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Maritime Communications: A Survey on Enabling Technologies, Opportunities, and Challenges
海上通信:关于启用技术、机遇和挑战的调查

Fahad S. Alqurashi , Student Member, IEEE, Abderrahmen Trichili , Senior Member, IEEE,
Fahad S. Alqurashi ,IEEE 学生会员,Abderrahmen Trichili ,IEEE 高级会员,
Nasir Saeed , Senior Member, IEEE, Boon S. Ooi , Senior Member, IEEE,
Nasir Saeed ,IEEE 高级会员,Boon S. Ooi ,IEEE 高级会员,
and Mohamed-Slim Alouini , Fellow, IEEE
以及 Mohamed-Slim Alouini ,IEEE 院士

Abstract 摘要

Water covers of the Earth's surface, where the steady increase in oceanic activities has promoted the need for reliable maritime communication technologies. The existing maritime communication systems involve terrestrial, aerial, and space networks. This article presents a holistic overview of the different forms of maritime communications and provides the latest advances in various marine technologies. This article first introduces the different techniques used for maritime communications over the radio frequency (RF) and optical bands. Then, we present the channel models for RF and optical bands, modulation and coding schemes, coverage and capacity, and radio resource management in maritime communications. After that, this article presents some emerging use cases of maritime networks, such as the Internet of Ships and the ship-to-underwater Internet of Things. Finally, we highlight a few exciting open challenges and identify a set of future research directions for maritime communication, including bringing broadband connectivity to the deep sea, using terahertz and visible light signals for on-board applications, and data-driven modeling for radio and optical marine propagation.
水覆盖了地球表面的百分之七十,海洋活动的持续增加促进了可靠海上通信技术的需求。现有的海上通信系统涉及陆地、空中和空间网络。本文全面介绍了不同形式的海上通信,并提供了各种海洋技术的最新进展。本文首先介绍了在无线电频率(RF)和光学波段上用于海上通信的不同技术。然后,我们介绍了 RF 和光学波段的信道模型、调制和编码方案、覆盖范围和容量,以及海上通信中的无线资源管理。之后,本文介绍了一些新兴的海上网络用例,如船舶互联网和船舶到水下物联网。 最后,我们强调了一些激动人心的开放性挑战,并确定了海洋通信未来研究方向的一组,包括将宽带连接带入深海,使用太赫兹和可见光信号进行机载应用,以及基于数据驱动的无线电和光学海洋传播建模。

Index Terms-Automatic identification system (AIS), free space optics (FSOs), Internet of Ships (IoS), maritime communication, satellite communication, very high frequency (VHF)/ultra-high frequency (UHF).
索引词-自动识别系统(AIS),自由空间光学(FSOs),船舶物联网(IoS),海洋通信,卫星通信,超高频(VHF)/超高频(UHF)。

