Computer Networks最新文献_第8页

Efficient intrusion detection via heterogeneous graph attention networks and parallel provenance analysis 基于异构图关注网络和并行源分析的高效入侵检测

IF 4.4 2区计算机科学

Computer Networks Pub Date : 2025-07-23 DOI: 10.1016/j.comnet.2025.111552

Lin Wu , Yu-Lai Xie , Shi-Xun Zhao , Pan Zhou , Dan Feng , Avani Wildani , Ya-Feng Wu

{"title":"Efficient intrusion detection via heterogeneous graph attention networks and parallel provenance analysis","authors":"Lin Wu , Yu-Lai Xie , Shi-Xun Zhao , Pan Zhou , Dan Feng , Avani Wildani , Ya-Feng Wu","doi":"10.1016/j.comnet.2025.111552","DOIUrl":"10.1016/j.comnet.2025.111552","url":null,"abstract":"<div><div>In recent years, Advanced Persistent Threats (APTs) have emerged as a significant and pervasive form of cyber attack that uses sophisticated, covert techniques to infiltrate and persist in vulnerable systems, posing a significant threat to businesses and organizations. Recent studies have highlighted the potential of using provenance for APT detection. Provenance is a kind of data that records the history and dependencies of system objects (such as files, processes, and sockets) and is usually converted into a provenance graph for analysis. However, the previous methods have several limitations : (1) The large amount of data generated by long-term APT attacks has a great storage overhead and reduces the analysis efficiency. (2) Requires prior attack knowledge and cannot cope with unknown attacks. (3) It fails to consider the rich semantic information in the provenance graph fully. In this paper, we propose IDS-HGAT, a novel intrusion detection system based on a heterogeneous graph attention network. The system can reduce the number of nodes by preprocessing while retaining the graph structure information. IDS-HGAT can consider the semantic information of different types of nodes and edges and the structure information of the provenance graph, and effectively aggregate the semantic information to build a classification model without constructing a rule base. In order to improve the detection efficiency, IDS-HGAT employs the Stream data type in Redis to build a message queue to support parallel storage and acquisition of provenance data. The experimental results show that IDS-HGAT is better than the existing state-of-the-art methods in terms of precision rate, false alarm rate, and time cost.</div></div>","PeriodicalId":50637,"journal":{"name":"Computer Networks","volume":"270 ","pages":"Article 111552"},"PeriodicalIF":4.4,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144714130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Betastack: Enhancing base station traffic prediction with network-specific Large Language Models Betastack：使用特定于网络的大型语言模型增强基站流量预测

IF 4.4 2区计算机科学

Computer Networks Pub Date : 2025-07-22 DOI: 10.1016/j.comnet.2025.111557

Quanfeng Lv , Yuan Chang , Tong Li , Jingguo Ge

{"title":"Betastack: Enhancing base station traffic prediction with network-specific Large Language Models","authors":"Quanfeng Lv , Yuan Chang , Tong Li , Jingguo Ge","doi":"10.1016/j.comnet.2025.111557","DOIUrl":"10.1016/j.comnet.2025.111557","url":null,"abstract":"<div><div>Accurate traffic forecasting in base station networks is crucial for efficient network management, resource allocation, and ensuring quality of service. This paper introduces BetaStack, a novel network-specific Large Language Model (LLM) designed to enhance base station traffic prediction. Unlike existing approaches, BetaStack incorporates physical constraints and a specialized network protocol embedding layer that captures the hierarchical structure of network traffic data. Through fine-tuning with these network-specific adaptations and a self-regressive prediction mechanism, BetaStack effectively leverages the powerful sequence modeling capabilities of LLMs to address the intricacies of network traffic. Extensive experiments on real-world data from base station cells in Guangdong, China demonstrate that BetaStack achieves significant performance improvements over both state-of-the-art time-series forecasting models and specialized network traffic prediction models. These results underscore the potential of BetaStack to improve the accuracy of network traffic prediction, enabling more efficient network management. The code can be found in <span><span>https://github.com/lqf0624/BetaStack.git</span><svg><path></path></svg></span>.</div></div>","PeriodicalId":50637,"journal":{"name":"Computer Networks","volume":"270 ","pages":"Article 111557"},"PeriodicalIF":4.4,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144686301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Energy-efficient and reliable data collection in receiver-initiated wake-up radio enabled IoT networks 在接收器启动的唤醒无线电支持的物联网网络中节能可靠的数据收集

