IEEE Open Journal of the Communications Society最新文献

{"title":"A Survey on Advancements in THz Technology for 6G: Systems, Circuits, Antennas, and Experiments","authors":"Sidharth Thomas;Jaskirat Singh Virdi;Aydin Babakhani;Ian P. Roberts","doi":"10.1109/OJCOMS.2025.3549710","DOIUrl":"https://doi.org/10.1109/OJCOMS.2025.3549710","url":null,"abstract":"Terahertz (THz) carrier frequencies (100 GHz to 10 THz) have been touted as a source for unprecedented wireless connectivity and high-precision sensing, courtesy of their wide bandwidth availability and small wavelengths. However, noteworthy implementation challenges persist, ranging from limitations in semiconductor device technologies to antenna design and packaging, as well as system-level issues such as high path loss, complex beam management, and regulatory constraints. In this paper, we survey recent advancements on 6G networks using THz frequencies, with a particular emphasis on the 200–400 GHz frequency range and the IEEE 802.15.3d standard. This band offers a compelling balance by providing ample bandwidth for high data-rate communications, while also exhibiting lower atmospheric absorption for longer-range transmission, and can be viably realized using current semiconductor technologies. Unlike other existing surveys in this domain, we provide a comprehensive and holistic overview of THz systems, circuits, device technology, and antennas while also highlighting recent experimental demonstrations of 6G networks using THz frequencies. Throughout this paper, we review the state-of-the-art in 6G network implementation using THz, and call attention to open problems, future prospects, and areas of further improvement in THz communication technologies to fully realize their potential in next-generation wireless connectivity.","PeriodicalId":33803,"journal":{"name":"IEEE Open Journal of the Communications Society","volume":"6 ","pages":"1998-2016"},"PeriodicalIF":6.3,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10918779","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143706792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Toward Building a Digital Twin for Network Operations and Management","authors":"Daniel González-Sánchez;Luis Bellido;Ignacio D. Martinez-Casanueva;David Martínez-García;David Fernández;Diego R. Lopez","doi":"10.1109/OJCOMS.2025.3549873","DOIUrl":"https://doi.org/10.1109/OJCOMS.2025.3549873","url":null,"abstract":"With the growth of telecommunication networks driven by resource-intensive applications, the expansion of IoT, the rise of data centers, and the advancements of 5G and future 6G networks, monitoring and maintenance are becoming increasingly important for network operators. In this sense, the Network Digital Twin (NDT) is emerging as a promising technology to mirror a network’s whole operational and management lifecycle to optimize its performance without compromising the real network. In this work, we propose an NDT solution supported by a new data integration methodology and a prototypical architecture for translating information from the network management domain into a knowledge-based interoperable model. Our case study shows how this NDT can be used to reveal the capabilities of real networks in terms of configuration and operational status, providing benefits for network control and management to facilitate the application of closed-loop network automation systems.","PeriodicalId":33803,"journal":{"name":"IEEE Open Journal of the Communications Society","volume":"6 ","pages":"2583-2598"},"PeriodicalIF":6.3,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10919072","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enabling Reliable Latency in Wi-Fi 8 Through Multi-AP Joint Scheduling","authors":"David Nunez;Pasquale Imputato;Stefano Avallone;Malcolm Smith;Boris Bellalta","doi":"10.1109/OJCOMS.2025.3549586","DOIUrl":"https://doi.org/10.1109/OJCOMS.2025.3549586","url":null,"abstract":"The rapid evolution of wireless communication systems, driven by increasing demands for high throughput, low latency, and reliable connectivity, presents significant challenges for traditional Wi-Fi networks. To address these limitations, the forthcoming IEEE 802.11bn amendment will likely introduce Multi-Access Point Coordination (MAPC) as a pivotal feature to enhance performance in dense network deployments. This paper proposes a comprehensive MAPC framework leveraging Coordinated Spatial Reuse (C-SR) to enable multi-AP scheduling and optimize resource allocation. First, we present a C-SR mechanism for grouping compatible devices and optimizing transmission power, facilitating simultaneous transmissions to boost network capacity. Then, we propose and evaluate three multi-AP schedulers targeting different goals: maximizing the number of packets delivered per transmission, always scheduling the oldest packet in the network, and a third solution aiming to combine the strengths of both. Results exhibit a superior performance of the proposed MAPC algorithms compared to Enhanced Distributed Channel Access (EDCA), achieving a reduction in the 99th percentile delay in four-AP scenarios, of up to 92% and 48% for best effort and constant bitrate video traffic, respectively.","PeriodicalId":33803,"journal":{"name":"IEEE Open Journal of the Communications Society","volume":"6 ","pages":"2090-2101"},"PeriodicalIF":6.3,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10918755","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143769421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimizing