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Edge computing provides computing capability at close-user proximity to reduce service latency for end users. To improve the efficiency of edge computing infrastructures, geographically-distributed edge datacenters can co-work with each other and with cloud datacenters, forming a new paradigm referred to as cooperative edge-cloud computing. In this context, applications typically run on a virtual machine (VM) that can be replicated at multiple sites, and thus user traffic can be served at all the sites where corresponding VMs reside. For the performance of many applications, latency is a critical parameter. In this work, taking applications latencies as the primary constraint, we model the problem of VM placement and workload assignment as a mixed integer linear program and develop heuristic algorithms accordingly. The goal is to minimize the consumption of information technology (IT) infrastructures for placing VMs in cooperative edge-cloud computing, while meeting the heterogeneous latency demands of different applications. Some preliminary results indicate that edge datacenters resource efficiency can be optimized by proper cross-site VM placement and workload re-direction.

Efficient real-time disparity estimation is critical for the application of stereo vision systems in various areas. Recently, stereo network based on coarse-to-fine method has largely relieved the memory constraints and speed limitations of large-scale network models. Nevertheless, all of the previous coarse-to-fine designs employ constant offsets and three or more stages to progressively refine the coarse disparity map, still resulting in unsatisfactory computation accuracy and inference time when deployed on mobile devices. This paper claims that the coarse matching errors can be corrected efficiently with fewer stages as long as more accurate disparity candidates can be provided. Therefore, we propose a dynamic offset prediction module to meet different correction requirements of diverse objects and design an efficient two-stage framework. In addition, a disparity-independent convolution is proposed to regularize the compact cost volume efficiently and further improve the overall performance. The disparity quality and efficiency of various stereo networks are evaluated on multiple datasets and platforms. Evaluation results demonstrate that, the disparity error rate of the proposed network achieves 2.66% and 2.71% on KITTI 2012 and 2015 test sets respectively, where the computation speed is 2× faster than the state-of-the-art lightweight models on high-end and source-constrained GPUs.

Quantum key distribution (QKD) has demonstrated a great potential to provide future-proofed security, especially for 5G and beyond communications. As the critical infrastructure for 5G and beyond communications, optical networks can offer a cost-effective solution to QKD deployment utilizing the existing fiber resources. In particular, measurement-device-independent QKD shows its ability to extend the secure distance with the aid of an untrusted relay. Compared to the trusted relay, the untrusted relay has obviously better security, since it does not rely on any assumption on measurement and even allows to be accessed by an eavesdropper. However, it cannot extend QKD to an arbitrary distance like the trusted relay, such that it is expected to be combined with the trusted relay for large-scale QKD deployment. In this work, we study the hybrid trusted/untrusted relay based QKD deployment over optical backbone networks and focus on cost optimization during the deployment phase. A new network architecture of hybrid trusted/untrusted relay based QKD over optical backbone networks is described, where the node structures of the trusted relay and untrusted relay are elaborated. The corresponding network, cost, and security models are formulated. To optimize the deployment cost, an integer linear programming model and a heuristic algorithm are designed. Numerical simulations verify that the cost-optimized design can significantly outperform the benchmark algorithm in terms of deployment cost and security level. Up to 25% cost saving can be achieved by deploying QKD with the hybrid trusted/untrusted relay scheme while keeping much higher security level relative to the conventional point-to-point QKD protocols that are only with the trusted relays.

Due to the development of broadband access technologies including FTTx and 5G, the traffic in metro and core networks is forecasted to be more dynamic. To support this dynamicity, flex-grid elastic optical networks (EONs) have started to become prolific over the past few years. During the migration from the legacy fixed-grid wavelength division multiplexing optical networks to flex-grid EONs, a transition technology called the fixed/flex-grid optical network has become popular. In such fixed/flex-grid networks, the energy consumption caused by serious capacity mismatch between variable IP traffic and the different optical channel capacities is significantly high to be ignored. In fact, energy-efficient traffic grooming (i.e., to aggregate multiple fine-grained IP flows and map them onto a lightpath) is a challenge in IP-over-fixed/flex-grid optical networks because co-existing fixed-grid and flex-grid nodes have different traffic grooming ability and energy consumption models. To overcome the challenge, we propose an auxiliary-graph-based energy-efficient traffic-grooming ( EETG ) algorithm in IP-over-fixed/flex-grid optical networks for the first time. The construction of an auxiliary graph (AG) model for each connection request is one of the core steps. The well-designed weight-assignment scheme of the AG establishes the relationships between traffic grooming operations and specific energy consumption models. The final traffic grooming operations are undertaken based on the calculated weight-minimized path. The simulation results show that the EETG algorithm achieves 1) the least energy consumption compared with the state-of-the-art traffic grooming algorithms under the non-blocking scenario; and 2) achieves the tradeoff between energy consumption and blocking probability under the blocking scenario.

The difference in force chains can be used to evaluate asphalt mixture skeleton structure. In this study, different asphalt mixture discrete element method models were established via the two-dimensional particle flow code software to analyze force chain identification criteria. And then, the force chain lengths of different asphalt mixtures were quantified preliminarily. Results indicate that the average contact force [Formula: see text] needs to be set as the contact force threshold value. The recommended angle threshold value is 45°. For asphalt mixtures, less than 50% aggregate content is involved in transferring external loading. Whether the aggregate is located on the force chains should be regarded as an important criterion to judge whether the aggregate is involved in the asphalt mixture skeleton composition. Although dense-graded asphalt concrete will generate many force chains, most of them are short length force chains that are not conducive to transferring load.

