Patent Description:
In order to meet consumer and industrial demand for natural resources, companies often invest significant amounts of time and money in searching for and extracting oil, natural gas, and other subterranean resources from the earth. Once a desired subterranean resource is discovered, drilling and production systems are employed to access and extract the resource. These systems may be offshore depending on the location of the desired resource. Such systems generally include a wellhead, pumps, underwater conduits, and other equipment that enable drilling and extraction operations.

The costs associated with drilling, installing, and extracting these natural resources may be significant. Operators may therefore monitor the installation and operation of these systems to ensure desired operation, to comply with regulations, etc. However, the harsh sea environment and size of the equipment used in drilling and extraction operations, may make fixed equipment monitoring and cable connections undesirable. Operators may therefore use underwater vehicles to monitor these systems and equipment. The underwater vehicles may collect information regarding the operation and condition of the systems using a variety of sensors. The information collected by these sensors is transmitted to the surface using acoustic communication. However, the underwater acoustic environment is constantly changing. For example, changing thermoclines and water temperatures as well as acoustic energy generated by subsea equipment and surface vessels may interfere with data transfer from the underwater vehicles. Unfortunately, tuning communications equipment in response these changing conditions involves bring an underwater vehicle to the surface and updating communication parameters using a physical connection or a Wi-Fi link. Surfacing the underwater vehicle may therefore waste time and money as equipment and personnel are unable to perform other tasks. The paper by <NPL>, presents a literature survey on existing UAC channel environments, parameters and their measurement/estimation methods reviews and describes cognitive intelligence algorithms for use in channel parameter identification, measurement estimation and mapping. <CIT> describes a method of determining a position of a submersible vehicle within a body of water. The document by <NPL>, describes a hybrid-data and model based framework which allows AUVs with acoustic sensors to follow a path that optimizes their ability to maintain connectivity with an acoustic contact for communication.

In a first aspect, the invention resides in a subsea telecommunication system as defined in claim <NUM>. Preferred embodiments are defined in claims <NUM> to <NUM>.

In another aspect, the invention resides in a method of updating a subsea telecommunication system as defined in claim <NUM>. Preferred embodiments are defined in claims <NUM> to <NUM>.

These aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:.

As used herein, the term "coupled" or "coupled to" may indicate establishing either a direct or indirect connection, and is not limited to either unless expressly referenced as such. The term "set" may refer to one or more items. Wherever possible, like or identical reference numerals are used in the figures to identify common or the same elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale for purposes of clarification.

Furthermore, when introducing elements of various embodiments of the present disclosure, the articles "a," "an," and "the" are intended to mean that there are one or more of the elements. Furthermore, the phrase A "based on" B is intended to mean that A is at least partially based on B. Moreover, unless expressly stated otherwise, the term "or" is intended to be inclusive (e.g., logical OR) and not exclusive (e.g., logical XOR). In other words, the phrase A "or" B is intended to mean A, B, or both A and B.

As explained above, subsea drilling and extraction operations can be very expensive. Accordingly, these subsea operations are monitored to check for equipment integrity, compliance with regulations, among other reasons. However, the harsh sea environment and size of the equipment used in drilling and extracting, may make fixed equipment monitoring and cable connections undesirable. System operators may therefore use underwater vehicles to monitor this equipment. The underwater vehicles may collect information regarding the operation and condition of the systems using a variety of sensors. The information collected by these sensors is transmitted to the surface using acoustic telecommunication. However, the underwater acoustic environment is dynamic. For example, surface and underwater vessels move with respect to each other. Acoustic reflections on the seabed and surface may also change as the underwater vehicles and surfaces vessels move. The presence of thermoclines may cause acoustic signals (e.g., acoustic rays) to bend. In addition, noise generated by propellers, thrusters, or other active subsea equipment can create large acoustic noise signatures. These combined effects of noise and variation in the propagation of the acoustic signal can interfere with the reliability and transmission of information through acoustic telecommunication.