Energy Consumption for vRAN Placement in O-RAN Systems With Flexible Transport Networks","authors":"William T. Pires-JR;Gabriel M. Almeida;Sand L. Corrêa;Cristiano B. Both;Leizer L. Pinto;Kleber V. Cardoso","doi":"10.1109/OJCOMS.2025.3568689","DOIUrl":"https://doi.org/10.1109/OJCOMS.2025.3568689","url":null,"abstract":"Virtualized RAN (vRAN) matches O-RAN Alliance specifications while transitioning towards virtualized functions on general-purpose computing platforms. However, the energy consumption of these systems remains a major concern. Although this issue has been addressed in the literature, previous works oversimplify routing decisions, overlook the benefits of flexible split choices, or neglect the energy consumption of the transport network. Additionally, most studies employing optimal solutions exhibit very limited scalability due to their high computational time. In this work, we present a comprehensive and efficient Mixed Integer Linear Programming model to minimize the energy consumption of O-RAN systems, addressing the limitations of current approaches. We also design and implement a synthetic data generator to evaluate our model across various network usage profiles, topologies, and reasonable-size networks. We achieved valuable insights and promising results in our evaluation. For example, our results show that when devices require high throughput, the transport network incurs significant energy costs and reduces the centralization rate. We also observed that hierarchical RAN topologies can achieve greater energy efficiency than ring topologies, with our approach enabling up to 15% more centralization while saving around 28% of energy and consuming at least one order of magnitude less time than other strategies.","PeriodicalId":33803,"journal":{"name":"IEEE Open Journal of the Communications Society","volume":"6 ","pages":"4279-4294"},"PeriodicalIF":6.3,"publicationDate":"2025-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10994470","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144108317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Secret Key Generation Over Multi-Mode Fiber: Channel Measurements, Key Rate Analysis, and System Implementation","authors":"Pin-Hsun Lin;Paul Nowitzki;Eduard A. Jorswieck;Dennis Pohle;Juergen Czarske","doi":"10.1109/OJCOMS.2025.3549090","DOIUrl":"https://doi.org/10.1109/OJCOMS.2025.3549090","url":null,"abstract":"Secret keys are critical for many security mechanisms including secure data transmission. An efficient secret key generation and sharing scheme enhances the secure transmission rate. Meanwhile, secret keys are scarce resources for classical encryption schemes like the Rivest-Shamir-Adleman (RSA) cryptosystem and its post-quantum security counterparts in quantum applications. Therefore, harnessing every available random source for secret key extraction is crucial for maximizing the key rate across a range of potential applications. In this paper, we investigate the achievable rate of the secret key generation (SKG)-channel-model based on an actual measured multi-mode fiber (MMF) channel, where there is an additional public discussion channel between the legitimate parties, which the adversary can perfectly overhear. In particular, we first measure the MMF transmission matrix using digital holography, then design power allocation schemes among the modes. Our schemes can achieve a positive secret key rate at 51.3 bit per channel use, under a mode-dependent loss of 1 dB and a transmit power of 20 dBm. In addition, we implement an SKG system via MMF by explicitly designing the wiretap codes and discussion protocol. More specifically, we design the hash function and point-to-point channel encoder/decoder for each mode in the MMF based on Hayashi’s wiretap coding. The designed system can achieve a secret key rate-leakage trade-off at <inline-formula> <tex-math>$R_{SK} = 23.6$ </tex-math></inline-formula> bits per channel use and an average leakage rate at <inline-formula> <tex-math>$ 4.22 cdot 10^{-3}$ </tex-math></inline-formula> bits per channel use per mode, at the transmit power <inline-formula> <tex-math>$textsf {P}_{T}$ </tex-math></inline-formula> at 50 dBm and mode-dependent loss at 1 dB with the error probability constraint at Bob as <inline-formula> <tex-math>$10^{-5}$ </tex-math></inline-formula>. This demonstrates the feasibility and effectiveness of generating SKG via MMF, aligning with the common approaches of post-quantum cryptography and quantum key distribution in addressing the challenges posed by emerging quantum computers.","PeriodicalId":33803,"journal":{"name":"IEEE Open Journal of the Communications Society","volume":"6 ","pages":"1-1"},"PeriodicalIF":6.3,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10916747","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143850888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Opportunistic Scheduling With Beam Focusing in Distributed RIS-Aided MU-MIMO Systems","authors":"Youssef Hussein;Mohamad Assaad;Thierry Clessienne","doi":"10.1109/OJCOMS.2025.3567807","DOIUrl":"https://doi.org/10.1109/OJCOMS.2025.3567807","url":null,"abstract":"This paper introduces a novel cooperative framework for distributed Reconfigurable Intelligent Surfaces (RISs) in MU-MIMO systems, aimed at enhancing adaptability and performance. Multiple RISs