Quantum key distribution (QKD) provides information-theoretic security based on the laws of quantum mechanics. The construction of QKD network (QKDN) is an important foundation for the widely use of quantum keys (QKs). Considering the link status flooding and unreasonable link costing of the existing researches, we propose a new routing scheme for QKDN based on application demand adaptation, named ADA-QKDN in this paper. Firstly, the routing management center is set up based on the idea of software defined network, which is used to collect the network topology information and complete the path selection, so as to reduce the data processing pressure of quantum nodes. Then, the application demand is taken as an important factor in the routing strategy. Meanwhile, the link evaluation indicators are dynamically adjusted, which is designed to provide optimal paths for applications and maximize the utilization efficiency of link resources. Finally, the impact of path hops is considered comprehensively to minimize the wastage of QKs. The simulation results show that compared with those existing schemes, the proposed ADA-QKDN increases the request success rate by more than 10%, while the effective key rate is similar to the routing schemes based on shortest path first algorithm.

With the emergence of cloud services based on data centers, demands for bandwidth-intensive applications have increased dramatically, and application services have transferred to a more diversified direction. Management as well as capacity of the backbone network needs further development to catch up with rapidly evolved application demands. Optical network virtualization can facilitate the sharing of physical infrastructure among multiple network applications. Virtual Network Embedding (VNE), the main implementation of network virtualization, determines how to map a virtual network request onto physical substrate. To expand the network capacity, flexible-grid elastic optical networks have been considered as a promising supporting technology for the future infrastructure of the next-generation Internet. However, due to the expense of key enabling equipment for flexible grid optical networks, the brown-field migration from a fixed grid to a flexible grid gave birth to the co-existing fixed/flexible grid. Based on the co-existing fixed/flexible grid optical networks, we investigate the problem of Virtual Optical Network (VON) provisioning, and present a flexible-grid-aware virtual network embedding algorithm to map the virtual networks onto the substrate network. In addition, the performance of the algorithm was evaluated under four different network scenarios. Simulation results show that the proposed algorithm can achieve better performance in all four scenarios.

A ciphertext mapping method based on Gray code is proposed to improve the security of quantum noise stream cipher (QNSC). The experiment is conducted in 1024 × 1024 -quadrature amplitude modulation (QAM) coherent optical communication system over 300 km. Experimental results verify that the proposed scheme does not affect the transmission performance. Meanwhile, the performance analysis reveals that the attacker's bit error rate (BER) increases to about 0.5 per bit position per symbol. The advantage of proposed scheme is that QNSC makes use of basis with fewer bits for encryption/decryption.

We propose a resource allocation algorithm that considers computing, storage and transport resources collaboratively for data center allopatric services in elastic optical network (EON). Simulation results show the proposed algorithm can reduce service congestion rate and improve resource utilization.

This paper proposes a service priority based cross-layer routing and resource allocation algorithm in QKD-ON. Results show it achieves good performance in terms of service success ratio and resource utilization.

This paper addresses the survivability issue by proposing a hybrid-trusted/untrusted-relay based protection strategy in QKD-ON. Simulation results show it performs well on service blocking rate and protection path construction rate.

We design and implement a satellite optical switching hardware platform based on optical burst switching (OBS) technology. The hardware platform runs stably and realizes 20*20 channels of Microseconds level optical switching, which meets the requirements of quality of service (QoS) in the current optical network.

With the integration progress of space- and ground-based Internet, the demand for large-scale satellite networks is increasing. However, the efforts on constellation design for large-scale satellite networks are rarely observed. Based on the single satellite coverage model and multiple coverage theory of circular orbit constellation, this paper proposes a large-scale satellite constellation design method to meet the requirements of multi-coverage. Finally, the influence of constellation parameters on coverage performance is simulated and analyzed, and the correctness of constellation parameters is verified by simulation.

The fast and diversified development of Internet services leads to numerous services with differentiated delay tolerance of optical connections set-up are converging in the optical network. Consequently, the average set-up delay of optical connection is increased, which will inevitably bring pressures to optical networks. To solve this problem, a delay aware routing spectrum assignment (RSA) algorithm based on services scheduling in priority queues with dynamic virtual topology construction (QVT-RSA) is proposed. First, the QVT-RSA algorithm reasonably identifies various different services and arranges them in order according to their priority, waiting time and delay tolerance requirements. Then, software defined networks (SDN) controller with multi-threads technology is adopted to innovatively parallel serve the ordered service requests to reduce the average set-up delay of optical connections, which also offset the induced delay caused by services scheduling. The network resource is accurately shared among multi-threads using the proposed mutual exclusive resource utilization model realized by dynamic virtual topology construction. The continuously coloring and usable virtual topology linkage reconfiguration can provide topology resources for service requests and adapt the dynamic transformation among serving, waiting and new arriving service requests. The shortest-path routing and first fit spectrum assignment (SPFF-RSA) algorithm is used as the baseline algorithm. Furthermore, by combining the SPFF-RSA algorithm and partial strategy of our strategy, the QSPFF-RSA and V-RSA algorithms are proposed as baseline algorithms as described in V-B. The simulation experiment results demonstrate that the average optical connections set-up delay of QVT-RSA algorithm is reduced compared with SPFF-RSA and QSPFF-RSA algorithms, and the blocking probability of QVT-RSA algorithm is reduced compared with SPFF-RSA, QSPFF-RSA and VRSA algorithms. The optical connections set-up success probability within delay tolerance about high, medium and low priority services of QVT-RSA algorithm is higher than that of the SPFF-RSA, QSPFF-RSA and VRSA algorithms.