I. INTRODUCTION I. 引言

T HE RECENT progress in terrestrial communication technologies has unlocked unprecedented data rates, enabling various new applications. With the upcoming sixth generation (6G) era, the capacity growth is expected to improve by 10 to 100 times [1], [2]. Despite the recent advancements in wireless communications on land, offering reliable, and high-speed data rates for marine communication remains challenging. Maritime communication is crucial due to the dramatic increase in oceanic activities, including naval shipping
最近陆地通信技术的进步已经解锁了前所未有的数据速率,使各种新应用成为可能。随着即将到来的第六代(6G)时代,预计容量增长将提高 10 到 100 倍[1],[2]。尽管近年来陆地无线通信取得了进展,为海洋通信提供可靠和高速数据速率仍然具有挑战性。由于海洋活动的急剧增加,包括海军航运,海上通信至关重要。
Manuscript received 13 September 2022; accepted 28 October 2022. Date of publication 4 November 2022; date of current version 6 February 2023. This work was supported in part by the Office of the Sponsored Research (OSR) at King Abdullah University of Science and Technology (KAUST) and in part by the Research and Sponsored Projects Office at UAE University (UAEU). (Corresponding author: Nasir Saeed.)
手稿收到日期为 2022 年 9 月 13 日;接受日期为 2022 年 10 月 28 日。出版日期为 2022 年 11 月 4 日;当前版本日期为 2023 年 2 月 6 日。本工作部分得到了沙特阿卜杜拉国王科技大学(KAUST)赞助研究办公室(OSR)和阿联酋大学(UAEU)研究与赞助项目办公室的支持。(通讯作者:纳西尔·赛义德。)
Fahad S. Alqurashi, Abderrahmen Trichili, Boon S. Ooi, and Mohamed-Slim Alouini are with the Computer, Electrical and Mathematical Sciences and Engineering Department, King Abdullah University of Science and Technology, Thuwal 21955, Makkah, Saudi Arabia (e-mail: fahad.alqurashi@kaust.edu.sa; abderrahmen.trichili@kaust.edu.sa; boon.ooi@kaust.edu.sa; slim.alouini @kaust.edu.sa).
Fahad S. Alqurashi,Abderrahmen Trichili,Boon S. Ooi 和 Mohamed-Slim Alouini 就职于沙特阿拉伯麦加 Thuwal 21955 的科技大学计算机、电气和数学科学与工程系(电子邮件:fahad.alqurashi@kaust.edu.sa;abderrahmen.trichili@kaust.edu.sa;boon.ooi@kaust.edu.sa;slim.alouini@kaust.edu.sa)。
Nasir Saeed is with the Department of Electrical and Communications Engineering, United Arab Emirates University, Al Ain, UAE (e-mail: mr.nasir.saeed @ieee.org).
Nasir Saeed 就职于阿联酋艾因的阿拉伯联合酋长国大学电气与通信工程系(电子邮件:mr.nasir.saeed@ieee.org)。
Digital Object Identifier 10.1109/JIOT.2022.3219674 and logistics, offshore oil exploration, wind farming, fishing, and tourism, among others. Maritime communication is equally needed for Internet of Things (IoT) applications, such as environmental monitoring and climate change control. Nevertheless, fourth generation (4G), and fifth generation (5G) are limited in maritime environments as base stations cannot be installed far offshore and in oceans, restricting their use to onshore scenarios only. For these reasons, satellites are a crucial pillar in maritime communications. Satellites are essential in providing connectivity in unconnected oceans at the expense of high proprietary terminal and operation costs, in addition to the limited available bandwidth [3], [4]. Recently, aerial wireless solutions, such as unmanned aerial vehicles (UAVs) and helikites are being introduced to maritime communication applications [5], [6]. Presently, most of the technologies for ship-to-ship and ship-to-shore communication use medium frequency (MF), high frequency (HF), very HF (VHF), and ultrahigh-frequency (UHF) bands. Although these bands can ensure relatively long propagation distances, they support only basic applications, such as half-duplex voice calling, text messaging, and the automatic identification system (AIS). Therefore, improving the quality of life on board when sailing for long distances requires more advanced communication systems beyond those offered by satellites or maritime radio. Radio maritime communication is subject to various impairments, including rain causing significant signal scattering and sea waves causing vibrations affecting antenna height and orientation. Water surface reflections also cause a number of rays to reflect and interfere with each other.
数字对象标识符 10.1109/JIOT.2022.3219674 和物流、海上石油勘探、风力发电、渔业和旅游等领域。海上通信同样在物联网(IoT)应用中至关重要,如环境监测和气候变化控制。然而,第四代(4G)和第五代(5G)在海上环境中受限,因为基站无法远离海岸和海洋安装,仅限于陆地场景的使用。因此,卫星在海上通信中是至关重要的支柱。卫星在提供未连接海洋的连接方面至关重要,但需要高昂的专有终端和运营成本,以及有限的可用带宽。最近,空中无线解决方案,如无人机(UAVs)和氦风筝,正在引入到海上通信应用中。目前,大多数船舶间和船岸间通信技术使用中频(MF)、高频(HF)、超高频(VHF)和超高频(UHF)频段。 尽管这些频段可以确保相对较长的传播距离,但它们仅支持基本应用,如半双工语音通话、短信和自动识别系统(AIS)。因此,提高航行长距离时船上生活质量需要更先进的通信系统,而不是卫星或海事无线电提供的系统。海上无线电通信会受到各种干扰,包括雨水引发的信号散射以及海浪引发的振动影响天线高度和方向。水面反射也会导致多条射线反射并相互干扰。
Besides the radio frequency (RF) band, optical wireless communication-based solutions in the infrared band, known as free space optics (FSOs), also provide connectivity for maritime networks. Due to the collimated nature of laser beams, optical-based maritime communication systems are not affected by water surface reflections. However, FSO signals are affected by sea waves and weather conditions. Sea waves lead to pointing errors between FSO terminals, while weather conditions such as fog create scatterings of optical signals. Turbulence caused by the random variations of the refractive index of the atmospheric channel is also a major concern for FSO links causing scintillation and random light beam movements at the detector plane. There are also hybrid solutions proposed for maritime communication that install FSO on top of the RF infrastructure, which aim to provide more robust communication to FSO and RF propagation effects
除了无线电频段外,基于红外波段的光无线通信解决方案,即自由空间光学(FSOs),也为海上网络提供连接。由于激光束的准直特性,基于光学的海上通信系统不受水面反射的影响。然而,FSO 信号受海浪和天气条件的影响。海浪导致 FSO 终端之间的指向误差,而雾等天气条件会导致光信号的散射。由大气通道折射率的随机变化引起的湍流也是 FSO 链路的主要问题,导致闪烁和探测器平面上的随机光束移动。还有为海上通信提出的混合解决方案,将 FSO 安装在射频基础设施之上,旨在为 FSO 和射频传播效果提供更强大的通信
TABLE I 表格 I
SUMmary of RELATED SURVEYS
相关调查总结
Ref. Year Area of focus 关注领域
2014
Presents video transmission scheduling in maritime
展示海上视频传输调度
wideband communication networks.
宽带通信网络。
2019
Surveys advancements in autonomous maritime
调查自主海上航行的进展
systems with an overview of current and future
系统概述目前和未来的情况
communication technologies.
通信技术。
2019
Provides an overview of existing maritime com-
提供现有海洋通信系统的概述
munication systems and introduces LTE-maritime
并介绍了韩国进行的 LTE-海洋网络项目
network, a project being conducted in South Korea,
一个在韩国进行的项目
aiming to provide 100 km marine coverage.
旨在提供 100 公里的海洋覆盖范围。
2019
Presents the pros and cons of existing maritime
展示现有海事通信技术的优缺点
communication technologies and proposes a mar-
并提出了一种海事
itime giant cellular network architecture (Magic-
巨型蜂窝网络架构(Magic-
Net).
2021
Provides an overview of the key elements and main
提供了 IoS 范式的关键要素和主要特征的概述。
characteristics of the IoS paradigm.
讨论了混合卫星-陆地海上网络。
2021
Discusses hybrid satellite-terrestrial maritime net-
works.
2018
Surveys different RF channel models for maritime
调查不同的海事射频信道模型
communications. 用于通信。
while having higher data rates. Various models have been proposed in the literature for RF and optical wave propagation through oceanic environments.
同时具有更高的数据速率。文献中提出了各种模型,用于射频和光波在海洋环境中的传播。
In recent years, there has been a growing interest in developing maritime communication networks (MCNs), and multiple surveys related to this topic have been published [7], [8], [9], [10], [11], [12], [13], [14]. These articles covered various aspects of maritime communication, such as the different network architectures, RF channel models, communication and networking of autonomous marine systems, and the IoT in maritime environments. For instance, a comprehensive survey on video transmission scheduling for wideband maritime communication is presented in [7]. Then, Zolich et al. [8] reviewed the major advancements in autonomous maritime systems and applications and also provided an overview of maritime communication and networking technologies. Furthermore, Jo and Shim [9] discussed the progress on a long-term evolution maritime (LTE-maritime) Korean project aiming to provide high data rates in orders of with coverage. Guan et al. [10] briefly reviewed current maritime communication and networking projects and introduced the key technologies and applications of a novel maritime giant cellular network (Magicnet) architecture based on seaborne floating towers acting as base stations to provide wide coverage. Aslam et al. [11] provided a comprehensive survey on the applications and challenges of maritime IoT technologies, also known as the Internet of Ships (IoS). Maritime communications and IoTs enabled by hybrid satellite-territorial networks were surveyed in [12]. Moreover, there are also a few surveys on maritime communications focusing on RF channel models [13], [14]. A summary of the area of focus of related surveys is given in Table I.
近年来,人们对发展海上通信网络(MCNs)表现出了越来越浓厚的兴趣,并且已经发表了多篇与此主题相关的调查报告[7],[8],[9],[10],[11],[12],[13],[14]。这些文章涵盖了海上通信的各个方面,比如不同的网络架构、无线电频道模型、自主海洋系统的通信和网络以及海上物联网。例如,文献[7]中介绍了用于宽带海上通信的视频传输调度的全面调查。此外,Zolich 等人[8]回顾了自主海洋系统和应用的重大进展,并概述了海上通信和网络技术。此外,Jo 和 Shim[9]讨论了长期演进海上(LTE-maritime)韩国项目关于提供 覆盖下的高数据速率的进展。Guan 等。 [10] 简要审查了当前的海上通信和网络项目,并介绍了基于海上浮动塔作为基站提供广泛覆盖的新型海事巨型蜂窝网络(Magicnet)架构的关键技术和应用。Aslam 等人[11] 对海事物联网技术的应用和挑战进行了全面调查,也被称为船舶互联网(IoS)。在[12]中对通过混合卫星-地面网络实现的海事通信和物联网进行了调查。此外,还有一些关于海事通信侧重于射频信道模型的调查[13],[14] 。相关调查重点领域的摘要如表 I 所示。