IF 4.4 2区计算机科学

Computer Networks Pub Date : 2025-07-21 DOI: 10.1016/j.comnet.2025.111548

Syed Luqman Shah , Ziaul Haq Abbas , Ghulam Abbas , Nurul Huda Mahmood

{"title":"Energy-efficient and reliable data collection in receiver-initiated wake-up radio enabled IoT networks","authors":"Syed Luqman Shah , Ziaul Haq Abbas , Ghulam Abbas , Nurul Huda Mahmood","doi":"10.1016/j.comnet.2025.111548","DOIUrl":"10.1016/j.comnet.2025.111548","url":null,"abstract":"<div><div>In unmanned aerial vehicle (UAV)-assisted wake-up radio (WuR)-enabled internet of things (IoT) networks, UAVs can instantly activate the main radios (MRs) of the sensor nodes (SNs) with a wake-up call (WuC) for efficient data collection in mission-driven data collection scenarios. However, the spontaneous response of numerous SNs to the UAV’s WuC can lead to significant packet loss and collisions, as WuR does not exhibit its superiority for high-traffic loads. To address this challenge, we propose an innovative receiver-initiated WuR UAV-assisted clustering (RI-WuR-UAC) medium access control (MAC) protocol to achieve low latency and high reliability in ultra-low power consumption applications. We model the proposed protocol using the <span><math><mrow><mi>M</mi><mo>/</mo><mi>G</mi><mo>/</mo><mn>1</mn><mo>/</mo><mn>2</mn></mrow></math></span> queuing framework and derive expressions for key performance metrics, i.e., channel busyness probability, probability of successful clustering, average SN energy consumption, and average transmission delay. The RI-WuR-UAC protocol employs three distinct data flow models, tailored to different network traffic scenarios, which perform three different MAC mechanisms: channel assessment (CCA) clustering for light traffic loads, backoff plus CCA clustering for dense and heavy traffic, and adaptive clustering for variable traffic loads. Simulation results demonstrate that the RI-WuR-UAC protocol significantly outperforms the benchmark sub-carrier modulation clustering protocol. By varying the network load, we capture the trade-offs among the performance metrics, showcasing the superior efficiency and reliability of the RI-WuR-UAC protocol.</div></div>","PeriodicalId":50637,"journal":{"name":"Computer Networks","volume":"270 ","pages":"Article 111548"},"PeriodicalIF":4.4,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144696465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Permissioned blockchain architecture enabling bounded-time PBFT consensus over deterministic networks 允许区块链架构在确定性网络上实现有界时间PBFT一致性

IF 4.4 2区计算机科学

Computer Networks Pub Date : 2025-07-21 DOI: 10.1016/j.comnet.2025.111547

Wenwei Huang , Tianyu Kang , Li Guo , Luo Deng

{"title":"Permissioned blockchain architecture enabling bounded-time PBFT consensus over deterministic networks","authors":"Wenwei Huang , Tianyu Kang , Li Guo , Luo Deng","doi":"10.1016/j.comnet.2025.111547","DOIUrl":"10.1016/j.comnet.2025.111547","url":null,"abstract":"<div><div>With the advent of next-generation network, the demand for time-sensitive services in fields such as the IoT the IoD has been increasing. Meanwhile, integrating blockchain technology is becoming increasingly meaningful in IoT scenario due to its enhanced security, transparency and fault tolerance. At this point, to enable blockchain systems to provide time-sensitive services in scenarios such as IIoT, this study proposes an permissioned blockchain architecture based on deterministic network aimed at reaching PBFT consensus in bounded time, referred to as confidence duration (CD). However, congestion can compromise the validity of the CD. To address this, we leverage the PBFT consensus model. This model demonstrates the architecture’s effectiveness by breaking down the consensus process into a series of finite, bounded-latency transmissions, thereby allowing for the calculation of the CD even under potential network congestion. Then, based on this model, this paper proposes a STA scheduling mechanism to address the congestion problem in the PBFT consensus. Finally, our simulations found that the architecture is effective, the computation of CD is correct and the STA scheduling mechanism can effectively address congestion to ensure functionality of CD.</div></div>","PeriodicalId":50637,"journal":{"name":"Computer Networks","volume":"270 ","pages":"Article 111547"},"PeriodicalIF":4.4,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144686297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A survey of existing attacks on 5G SA 针对5G SA的现有攻击调查