Network slicing is a key enabling technology to realize the provisioning of customized services in 5G paradigm. Due to logical isolation instead of physical isolation, network slicing is facing a series of security issues. Side Channel Attack (SCA) is a typical attack for slices that share resources in the same hardware. Considering the risk of SCA among slices, this paper investigates how to effectively allocate heterogeneous resources for the slices under their different security requirements. Then, a SCA-aware Resource Allocation (SCA-RA) algorithm is proposed for Ultra-reliable and Low-latency Communications (URLLC) and Enhanced Mobile Broadband (eMBB) slices in 5G RAN. The objective is to maximize the number of slices accommodated in 5G RAN. With dynamic slice requests, simulation is conducted to evaluate the performance of the proposed algorithm in two different network scenarios. Simulation results indicate that compared with benchmark, SCA-RA algorithm can effectively reduce blocking probability of slice requests. In addition, the usage of IT and transport resources is also optimized.

Quantum key distribution (QKD) has attracted much attention on secure communications across global networks. QKD over satellite networks can overcome the limitations of terrestrial optical networks, such as large attenuation over long distance fiber channel and difficulty of intercontinental domain communications. Different QKD networks (around the world) can intercommunicate through quantum satellites, leading to a global quantum network in near future. This raises a new resource allocation and management problem of QKD involving multiple satellite layers and distributed ground stations. Using existing schemes, a single satellite cannot perform QKD for ground stations for the whole day. Moreover, the research problem is more challenging due to limitations of satellite coverage: limited cover time of low earth orbit (LEO) satellite, high channel losses of geostationary earth orbit (GEO) satellite, etc. To overcome these limitations, our study proposes a double-layer quantum satellite network (QSN) implemented quantum key pool (QKP) to relay keys for ground stations. We propose a new architecture of trusted-repeater-based double-layer quantum satellite networks, comprising GEO and LEO satellites. We also address the routing and key allocation (RKA) problem for key-relay services over QSNs. We propose a novel joint GEO-LEO routing and key allocation (JGL-RKA) algorithm to solve the RKA problem. Simulative results show that the proposed scheme can increase success probability of key-relay services significantly. We also present the impact of different route selections mechanisms, number of satellite links, satellite node capability, and service granularity on network performance.

As an important bearer network of the fifth generation (5G) mobile communication technology, the optical transport network (OTN) needs to have high-quality network performance and management capabilities. Proof by facts, the combination of artificial intelligence (AI) technology and software-defined networking (SDN) can improve significant optimization effects and management for optical transport networks. However, how to properly deploy AI in optical networks is still an open issue. The training process of AI models depends on a large amount of computing resources and training data, which undoubtedly increases the carrying burden and operating costs of the centralized network controller. With the continuous upgrading of functions and performance, small AI-based chips can be used in optical networks as on-board AI. The emergence of edge computing technology can effectively relieve the computation load of network controllers and provide high-quality AI-based networks optimization functions. In this paper, we describe an architecture called self-optimizing optical network (SOON) with cloud-edge collaboration, which introduces control-layer AI and on-board AI to achieve intelligent network management. In addition, this paper introduces several cloud-edge collaborative strategies and reviews some AI-based network optimization applications to improve the overall network performance.

Based on Y-00 protocol, the Quantum Noise Stream Cipher (QNSC) directly encrypts the data by employing inherent quantum noise, and thus can provide physical layer security in optical fiber communication systems. With increase of bit position of ciphertext, the effect of noise on the higher bit positions of ciphertext decreases. In order to improve the effect of noise on the higher bit positions of ciphertext to protect the plaintext, XOR operation has to be used in QNSC. However, in multi-bit data QNSC system, multi-bit data has to perform XOR operation with additional seed key to protect the multi-bit data. With increase of bit number of plaintext, many additional seed keys have to be used to perform XOR operation. Thus, it is necessary to design a new mapping method without the additional seed key to protect the multi-bit data. In this paper, we propose a multi-bit data mapping method based on constellation rotation (CR) to expand the impact of noise on the higher bit positions of ciphertext to protect data. Without using additional seed key, CR-based QNSC fully expands the random impacts of noise on the multi-bit plaintext and further enhances the security of multi-bit plaintext in QNSC scheme. The CR-based multi-bit mapping method rotates the constellation diagram of plaintext by an angle to code the plaintext alternatively in constellation diagram. Based on IM/DD-OFDM, we conduct QAM/QNSC and PSK/QNSC simulation to test the performance of CR-based multi-bit mapping in optical back-to-back with ASE noise. At the same time, we compare the XOR-based BPSK/QNSC with CR-based BPSK/QNSC in different intensity noises. Results show that the bit error rate of multi-bit plaintext in different bit positions is close to 0.5 for multi-bit plaintext of PSK/QNSC and QAM/QNSC by using CR-based mapping. Thus, the effect of noise on the higher bit positions of plaintext is improved. Eve cannot obtain any information about plaintext. By comparing XOR-based BPSK/QNSC and CR-based BPSK/QNSC in one-bit system, we find that the bit error rate is close to 0.5 in both schemes. The advantage of CR-based QNSC is able to encrypt multi-bit plaintext without extra seed key and hardly affect the transmission performance of the legitimate receiver Bob.

