Data-driven Machine Learning has emerged as a promising approach for building accurate and robust statistical models from medical data, which is collected in huge volumes by modern healthcare systems. Existing medical data is not fully exploited by ML primarily because it sits in data silos and privacy concerns restrict access to this data. However, without access to sufficient data, ML will be prevented from reaching its full potential and, ultimately, from making the transition from research to clinical practice. This paper considers key factors contributing to this issue, explores how Federated Learning (FL) may provide a solution for the future of digital health and highlights the challenges and considerations that need to * Disclaimer: The opinions expressed herein are those of the authors and do not necessarily represent those of the institutions they are affiliated with, e.g. the U.S. Department of Health and Human Services or the National Institutes of Health. This is a pre-print version of https://www.nature.com/articles/s41746-020-00323-1 be addressed.

随着物联网，AI和ML/DL算法的出现，数据驱动的医疗应用已成为一种有前途的工具，用于从医学数据设计可靠且可扩展的诊断和预后模型。近年来，这引起了从学术界到工业的广泛关注。这无疑改善了医疗保健提供的质量。但是，由于这些基于AI的医疗应用程序在满足严格的安全性，隐私和服务标准（例如低延迟）方面的困难，因此仍然采用较差。此外，医疗数据通常是分散的和私人的，这使得在人群之间产生强大的结果具有挑战性。联邦学习（FL）的最新发展使得以分布式方式训练复杂的机器学习模型成为可能。因此，FL已成为一个积极的研究领域，尤其是以分散的方式处理网络边缘的医疗数据，以保护隐私和安全问题。为此，本次调查论文重点介绍了数据共享是重大负担的医疗应用中FL技术的当前和未来。它还审查并讨论了当前的研究趋势及其设计可靠和可扩展模型的结果。我们概述了FL将军的统计问题，设备挑战，安全性，隐私问题及其在医疗领域的潜力。此外，我们的研究还集中在医疗应用上，我们重点介绍了全球癌症的负担以及有效利用FL来开发计算机辅助诊断工具来解决这些诊断工具。我们希望这篇评论是一个检查站，以彻底的方式阐明现有的最新最新作品，并为该领域提供开放的问题和未来的研究指示。

通信技术和互联网的最新进展与人工智能（AI）启用了智能医疗保健。传统上，由于现代医疗保健网络的高性性和日益增长的数据隐私问题，AI技术需要集中式数据收集和处理，这可能在现实的医疗环境中可能是不可行的。作为一个新兴的分布式协作AI范例，通过协调多个客户（例如，医院）来执行AI培训而不共享原始数据，对智能医疗保健特别有吸引力。因此，我们对智能医疗保健的使用提供了全面的调查。首先，我们在智能医疗保健中展示了近期进程，动机和使用FL的要求。然后讨论了近期智能医疗保健的FL设计，从资源感知FL，安全和隐私感知到激励FL和个性化FL。随后，我们对关键医疗领域的FL新兴应用提供了最先进的综述，包括健康数据管理，远程健康监测，医学成像和Covid-19检测。分析了几个最近基于智能医疗保健项目，并突出了从调查中学到的关键经验教训。最后，我们讨论了智能医疗保健未来研究的有趣研究挑战和可能的指示。

联合学习（FL）是一个系统，中央聚合器协调多个客户解决机器学习问题的努力。此设置允许分散培训数据以保护隐私。本文的目的是提供针对医疗保健的FL系统的概述。 FL在此根据其框架，架构和应用程序进行评估。这里显示的是，FL通过中央聚合器服务器通过共享的全球深度学习（DL）模型解决了前面的问题。本文研究了最新的发展，并提供了来自FL研究的快速增长的启发，列出了未解决的问题。在FL的背景下，描述了几种隐私方法，包括安全的多方计算，同态加密，差异隐私和随机梯度下降。此外，还提供了对各种FL类的综述，例如水平和垂直FL以及联合转移学习。 FL在无线通信，服务建议，智能医学诊断系统和医疗保健方面有应用，本文将在本文中进行讨论。我们还对现有的FL挑战进行了彻底的审查，例如隐私保护，沟通成本，系统异质性和不可靠的模型上传，然后是未来的研究指示。