IF 4.4 2区计算机科学

Computer Networks Pub Date : 2025-07-19 DOI: 10.1016/j.comnet.2025.111545

Mengyi Gong, Ziling Wei, Shuhui Chen, Wanrong Yu, Fei Wang

{"title":"A survey of existing attacks on 5G SA","authors":"Mengyi Gong, Ziling Wei, Shuhui Chen, Wanrong Yu, Fei Wang","doi":"10.1016/j.comnet.2025.111545","DOIUrl":"10.1016/j.comnet.2025.111545","url":null,"abstract":"<div><div>Since the release of the Fifth Generation (5G) Stand-alone (SA) standard in 2018, there is a swift and widespread global adoption of 5G SA mobile network. For the present and foreseeable future, 5G technology will remain the core of mobile networks. Like previous generations of mobile networks, 5G networks have encountered numerous security issues during actual deployment and service provision, which have led to various serious impacts. Based on this, this paper systematically analyzes existing attacks targeting the User Equipment (UE), Radio Access Network (RAN), and core network of 5G networks. We propose a simple and effective method to investigate attacks on various parts of 5G networks, classify these attacks, and discuss their implications, causes, and defense solutions in detail. We find that most security issues have been theoretically addressed through defense solutions proposed in academic literature and 3rd Generation Partnership Project (3GPP) specifications. However, whether these solutions have been implemented in existing 5G networks remains to be verified. Through a deep analysis of existing 5G network security issues, this paper also proposes potential directions for future 5G security research, aiming to promote further research in the field of 5G security and enhance the overall security of future mobile networks.</div></div>","PeriodicalId":50637,"journal":{"name":"Computer Networks","volume":"270 ","pages":"Article 111545"},"PeriodicalIF":4.4,"publicationDate":"2025-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144696466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Joint optimization of data sensing and computing in the air–ground collaborative inference framework: A multi-agent hybrid-action DRL approach 空地协同推理框架中数据感知与计算的联合优化：一种多智能体混合动作DRL方法

IF 4.4 2区计算机科学

Computer Networks Pub Date : 2025-07-18 DOI: 10.1016/j.comnet.2025.111540

Xiaokun Fan , Yali Chen , Min Liu , Yuchen Zhu , Zhongcheng Li

{"title":"Joint optimization of data sensing and computing in the air–ground collaborative inference framework: A multi-agent hybrid-action DRL approach","authors":"Xiaokun Fan , Yali Chen , Min Liu , Yuchen Zhu , Zhongcheng Li","doi":"10.1016/j.comnet.2025.111540","DOIUrl":"10.1016/j.comnet.2025.111540","url":null,"abstract":"<div><div>Unmanned aerial vehicles (UAVs) are increasingly used for surveillance applications to take videos for Points of Interests (PoIs). Then, the sampled video data is fed into deep neural networks (DNNs) for inference. Due to the high computational complexity of DNNs, directly running DNN inference tasks on resource-constrained UAVs is intractable. To alleviate this issue, edge computing provides a promising solution by offloading tasks to the ground edge servers (ESs). However, how to flexibly schedule and tradeoff various resources for high-accuracy and low-delay inference is a challenge, especially in the complex scenario where video data sensing and DNN task processing are tightly coupled. Thus, this paper studies joint optimization for data sensing and computing in the air–ground collaborative inference framework. Specifically, the models for multi-UAV collaborative data sensing and collaborative inference between multiple UAVs and multiple ESs are designed. Then, we formulate an inference delay minimization problem by jointly optimizing UAVs’ 3D trajectories, number of sampled video frames and computation offloading, while satisfying accuracy, UAV energy budget and sensing mission requirements. Considering mixed continuous–discrete optimization variables, we propose a multi-agent proximal policy optimization (MAPPO) algorithm with a hybrid action space, called “MAPPO-HA”, to learn the optimal policies. Finally, simulation results demonstrate that our algorithm can achieve better performance compared with other optimization approaches.</div></div>","PeriodicalId":50637,"journal":{"name":"Computer Networks","volume":"270 ","pages":"Article 111540"},"PeriodicalIF":4.4,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144670879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Semantic Edge Computing and Semantic Communications in 6G networks: A unifying survey and research challenges 6G网络中的语义边缘计算和语义通信：一个统一的调查和研究挑战