Quantum Noise Stream Cipher (QNSC) is a physical layer encryption scheme to increase the security of fiber optics transmission. With the same launch power, the higher encryption constellation adopted, the higher security achieved. However, higher constellation modulations are limited by the bit resolution of DAC at transmitters, especially for the commercial transmission system adopting QPSK or 16QAM only. In the paper, we investigate the effect of bit-resolution limited DAC in QNSC system. We conduct simulation analysis in two scenarios. First, in an optical back-to-back condition with high OSNR, a QNSC system is influenced by quantization noise of DAC. Second, in an optical back-to-back condition with low OSNR, a QNSC system is affected by quantized noise of DAC and amplified spontaneous emission (ASE) noise of amplifier. Simulation results show that, the same as ASE noise, quantized noise can also mask the signal to ensure the security of QNSC system. Eve can eavesdrop just after transmitter to avoid interference of ASE noise, but cannot avoid the impact of quantization noise of DAC. The quantization noise introduced by low resolution DAC can still increase the difficulty of eavesdropping. Moreover, as long as the total noise remains unchanged, the transmission performance for Bob will not be affected

In the Internet Age, optical networks are vulnerable to numerous cyberattacks, and conventional key distribution methods suffer from the increased computational power. QKD can distribute information-theoretically secure secret keys between two parties based on the principles of quantum mechanics. Integrating QKD into optical networks can leverage existing fiber infrastructures with wavelength division multiplexing for the practical deployment of secret keys, and accordingly employ the secret keys for optical-layer security enhancement. Then, how to efficiently deploy and employ secret keys over QKD-integrated optical networks are emerging as two challenges. This article proposes a framework of key as a service (KaaS, i.e., providing secret keys as a service in a timely and accurate manner to satisfy the security requirements) to jointly overcome these two challenges. To enable the typical functions (i.e., secret-key deployment and employment) in KaaS, two secret-key virtualization steps, that is, key pool (KP) assembly and virtual key pool (VKP) assembly, are introduced. Also, we illustrate a new QKD-integrated optical network architecture from a holistic view, where the control layer is implemented by software defined networking for efficient network management. A time-shared KP assembly strategy and an on-demand VKP assembly strategy are presented for KaaS implementation. The success probabilities of KP assembly and VKP assembly are defined to evaluate the benefits of KaaS for efficiently deploying and employing secret keys as well as for security enhancement over QKD-integrated optical networks.

Background Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is life-saving for severe hematological conditions. However, its outcomes need further improvement, and co-infusion of mesenchymal stem cells (MSCs) may show promise. A growing body of research on this subject exists, while the results of different trials are conflicting. A systematic review and meta-analysis is needed to appraise the real efficacy and safety of MSC co-transplantation in allo-HSCT. Methods Studies comparing MSC co-transplantation in allo-HSCT with allo-HSCT alone were searched in six medical databases from inception to June 10, 2020. The primary outcomes were engraftment and graft-versus-host disease (aGVHD and cGVHD, respectively). Other outcomes included overall survival (OS), relapse rate (RR), non-relapse mortality (NRM), and immune reconstitution. Information was independently extracted by two investigators. Methodological quality was assessed using the Cochrane Collaboration tool. Meta-analysis was performed using RevMan 5.4. Results Six randomized controlled trials (RCTs) and 13 non-randomized controlled trials (nRCTs) were included. MSC co-infusion resulted in shorter times to neutrophil engraftment (RCTs: standardized mean difference (SMD) − 1.20, p = 0.04; nRCTs: SMD − 0.54, p = 0.04) and platelet engraftment (RCTs: SMD − 0.60, p = 0.04; nRCTs: SMD − 0.70, p = 0.01), a lower risk of cGVHD (RCTs: risk ratio (RR) 0.53, p = 0.01; nRCTs: RR 0.50, p Conclusion MSC co-infusion generally improved engraftment and reduced cGVHD, without increasing mortality or relapse. Regarding aGVHD and NRM, the effects of MSCs were not quite significant. Specifically, our data support the utilization of MSC co-transplantation in children and young individuals with HLA-nonidentical HSCT, but not in adult patients with hematological malignancies undergoing HLA-identical HSCT.

With traffic demand, the number of services carried in optical transport networks is increasing. However, due to some internal factors (e.g., device power failure, aging) and external factors (e.g., natural disasters), the link in the network may be damaged and some related services can be affected. Restoring these affected services efficiently is a challenging problem. In this paper, we convert the information of optical transport networks (with ODU-k switching capability) and the affected services into images (named a multi-modal method with image format). Then we propose a reinforcement-learning-based service restoration (RLSR) algorithm. In our experimental setup, RLSR uses advanced image recognition model MobileNetV2 and advantage actor-critic reinforcement learning algorithm. Numerical results show that the proposed method can achieve a higher ratio of service restoration than the benchmark and the restoration time is within the acceptable range ($\sim$0.086984s).

Quantum cryptography (QC) is currently under investigation to build highly secure optical communication networks. QC requires distribution of quantum keys (also called “secret” keys) on separate wavelength channels than those used to transmit the encrypted data. Hence, we propose a quantum-secured passive optical network (QS-PON) that supports both i) the traditional wavelength channels for secured data transmission, and ii) a quantum key distribution network (QKDN) running on separate dedicated wavelengths. The QKDN generates and stores secret keys that are then assigned to users’ demands served on traditional PON channels. To generate secret keys, quantum transmitters at the optical network units (ONUs) exchange qubits with a quantum receiver at the optical line terminal (OLT). Then, the generated secret keys are stored in quantum key pools (QKPs) installed at both OLT and the ONUs and assigned to users’ demands. Point-to-multipoint QKD systems have been experimentally demonstrated over various forms of quantum access networks (QANs), showing that an efficient mechanism to generate and assign quantum keys based on traffic requests is a critical component of QANs. In this study, we present a new QS-PON architecture, and we propose a dynamic secret-key provisioning (DSKP) algorithm that effectively generates and assigns secret keys from users’ demands. Our proposed DSKP algorithm features two phases, the lowest-first secret-key generation (LF-SKG) phase and the hierarchical-clustering secret-key consumption (HC-SKC) phase. In this study, we also provide an analytical model that describes how secret keys are generated and consumed in QKPs. In our illustrative numerical evaluation, we compare our algorithm for secret-key provisioning with a baseline IPACT-based solution in terms of service-rejection ratio, time-slot utilization, and guard- and relay-time saving. Results show that DSKP reduces service-rejection ratio and guard- and relay-time of about 16% and 39.54%, respectively.