B. Contributions B. 贡献

Motivated by the emerging research in maritime communication, this survey presents a holistic vision of marine communication and related technologies. We note that none of the previously presented references performs a complete survey of various aspects of maritime communication. Due to the prominent role of communication in marine life and industry, it is essential to study the different building blocks of maritime communication and the related emerging technologies. This article covers the latest advances in technologies connecting ships, ships, and shore, and those sailing on-board far from shores. We discuss the building blocks of maritime communication, including radio resource management, coverage and capacity, and modulation and coding schemes. We additionally present a handful of emerging applications of maritime IoT. We particularly highlight the emerging progress on the maritime IoT. Although underwater communication is out of the scope of the present survey, we cover the relationship between reliable maritime communication and IoUT. A few open issues related to maritime communication are highlighted. Moreover, future research directions are discussed, including using visible light communication (VLC) and terahertz (THz) band for on-board communication and intermedium communication. Harnessing and data-driven modeling for future maritime channel modeling.
受海上通信新兴研究的启发,本调查呈现了海洋通信及相关技术的整体愿景。我们注意到之前提到的参考资料中没有一篇对海上通信各个方面进行完整调查。由于通信在海洋生活和工业中的重要作用,研究海上通信的不同构建模块和相关新兴技术至关重要。本文涵盖了连接船舶、船舶和岸边以及远离海岸的船舶的最新技术进展。我们讨论了海上通信的构建模块,包括无线资源管理、覆盖范围和容量,以及调制和编码方案。我们还介绍了一些海洋物联网的新兴应用。我们特别强调了海洋物联网的新兴进展。尽管水下通信不在本调查的范围内,但我们涵盖了可靠海上通信与IoUT之间的关系。我们还强调了一些与海上通信相关的未解决问题。 此外,讨论了未来的研究方向,包括利用可见光通信(VLC)和太赫兹(THz)频段进行车载通信和中介通信。利用数据驱动建模进行未来海上信道建模。
This article is organized as follows.
本文的组织如下。
  1. In Section II, we provide an overview of the various forms of maritime communication, namely, RF, optical wireless, and hybrid RF/optical solutions for ship-to-ship, ship-to-shore, satellite-ship, and on-board communication.
    在第二部分中,我们概述了各种形式的海上通信,即射频、光无线和混合射频/光解决方案,用于船舶间、船岸间、卫星船和车载通信。
  2. In Section III, we present the building blocks of maritime communication, covering the different propagation effects and channel models as well as modulation schemes and resource management.
    在第三部分,我们介绍了海上通信的基本构件,涵盖了不同的传播效应和信道模型,以及调制方案和资源管理。
  3. In Section IV-A, we introduce the IoS and maritime IoT paradigms, and follow it by a discussion on IoUT.
    在第四部分-A 中,我们介绍了 IoS 和海上物联网范式,并进行了 IoUT 讨论。
  4. In Section V, we discuss the challenges and open problems of maritime communication and identify future research directions.
    在第五部分,我们讨论了海上通信的挑战和未解决的问题,并确定了未来的研究方向。
We conclude this article with a few remarks on the need for reliable maritime communication in Section VI.
我们在第六部分结束这篇文章,并就可靠的海上通信的需求发表了一些看法。

II. OVERVIEW OF MARITIme COMmUNicATions
二、海上通信概述

Ancient Greek ships used speaking trumpets that intensified and directed the human voice as a means of marine communication in the 5th century BC. For many centuries, homing pigeons and small boats were used to convey physical messages from ship to shore and ship to ship. Semaphore flag signaling became the principal means of maritime communication by the 18th century. Each flag represents a letter or signal. Light torches in the nighttime replaced flags. Until today, semaphore signaling is still recognized as a means of maritime communication. The development of the electromagnetic theory by Maxwell and the telephone invention by Marconi in the 19th century allowed for the wireless transfer of messages in the form of Morse codes. Using Morse codes over radio waves is also known as wireless telegraphy and was ensured by radio operators transferring and receiving messages at rates up to 200 words per minute. In the early 1900s, multiple naval warships were equipped with radiotelephones or "voice radio." The idea is to convert sound waves into radio at the transmitter using amplitude modulation and then
古希腊船只使用扩音喇叭,增强和引导人声作为公元前 5 世纪海洋通信的手段。几个世纪以来,信鸽和小船被用来传递从船到岸和船到船的物理信息。18 世纪,信号旗信号成为海上通信的主要手段。每面旗帜代表一个字母或信号。夜间用火炬取代旗帜。直到今天,信号旗通信仍被认为是海上通信的手段。19 世纪,麦克斯韦发展了电磁理论,马可尼发明了电话,允许以莫尔斯电码形式无线传输信息。在无线电波上使用莫尔斯电码也被称为无线电报,由无线电操作员以每分钟 200 个字的速度传输和接收信息。20 世纪初,多艘海军战舰配备了无线电话或“语音无线电”。其思想是在发射机上将声波转换为无线电,使用幅度调制,然后
Fig. 1. Maritime communication use cases.
图 1. 海上通信使用案例。
convert the received radio signals back to sound waves at the destination using frequencies ranging from 2 to . In 1950, a VHF band was allocated for marine use. In 1962, the Commercial Telecommunications Satellite Act, a U.S. federal statute, was put into effect, allowing the launching of satellites into outer space for telecommunication purposes [15]. This act supported the introduction of satellites in maritime communication. Many international organizations, including the International Association of Lighthouse Authorities, the International Telecommunication Union (ITU), and the International Maritime Organization, recognize the benefits of seamless data exchange for maritime communities. Nowadays, various platforms, including satellites, high-altitude platforms (HAPs), and UAVs, operating in different frequency bands, such as RF and optical, are used to provide maritime coverage, as seen in Fig. 1. In the following, we will present the various forms of maritime communications and highlight the latest progress in each of these technologies.
在目的地使用从 2 到 范围的频率将接收到的无线电信号转换回声波。1950 年,为海上使用分配了一个 VHF 波段。1962 年,美国联邦法令《商业电信卫星法》生效,允许将卫星发射到外太空用于电信目的[15]。该法案支持了卫星在海上通信中的引入。许多国际组织,包括国际灯塔管理机构协会、国际电信联盟(ITU)和国际海事组织,都认识到对海上社区进行无缝数据交换的好处。如今,各种平台,包括卫星、高空平台(HAPs)和无人机(UAVs),在不同频段(如射频和光学)上运行,用于提供海上覆盖,如图 1 所示。接下来,我们将介绍各种形式的海上通信,并重点介绍这些技术中的最新进展。