IF 4.4 2区计算机科学

Computer Networks Pub Date : 2025-07-18 DOI: 10.1016/j.comnet.2025.111531

Milin Zhang , Mohammad Abdi , Venkat R. Dasari , Francesco Restuccia

引用次数: 0

Learning to shape beams: Using a neural network to control a beamforming antenna 学习塑造波束：使用神经网络来控制波束形成天线

IF 4.4 2区计算机科学

Computer Networks Pub Date : 2025-07-18 DOI: 10.1016/j.comnet.2025.111544

Jose David Fernández-Rodríguez , Iván García-Aguilar , Rafael Marcos Luque-Baena , Ezequiel López-Rubio , Marcos Baena-Molina , Juan Francisco Valenzuela-Valdés

{"title":"Learning to shape beams: Using a neural network to control a beamforming antenna","authors":"Jose David Fernández-Rodríguez , Iván García-Aguilar , Rafael Marcos Luque-Baena , Ezequiel López-Rubio , Marcos Baena-Molina , Juan Francisco Valenzuela-Valdés","doi":"10.1016/j.comnet.2025.111544","DOIUrl":"10.1016/j.comnet.2025.111544","url":null,"abstract":"<div><div>The field of reconfigurable intelligent surfaces (RIS) has gained significant traction in recent years in the wireless communications domain, owing to the ability to dynamically reconfigure surfaces to change their electromagnetic radiance patterns in real-time. In this work, we propose utilizing a novel deep learning model that innovatively employs only the parameters of each signal or beam as input, eliminating the need for the entire one-dimensional signal or its diffusion map (two-dimensional information). This approach enhances efficiency and reduces the overall complexity of the model, drastically reducing network size and enabling its implementation on low-cost devices. Furthermore, to enhance training effectiveness, the learning model attempts to estimate the discrete cosine transform applied to the output matrix rather than the raw matrix, significantly improving the achieved accuracy. This scheme is validated on a 1-bit programmable metasurface of size 10<span><math><mo>×</mo></math></span>10, achieving an accuracy close to 95% using a K-fold methodology with K=10.</div></div>","PeriodicalId":50637,"journal":{"name":"Computer Networks","volume":"270 ","pages":"Article 111544"},"PeriodicalIF":4.4,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144680517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Enhanced RIS-assisted vehicular network with TDMA and Bayesian Compressive Sensing-based channel estimation 基于TDMA和贝叶斯压缩感知信道估计的增强ris辅助车辆网络