In hybrid electrical/optical networks, packet switching is energy-hungry while circuit switching is inflexible. To better align traffic’s requirements with the hybrid switching capability, we propose QoS-based forwarding schemes, and results show their benefits.

Optical circuit switching is a promising solution for hybrid optical/electrical switching in datacenter networks. We propose two fault-tolerance approaches for the partial circuit-based switching architecture, and results show they can improve the network resilience significantly.

Nowadays, network security has attracted more and more attention with confidential and sensitive information in critical areas such as government, military and finance, etc. Quantum key distribution (QKD) can share unconditional security of keys between two remote parties based on information theory and the laws of quantum physics, which is considered as a promising solution to guarantee networks' security. For Quantum key distribution optical networks (QKD-ONs), synchronization technology plays a fundamental role in its development. In this paper, we introduce a synchronization scheme in QKD-ON which provides a method to measure the synchronization precision. Base on this, a multi-path optimal resource allocation (MPORA) algorithm is proposed to improve the successful probability of encryption service and the utilization of key resources on the premise of ensuring the quality of QKD-ON synchronization.

Nowadays, multi-domain large-scale satellite laser networking has become an inevitable trend in satellite communications area. Software defined network (SDN) is introduced to the satellite networks to reduce the control complexity of satellite nodes and achieve flexible management of a large number of satellites. However, the routing problems in the dynamic satellite topology, which is caused by the nature of motion of satellite nodes, is not well studied yet. In this paper, we propose an adaptive snapshot routing strategy (ASRS), to optimize snapshot routing performance while reducing the occupation of precious on-board storage resources by snapshot storage. Finally, we built a satellite network simulator platform based on ONOS and conducted simulation to compare the performance of ASRS and a classic snapshot routing strategy (CSRS). The results showed that ASRS has obvious advantages in terms of on-board storage resource occupation and quality of service.

A traffic scheduling strategy based on edge coordination is proposed to mitigate DDoS attacks for edge nodes in TWDM-PON. Results reveal that our proposed algorithm effectively reduces service blocking and QoS degradation caused by DDoS.

We propose training-testing-decoupled (TTD) mode between cloud artificial intelligence (AI) and on-board AI to speed up the AI application. The experimental results show that TTD mode could reduce 12.5% of the time cost.

At present, endovascular thrombectomy (EVT) has been gradually became a standard therapy for stroke patients caused by emergent large-vessel occlusion (ELVO). However, the question about whether EVT is superior to medical treatment for mild stroke patients presenting with a low baseline National Institutes of Health Stroke Scale (NIHSS) score remains unclear. The aim of this systematic review and meta-analysis was to compare the safety and efficacy of EVT with medical treatment in mild stroke patients.A systematic review and meta-analysis was conducted through searching the PubMed, Embase and Cochrane Library databases. All statistical analyses were performed by using Review Manager 5.3 software. Primary outcomes of this meta-analysis were as follows: favorable functional outcome at 90 days (defined as a modified Rankin scale (mRS) score of 0-2); excellent functional outcome at 90 days (defined as a mRS score of 0-1); symptomatic intracerebral hemorrhage (sICH); mortality at 90 days.A total of 13 eligible studies with 2135 patients were included in this meta-analysis. The pooled results indicated that mild stroke patients underwent EVT had higher risk of sICH than those receiving medical treatment alone (OR = 3.21; 95% CI, 1.98-5.22; P0.001). In addition, no significant difference was found between the two groups in mortality at 90 days (OR = 1.80; 95% CI, 0.88-3.65; P=0.11). Meanwhile, no significant difference was found between the two groups in patients achieving favorable functional outcome at 90 days and excellent functional outcome at 90 days (OR = 1.10; 95% CI, 0.74-1.64; P = 0.65) (OR = 1.03; 95% CI, 0.79-1.35; P = 0.80).Our pooled results showed similar clinical outcomes at 90 days of EVT and medical treatment in mild stroke patients with ELVO, although patients underwent EVT had higher rates of sICH. However, due to several limitations of this meta-analysis, randomized controlled trials are needed to further evaluate the potential efficacy of EVT in mild stroke patients.

Receptor-interacting protein kinase-3 (RIPK3) is a multifunctional regulator of cell death and inflammation. RIPK3 controls cellular signalling through the formation of the domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, which is recognised to mediate renal fibrogenesis. The role of RIPK3 in diabetic kidney disease (DKD) induced renal fibrosis has not been previously determined. To define the action of RIPK3 in the development of diabetic kidney disease, wild-type (WT), RIPK3 -/- and endothelium-derived nitric oxide synthase (eNOS)-/- mice were induced to develop diabetes mellitus using multiple low doses of streptozotocin and maintained for 24 weeks. RIPK3 activity and NLRP3 expression were upregulated and fibrotic responses were increased in the kidney cortex of WT mice with established diabetic nephropathy compared to control mice. Consistently, mRNA expression of inflammasome components, as well as transforming growth factor beta 1 (TGFβ1), α smooth muscle actin (α-SMA) and collagen deposition were increased in diabetic kidneys of WT mice compared to control mice. However, these markers were normalised or significantly reversed in kidneys of diabetic RIPK3 -/- mice. Renoprotection was also observed using the RIPK3 inhibitor dabrafenib in eNOS-/- diabetic mice as demonstrated by reduced collagen deposition and myofibroblast activation. These results suggest that RIPK3 is associated with the development of renal fibrosis in DKD due to the activation of the NLRP3 inflammasome. Inhibition of RIPK3 results in renoprotection. Thus, RIPK3 may be a potential target for therapeutic intervention in patients with diabetic kidney disease.