使用人工智能（AI）赋予无线网络中数据量的前所未有的数据量激增，为提供无处不在的数据驱动智能服务而开辟了新的视野。通过集中收集数据集和培训模型来实现传统的云彩中心学习（ML）基础的服务。然而，这种传统的训练技术包括两个挑战：（i）由于数据通信增加而导致的高通信和能源成本，（ii）通过允许不受信任的各方利用这些信息来威胁数据隐私。最近，鉴于这些限制，一种新兴的新兴技术，包括联合学习（FL），以使ML带到无线网络的边缘。通过以分布式方式培训全局模型，可以通过FL Server策划的全局模型来提取数据孤岛的好处。 FL利用分散的数据集和参与客户的计算资源，在不影响数据隐私的情况下开发广义ML模型。在本文中，我们介绍了对FL的基本面和能够实现技术的全面调查。此外，提出了一个广泛的研究，详细说明了无线网络中的流体的各种应用，并突出了他们的挑战和局限性。进一步探索了FL的疗效，其新兴的前瞻性超出了第五代（B5G）和第六代（6G）通信系统。本调查的目的是在关键的无线技术中概述了流动的技术，这些技术将作为建立对该主题的坚定了解的基础。最后，我们向未来的研究方向提供前进的道路。

Today's AI still faces two major challenges. One is that in most industries, data exists in the form of isolated islands. The other is the strengthening of data privacy and security. We propose a possible solution to these challenges: secure federated learning. Beyond the federated learning framework first proposed by Google in 2016, we introduce a comprehensive secure federated learning framework, which includes horizontal federated learning, vertical federated learning and federated transfer learning. We provide definitions, architectures and applications for the federated learning framework, and provide a comprehensive survey of existing works on this subject. In addition, we propose building data networks among organizations based on federated mechanisms as an effective solution to allow knowledge to be shared without compromising user privacy.

Federated Learning (FL) has emerged as a promising distributed learning paradigm with an added advantage of data privacy. With the growing interest in having collaboration among data owners, FL has gained significant attention of organizations. The idea of FL is to enable collaborating participants train machine learning (ML) models on decentralized data without breaching privacy. In simpler words, federated learning is the approach of ``bringing the model to the data, instead of bringing the data to the mode''. Federated learning, when applied to data which is partitioned vertically across participants, is able to build a complete ML model by combining local models trained only using the data with distinct features at the local sites. This architecture of FL is referred to as vertical federated learning (VFL), which differs from the conventional FL on horizontally partitioned data. As VFL is different from conventional FL, it comes with its own issues and challenges. In this paper, we present a structured literature review discussing the state-of-the-art approaches in VFL. Additionally, the literature review highlights the existing solutions to challenges in VFL and provides potential research directions in this domain.

联合学习（FL）和分裂学习（SL）是两种新兴的协作学习方法，可能会极大地促进物联网（IoT）中无处不在的智能。联合学习使机器学习（ML）模型在本地培训的模型使用私人数据汇总为全球模型。分裂学习使ML模型的不同部分可以在学习框架中对不同工人进行协作培训。联合学习和分裂学习，每个学习都有独特的优势和各自的局限性，可能会相互补充，在物联网中无处不在的智能。因此，联合学习和分裂学习的结合最近成为一个活跃的研究领域，引起了广泛的兴趣。在本文中，我们回顾了联合学习和拆分学习方面的最新发展，并介绍了有关最先进技术的调查，该技术用于将这两种学习方法组合在基于边缘计算的物联网环境中。我们还确定了一些开放问题，并讨论了该领域未来研究的可能方向，希望进一步引起研究界对这个新兴领域的兴趣。

联邦学习一直是一个热门的研究主题，使不同组织的机器学习模型的协作培训在隐私限制下。随着研究人员试图支持更多具有不同隐私方法的机器学习模型，需要开发系统和基础设施，以便于开发各种联合学习算法。类似于Pytorch和Tensorflow等深度学习系统，可以增强深度学习的发展，联邦学习系统（FLSS）是等效的，并且面临各个方面的面临挑战，如有效性，效率和隐私。在本调查中，我们对联合学习系统进行了全面的审查。为实现流畅的流动和引导未来的研究，我们介绍了联合学习系统的定义并分析了系统组件。此外，我们根据六种不同方面提供联合学习系统的全面分类，包括数据分布，机器学习模型，隐私机制，通信架构，联合集市和联合的动机。分类可以帮助设计联合学习系统，如我们的案例研究所示。通过系统地总结现有联合学习系统，我们展示了设计因素，案例研究和未来的研究机会。