are strategically deployed to ensure Line-of-Sight (LoS) connectivity with the Base Station (BS) and among each other, thereby improving coverage in traditionally weak zones. Each RIS can dynamically switch between acting as a main RIS (mRIS) to directly serve users or as an intermediate RIS (iRIS) to relay signals to another mRIS. A key contribution of this work is the optimization of mRIS phase shifts using a statistical RIS response function to enhance signal strength. Additionally, iRIS configurations utilize a beam focusing codebook for efficient signal transmission. An opportunistic scheduling scheme based on Lyapunov optimization adapts to user distribution and network conditions to optimize the use of the resulting spatial multiplexing gains, ensuring fairness and stability. Two scheduling policies are proposed: Slot-Based RIS Operational Mode Assignment (SB-ROMA) for high adaptability and Coherence-Time RIS Operational Mode Assignment (CT-ROMA) for reduced computational overhead. Analytical and simulation results validate the effectiveness of the proposed designs.","PeriodicalId":33803,"journal":{"name":"IEEE Open Journal of the Communications Society","volume":"6 ","pages":"4260-4278"},"PeriodicalIF":6.3,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10990181","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144090698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inter-AGV Scheduling and a Novel Multi-Agent Collaborative Protocol for Intra-AGV Resource Allocation in MEC-Enabled Multi-AGV Scenarios","authors":"Javier Palomares;Estela Carmona-Cejudo;Cristina Cervelló-Pastor;Estefanía Coronado;Hatim Chergui;Muhammad Shuaib Siddiqui","doi":"10.1109/OJCOMS.2025.3567585","DOIUrl":"https://doi.org/10.1109/OJCOMS.2025.3567585","url":null,"abstract":"In modern novel collaborative multi-Automated Guided Vehicle (AGV) systems, vehicles are responsible for executing both mission-critical process-related operations and purely computational tasks, such as collision avoidance. This work investigates the problem of joint inter-AGV task placement and intra-AGV computational resource allocation in MEC-enabled multi-AGV environments. To address this challenge, a two-step strategy is proposed to maximize the number of scheduled and completed tasks across multiple AGVs while ensuring fair and efficient resource use within each AGV. The problem of inter-AGV task placement is solved by dynamically applying a catalog of deep reinforcement learning (DRL) models for varying numbers of AGVs. Training time for these models is reduced threefold by using datasets from existing optimization solvers. Transfer learning further reduces training times by up to 51%. Second, a multi-agent deep reinforcement learning (MADRL)-based collaborative protocol for dynamic intra- AGV resource allocation (MACP-DRA) is proposed, allowing AGVs to adjust computational resources dynamically. It incorporates a minimum guaranteed share strategy to ensure fair resource distribution while optimizing performance under dynamic workloads. Compared to existing MADRL approaches, MACP-DRA enhances conflict resolution efficiency while maintaining low computational cost. Evaluation results demonstrate that the proposed inter-AGV scheduling strategy approaches optimal performance while achieving a superior trade-off between decision time and task completion rates. Compared to a multi-agent DRL baseline, the proposed MACP-DRA models reduced resource conflicts by 54.9%, task processing delays by 35.7%, and resource underutilization by 9.93%, while maintaining minimal computational and energy consumption overhead.","PeriodicalId":33803,"journal":{"name":"IEEE Open Journal of the Communications Society","volume":"6 ","pages":"4238-4259"},"PeriodicalIF":6.3,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10990154","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144090699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Near-Field Nulling Control Beamfocusing Optimization for Multi-User Interference Suppression","authors":"Yuanzhe Gong;Mohammadhossein Karimi;Tho Le-Ngoc","doi":"10.1109/OJCOMS.2025.3548457","DOIUrl":"https://doi.org/10.1109/OJCOMS.2025.3548457","url":null,"abstract":"This paper presents comprehensive full-wave simulation-based studies of near-field beam radiation patterns for large-scale arrays, accounting for realistic electromagnetic wave characteristics, heterogeneous element radiation patterns, and array element interactions. These simulations thoroughly investigate and illustrate the radiation behaviors of antenna arrays at different observation distances. To leverage the advantages offered by distance-dependent radiation patterns in the near-field, we consider two nulling control beamfocusing algorithms to effectively mitigate multi-user interference (MUI) in massive multiple-input multiple-output (mMIMO) systems by achieving considerable focusing gain differences between the desired and interference locations. Firstly, a linear constraint minimum variance (LCMV) scheme to effectively control radiation nulls in the Fresnel region is developed. By adjusting the array feeding magnitudes and phase shifters, an average gain difference of 29.2 dB between desired and undesired users can be achieved, with minimal gain degradation of 0.4 dB at the desired user compared to the maximum directivity beamfocusing scheme. Moreover, a constant-modulus beamfocusing scheme based on a perturbation-based