WO2018002702A1

WO2018002702A1 - Underwater communication system

Info

Publication number: WO2018002702A1
Application number: PCT/IB2017/000788
Authority: WO
Inventors: Brendan Peter Hyland
Original assignee: Wfs Technologies Ltd
Priority date: 2016-06-28
Filing date: 2017-06-28
Publication date: 2018-01-04
Also published as: GB201611233D0; GB2566660A; GB2566660A8; GB201900992D0

Abstract

A wireless communication system comprising a transmission unit having a data input; a modulator, for modulating the data onto a carrier signal, and a transmitter for transmitting modulated visible light communication electromagnetic signals, and a remote reception unit having a receiver for receiving modulated visible light communication electromagnetic and/or magnetic signals, wherein at least one of the transmission unit and/or remote reception unit is placed in a liquid propagating medium. The wireless transmission system may also be operable to transmit using a hybrid communication system technique using visible light, acoustic or electromagnetic transmission techniques interchangably depending on the optimal transmission technique for the surrounding environmental conditions.

Description

Underwater communication system

The present invention relates to an underwater communication system for use

communicating data between remote units.

As communication of data becomes an increasingly important part of the modern world so too do effective ways of implementing useful data communication in all environments.

Over the past decade, communication of data in underwater or through water has increased in capability due to the development of use of through fluid data transmission using electromagnetic data carrying signals. However, additional data communication techniques including hybrid systems have also become more commonplace.

An object of the present invention to provide an underwater communication system for communicating data between remote units.

Another object of the present invention is to provide an underwater communication system which can communicate using acoustic and/or electromagnetic signals. Another object of the present invention is to provide a network of underwater

communication system for communicating data between remote units.

These and other aspects of the present invention are achieved in an underwater

communication system for communicating data between remote units. The data is communicated via a wireless communications system. The wireless communications system has a transmission unit which includes a transmitter for transmitting modulated visible light communication electromagnetic signals. The communications system further has a remote reception unit having a receiver for receiving modulate visible light communication electromagnetic and magnetic signals. At least one of the transmission unit and remote reception unit is placed in a fluid propagating medium. Furthermore, a network of communication units comprising at least one of a transmission unit and a reception unit may communicate data via wireless communications techniques. The communication units may be arranged within communicable range of at least one other communication unit to form a mesh of communication units forming a communication network. Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings of which:

Figure 1 is a schematic illustration of an underwater communication system according to an embodiment of the present invention, and

Figure 2 is a schematic illustration of an underwater communication system according to another embodiment of the present invention.

Figure 3 is a schematic illustration of a network of underwater communication units according to another embodiment of the present invention.

Figure 4 is a schematic illustration of a network of underwater communication units according to another embodiment of the present invention. As is shown in Figure 1 , there is provided a communication system 10, deployed underwater 12 comprising a first communication unit 14, and a second communication unit 16. Each communication unit 14, 16 can be a visible light communication unit such as an LED communication unit, for example operating at 10MB over 5m, or a laser communication unit, the communication unit can also be a hybrid communication unit incorporating one or more of optical communications system, an acoustic communication system and an electromagnetic communication system thus enabling a communication range from below lcm to over 200m to be achieved by the optimal communication system option though the typical transmission range for the system is likely to be between 5cm and 20m. Each communication unit can be battery power or have a renewable energy source, alternatively, a battery swap out system can be used, or an inductive coupling transfer unit, in addition to this, the communication unit can be provided with a cabled connector.

The first communication unit 14 is, in this case, a transmission unit having a data input 18, a modulator 20, for modulating the data input from data input 18 onto a carrier signal, and a transmitter 22. The data input may be from sensors such as, but not limited to, temperature, pressure, flow, vibration or acceleration, acoustic sensors including microphones, a camera capturing either still or video footage, or an electronic data system or the like.

The carrier signal or wave usually has a much higher frequency than the input signal does. The purpose of the carrier signal is usually either to transmit the information through space as an optical or electromagnetic wave, or to allow several carriers at different frequencies to share a common physical transmission medium by frequency division multiplexing. The carrier wave usually has a much higher frequency than the input signal does. The frequency range for the communication system is ideally within the range of from 10Hz to 5GHz for radio communication, optical communication in the region of 350nm to 500nm and low acoustic frequencies of around 9kHz but ideally within the range of 1 kHz to 250kHz.

The carrier signal usually has frequency modulation (FM) in which the amplitude of the carrier signal is varied in accordance with the instantaneous amplitude of the modulating signal,or amplitude modulation (AM) in which the amplitude of the carrier signal is varied in accordance with the instantaneous amplitude of the modulating signal, applied to make the carrier carry information. However, because the information transmitted by a radio signal is not at the carrier frequency itself but contained in sidebands on either side of the carrier, the energy of the carrier component is not useful in transmitting the information. Therefore, in many modern modulation methods the carrier signal is not transmitted. For example, in single-sideband modulation (SSB), the carrier is suppressed (and in some forms of SSB, eliminated). The carrier must then, in these circumstances, be reintroduced at the receiver 16 by a beat frequency oscillator (BFO).