推荐系统已广泛应用于不同的应用领域，包括能量保存，电子商务，医疗保健，社交媒体等。此类应用需要分析和挖掘大量各种类型的用户数据，包括人口统计，偏好，社会互动等，以便开发准确和精确的推荐系统。此类数据集通常包括敏感信息，但大多数推荐系统专注于模型的准确性和忽略与安全性和用户隐私相关的问题。尽管使用不同的风险减少技术克服这些问题，但它们都没有完全成功，确保了对用户的私人信息的密码安全和保护。为了弥合这一差距，区块链技术作为推动推荐系统中的安全和隐私保存的有希望的策略，不仅是因为其安全性和隐私性突出特征，而且由于其恢复力，适应性，容错和信任特性。本文介绍了涵盖挑战，开放问题和解决方案的基于区块链的推荐系统的整体综述。因此，引入了精心设计的分类，以描述安全和隐私挑战，概述现有框架并在使用区块链之前讨论其应用程序和利益，以指示未来的研究机会。

医疗AI通过支持基于证据的医学实践，个性化患者治疗，降低成本以及改善提供者和患者体验，推进医疗保健的巨大潜力。我们认为解锁此潜力需要一种系统的方法来衡量在大规模异构数据上的医疗AI模型的性能。为了满足这种需求，我们正在建立Medperf，这是一个开放的框架，用于在医疗领域的基准测试机器学习。 Medperf将使联合评估能够将模型安全地分配给不同的评估设施，从而赋予医疗组织在高效和人类监督过程中评估和验证AI模型的性能，同时优先考虑隐私。我们描述了当前的挑战医疗保健和AI社区面临，需要开放平台，Medperf的设计理念，其目前的实施状态和我们的路线图。我们呼吁研究人员和组织加入我们创建Medperf开放基准平台。

The advent of Federated Learning (FL) has ignited a new paradigm for parallel and confidential decentralized Machine Learning (ML) with the potential of utilizing the computational power of a vast number of IoT, mobile and edge devices without data leaving the respective device, ensuring privacy by design. Yet, in order to scale this new paradigm beyond small groups of already entrusted entities towards mass adoption, the Federated Learning Framework (FLF) has to become (i) truly decentralized and (ii) participants have to be incentivized. This is the first systematic literature review analyzing holistic FLFs in the domain of both, decentralized and incentivized federated learning. 422 publications were retrieved, by querying 12 major scientific databases. Finally, 40 articles remained after a systematic review and filtering process for in-depth examination. Although having massive potential to direct the future of a more distributed and secure AI, none of the analyzed FLF is production-ready. The approaches vary heavily in terms of use-cases, system design, solved issues and thoroughness. We are the first to provide a systematic approach to classify and quantify differences between FLF, exposing limitations of current works and derive future directions for research in this novel domain.

In recent years, mobile devices are equipped with increasingly advanced sensing and computing capabilities. Coupled with advancements in Deep Learning (DL), this opens up countless possibilities for meaningful applications, e.g., for medical purposes and in vehicular networks. Traditional cloudbased Machine Learning (ML) approaches require the data to be centralized in a cloud server or data center. However, this results in critical issues related to unacceptable latency and communication inefficiency. To this end, Mobile Edge Computing (MEC) has been proposed to bring intelligence closer to the edge, where data is produced. However, conventional enabling technologies for ML at mobile edge networks still require personal data to be shared with external parties, e.g., edge servers. Recently, in light of increasingly stringent data privacy legislations and growing privacy concerns, the concept of Federated Learning (FL) has been introduced. In FL, end devices use their local data to train an ML model required by the server. The end devices then send the model updates rather than raw data to the server for aggregation. FL can serve as an enabling technology in mobile edge networks since it enables the collaborative training of an ML model and also enables DL for mobile edge network optimization. However, in a large-scale and complex mobile edge network, heterogeneous devices with varying constraints are involved. This raises challenges of communication costs, resource allocation, and privacy and security in the implementation of FL at scale. In this survey, we begin with an introduction to the background and fundamentals of FL. Then, we highlight the aforementioned challenges of FL implementation and review existing solutions. Furthermore, we present the applications of FL for mobile edge network optimization. Finally, we discuss the important challenges and future research directions in FL.

随着各种公开的AI伦理原则的共识，差距仍然可以随时采用设计和开发负责任的AI系统。我们研究了来自澳大利亚国家科学研究机构（CSIRO）的研究人员和工程师的实践和经验，他们参与设计和开发AI系统的一系列目的。半结构化访谈用于检查参与者的做法如何与澳大利亚政府提出的一套高级AI伦理原则涉及并对齐。原则包括：隐私保护和安全，可靠性和安全性，透明度和解释性，公平性，竞争性，责任，人以人为本的价值观和人类，社会与环境福祉。研究了研究人员和工程师的见解以及在原则的实际应用中为它们提供的挑战。最后，提供了一系列组织响应，以支持实施高级AI道德原则。

To apply federated learning to drug discovery we developed a novel platform in the context of European Innovative Medicines Initiative (IMI) project MELLODDY (grant n{\deg}831472), which was comprised of 10 pharmaceutical companies, academic research labs, large industrial companies and startups. The MELLODDY platform was the first industry-scale platform to enable the creation of a global federated model for drug discovery without sharing the confidential data sets of the individual partners. The federated model was trained on the platform by aggregating the gradients of all contributing partners in a cryptographic, secure way following each training iteration. The platform was deployed on an Amazon Web Services (AWS) multi-account architecture running Kubernetes clusters in private subnets. Organisationally, the roles of the different partners were codified as different rights and permissions on the platform and administrated in a decentralized way. The MELLODDY platform generated new scientific discoveries which are described in a companion paper.

