Synopsis

Advancements in maritime communications are severely lagging behind its land counterpart. Existing marine communication technologies usually have very limited capacity and are extremely expensive to operate. Novel solutions are demanded to meet the imminent requirements for broadband marine mobile wireless access. The purpose of this project is to fill the void of marine broadband wireless communications by developing long-range self-powered ocean wireless communication links. The ocean wireless link is composed of compact, maintenance-free and low cost floating wireless base stations (BS) that can be simply dropped into the water. Once in the water, the BSs start to harvest energy from ocean waves and establish communication links with each other. Users' broadband traffic, then, can be delivered to the Internet through these links. This project will bring revolutionary change to the maritime communications. New maritime networked applications and operation scenarios that are infeasible but highly desirable in the past can be enabled by this technology. It can have significant impact on all aspect of ocean related industry, such as fishing, recreational boating, marine transportation, oil and gas industry, ocean scientific study, and national security and defense. The project will focus on two thrust areas: Thrust 1 is about ocean wave energy harvesting. For a BS to provide large coverage range and high capacity links to its users and other BSs, the BS must consume a large amount of energy. It is nontrivial to design such an energy-harvesting unit while staying low-cost, compact and maintenance-free. Existing technologies are too large in size and hence are expensive and hard to be stabilized in rough ocean states and require frequent maintenance. This project solves this critical challenge by a novel power takeoff mechanism. This design enables the researchers to build an ocean wave energy harvester that can effectively harvest tens watts of power on typical ocean states with a floating buoy of less than 1 meter diameter. Thrust 2 is about building the high capacity marine communication links. The constantly moving ocean waves can affect the capacity, stability and range of the backhaul links among BSs. In this project, we will study how to analyze and model the channel and design antenna and radio hardwares to handle the complex channel of ocean communication links. The researchers will also study the unique features of ocean communication links and their potential beneficial and/or harmful impact on network communications.

Personnel

  1. Yaling Yang (faculty)
  2. Lei Zuo (faculty)
  3. Majid Manteghi (faculty)
  4. Kexiong Zeng (Ph.D.)
  5. Alireza Shahanaghi (Ph.D.)
  6. Xiaofan Li (M.S.)
  7. Eric Dupuis (Ph.D.)
  8. Ali Fahraji (Ph.D.)
  9. Pedram Loghmannia (Ph.D.)

Related Publications

  1. Xiaofan Li, Changwei Liang and Lei Zuo, Design and Analysis Of a Two-Body Wave Energy Converter With Mechanical Motion Rectifier, 2016 ASME Design Engineering Technical Conference (IDETC), Charlotte, NC, USA.
  2. Alireza Shahanaghi, Yaling Yang, and R. Michael Buehrer, "On the Link Modeling of Static Wireless Sensor Networks in Ocean Environments", Infocom 2019
  3. Ali Hosseini-Fahraji, Kexiong Zeng, Yaling Yang, Majid Manteghi, A Self-Sustaining Maritime Mesh Network, Ali Hosseini-Fahraji, Kexiong Zeng, Yaling Yang, Majid Manteghi, US National Committee of URSI National Radio Science, 2019
  4. Sun, Sihao. Maritime Mesh Network Simulation. (2018). Virginia Tech, Master Thesis
  5. Yu, Sihan. Ocean Wave Simulation and Prediction. (2018). Virginia Tech. Master Thesis
  6. Zeng, Kexiong. Threat and Application of Flexible Radio Systems. (2018). Virginia Tech. Ph.d. dissertation

Project Progress (1/28/2019)

(1) Designed and developed a lab prototype of ocean wave energy harvesting buoy. We also tested the lab prototype in a wave tank. The testing results are very promising. The test of the prototype in wave tank demonstrated that our design can generate 50-100watts conntinuos energy in typical ocean states. We are currently in the process of building the prototype to test in real ocean environment.

(2) Designed and developed a prototype wireless radio that operates in TV white space. We also tested the prototype radio in a land environment. The prototype radio is composed of a wifi wireless router and a up/down converter to convert the 2.4GHz output of the wifi radio chip to TV white space. The source code that are installed on the prototype radio can be downloaded from here.

(3) Build the simulation of ocean wave and studied the impact of wave height on ocean mesh network connectivity. We leveraged oceanographic statistic model of ocean waves to build a simulation of ocean wave that captures ocean surface movements under various weather conditions. We are currently integrating the ocean wave simulation with ns-3 simulator so that we can simulate network protocol designs in ocean environment. We have also studied wave height distribution, analyzed the relationship between wave height and link connectivity, and examed how cluster-based buoy deployment strategy may enhance network connectivity in rough sea states. The source files for the ocean simulation can be found here

(4) See this video for outline of our project idea, photos of our prototype and recording of our test process in wave tank.

(5) We have performed field experiment of our radio prototype in Claytor lake, Virginia. We set our radios to have 500-meter line-of-sight initial separation distance, which then gradually increased to 1500-meter. The two radios are configured to establish an half-duplex mesh backhaul link between them. TV channel 14 with center frequency 473 MHz and a 5 MHz bandwidth are used for link measurement. The two radios both transmit at 25 dBm via a 5-meter omnidirectional antenna with 2 dBi gain and -2dbm cable loss. From the measurement, the path loss exponent of our radio is 2.8329 and fits theoretical model nicely. The peak UDP throughput over the link is 6Mbps at any received signal strength over -62DBm and the minimum received signal strength for the receiver to receive 1Mbps is -83dbm.

(6) We are developing theoretical models that capture the relationship between wireless link stability, wind speed and ocean wave height. One of the models will appear in Infocom 2019 (see the above publication list.)

(7) We experiments with different machine learning techniques for predicting future wave heights. The results showing that multi-linear regression methods produced the best results comparing to neural-network-based learning method.

The simulated ocean wave The tank test Radio Radio test field test

Broader Impact

The marine industry has long realized that despite of the tremendous developments in terrestrial radio technologies, advancements in maritime communications are severely lagging behind its land counterpart, and novel solutions are demanded to meet the imminent user requirements. The user demands for marine communications are much higher than the severely limited capacity offered by the existing technologies. The research results of this project can mend the large gap and potentially bring revolutionary change to the maritime communications. New maritime networked applications and operation scenarios that are infeasible but highly desirable in the past can be enabled by our technology. Thus, our project can have significant impact on all aspect of ocean related industry, which has generated more than 138 billion GDP to US economics in 2004. The proposed technology will also significantly extend the active region of human life, which will increase the response time in emergence events like plane landing on water or cruise ship disasters. It will also make the off-shore energy exploration and operation much easier. The proposed ocean network system will also have a wide range of national security and defense applications.