A. RF Technologies for Maritime Communications
A. 用于海上通信的射频技术

Maritime radio provides commercial and recreational communications uses and allows search and rescue assistance to ships in distress. An ITU-designated band for marine radio in the VHF band is the VHF maritime mobile band from 156 and . Marine VHF transceivers are installed in all large vessels and most seagoing crafts where a particular VHF frequency, known as Channel , is designated as an international distress frequency. VHF terminal can be portable on a vessel or installed, allowing higher transmission power. Various VHF systems allow the following functionalities.
海事无线电提供商业和娱乐通信用途,并为处于困境的船只提供搜索和救援援助。ITU 指定的 VHF 频段中的海事无线电波段是来自 156 和 的 VHF 海事移动波段。海事 VHF 收发机安装在所有大型船只和大多数远洋船只上,其中一个特定的 VHF 频率,称为 Channel ,被指定为国际紧急频率。VHF 终端可以在船只上便携或安装,允许更高的传输功率。各种 VHF 系统允许以下功能。
  1. Voice Only: Which relies on the human voice for calling and communicating.
    仅语音:依靠人声进行呼叫和通信。
  2. Digital Selective Calling (DSC): In addition to the voice calling functionality, the DSC allows the user to communicate with another vessel using a unique identifier known as the maritime mobile service identity (MMSI). The MMSI information is transmitted digitally, and once detected by a receiver, the operator of the receiving vessel will be alerted of the incoming call. DSC allows the automatic transfer of the caller's coordinates when sending a distress call if connected to a global positioning system (GPS).
    数字选择呼叫(DSC):除了语音呼叫功能外,DSC 允许用户使用称为海事移动业务识别码(MMSI)的唯一标识符与另一艘船只进行通信。MMSI 信息以数字形式传输,一旦被接收器检测到,接收船只的操作员将收到来电警报。DSC 允许在发送紧急呼叫时自动传输呼叫者的坐标,如果连接到全球定位系统(GPS)。
  3. Automatic Identification System: AIS allows the digital transfer of MMSI together with other information, including the vessel specification, real-time coordinates, speed, and course, to avoid collisions. AISs also transfer application-specific messages (ASM) to ships in ports and underway for safe navigation and boost maritime security. AIS operates as a mesh network, extending the communication ranges, and enabling access to maritime traffic.
    自动识别系统:AIS 允许 MMSI 的数字传输以及其他信息,包括船舶规格、实时坐标、速度和航向,以避免碰撞。 AIS 还向港口和航行中的船舶传输特定于应用程序的消息(ASM),以确保安全导航并增强海上安全。 AIS 作为网状网络运行,扩展通信范围,并实现对海上交通的访问。
  4. Text Messaging: It is also possible to send and receive text messages between VHF terminals using the Radio Technical Commission for Maritime RTCM 12301.1 standard.
    文本消息:还可以使用海事无线电技术委员会的 RTC 12301.1 标准在 VHF 终端之间发送和接收文本消息。
According to the IMO, fitting an AIS transceiver is required in any cargo ship over 300 gross tonnage and all people transporting vessels. AIS transceivers use two ITU-designated VHF frequencies, known as marine band channel at 161.975 MHz and channel 88B at . Each AIS transmits and receives over two channels to avoid interference. AIS transmission is based on a Gaussian minimum shift keying (GMSK) frequency modulation (FM) at a data rate of . Each time frame lasts and is divided into 2250 time slots, where each slot is and contains 256 bits of data. AIS equipment uses self-organized time-division multiple access
根据IMO规定,任何货船总吨位超过300吨和所有运输船只都需要安装AIS发射接收机。AIS发射接收机使用两个ITU指定的VHF频率,分别是161.975 MHz的海事频段通道 的88B通道。每个AIS通过两个频道进行发送和接收,以避免干扰。AIS传输基于高斯最小频移键控(GMSK)频率调制(FM),数据速率为 。每个时间帧持续 ,分为2250个时间槽,每个槽为 ,包含256位数据。AIS设备使用自组织的时分多址接入。
(SOTDMA) datalink schemes that are responsible for data transmission by using a reference time derived from GPS signaling to synchronize numerous data streams sent from many AIS transponders on a single band channel [16]. VHF data exchange system (VDES) is another VHF-enabled technology, which is seen as the successor of AIS offering the same functions of an AIS with the ability to connect to satellite using the same antenna and providing a higher data rate. Radio maritime communication is also possible on the MF and HF bands. For example, navigation data (NAVDAT) is a safety and security maritime digital broadcasting system that operates in the bands. In the bands, radio waves are reflected at ionospheric layers, enabling longer propagation distances, reaching several hundreds of kilometers. NAVDAT is set to complement and possibly replace the direct printing navigational TEleX (NAVTEX) system operating in the MF band. NAVDAT also provides extended coverage compared to NAVTEX, enabling a maximum offshore range of 200 nautical miles . In the following, we discuss several wireless access technologies in the RF band for maritime communications.
(SOTDMA)数据链路方案负责使用从GPS信号中衍生的参考时间来同步单频频段上许多AIS发送的许多数据流。VHF数据交换系统(VDES)是另一种VHF启用技术,被视为AIS的后继者,具有与AIS相同的功能,并具有连接卫星的能力,使用相同天线并提供更高的数据速率。海上无线电通信也可以在MF和HF频段上进行。例如,导航数据(NAVDAT)是一个安全和安全的海上数字广播系统,其在 频段上运行。在 频段上,无线电波在电离层上反射,使传播距离更长,可达数百公里。NAVDAT旨在补充并可能取代在MF频段上运行的直接打印导航TEleX(NAVTEX)系统。NAVDAT还提供了比NAVTEX更广泛的覆盖范围,最大的离岸范围达到了200海里 。 在以下内容中,我们将讨论几种用于海事通信的 RF 频段的无线接入技术。
