleneck fairness based solutions detect the bottleneck and conduct different congestion control algorithms at different bottleneck sets to increase throughput while remaining fair to single TCP. However, existing solutions generally detect shared bottlenecks through delay correlation and loss correlation between two flows, which often lead to misjudgement in dynamic and complex network scenarios. Therefore, in this paper, we first propose a new Shared Bottleneck based Congestion Control scheme, called SB-CC, which leverages ECN (Explicit Congestion Notification) mechanism to detect shared bottlenecks among subflows and estimate the congestion degree of each subflow. Then, with the congestion degree, SB-CC balances the loads among all subflows, and smooths out congestion window fluctuation. Also, in order to prevent throughput degradation due to out-of-order packets, we propose a Shared Bottleneck based Forward Prediction packet Scheduling scheme, called SB-FPS. SB-FPS distributes data according to the window size changes of each subflow, and thus could more accurately schedule data in shared bottleneck scenarios. We implement our proposed scheme in the Linux kernel and simulation platform to evaluate the performance in different scenarios. Measurement results indicate that our scheme can detect the bottleneck more accurately and improve the overall network performance while still keeping bottleneck fairness.