The subsea telecommunication system discussed below updates physical layer parameters and data delivery parameters in real time in response to changes in the acoustic communication channel and acoustic noise as the underwater vehicle conducts missions. The ability to update physical layer parameters and data delivery parameters in real time increases the reliability and the transmission of data to and from the underwater vehicle during a mission (e.g., monitoring, mapping) as well as saves the time typically involved in surfacing the underwater vehicle to provide parameter updates.

<FIG> is a schematic view of a subsea telecommunications system <NUM> capable of changing physical layer parameters and data delivery parameters in real time. As explained above, the subsea environment provides a challenging environment for wireless communication (e.g., acoustic telecommunication). The ability to change physical layer parameters and/or data delivery parameters of the subsea telecommunications system <NUM> in real-time may save time and improve communication between surface vessels and underwater vehicles, as well as between one or more underwater vehicles.

The subsea telecommunications system <NUM> may include one or more surface vessels <NUM> (e.g., boat, ship, platforms) and one or more underwater vehicles <NUM> (e.g., autonomous underwater vehicles, unmanned undersea vehicles, remotely operated underwater vehicles). The surface vessel <NUM> may include a crane <NUM> that enables deployment and retrieval of the underwater vehicle <NUM>. For example, the surface vessel <NUM> may carry the underwater vehicle <NUM> to a deployment site where it is deployed. The deployment site may include a variety of oil and gas infrastructure <NUM> such as production pipes, subsea wellheads, risers, pumping equipment, among others. At the deployment site, the surface vessel <NUM> deploys the underwater vehicle <NUM> to conduct maintenance, inspection, mapping, research, among other tasks.

In order to wirelessly communicate with the underwater vehicle <NUM>, the surface vessel <NUM> includes one or more modems <NUM> (e.g., acoustic modem). The modem <NUM> includes one or more transmitters <NUM> and one or more receivers <NUM>. In operation, the modem <NUM> enables subsea acoustic communication with one or more underwater vehicles <NUM> by transmitting data with the transmitter <NUM> and receiving data with the receiver <NUM>. As will be explained below, the modem <NUM> couples to a computer system <NUM> (e.g., controller) that changes the physical layer parameters and/or the data layer parameters of the modem <NUM> in response to subsea conditions detected with sensors on the surface vessel <NUM> and/or the underwater vehicle <NUM> (e.g., sensors <NUM>, sensors <NUM>). These subsea conditions (e.g., environmental parameters) may include water temperature (e.g., thermoclines), salinity, acoustic noise (e.g., motors, pumps), among others. By changing the physical layer and/or the data layer of the modem <NUM>, the accuracy, speed, reliability, etc. of communication between the underwater vehicle <NUM> and the surface vessel <NUM> may increase.

The computer system <NUM> includes a processor <NUM> and a memory <NUM>. For example, the processor <NUM> may be a microprocessor that executes software to change the physical layer parameters, the data delivery parameters, process data received from the underwater vehicle <NUM> (e.g., sensors <NUM>), control the surface vessel <NUM>, among others. The processor <NUM> may include multiple microprocessors, one or more "general-purpose" microprocessors, one or more special-purpose microprocessors, and/or one or more application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or some combination thereof. For example, the processor <NUM> may include one or more reduced instruction set (RISC) processors.

The memory <NUM> may include a volatile memory, such as random access memory (RAM), and/or a nonvolatile memory, such as read-only memory (ROM). The memory <NUM> may store a variety of information and may be used for various purposes. For example, the memory <NUM> may store processor executable instructions, such as firmware or software, for the processor <NUM> to execute. The memory <NUM> may include ROM, flash memory, a hard drive, or any other suitable optical, magnetic, or solid-state storage medium, or a combination thereof. The memory <NUM> may store data, instructions, and any other suitable data.