  1. Standard Wireless Access Technologies: Efforts have been made to provide high-speed data connectivity using standard wireless access techniques beyond voice calls, text messaging, and safety information exchange.
    标准无线接入技术:已经付出了努力,利用标准无线接入技术提供高速数据连接,超越了语音电话、短信和安全信息交换。
For instance, the TRI-media Telematic Oceanographic Network (TRITON) project was conducted to provide broadband Internet offshore using a wireless mesh network of ships connected to terrestrial networks via an onshore station. TRITON is based on the IEEE 802.16 [Worldwide Interoperability for Microwave Access (WiMAX)] [17]. Within the project Mare-Fi, aiming to provide WiFi broadband maritime communication for fishing ships and small vessels off-cost, a data rate at a distance of was demonstrated [18]. The MariComm, maritime broadband communication system was launched to target beyond transfer rates at a distance from the shore [19] in a multihop configuration. The multihop relay network was tested with four vessels acting as relays and reported a maximum data rate of with a total distance of using longterm evolution (LTE) for the shore-to-ship link and wireless LAN (WLAN) for ship-to-ship communication. BLUECOM+ is another project that was launched with the aim of providing broadband Internet connectivity at large distances. Simulation results revealed that BLUECOM+ could provide communication at from shore [6]. BLUECOM+ leverages the following to provide such connectivity.
例如,TRI-media Telematic Oceanographic Network(TRITON)项目旨在通过一种无线网状网络,将船舶连接到陆地网络,从而提供离岸宽带互联网。TRITON基于IEEE 802.16 [全球微波接入互操作性(WiMAX)]。在Mare-Fi项目中,旨在为渔船和小型船只提供WiFi宽带海上通信,演示了在距离 处的 数据速率。MariComm是一种海上宽带通信系统,旨在以多跳配置,在距离岸边 的地方实现超过 的传输速率。多跳中继网络通过四艘船作为中继进行测试,并报告了在总距离为 时的最大数据速率为 ,其中使用LTE进行岸船链路通信,使用无线局域网(WLAN)进行船船通信。BLUECOM+是另一个旨在提供大距离宽带互联网连接的项目。 模拟结果显示,BLUECOM+ 可以在离岸 提供 通信 [6]。BLUECOM+ 利用以下内容提供这种连接性。
  1. Helikites, a combination of kites carrying radio relays even at extreme conditions (of windspeed of ) without being severely affected by sea conditions. Helikites can be either tethered on land or sea platforms.
    Helikites,一种风筝组合,即使在极端条件下(风速为 ),也能携带无线中继器而不受海况严重影响。Helikites 可以被系在陆地或海上平台上。
  2. Using the unused TV channels in the VHF and UHF bands for long-range Line-of-Sight (LoS) transmission.
    利用 VHF 和 UHF 频段中未使用的电视信道进行远程视距(LoS)传输。
  3. Multihop relaying for radio range extension of standard wireless communication, such as universal mobile telecommunications system (UMTS) and LTE.
    用于标准无线通信的无线电覆盖范围扩展的多跳中继,例如通用移动通信系统(UMTS)和 LTE。
The BLUECOM + trials deployment reported single-hop and two-hop land-sea communications. The air-air links use IEEE at 500 and , while air-sea links are based on UMTS or LTE. The two-hop testing involved two helikites tethered at altitude from two vessels [20].
BLUECOM + 试验部署报告了单跳和双跳陆海通信。空空链路使用 IEEE 在 500 和 ,而空海链路基于 UMTS 或 LTE。双跳测试涉及两个在两艘船上从 高度系留的风筝[20]。
LTE-maritime is another exciting project aiming to provide broadband connectivity at sea. Reports from the test-bed implementation of the LTE-maritime showed communication at a shore-to-ship distance of up to using base stations located at high altitude regions on land [9].
LTE-海事是另一个旨在在海上提供宽带连接的激动人心的项目。来自 LTE-海事测试床实施的报告显示了在陆地高海拔地区的基站上,岸船距离高达 的通信[9]。
  1. Satellites-Based Maritime Communication System: In addition to VDES, maritime communication systems primarily use satellites to provide a wider coverage than standard techniques that utilize microwave frequency bands in the band (see Fig. 2 for different satellite frequency bands). Among various satellite constellations, some popular ones are Inmarsat, Iridium, and Thuraya. Inmarsat relies on a 14 geostationary Earth orbit (GEO) satellite constellation operating in the L-band to provide near-global connectivity with relatively high data rates reaching up to . Tapping on band satellites on a low-Earth orbit (LEO), the Iridium constellation provides voice and messaging global connectivity, including polar regions. With coverage in more than 160 countries, Thuraya provides voice and data coverage. Thuraya operates using two GEO satellites in the L-band. Given that a single GEO satellite can provide a coverage of more than , Thuraya achieves beyond global coverage. The data rates of Thuraya using the ThurayaIP device are limited to .
    基于卫星的海上通信系统:除了VDES外,海上通信系统主要利用卫星提供比传统微波频带更广覆盖范围的通信。不同的卫星频段可见图2。在各种卫星星座中,一些流行的包括Inmarsat、Iridium和Thuraya。Inmarsat依赖于14颗地球同步轨道(GEO)卫星星座,在L波段提供接近全球覆盖,数据速率高达 。Iridium星座利用低地球轨道(LEO)上的L波段卫星,提供语音和消息全球覆盖,包括极地地区。Thuraya在160多个国家提供语音和数据覆盖。Thuraya使用L波段的两颗GEO卫星运行。考虑到单颗GEO卫星可提供覆盖超过 ,Thuraya实现了超越 的全球覆盖。ThurayaIP设备的数据速率受限于
There are also many very small aperture terminal (VSAT)based solutions that can offer nearly global voice and Internet coverage using LEO and GEO satellites [21], [22], [23]. Some VSAT service providers offer products with on-board data rates up to a few tens of Mbps.