Other modulation techniques can include double-sideband modulation (DSB), double- sideband modulation with carrier (DSB-WC), double-sideband suppressed-carrier transmission (DSB-SC), double-sideband reduced carrier transmission (DSB-RC), single- sideband modulation (SSB, or SSB-AM), single-sideband modulation with carrier (SSB- WC), single-sideband modulation suppressed carrier modulation (SSB-SC), vestigial sideband modulation (VSB, or VSB-AM), quadrature amplitude modulation (QAM), angle modulation, which is approximately constant envelope, phase modulation (PM) where the phase shift of the carrier signal is varied in accordance with the instantaneous amplitude of the modulating signal, and transpositional modulation (TM), in which the waveform inflection is modified resulting in a signal where each quarter cycle is transposed in the modulation process. It will be appreciated that any other suitable modulation technique could also be used.

Second communication unit 16 is a remote reception unit 16 which, depending on the transmission technique selected can be anything in the region of less than 1cm to over 200m, however it is most likely that the second commumcation unit 16 will be betwee 5m to 20m from the first communication unit 14. The reception unit 16 includes a receiver 24, a demodulator 26 and a data output 28. The transmission unit 14 can communicate with remote reception unit 16 by transmission of visible light communication electromagnetic signals, a hybrid system such that variance between visible light communication and electromagnetic communication or acoustic communication can be used when appropriate for the transmission conditions.

In Figure 2 there is shown a communication system 110, deployed underwater 112, whether in wave wash so that it is intermittently submerged or it may be fully submerged either just below the surface, deployed upon the seabed or arranged to be suspended or in travel at any depth between the water surface and the seabed. The communication system 110 may also be deployed in a pond, lake, tank, pool, basin or any other liquid holding or receiving vessel.

The communication system 110 comprises a first communication unit 114 and a second communication unit 116. The first commumcation unit is a transmission unit 114 having a data input 118, a modulator 120, for modulating the data input from data input 118 onto a carrier signal, a selection mechanism 121, a first transmitter 122 and a second transmitter

123. Second communication unit 116 is a remote reception unit 116 having a first receiver

124, a second receiver 125, a demodulator 126 and a data output 128. The transmission unit 14 can secretively communicate with remote reception unit 116 by transmission of visible light communication electromagnetic signals via transmitter 122 to receiver 124 and the transmission unit can further selectively communication via transmitter 123 to receiver 125 using an alternative communication technique such as lower frequency electromagnetic signals, visible light communication electromagnetic signals, optical signals or acoustic signals. The hybrid wireless communication system supports time and frequency division duplexing modes one of the communication units 114, 116 can be a base station having a communication range based on one or more of the optical, acoustic and electromagnetic transmission techniques, in addition, at least one other communication unitl 14, 116, namely a secondary unit may be deployed, positioned, or operable as a mobile stations within the base station communication range. The base station divides each available frequency resource into frames for communication, and each frame switches between a real-time service mode and a non-real-time service mode at a switching time within the frame.

Communication is performed with the secondary units or mobile stations within the base station communication range via at least one of an uplink and a downlink in the real-time service mode of each frame according to the frequency division duplexing mode.

Communication is performed with the secondary mobile stations via the uplink and the downlink in the non-real-time service mode of each frame according to an ad hoc mode based on the time division duplexing mode It will be appreciated that each of transmission units 14, 114 and reception units 16, 116 may be transceiver units able to operate as both a transmission and reception unit. LED based blue-green hardware may be used as the transmission mechanism for the visible light communication electromagnetic signal components of the communication units. In use, the communication systems may operate using visible light radio communication having, for example, a bandwidth of 100bps; range of 10m at a frequency of 3 kHz, or for example, 10MB over up to 5m, which would be of particular value for across seabed communication networking as well as extending the range of transmission possible for communications such as covert AUV communication and diver text level style

communications. At bandwidths of, for example 9.6kbps. frequency of 6.25kHz and 15-25m transmission range the system could be useful in communicating data including voice and/or video/image data. Furthermore, at 50kbps bandwidth, a frequency of approximately

62.3kHz and 7- 10m range video data could be transmitted effectively. At closer range communication for a docking data dump type arrangement bandwidths in the range of IGbps could be transmitted at 2.4GHz for example WiFi frequency. Acoustic systems can achieve transmission across bandwidths in the region of 500bps. The visible light electromagnetic communication signals can be used to transmit across a range of bandwidths, for example 10Mbps, 100Mbps or 200Mbps at distances between 375nm to 2-3m through seawater. Within each transceiver unit, a single Software Defined Radio (SDR) platform can support one or more of electromagnetic, visible light electromagnetic communication, optical or acoustic transmission or alternatively discreet boards could be used for each creating a hybrid underwater wireless communications system incorporating radio, visible light electromagnetic, acoustic and optical technologies which is compact, energy-efficient, able to be used at depths of 4,000m and suitable for integration with AUVs, ROVs and subsea instrumentation. Each communication unit may be suitable for use in point-to-point and dynamic mesh networks. Each communication unit can also incorporate several levels of security to accommodate both industrial and defence requirements, for example, preventing unauthorized interceptors from accessing telecommunications in an intelligible form, while still delivering content to the intended recipients. The field includes cryptographic security, transmission security, emissions security and physical security of equipment and data input systems. Such security techniques can be used for both analogue and digital applications, and both wired and wireless links. For example, voice over secure internet protocol VOSIP has become the de facto standard for securing voice communication, replacing the need for Secure Terminal Equipment (STE).