Quantum key distribution (QKD) promises to deliver secure keys, which can be applied for security demands in optical networks by using cost-efficient and scalable lightpaths. To achieve such secure communication, the QKD integrated with optical networks has become a promising scenario to provide key provisioning services in optical networks. As an inevitable problem, the occurrence of failures becomes a challenge for the resiliency of the network. In that context, this paper studies the resilient QKD-integrated optical networks against single link failure. By analyzing and quantifying the key provisioning services, we constructed the secret-key flow model (SKFM) for the failure-affected and failure-unaffected cases. Based on the SKFM, a secret-key recovery strategy (SKRS) including three algorithms (i.e., one-path recovery method (OPRM), multi-path recovery method (MPRM), and time window-based recovery method (TWRM)) is designed to recover failure-affected key provisioning services in the network. The simulation work has been conducted to evaluate the performance of OPRM, MPRM, and TWRM in terms of key-service recovery ratio, secret-key recovery ratio, wavelength consumption ratio, and secret-key consumption ratio. Numerical results show that the three algorithms can recover failure-affected key provisioning services effectively, i.e., the MPRM outperforms the OPRM and the TWRM outperforms the MPRM. Better recovery can be realized by sacrificing more wavelength and secret-key resources, which are also required for the delivery of the QKD in the network. Thus, a trade-off can be achieved between the recovery of key provisioning services and the delivery of the QKD on wavelength resources and secret-key resources.

This paper proposes a novel key distribution system based on the measurement of the bit error rate (BER) in a fiber channel. By carrying out the loopback BER measurement at both the transmitting and the receiving end, the BER is quantified and codified to generate consistency keys. Alice and Bob respectively encrypt the signal with the help of the public key base at the transmitting end. At the receiving end the data are decrypted and then the BER is measured. The security of generated keys in the system is enhanced by the use of the encryption base and the randomness of the channel. Additionally, noise sources are added to the channel so that the random noise conceals signals and Eve cannot eavesdrop the useful information in it. Due to the randomness of the channel noise, the generated keys have good randomness. This system at a high key generation rate is compatible with the existing communication device and its measurement is simple. The 10G bit/s-200 km coherent optical communication system is used to measure the BER of the security feature information of the extracted channel. The experimental results show that the key distribution system obtains a consistency rate of 98% with the key generation rate 2 Mbps, both of which have been significantly improved.

As a concept to enhance and extend cloud-computing capabilities, edge computing aims to provide Internet-based services in the close proximity to users by placing IT infrastructures at the network edge in forms of tiny datacenters. Taking advantage of the close distance to end user and access networks, edge datacenters can provide low-latency and context-aware services and further improve users' quality of experience. As the network edge is a geographically spread concept, the edge datacenters are usually highly distributed so that they can provide nearby storage and processing capabilities to most of the end users. Furthermore, edge datacenters also co-work with centralized cloud datacenters for service orchestration. Such decentralization and collaboration are expected to introduce significant transformations to both infrastructures and applications. To provide an overview of how edge can be integrated with cloud-computing and how edge computing can benefit applications, this paper studies the infrastructure and application issues of edge computing and networking in several sub-aspects, including related concepts, infrastructures, resource management and virtualization, performance, and applications.

Nowadays, critical sectors in government, finance, and military are facing increasingly high security challenges. However, traditional public-key crypto-systems based on computational complexity are likely to suffer from upgrade computational power. Quantum key distribution (QKD) is a promising technology to effectively address the challenge by providing secret keys due to the laws of quantum physics. Limited by the transmission distance of quantum communications, remote parties have to share secret keys by exchanging keys through the trusted relay nodes hop by hop. However, if relaying hop by hop is still used in metro quantum-optical networks (MQON), a large amount of key resources will be wasted since the distance between any two nodes is short. Therefore, the problem of how to distribute quantum keys with lower waste of key resources over MQON is urgent. In order to solve this problem, we design a novel quantum node structure that is able to bypass itself. Also, by extending the connectivity graph, auxiliary graphs are constructed to describe the adjacency of quantum nodes in different levels influenced by the physical distance. Based on the novel node, two routing, wavelength and time-slot assignment algorithms are proposed, in which some middle nodes can be bypassed to reduce the resource consumption as long as the distance between the two parties meets the requirement of quantum key distribution. Simulations have been conducted to verify the performance of the proposed algorithms in terms of blocking probability, resource utilization, number of bypassed nodes, and security rate per service. Numerical results illustrate that our algorithms perform better on resource utilization than a traditional scheme without bypass. Furthermore, a tradeoff between the keys saved and blocking probability is analyzed and discussed in our paper.

This paper describe a long-haul stealth communication based on different state bases unidirectional loopback (DSBUL) in optical fiber link. In order to prevent the optical signal in the optical fiber from being directly detected by the eavesdropping, our scheme combine the quantum noise stream cipher with a novel signal expension technology. We demonstrate digital signal processing (DSP) algorithm steps of transmitter and receiver in detail and experimentally implement a long-haul stealth communication based on DSBUL system, which can be compatible with existing coherent optical communication systems without changing any hardware structure. The stealth transmission distance (L) is 300 kilometers with free bit error rate. And transmission rate is over 550 kbps. In additional, we evaluate the security of this scheme with capability against various tapping attacks.