还有许多基于非常小孔径终端(VSAT)的解决方案,可以利用低轨和地球同步卫星[21],[22],[23]提供几乎全球范围的语音和互联网覆盖。一些 VSAT 服务提供商提供的产品的数据速率高达几十兆每秒。
A summary of terrestrial and space-based RF maritime communication systems and the various projects aiming to provide maritime broadband coverage is given in Table II.
给出了陆地和空间射频海上通信系统的总结以及旨在提供海上宽带覆盖的各种项目的表 II。
  1. Aerial Networks for Maritime Communication: Aerial networks involve the use of UAVs, flying up to a few hundred meters above the sea surface and HAPs flying at the stratosphere, at least from the ground. Recent use of UAVs improves search and rescue missions by providing quick on-demand network deployment after disasters and also supporting mobility [5]. In maritime networks, UAVs can relay the information sent from a ground station to mobile vessels beyond the LoS limit or when an LoS path is unavailable. Moreover, UAVs can also help retrieve information from IoT devices located in the oceans and relay information to/ from unmanned surface vehicles (USVs). The main restriction of using UAVs is the limited flying time restricted by the carried load and the battery or fuel cell [24]. Using a tethered UAV connected by an electrical cable connected to a power source can help relieve such limitations. Recent studies have shown the feasibility of using tethered UAVs fixed on buoys [25]. Tethered UAVs can hover in a certain place tens of meters above the seawater with limited coverage and mobility. In addition to the power cable, tethered UAVs can be connected with optical fibers to enable high transmission rates. Due to their higher flying altitude compared to UAVs, HAPS flying at about from sea level
    海上通信的空中网络:空中网络涉及使用无人机,飞行高度可达海面上方几百米,以及高空平台飞行在平流层,至少距离地面 。最近使用无人机改善了搜索和救援任务,提供了灾难后快速的按需网络部署,并支持移动性[5]。在海上网络中,无人机可以中继从地面站发送的信息到超出视距限制的移动船只,或者在视距路径不可用时。此外,无人机还可以帮助检索位于海洋中的物联网设备的信息,并将信息中继到/从无人表面船只(USVs)。使用无人机的主要限制是受携带负载和电池或燃料电池限制的有限飞行时间[24]。使用通过电缆连接到电源的系留无人机可以帮助缓解这些限制。最近的研究表明了使用固定在浮标上的系留无人机的可行性[25]。系留无人机可以在海水上方数十米的某个地方悬停,具有有限的覆盖范围和移动性。 除了电源电缆外,系留式无人机还可以通过光纤连接,实现高传输速率。由于高空飞行高度比无人机更高,高空平台系统飞行高度约为海平面
Fig. 2. Electromagnetic spectrum in frequency and wavelength. ELF: extremely low frequency; VLF: very low frequency; LF: low frequency; MF: middle frequency; HF: High frequency; VHF: very high frequency; UHF: ultra high frequency: SHF: super high frequency; EHF: extremely high frequency; IR: infrared; and UV: ultraviolet. Frequency bands in the region between 1 and are denoted by letters by IEEE.
图 2. 频率和波长中的电磁谱。 ELF:极低频; VLF:超低频; LF:低频; MF:中频; HF:高频; VHF:超高频; UHF:超高频; SHF:超高频; EHF:极高频; IR:红外线; UV:紫外线。 IEEE 将 1 和 之间的频段用字母表示。
TABLE II 表 II
SUMmARY OF RF-BASED MARITIME COMMUNICATION SYSTEMS AND PROJECTS
基于射频的海上通信系统和项目总结
System Technology and Band 技术和频段 Coverage Max Data Rates 最大数据速率 Use Cases
DSC VHF, Maritime band VHF,海事波段 Maritime voice calling 海事语音呼叫
AIS VHF, Maritime band VHF,海事波段 Track and monitor vessels movements
跟踪和监视船只运动
NAVDAT
MF,
Broadcasting of security and safety informa-
广播安全和安全信息
tion from shore to ships
从岸到船的传输
VDES VHF 300 kbits
Establishing digital two-way communication
建立数字双向通信
between ships, satellite, and shore
船舶、卫星和岸之间
TRITON IEEE
shore-to-ship:
从岸到船:
ship-to-ship:
船到船:
Providing offshore broadband internet access
提供离岸宽带互联网接入
Mare-Fi IEEE Offshore WiFi connectivity
远程海上 WiFi 连接
MariComm
LTE/WLAN
Providing broadband internet to ships
为船舶提供宽带互联网
BLUECOM+
Air-Air: IEEE ,
空对空:IEEE
500/700 MHz
Air-Surface: LTE,
空地:LTE,
Providing broadband internet access
提供宽带互联网接入
LTE-maritime
LTE,
Uplink:
Downlink:
Ship-to-shore communication
船到岸通信
Inmarsat
GEO satellites, 地球同步卫星
Uplink:
Downlink:
Global, except polar regions
全球,除极地地区
Mobile and data services
移动和数据服务
Iridium LEO satellites, Ku band
LEO 卫星,Ku 频段
Global, except polar regions
全球,极地地区除外
Providing on-ship voice calling and internet
提供船上语音通话和互联网
access
Thuraya GEO satellites, band
GEO 卫星, 频段
161 countries 161 个国家
Providing on-ship voice calling and internet
提供船上语音通话和互联网
access
VSAT
LEO and GEO satellites,
低地球轨道(LEO)和地球静止轨道(GEO)卫星
and bands
和频段
Global, except polar regions
全球,极地地区除外
Providing on-ship voice calling and internet
提供船上语音通话和互联网
access
offer an extended coverage radius that could reach hundreds of kilometers [26]. The autonomy of HAPS can be as long as several months and, with fewer load weight restrictions, can carry large antennas [27]. A recent demonstration by Airbus and NTT DOCOMO, INC. Using their solar-powered Zephyr HAPS aiming to extend connectivity in the air and sea has reported connectivity in a range of up to [28]. The HAPS-enabled connectivity to mobile terminals could allow users to use their mobile devices without needing a dedicated antenna.
提供了可覆盖数百公里的扩展覆盖范围 [26]。 HAPS 的自主性可长达数月,并且在更轻的负载限制下,可以携带大型天线 [27]。空中客车和 NTT DOCOMO, INC 最近进行的一次演示,他们使用太阳能动力的 Zephyr HAPS 旨在扩展空中和海上连接,并报道了范围高达 的连通性 [28]。 HAPS 启用的移动终端连接可以允许用户在不需要专用天线的情况下使用他们的移动设备。