Explainable Artificial Intelligence (XAI) is transforming the field of Artificial Intelligence (AI) by enhancing the trust of end-users in machines. As the number of connected devices keeps on growing, the Internet of Things (IoT) market needs to be trustworthy for the end-users. However, existing literature still lacks a systematic and comprehensive survey work on the use of XAI for IoT. To bridge this lacking, in this paper, we address the XAI frameworks with a focus on their characteristics and support for IoT. We illustrate the widely-used XAI services for IoT applications, such as security enhancement, Internet of Medical Things (IoMT), Industrial IoT (IIoT), and Internet of City Things (IoCT). We also suggest the implementation choice of XAI models over IoT systems in these applications with appropriate examples and summarize the key inferences for future works. Moreover, we present the cutting-edge development in edge XAI structures and the support of sixth-generation (6G) communication services for IoT applications, along with key inferences. In a nutshell, this paper constitutes the first holistic compilation on the development of XAI-based frameworks tailored for the demands of future IoT use cases.

为了满足下一代无线通信网络的极其异构要求，研究界越来越依赖于使用机器学习解决方案进行实时决策和无线电资源管理。传统的机器学习采用完全集中的架构，其中整个培训数据在一个节点上收集，即云服务器，显着提高了通信开销，并提高了严重的隐私问题。迄今为止，最近提出了作为联合学习（FL）称为联合学习的分布式机器学习范式。在FL中，每个参与边缘设备通过使用自己的培训数据列举其本地模型。然后，通过无线信道，本地训练模型的权重或参数被发送到中央ps，聚合它们并更新全局模型。一方面，FL对优化无线通信网络的资源起着重要作用，另一方面，无线通信对于FL至关重要。因此，FL和无线通信之间存在“双向”关系。虽然FL是一个新兴的概念，但许多出版物已经在FL的领域发表了发布及其对下一代无线网络的应用。尽管如此，我们注意到没有任何作品突出了FL和无线通信之间的双向关系。因此，本调查纸的目的是通过提供关于FL和无线通信之间的相互依存性的及时和全面的讨论来弥合文学中的这种差距。

联邦学习的出现在维持隐私的同时，促进了机器学习模型之间的大规模数据交换。尽管历史悠久，但联邦学习正在迅速发展，以使更广泛的使用更加实用。该领域中最重要的进步之一是将转移学习纳入联邦学习，这克服了主要联合学习的基本限制，尤其是在安全方面。本章从安全的角度进行了有关联合和转移学习的交集的全面调查。这项研究的主要目标是发现可能损害使用联合和转移学习的系统的隐私和性能的潜在脆弱性和防御机制。

网络威胁情报（CTI）共享是减少攻击者和捍卫者之间信息不对称的重要活动。但是，由于数据共享和机密性之间的紧张关系，这项活动带来了挑战，这导致信息保留通常会导致自由骑士问题。因此，共享的信息仅代表冰山一角。当前的文献假设访问包含所有信息的集中数据库，但是由于上述张力，这并不总是可行的。这会导致不平衡或不完整的数据集，需要使用技术扩展它们。我们展示了这些技术如何导致结果和误导性能期望。我们提出了一个新颖的框架，用于从分布式数据中提取有关事件，漏洞和妥协指标的分布式数据，并与恶意软件信息共享平台（MISP）一起证明其在几种实际情况下的使用。提出和讨论了CTI共享的政策影响。拟议的系统依赖于隐私增强技术和联合处理的有效组合。这使组织能够控制其CTI，并最大程度地减少暴露或泄漏的风险，同时为共享的好处，更准确和代表性的结果以及更有效的预测性和预防性防御能力。

Federated Learning is a distributed machine learning approach which enables model training on a large corpus of decentralized data. We have built a scalable production system for Federated Learning in the domain of mobile devices, based on TensorFlow. In this paper, we describe the resulting high-level design, sketch some of the challenges and their solutions, and touch upon the open problems and future directions.