nulling control beamfocusing algorithm employing particle swarm optimization is proposed. Using only phase shifters, an average gain difference of 26.1 dB between desired and undesired users can be achieved. Iterative full-wave simulations are conducted to investigate how the achievable beamfocusing gain difference varies with different desired and interference user locations. Finally, a deep neural network (DNN) is trained for MUI suppression based on the LCMV-generated beamfocusing vectors. The model achieves a phase error of less than 0.021 radians and a magnitude error of 0.17 dB in the predicted feeding weights. The resulting near-field beam patterns using the LCMV-based vector and the DNN-predicted vector show good agreement.","PeriodicalId":33803,"journal":{"name":"IEEE Open Journal of the Communications Society","volume":"6 ","pages":"1727-1746"},"PeriodicalIF":6.3,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10912511","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143645298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Secrecy Performance of a RIS-Assisted Wireless Network: A Comprehensive Analysis Under Outdated CSI","authors":"Tasneem Alshamaseen;Elmehdi Illi;Syed Waqas Haider Shah;Saud Althunibat;Marwa Qaraqe","doi":"10.1109/OJCOMS.2025.3547960","DOIUrl":"https://doi.org/10.1109/OJCOMS.2025.3547960","url":null,"abstract":"Reconfigurable intelligent surfaces have manifested notable merits in enhancing networks’ security from a physical layer perspective by leveraging smart genuine signal reflection using its reflective elements (REs) towards legitimate users. However, outdated channel state information (CSI) poses a major challenge to RIS’s physical layer security gains. This work explores the impact of varying degrees of outdated CSI on the secrecy performance of RIS-assisted wireless networks. More specifically, the system in consideration consists of a source communicating with a legitimate receiver via an RIS in the presence of a potential eavesdropper. To this end, the secrecy outage probability (SOP) metric is derived under the presence of outdated CSI (aging) at the RIS controller, considering four scenarios based on the availability of direct links between the transmitter and both receivers (i.e., the legitimate one and the eavesdropper). This provides a comprehensive evaluation of the system’s resilience to CSI aging. Additionally, numerical evaluations are provided to determine the minimum number of RIS REs required to achieve a target SOP. The obtained results demonstrate that the adopted system can achieve an acceptable SOP level even with 10% outdated CSI (i.e., <inline-formula> <tex-math>$rho = 0.9$ </tex-math></inline-formula>). This resilience indicates that the system can reduce channel estimation frequency to reconfigure the RIS, thus decreasing overall system overhead and complexity and improving energy efficiency. Moreover, increasing the number of REs can mitigate CSI aging effects where an SOP level of <inline-formula> <tex-math>$3 times 10^{-5}$ </tex-math></inline-formula> can be achieved with 140 REs at <inline-formula> <tex-math>$rho = 0.9$ </tex-math></inline-formula> in the absence of a transmitter-receiver direct link. Lastly, Monte Carlo simulations validate the analytical findings.","PeriodicalId":33803,"journal":{"name":"IEEE Open Journal of the Communications Society","volume":"6 ","pages":"1914-1930"},"PeriodicalIF":6.3,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10909700","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143676000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Visually Secure Deep Joint Source-Channel Coding With Chaotic Map Against Deep Known-Plaintext Attack","authors":"Yuyang Fu;Katsuya Suto","doi":"10.1109/OJCOMS.2025.3548079","DOIUrl":"https://doi.org/10.1109/OJCOMS.2025.3548079","url":null,"abstract":"In recent years, deep learning-based joint source-channel coding (DJSCC) has gained significant attention for its impressive performance in image transmission. Unlike traditional separate source-channel coding (SSCC) methods, DJSCC performs particularly well in low signal-to-noise ratio (SNR) and limited bandwidth environments. However, ensuring the security of private information during transmission remains a critical concern. A notable limitation of DJSCC is its incompatibility with traditional encryption methods used for secure communications, making it vulnerable to eavesdropping attacks. To address this issue, we propose integrating a chaotic map encryption method into the DJSCC framework for secure wireless image transmission. This approach leverages chaotic sequence to shuffle the position of the elements in latent space without altering the values of the latent tensor. This allows the encryption process to be designed independently of DJSCC, eliminating the need for re-training the end-to-end model. Our proposed method preserves DJSCC’s superior transmission characteristics, ensuring high-quality image reconstruction at the receiver, while effectively ensuring the security against deep learning-based known plaintext attacks (Deep KPA).","PeriodicalId":33803,"journal":{"name":"IEEE Open Journal of the Communications Society","volume":"6 ","pages":"1847-1858"},"PeriodicalIF":6.3,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10912450","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143676035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}