B. On-Board Communications
B. 机载通信

Another major aspect of maritime communications is the connectivity among different entities on the ship. Unlike conventional indoor radio wave propagation, radio wave propagation inside ships principally constructed with steel can be different. For instance, radios are used for communication between ship crew members, and a wireless sensor network (WSN) may be used to monitor the movement of perishable and dangerous goods in shipping containers [29]. Therefore, it is essential that the wireless channel for
海上通信的另一个重要方面是船舶上不同实体之间的连接性。与传统的室内无线电波传播不同,主要由钢铁构造的船舶内部的无线电波传播可能会有所不同。例如,无线电用于船员之间的通信,无线传感器网络(WSN)可能用于监测运输集装箱中易腐和危险货物的运动[29]。因此,对于无线信道是至关重要的。

on-board applications is carefully modeled considering various scenarios. Balboni et al. [30] reported a series of seminal investigations on radio channel characterization inside navy ships at a frequency range in the microwave band between and . The authors reported root-mean-square (RMS) delay spreads ranging between 70 and [30] and path loss gradients ranging from to unity. Path loss and the RMS delay spread were found independent of frequency over the considered frequency range. For on-board communications, channel measurements have been reported in different types of ships in various studies [31], [32], [33], [34]. The channel impulse responses inside compartments and within a passageway of a ship were obtained using a vertical network analyzer for 2 and [31]. Channel sounding measurements were conducted in the restaurant hall and corridors of a cruise ship at [32], [33]. LoS and Non-LoS (NLoS) channel measurements and 3-D ray-tracing simulations were performed in the UHF band (from 225 to ) inside a cargo hold of a merchant ship [34], deriving the path LoS models for both scenarios. In [35], the channel characteristics and temporal fluctuations related to the propagation of VHF waves between the engine control room (ECR) and the bridge room have been examined in a vessel. Due to the dense multipath environment formed by the metallic structures inside the channel, broadband propagation may be impossible. Furthermore, De Beelde et al. [36] tested the channel in three separate places within the ship in a broader comprehensive investigation conducted in larger bands , , and ). The path loss exponents for sub were 1.21, 1.14, and 1.36 for , and , respectively. However, the path loss exponent for mmWave wireless communications was more significant, i.e., 1.9 .
在机载应用中,考虑了各种场景进行了仔细的建模。Balboni等人[30]报道了一系列关于在微波频段内海军舰船上的射频信道特性的开创性研究。作者报告的均方根(RMS)时延展宽在70和 之间[30],路径损耗梯度在 至1之间。发现路径损失和RMS时延展宽在所考虑的频率范围内与频率无关。对于舰载通信,通过不同研究[31],[32],[33],[34]报告了在各种类型的舰船内进行的信道测量。使用垂直网络分析仪分别在一艘船的舱室内和通道内获取了2和 的信道脉冲响应[31]。在一艘游轮的餐厅大厅和走廊进行了 的信道深度测量[32],[33]。 在 UHF 频段(从 225 到 )内,在一艘商船的货舱内进行了 LoS 和非 LoS(NLoS)信道测量和 3-D 射线追踪模拟[34],得出了两种情景下的 LoS 模型路径。在[35]中,研究了 VHF 波在控制室和驾驶室之间传播的信道特性和时间波动。由于信道内金属结构形成的密集多径环境,宽带传播可能是不可能的。此外,De Beelde 等人在更广泛的调查中在船内的三个不同位置测试了信道,使用了更大的频段 。对于子 ,子 和子 ,路径损耗指数分别为 1.21,1.14 和 1.36。然而,毫米波无线通信的路径损耗指数更大,即 1.9。