Within each hybrid communication unit, algorithms for point to point communication, multipoint to point, point to multipoint or collective or broadcasting communication can be embedded to monitor each communications channel and seamlessly switch in real time. Within the electromagnetic transmission unit is included architecture for example, carrier- frequency gating systems for exciting static electronic switches such as thyristors, which are able to switch between several carrier frequencies to support bandwidths over the range of 10bps to 100kbps. In addition, algorithms to accommodate differing latencies of each wireless technology are also integrated within the communication unit processing system. Encryption technology suitable for use on bandwidth-limited systems, such as symmetric- key schemes, or public key encryption schemes, is embedded within the processing capability of each communication unit in order to optimise performance. In addition, development of software techniques to support covert communications is integrated within the communication units such as data hiding in the OSI (Open Systems Interconnection) model or data hiding in the LAN (Local Area Network) environment. In addition, the system incorporates improved receiver sensitivity and improved DSP (Digital Signal Processing) filtering and optimised antenna design enabling transmission of data to communication unit nodes arranged up to 5km apart.

In Figures 3 and 4, examples of environments in which the communication system can be deployed are shown. In figure 3, a FSPO 310 has cable communication links 320 to buoy 315 and operations platform 3,05, each of the buoy 315 and operation platform 305 are connected to risers 330 which are in communication with seabed hardware 340. At each of the units 305, 310, 315, 330, 340, communication units 350, which can be communication units such as 14, 16, 114, 116 detailed above, are provided, enabling wirless communication to take place providing reliable realtime data transfer.

In Figure 4, an FSPO 310 with a communication unit 350 having a laptop as the data input and data output interface, is shown. The FSPO is operates a riser 320 which is connected to a seabed wellhead 360. At various points along the riser, communication units 350 are deployed to monitor the stress, strains, and performance of flow, of the riser 320. As can be seen, the communication technique used at each point along the riser 320 can vary depending on the local conditions, so in turbid conditions such as at the seabed, the units 350 may be transmitting using electromagnetic signals. However closer to the surface, the conditions may be clear and therefore visible optical communication may be most suitable. An advantage of the present invention is that it provides a communication system for use underwater which can use visible light communication electromagnetic signals to

communicate data through liquid.

A further advantage of at least one embodiment of the present invention is that it can provide hybrid communication options in order to optimise effective through fluid data transmission. In one embodiment the system provides an integrated processing system can selectively determine the transmission technique used to optimise one or more of bandwidth, distance or speed of data being transmitted through liquid.

It will be appreciated by those skilled in the art that various modifications may be made to the invention herein described without departing from the scope thereof. For example, the communication system may be used within a subsea docking system or may alternatively be incorporated within a mobile communication device which may be carried by a person. The system may include transmission using visible light communication electromagnetic signals and be integrated with an acoustic transmission system or alternatively one or more of acoustic, electromagnetic and/or magnetic or optical may be integrated with a system using visible light communication electromagnetic signals.

Claims

1. A wireless communication system comprising:

a transmission unit having:

a data input;

a modulator, for modulating the data onto a carrier signal, and a transmitter for transmitting modulated visible light communication electromagnetic signals, and

a remote reception unit having:

a receiver for receiving modulated visible light communication electromagnetic and/or magnetic signals,

wherein at least one of the transmission unit and/or remote reception unit is placed in a fluid propagating medium.

2. A wireless communication system wherein each transmitter unit is a transceiver unit which includes functionality of both a transmission unit and a reception unit.

3. A wireless communication system wherein each receiver unit is a transceiver unit which includes functionality of both a transmission unit and a reception unit.

4. A wireless communication system wherein each transceiver unit is a hybrid communication unit operable to communicate using at more than one of electromagnetic, acoustic or optical data carrying types of signals.

5. A network of communication units comprising at least one of a transmission unit and a reception unit wherein the communication units are arranged within communicable range of at least one other communication unit to form a mesh of communication units operable as a communication network.

6. A network of communication units as claimed in claim 5 wherein each

communication unit is provided with a processor unit.

7. A network of communication units as claimed in claim 6 wherein each processor is operable to carry out processing on the data, implement data control and instruct

transmission and reception of data from and to the communication unit to a desired other communication unit or external communication device as required and according to at least one predetermined criteria.

8. A network of communication units as claimed in claim 5 wherein each transmitter unit is a transceiver unit which includes functionality of both a transmission unit and a reception unit.

9. A network of communication units as claimed in claim 5 wherein each receiver unit is a transceiver unit which includes functionality of both a transmission unit and a reception unit.

10. A network of communication units as claimed in claim 8 wherein each transceiver unit is a hybrid communication unit operable to communicate using at more than one of electromagnetic, acoustic or optical data carrying types of signals.