As illustrated, the underwater vehicle <NUM> similarly includes one or more modems <NUM> (e.g., acoustic modem). The modem <NUM> includes one or more transmitters <NUM> and one or more receivers <NUM>. In operation, the modem <NUM> communicates (e.g., acoustic telecommunication) with the modem <NUM> (e.g., surface vessel modem) and/or with the modems of other underwater vehicles <NUM>. In order to move around, the underwater vehicle <NUM> includes a motor <NUM> that may drive a propeller <NUM>. The underwater vehicle <NUM> also includes one or more sensors <NUM>. These sensors <NUM> may be salinity sensors, temperature sensors, cameras (e.g., infrared, optical), chemical sensors, radar, etc. In operation, the underwater vehicle <NUM> uses the sensors <NUM> to sense the conditions of the water, monitor equipment, map, etc. For example, as the underwater vehicle <NUM> dives toward the target, it collects in-situ information related to the vertical acoustic velocity, the presence of underwater currents and the acoustic noise level near the target. Data from the sensors <NUM> may be received by a computer system <NUM> (e.g., controller) on the underwater vehicle <NUM>, which then processes and/or transfers the data to the modem <NUM> for transmission to the surface vessel <NUM>. The computer system <NUM>, may include a processor <NUM> and a memory <NUM>.

During operation, the computer system <NUM> may process incoming communication from other modems (e.g., modem <NUM>) as well as transmit data through the modem <NUM> (e.g., sensor data). For example, the computer system <NUM> may receive instructions from the computer system <NUM> to change physical and/or data layers of the modem <NUM>. The computer system <NUM> may also receive travel instructions (e.g., travel coordinates), speed of travel instructions, sensor instructions (e.g., camera movement instructions), among others.

<FIG> is a flowchart of a method <NUM> for setting a physical layer of a subsea telecommunications system <NUM>. The method <NUM> may begin by retrieving data an acoustic communication channel and/or noise proximate a target area of operation, step <NUM>. The retrieved data may include historical and/or predicted salinity, water temperature, acoustic noise (e.g., manmade, geological), thermoclines, among others. The method <NUM> then characterizes the physical layer of the subsea telecommunication system <NUM>, step <NUM>. The physical layer is characterized by characterizing the acoustic communication channel and the noise channel.

In order to characterize the acoustic communication channel, the method <NUM> may predict a sound velocity profile, predict a channel spread, simulate a Doppler shift, or a combination thereof. The method <NUM> may characterize the noise using time analysis of the noise (e.g., energy, peak-peak, median, sliding average, peak detection), spectral analysis of the noise frequency (e.g., fast Fourier transform, Welch's average, parametric spectral analysis), time frequency analysis of the evolution of the noise frequency over time (e.g., Fourier transform, Wigner-Ville, wavelets), and/or statistical analysis of the noise (e.g., Bayesian estimation, percentile), or a combination thereof. The method <NUM> may also determine the desired data delivery parameters, step <NUM>. Data delivery parameters may include latency, quality (e.g., data fidelity), spatial resolution, temporal resolution, etc. of the different data feeds. These data delivery parameters may be determined based on the intended operation of the underwater vehicle <NUM> and/or provided by an operator (e.g., personal preferences). For example, will the underwater vehicle be traversing, hovering, inspecting (e.g., inspecting equipment, pipeline).

The method <NUM> then conducts a communication performance simulation for the acoustic communication channel using the characterization of the physical layer and the data delivery parameters, step <NUM>. The communication performance simulation may include estimating a propagation channel using a ray-tracing technique and/or using a sound velocity profile. The Doppler Effect may be simulated using the laws of mechanics. Acoustic noise may be simulated in accordance with historic values and/or predicted values including signal level, energy distribution across bandwidth, etc. One or several simulated telecommunication signals with fixed parameters (e.g., carrier frequency, data rate, constellation order) are then generated and propagated using the simulated physical layer parameters and data delivery parameters. For example, two or more sets of different data delivery parameters and/or physical layer parameters may be used in the simulated telecommunication signals. The communication performance simulation may then estimate the reliability and performances of the simulated telecommunication signals. The results obtained using the different telecommunications parameters (e.g., physical layer parameters, data delivery parameters) are compared, and the set of parameters (e.g., physical layer parameters, data delivery parameters) accounting for the best performance may be selected.