Derived from quantum cryptography, quantum key distribution (QKD) can deliver secret keys between two users to secure communication under a certain scale. Nowadays, QKD integrated in backbone, metro, and access areas has been respectively studied and tested around the world. Although the experiments in various scenarios can verify the feasibility of QKD, the situation of QKD between two end users from metro to access networks has not been considered up to now. In this paper, we propose a QKD Network (QKDN) architecture for end-to-end QKD from metro to access networks in a costefficient manner. The cost efficiency can be achieved by sharing Quantum Receivers (Qrecs) in the metro network with the Quantum Transmitters (Qtras) in various access networks since the distance between any two end users within a metro network permits to distribute quantum keys. Under such an architecture, an end-to-end QKD scheme is designed to provide secret keys for end users in different access networks, by mapping Qrecs and allocating time slots according to security requests. Through the end-to-end QKD scheme, the occupation of Qrecs and time slots can be appropriately improved. To verify the effectiveness of the scheme, simulation is conducted on two different topologies respectively. Performances are evaluated in terms of three parameters: i) the failure ratio of end-to-end QKD (FQ), ii) the utilization ratio of time slots (TU), and iii) the utilization ratio of Qrecs (QU). Simulation results show that the topology with more nodes will lower the QU by distributing requests to more numbers of Qrecs. Moreover, the topology with bigger node connectivity can lower FQ since a shorter path will be selected to save the unnecessary occupation of link resources for other end-to-end requests.

In this paper, a collective self-learning method based on knowledge sharing is proposed to predict alarms in multi-domain autonomous optical networks. The well-considered architecture is rendered, together with various alternatives for combining machine learning (ML) knowledge. The proposed method has been tested in the commercial large-scale multidomain network with 274 nodes and 487 links. Experimental results show that it can achieve high accuracy for alarm prediction. In addition, it can achieve similar performance with much better flexibility than a collective scheme based on training data sharing as well as more superior accuracy and robustness than an individual ML model.

Machine learning (ML) is an effective solution to deal with some networking issues in large scale optical transport networks. Alarm (caused by failure, disaster, etc.) prediction is a typical and important use-case, where ML algorithm can work to predict events in advance. By accurate prediction, network administrators can be guided to undertake preventive measures ahead of time, thus avoiding the adverse effect. For training and testing of such event prediction models, it’s first and foremost to build a high-quality data set from real networks. However, the data collected from large-scale optical transport networks are inferior in quality and demand prompt pre-processing, for they are sometimes invalid, incomplete, inconsistent, and even inaccurate. After data pre-processing, there is only a small amount of available data left to build an ML data set, which extremely limits the performance of the alarm prediction model. This paper proposes a machine-learning-based alarm prediction method using self-optimizing data augmentation based on generative adversarial networks (GANs) for optical transport networks. Experimental results on a commercial backbone synchronous digital hierarchy (SDH) network with 274 nodes and 487 links demonstrate that the proposed method can achieve high accuracy for alarm prediction.

We propose a routing and wavelength allocation method in spatial division multiplexing (SDM) based on quantum key distribution (QKD) optical networks. Especially, for the routing and wavelength allocation of quantum services, we design an auxilia/y matrix-based core allocation and a routing method based on inter-core crosstalk (IC-XT) evaluation. For classic services in SDM optical networks, we design a resource allocation method. Through the proposed hybrid resource allocation strategy, the IC-XT of quantum services can be reducedt Moreover, the amount of available secret keys stored by the node has also increased in SDM optical networks.

In software defined optical networks (SDON), a single controller can hardly manage all the optical devices especially in the large-scale networks, while multiple controllers deployed in the network can solve it. Recently, more and more attention has been paid to the multi-controller architecture, and the deployment of controllers is an important issue in large software defined optical networks. However, the existing architectures focus on static mapping of controllers and switches and do not consider load balance among different controllers. It is worth further studying the cooperation of multiple controllers. This paper presents a multi-controller coordinated deployment strategy (Switch Migration Based Controller Placement, SMBCP) based on load balancing. Simulation results show that SMBCP can significantly reduce the load difference among different controllers in SDON and reduce the migration cost of switches, thus improving the load balance of the controller.

Security threat is a challenging issue for data transmission in optical networks. Quantum key distribution (QKD) is a promising security solution to optical networks to provide secure keys. Meanwhile, key update is of importance to enhance the security of key in the networks. The previous update method is to provide a fixed key-updating period which has a strong regularity to be easily found. To enhance the security of data services, we proposed a quantum key-updating process by introducing the architecture of SDON secured by QKD. Then, a flexible quantum key-updating method (Flex-KUM) and a quantum key-updating algorithm based on Flex-KUM are designed in the comparison with the fixed method with different update periods. The results show that a higher level of security requires more updating keys, which leads to an increase in the blocking probability. Therefore, there is a trade-off between the enhanced security and resources.