C. FSO and Hybrid RF/FSO for Maritime Communications
C. FSO 和混合 RF/FSO 用于海上通信

A particular advantage of FSO in maritime communication is the difficulty of interception and immunity to jamming contrary to RF signals, opening many military and civil applications opportunities. Various demonstrations were conducted mostly for military applications investigating the potential of FSO deployment in maritime military communication. Initial laser-based maritime communication demonstrations date back to 1970s [37]. A full-duplex heterodyne laser transmission was demonstrated using two lasers over an 18.2-km maritime link in San Diego (California, U.S.) within the optical convert communications using laser transceivers (OCCULT) experimental research initiative [37]. An automatic acquisition mechanism was involved with reciprocal pointing and tracking to ensure stable communication of the coherent two-way communication. In 2006, within the yearly Trident Warrior exercise, FSO systems were installed on two naval vessels [38]. A high-quality 300-Mb/s uncompressed video transmission was reported over a maximum distance of in the Pacific, and the data link was transmitted with no disruptions or delay over [38]. A bidirectional mutiGbps FSO transmission was conducted off the mid-Atlantic coast between a tower on Cedar Island (Virginia, U.S.) and
FSO在海上通信中的一个特殊优势是与RF信号相比,拦截困难和免疫干扰,为许多军事和民用应用提供了机会。各种演示主要用于军事应用,探讨FSO在海上军事通信中的部署潜力。最初基于激光的海上通信演示可以追溯到1970年代。在加利福尼亚州圣迭戈的18.2公里海上链路上,通过使用两个激光器进行全双工混频激光传输的演示,这是光学转换通信使用激光收发器(OCCULT)实验研究计划的一部分。自动获取机制涉及相互指向和跟踪,以确保相干的双向通信的稳定通信。2006年,在每年的三叉戟战士演习中,FSO系统安装在两艘海军舰艇上。在太平洋最大距离上报告了高质量的300Mb/s未压缩视频传输,并且数据链路在没有中断或延迟的情况下传输了。 在美国弗吉尼亚州 Cedar Island 的塔楼之间,在大西洋中部进行了双向多 Gbps FSO 传输。和
Fig. 3. Diagram of an MRR-based FSO. The MRR couples a corner-cube retro-reflector and a modulator.
图 3. 基于 MRR 的 FSO 示意图。MRR 将一个角立方体反射器和一个调制器耦合在一起。
a JHU/APL research vessel with varying distances between 2 and [39]. In 2017, a team from the Johns Hopkins University Applied Physics Laboratory (APL) demonstrated up to FSO communication between two moving ships [40]. During the 14-h up-time of the FSO terminal in a ship-to-shore configuration, data rates between 1 and were reported for ranges exceeding . FSO link ensured voice communications for distances more than and sent messages up to the maximum available distance of .
约翰斯·霍普金斯大学应用物理实验室(JHU/APL)的研究船具有2和 之间的不同距离[39]。 2017年,约翰斯·霍普金斯大学应用物理实验室(APL)的团队在两艘移动船只之间展示了高达 的FSO通信[40]。在船舶到岸基的FSO终端的14小时正常运行时间内,对于超过 的范围,报道了1到 的数据速率。FSO链路确保了超过 的距离进行语音通信,并发送了多达最大可用 距离的信息。
Moreover, modulating retro-reflector (MRR)-based maritime links were demonstrated in [41], [42], and [43]. The diagram of an MRR is shown in Fig. 3 that combines an optical retro-reflector with a modulator to reflect modulated optical signals (initially emitted by a laser interrogator) directly back to an optical receiver, allowing the MRR to function passively as an optical communication device without emitting its own optical power. MRRs are mainly used in maritime for FSO link characterizations. FSO transmissions involving an array of MRRs with data rates ranging from 100 to were conducted in the Chesapeake Bay (in the Mid-Atlantic region, US) over 32.4-km folded round-trip distance [41]. Using an array of 5 quantum-well-based MRR, a series of shore-to-boat FSO communications using a laser over a distance of in the Chesapeake Bay achieving data rates up to [42]. A 32-km round-trip FSO communication using a laser modulated by an analog RF signal was reported through a maritime link using a retro-reflector at the Tilghman Island [43].
此外,在[41]、[42]和[43]中展示了基于调制反射器(MRR)的海上链接。MRR的示意图如图3所示,它将光学反射器与调制器结合在一起,将调制的光学信号(最初由激光询问器发射)直接反射回光学接收器,使MRR能够 passively 作为光通信设备运行,而无需发射自己的光功率。MRR主要用于海上FSO链接特性。在美国中大西洋地区的切萨皮克湾(Chesapeake Bay)进行了一系列涉及一组MRR的FSO传输,数据速率范围从100到 ,覆盖32.4公里的往返距离[41]。使用5个基于量子阱的MRR阵列,在切萨皮克湾进行了一系列岸对船FSO通信,使用 激光,覆盖了 的距离,实现了高达 的数据速率[42]。通过在Tilghman岛使用反射器的海上链接,报告了一次32公里往返FSO通信,使用模拟RF信号调制的 激光[43]。
Beyond high-data-rate transmission and the use of MRRs, other experimental efforts involved deep investigations of the various propagation effects on FSO in maritime environments. For instance, the effects of turbulence and extinction on a 7.2-km FSO maritime path were investigated in [44]. A summary of FSO trials and demonstrations is given in Table III.
除高数据传输速率和 MRR 的使用外,其他实验努力涉及对海上光自由空间光通信的各种传播效应的深入研究。例如,[44]中调查了湍流和消光对 7.2 公里 FSO 海上路径的影响。表 III 总结了 FSO 试验和演示情况。
FSO is not only restricted to horizontal links but can also be involved in vertical links, such as HAPS to vessel links. FSO is also a core technology to provide fiber-like data rates in satellite crosslinks in large LEO constellations aiming to provide wide maritime connectivity, such as Telesat Lightspeed and SpaceX Starlink constellations [46], [47].
FSO 不仅局限于水平链接,还可以参与垂直链接,例如 HAPS 到船只的链接。FSO 还是在旨在提供宽广的海上连接的大型 LEO 星座中提供类似光纤数据速率的核心技术,如 Telesat Lightspeed 和 SpaceX Starlink 星座[46],[47]。
Besides FSO-only links, various terrestrial hybrid RF/FSO schemes are also recently investigated in [48], [49], and [50]. These hybrid links can be well suited for maritime communication between ships and ships to shore. Nevertheless, research
除了仅使用 FSO 链接外,最近还研究了各种陆基混合 RF/FSO 方案,参见[48],[49]和[50]。这些混合链接非常适合船舶间和船到岸的海上通信。然而,研究
TABLE III 第三表
SUMmARY OF FSO FIELd TRIALS ANd DEMONSTRATIONS
FSO 现场试验和演示摘要
Ref. Year Demonstration description
演示描述
Major outcomes 主要成果
[37] 1977
lasers operating at were used to build
用于构建 激光器在 工作的
heterodyne systems for full-duplex ship-to-ship communi-
全双工船舶间通信的混频系统
cation at close .
闭合处的 cation
- Automatic acquisition and reciprocal pointing and track-
- 自动采集和互相指向和跟踪机制涉及。
ing mechanisms were involved.
主要涉及自动采集和互相指向和跟踪机制。
- Reciprocal pointing and tracking ensured stable commu-
- 相互指向和跟踪确保了稳定的通信-
nication.
- High-frequency stability is achieved.
- 实现了高频稳定性。
2010
- A high-speed FSO transmission, in the form of a pre-
- 以预-形式进行高速 FSO 传输
taped video and live video feed between two US navy
两艘美国海军舰船之间的录像和直播视频传输在 10 小时内建立起来。
vessels, was established over 10 hours.
传输范围高达<code0></code0>,速度达到 300 兆位。
- Up to transmission range and 300 Mbits were
reported.
- No artifacts or delays in the videos were reported in clear
- 在晴朗的天气传输中,视频中没有报告任何工件或延迟
weather transmission. - 在雨天,视频中出现了轻微的工件
- During rain, slight video artifacts were obtained at ranges
- 在雨天,视频中出现了轻微的工件
less than .
小于
[39] 2010
- Two bidirectional ship-to-shore FSO field trials
- 两艘双向船到岸 FSO 现场试验
conducted off the mid-Atlantic coast near Wallops Island
在 Wallops Island 附近的大西洋中部海域进行
in July and September 2009
2009 年 7 月和 9 月期间
- The propagation distance was varied from 2 to ,
- 传播距离从 2 变化到
visual horizon. 可视地平线。
- Two adaptive optics (AO) units were used to compensate
- 使用两个自适应光学(AO)单元来补偿光束失真和指向误差。
for beam distortions and pointing errors.
- 实现了高达<code0></code0>的数据传输速率。
- Up to data rate was achieved.
- Daytime atmospheric turbulence is stronger than night-
- 白天大气湍流比夜晚强
time.
2017
- Demonstration of high-speed FSO transmission using
- 利用由 APL 工程师在 2017 年三叉戟项目中开发的高速 FSO 传输进行演示
terminals developed by APL Engineers in the 2017 Trident
- 术语由 APL 工程师在 2017 年三叉戟项目中开发
Warrior exercise. 战士练习。
- Demonstrations involved ship-to-ship and ship-to-shore
- 演示涉及船舶间和船岸间
communications. 通信。
- Up to a 7.5 Gbps transmission rate between two moving
- 两艘移动船只之间的传输速率达到了 7.5 Gbps
vessels was reported. 船与岸测试总共运行了 14 小时:
- For 14 hours total up-time in ship-to-shore testing:
* Error-free transmissions with data rates between 1 and
* 数据速率在 1 到 2 Gbps 之间进行无误差传输,覆盖范围更多。
2 Gbps at more than ranges.
* 在多达 范围内的语音通信。
* Voice communications for ranges up to .
* 范围覆盖高达 的语音通信。
* Operational chat messaging at maximum LoS of .
* 在最大视距下的操作性聊天消息。
- Sea spray and fog were the major challenges.
- 海雾和雾是主要挑战。
2002
- MRR-based round-trip transmission using an
- 基于 MRR 的往返传输使用 an。
array of 22 MRR.
22 个 MRR 的数组。
- The height of the laser interrogator was from
- 激光询问仪的高度是 来自
the water surface, while the height of the MRR from the
水面,而 MRR 的高度是
surface was set to 15 to strengthen the propagation effects
表面被设置为 15,以加强传播效果
of the propagating laser beams.
传播的激光束。
- Data rates between 100 and were demonstrated
- 在 100 和 之间的数据速率得到了证明
with a bit error rate (BER) below