After performing the communication performance simulation, the method <NUM> may adjust the physical layer parameters of the subsea telecommunication system <NUM> (e.g., modems <NUM> and <NUM>), step <NUM>. Physical layer parameters may include carrier frequency, bandwidth, error correcting codes, modulation order, symbol rate, among others.

After adjusting the physical layer parameters, the underwater vehicle <NUM> may be launched. As the underwater vehicle <NUM> navigates to the target location (e.g., dives), the underwater vehicle <NUM> transmits data to the surface vessel <NUM>. The transmitted data may include salinity data, temperature data, acoustic noise data, among others. The method <NUM> collects this data from the underwater vehicle <NUM> during the mission, step <NUM>. In some embodiments, the data from the underwater vehicle <NUM> is analyzed and compared to the retrieved data (e.g., historical and/or predicted data) used to characterize the physical layer, step <NUM>. The method <NUM> determines if the variation between the data used to characterize the physical layer and the data collected during the dive is greater than a threshold difference, step <NUM>. For example, is the noise greater or less than expected. If the difference does not exceed a threshold, the physical layer parameters remain the same and the method <NUM> continues to collect data from the underwater vehicle <NUM>, step <NUM>. If the difference exceeds the threshold, the method <NUM> recharacterizes the physical layer (e.g., acoustic communication channel, noise channel), step <NUM>. Recharacterizing the acoustic communication channel of the physical layer may include measuring a sound profile during the dive and/or using an acoustic transducer and acoustic receiver (e.g., secondary sensor) located at a known distance from each other. Recharacterizing the acoustic communication channel may also include measuring a Doppler shift using pilot sequences transmitted from the surface vessel <NUM> and/or the underwater vehicle <NUM>. Furthermore, recharacterizing the acoustic communication channel may also include measuring a channel spread using pilot sequences transmitted from the surface vessel <NUM> and/or the underwater vehicle <NUM>.

After recharacterizing the physical layer, the method <NUM> updates the communication performance simulation with the recharacterized physical layer and the data delivery parameters, step <NUM>. In other words, the method <NUM> reruns the communication performance simulation. In response to the results of the updated communication performance simulation, the method <NUM> determines the physical layer parameters changes using a decision algorithm and/or using feedback from an operator, step <NUM>.

After determining the changes to the physical layer parameters, the method <NUM> adjusts the physical layer parameters and/or adjusts vehicle operation, <NUM>. Vehicle operation adjustments, may include changing the position of the surface vessel <NUM> (e.g., position of the surface vessel <NUM> with respect to the underwater vehicle <NUM>), changing the position of the underwater vehicle <NUM> (e.g., the position of the underwater vehicle <NUM> with respect to the surface vessel <NUM>), changing the speed of the surface vessel <NUM> (e.g., acoustic signature), changing the speed of the underwater vehicle <NUM> (e.g., acoustic signature), changing the depth of the underwater vehicle <NUM>, or a combination thereof. These changes may improve communication by reducing distance between the surface vessel <NUM> and the underwater vehicle <NUM>, align modems, reduce acoustic noise (e.g., acoustic noise generated by the motors of the surface vessel <NUM>, the underwater vehicle <NUM>), etc. After adjusting the physical layer parameters and/or vehicle parameters the method <NUM> returns to the collection of data from the underwater vehicle <NUM> during the mission, step <NUM>.

In some embodiments, as the mission or operation of the underwater vehicle <NUM> changes (e.g., traversing, hovering, inspecting), the method <NUM> may adjust the data delivery parameters, step <NUM>. The adjustment may be automatic in response to detecting the operation of the underwater vehicle <NUM> and/or with input from an operator. Once the data delivery parameters change, the method <NUM> may return to step <NUM> and update the communication performance simulation to optimize acoustic telecommunication, step <NUM>.