Quantum key distribution (QKD) networking over wavelength-division multiplexing (WDM) network infrastructure provides a new paradigm for secure communications across the networks. With limited wavelength resources in existing WDM networks, how to efficiently schedule QKD to provision sufficient secret keys over WDM networks becomes a new challenge. This study proposes a new time-scheduled scheme in combination with quantum key pool (QKP) technique to overcome this challenge. A new architecture of QKD-over-WDM networks is presented, in which QKPs are constructed to decouple secret-key resources from the underlying infrastructure for timely secret-key provisioning. In the time-scheduled scheme, routing, wavelength, and time-slot allocation (RWTA) problem is proposed for efficient QKP construction (QKPC) over WDM networks, in which three sub-problems (i.e., secret-key consumption, time-slot allocation, and time-slot continuity) are discussed, respectively. An integer linear programming (ILP) model and a novel joint path-and-link-based RWTA (JPL-RWTA) heuristic algorithm are designed to solve the RWTA problem, in which the three sub-problems are addressed together. Simulation results indicate that the ILP model and JPL-RWTA algorithm are effective approaches to obtain the positive balance between resource utilization of QKPC and successful probability of QKPC (SPQKPC). Moreover, the SPQKPC can be increased at the cost of reducing the flexibility of secret-key consumption, the uniformity of time-slot allocation, and the proportion of time-slot continuous QKPC to time-slot discrete QKPC requests.

Optical network security is attracting increasing research attention, as loss of confidentiality of data transferred through an optical network could impact a huge number of users and services. Data encryption is an effective way to enhance optical network security. In particular, QKD is being investigated as a secure mechanism to provide keys for data encryption at the endpoints of an optical network. In a QKD-enabled optical network, apart from TDChs, two additional channels, called QSChs and PIChs, are required to support secure key synchronization. How to allocate network resources to QSChs, PIChs, and TDChs is emerging as a novel problem for the design of a security-guaranteed optical network. This article addresses the resource allocation problem in optical networks secured by QKD. We first discuss a possible architecture for a QKD-enabled optical network, where an SDN controller is in charge of allocating the three types of channels (TDCh, QSCh, and PICh) over different wavelengths exploiting WDM. To save wavelength resources, we propose to adopt OTDM to allocate multiple QSChs and PIChs over the same wavelength. An RWTA algorithm is designed to allocate wavelength and time slot resources for the three types of channels. Different security levels are included in the RWTA algorithm by considering different key updating periods (i.e., the period after which the secure key between two endpoints has to be updated). Illustrative simulation results show the effects of different security-level configuration schemes on resource allocation.

As the significant infrastructure of the communication network, the security of the optical fiber is critical. Optical fiber eavesdropping is a common attack in optical communications, which can easily lead to leakage of information. To deal with this problem, this paper proposes a Machine Learning (ML)-based scheme to detect and locate physical-layer eavesdropping. To improve the efficiency and accuracy of eavesdropping detection, both Optical Performance Monitoring (OPM) data and eye-diagrams are adopted as input data. Three different ML classifiers are designed and tested to realize eavesdropping detection, location and split ratio recognition, respectively. To demonstrate the feasibility of the proposed scheme, an experiment is conducted in end-to-end fiber transmission system with Coherent Optical Orthogonal Frequency Division Multiplexing (CO-OFDM). The eavesdropping is simulated and performed by placing optical coupler in different positions. In addition, different splitting ratios are considered, including 95/5, 90/10. Results indicate that the ML scheme achieves 100% and 92.76% accuracy in eavesdropping detection and location, respectively.

We are pleased to provide readers with the newest and important technologies presented in Asia Communications and Photonics Conference (ACP) and International Conference on Information Photonics and Optical Communications (IPOC) 2020 (ACP/IPOC 2020), through this Special Issue published by the IEEE Photonics Technology Letters (PTL) journal. Technologies of photonics and optical communications (POCs) have developed rapidly in the last decades and have evolved to become a key-enabling component for the applications of high-speed telecommunications, advanced microwave signal generation and processing, astronomy observations, and even for quantum information processing and computing. The field of POC continues attracting a great deal of attention and keeps progressing in several important directions. Based on the nowadays matured exploration methods, current research is mainly directed towards implementations in integrated formats, such as high-speed optical transmission, big-capacity optical switching, automated optical-network/system evolution, and so on. In addition, intensive research is being conducted toward the utilization of POC across the abovementioned practical application areas and others.

Loading mode plays a key role in the fatigue performance evaluation of asphalt mixtures. However, the stress-controlled mode and strain-controlled mode cannot reflect the pavement structure loading conditions. In this paper, a simplified pavement analysis model was designed to analyze the loading conditions of pavement structure, and the energy-controlled mode was put forward. The improved 4PB beam fatigue test procedures were proposed to achieve the energy-controlled mode. And the traditional 4PB beam fatigue tests were also conducted under stress-controlled mode and strain-controlled mode for comparative analysis, respectively. Results show that stress-controlled mode and strain-controlled mode can only reflect two kinds of critical loading conditions in the pavement structures, and do not have universal applicability. An intermediate loading condition that the stored energy approximately remains constant is found. The energy-controlled mode can be achieved well by improved test procedures. And the fatigue life N f of asphalt mixtures measured under energy-controlled mode falls in between fatigue life N f that is measured based on the stress-controlled mode and strain-controlled mode. The test results coincide with the theoretical analysis of simplified pavement analysis model. Therefore, the energy-controlled mode is more suitable to evaluate the fatigue performance of asphalt mixtures.

In software defined optical networks (SDON), the centralized control plane may encounter numerous intrusion threatens which compromise the security level of provisioned services. In this paper, the issue of control plane security is studied and two machine-learning-based control plane intrusion detection techniques are proposed for SDON with properly selected features such as bandwidth, route length, etc. We validate the feasibility and efficiency of the proposed techniques by simulations. Results show an accuracy of 83% for intrusion detection can be achieved with the proposed machine-learning-based control plane intrusion detection techniques.