IF 4.4 2区计算机科学

Computer Networks Pub Date : 2025-07-17 DOI: 10.1016/j.comnet.2025.111525

Xiaoliang Zhang , Miao Wang , Mengxiong Wang , Liqiang Wang , Hong Zhang

{"title":"Enhanced RIS-assisted vehicular network with TDMA and Bayesian Compressive Sensing-based channel estimation","authors":"Xiaoliang Zhang , Miao Wang , Mengxiong Wang , Liqiang Wang , Hong Zhang","doi":"10.1016/j.comnet.2025.111525","DOIUrl":"10.1016/j.comnet.2025.111525","url":null,"abstract":"<div><div>In recent years, vehicular communication networks have become increasingly critical for intelligent transportation systems and autonomous driving applications. However, traditional vehicular networks face significant challenges in achieving reliable high-throughput communication, particularly for vehicles at the network edge or in non-line-of-sight scenarios. While Reconfigurable Intelligent Surface (RIS) technology offers promising solutions through programmable signal reflections, the joint optimization of RIS configuration and resource allocation in dynamic vehicular environments remains a complex and open challenge. In this paper, we propose an RIS-assisted uplink multi-input single-output (MISO) vehicular network communication system, where vehicle sensors transmit the collected data to roadside units (RSUs) in their specific time slots. To enhance transmission efficiency and reliability, we employ an adaptive Time Division Multiple Access (TDMA) scheme, which assigns dedicated time slots to each vehicle, thereby avoiding signal collisions and improving spectrum utilization. Furthermore, to address the channel estimation challenge in mobile scenarios, we develop a practical and efficient channel estimation framework based on Bayesian Compressive Sensing (BCS). Specifically, to leverage the inherent sparsity in the channel structure, our approach minimizes pilot overhead while enabling accurate and efficient recovery of the channel state information (CSI) in both direct and RIS-assisted paths under Rician fading conditions. To maximize the system throughput through the joint optimization of RIS phase shifts, power allocation, and time slots, we utilize the Block Coordinate Descent (BCD) algorithm to solve this non-convex optimization problem. The numerical results demonstrate that the proposed BCS-based method significantly enhances channel estimation accuracy and system throughput compared to other state-of-the-art approaches.</div></div>","PeriodicalId":50637,"journal":{"name":"Computer Networks","volume":"270 ","pages":"Article 111525"},"PeriodicalIF":4.4,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144686298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Optimizing UAV scheduling and trajectory planning: An online auction framework 优化无人机调度和轨迹规划：一个在线拍卖框架

IF 4.4 2区计算机科学

Computer Networks Pub Date : 2025-07-17 DOI: 10.1016/j.comnet.2025.111528

Kaiwei Mo , Xianglong Li , Zongpeng Li , Hong Xu

{"title":"Optimizing UAV scheduling and trajectory planning: An online auction framework","authors":"Kaiwei Mo , Xianglong Li , Zongpeng Li , Hong Xu","doi":"10.1016/j.comnet.2025.111528","DOIUrl":"10.1016/j.comnet.2025.111528","url":null,"abstract":"<div><div>Unmanned Aerial Vehicles (UAVs) are envisioned to be a critical form of network service provisioning, when the ground infrastructure is vulnerable to disruptions from conflicts and natural disasters. Existing methodologies often fall short in fully optimizing UAV scheduling and resource allocation, leading to suboptimal service performance. This work aims to enhance social welfare through refining UAV scheduling and trajectory planning processes. To address this complex challenge, we first formulate social welfare maximization into a non-traditional integer linear program, and subsequently transform it into its exponential and dual forms. We propose a bifurcated framework called Online Scheduling and Trajectory (OST) which comprises two algorithms: The <span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>O</mi><mi>S</mi><mi>T</mi></mrow></msub></math></span> algorithm is responsible for managing task bids and allocating UAV resources by taking into account bid values, available resources, and task requirements, prioritizing tasks based on their intrinsic value. The <span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>d</mi><mi>u</mi><mi>a</mi><mi>l</mi></mrow></msub></math></span> algorithm optimizes task selection and UAV trajectory planning by balancing the costs and benefits associated with each task. Theoretical analysis demonstrates that the proposed approach achieves an equilibrium that significantly enhances social welfare by ensuring optimal decisions regarding task allocation and resource distribution. Empirical evaluations corroborate these findings, illustrating notable improvements in network service efficiency and validating the practical applicability of our method in maximizing social welfare.</div></div>","PeriodicalId":50637,"journal":{"name":"Computer Networks","volume":"270 ","pages":"Article 111528"},"PeriodicalIF":4.4,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144686299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0