<FIG> is a flowchart of a method <NUM>, not according to the invention, for setting a data layer of a subsea
telecommunications system <NUM>. As explained above, the underwater vehicle <NUM> may operate in different modes (e.g., traversing, hovering, inspecting). Depending on the mode of operation, a certain set of data delivery parameters may be selected (e.g., latency, data fidelity, spatial resolution, temporal resolution of all the different data feeds). For example, a real-time video feed may be transmitted from the underwater vehicle <NUM> to the surface vessel <NUM> while inspecting equipment. In this situation, the quality and resolution of each frame may be more important than latency and the temporal resolution of the video feed. In another mode of operation, such as steering, minimizing the latency of the data feed may be more important than other parameters. Data delivery parameters may also be selected that facilitate transmission of different data streams (e.g., the transmission of the video and sonar measurements). For example, data delivery parameters may be selected that enhance communication robustness for multiple data streams.

The method <NUM> begins by determining the underwater vehicle's mode of operation, step <NUM>. The mode of operation may be determined by a user, machine learning, and/or signal processing algorithms. For example, an operator may determine that the underwater vehicle <NUM> is approaching a target location and that the underwater vehicle <NUM> will then operate in an inspection mode. The method <NUM> may then determine data delivery parameters using an algorithm in response to the mode of operation, step <NUM>. The data delivery parameters are then transmitted to the underwater vehicle, step <NUM>. The underwater vehicle <NUM> receives the data delivery parameters, step <NUM>. The underwater vehicle <NUM> then updates the data delivery parameters, step <NUM>. In some embodiments, the method <NUM> may include transmission of an acknowledgement from the underwater vehicle <NUM> that the parameters have been updated.

<FIG> is a flowchart of a method <NUM>, not according to the invention, for setting a data layer of a subsea
telecommunications system <NUM>. The method <NUM> begins by selecting desired data deliver parameters, step <NUM>. For example, an operator may bypass a decision algorithm and select desired data delivery parameters for a specific type of data transmission (e.g., video feed for inspecting equipment, steering). The method <NUM> then transmits the data delivery parameters to the underwater vehicle <NUM> (e.g., transmit from the surface vessel <NUM>). The underwater vehicle <NUM> receives the data delivery parameters, step <NUM>. The underwater vehicle <NUM> then updates the data delivery parameters, step <NUM>. In some embodiments, the method <NUM> may include transmission of an acknowledgement from the underwater vehicle <NUM> that the parameters have been updated.

<FIG> is a flowchart of a method <NUM>, not according to the invention, for setting a data layer of a subsea
telecommunications system <NUM>. The method <NUM> begins by determining the underwater vehicle's mode of operation, step <NUM>. The mode of operation may be determined through machine learning and/or signal processing algorithms. For example, the underwater vehicle <NUM> may determine that the underwater vehicle <NUM> is in a steering mode, hovering mode, or an inspection mode. The method <NUM> may then determine data delivery parameters in response to the mode of operation (e.g., determine data delivery parameters using an algorithm), step <NUM>. The underwater vehicle <NUM> then updates the data delivery parameters, step <NUM>. In some embodiments, the method <NUM> may include transmission of an acknowledgement from the underwater vehicle <NUM> that the parameters have been updated.

Claim 1:
A subsea telecommunication system (<NUM>), comprising:
a first acoustic modem (<NUM>) configured to couple to a first vehicle (<NUM>) and to communicate acoustically;
a second acoustic modem (<NUM>) configured to couple to a second vehicle (<NUM>) and to communicate acoustically with the first acoustic modem (<NUM>), wherein the second vehicle (<NUM>) is an underwater vehicle (<NUM>)and
a first computer system (<NUM>) configured to:
receive (<NUM>) an environmental parameter,
characterize (<NUM>) a physical layer of the subsea telecommunication system (<NUM>) in response to the environmental parameter, the physical layer comprising a noise channel and an acoustic communication channel;
determine desired data delivery parameters based on an intended operation of the underwater vehicle (<NUM>), the data delivery parameter comprising one of latency, data fidelity, spatial resolution, and temporal resolution of different data feeds;
conduct a communication performance simulation for the acoustic communication channel using the characterization of the physical layer and the desired data delivery parameters; and
in response to the communication performance simulation, adjust a physical layer parameter of the subsea telecommunication system (<NUM>) in real time, the physical layer parameter comprising one of carrier frequency, bandwidth, error correcting codes, modulation order and symbol rate.