OTHER SIGNAL TECHNOLOGY WITH GIMBAL ON A TETHERED AEROSTAT

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit of the filing date of U.S. Provisional Application No. 62/438,137, filed December 22, 2016, and U.S. Provisional Application No. 62/532,061, filed July 13, 2017, the disclosures of which are incorporated herein by reference.

BACKGROUND

[0002] Free-space optical links can enable communication links by transmitting and receiving signals. Steering mechanisms may maneuver the systems to point toward each other and to track the signals once acquisition is established. A high degree of pointing accuracy may be required to ensure that the optical link is well maintained. In addition, certain weather conditions may be required to maintain a good quality free space optical link.

BRIEF SUMMARY

[0003] Aspects of the disclosure provide for a system. The system includes an aerostat, an antenna assembly attached to the aerostat comprising a free-space optical antenna and a millimeter wave antenna, a tether connected to the aerostat, and one or more processors. The one or more processors are configured to operate a free-space optical communications link using the free-space optical antenna, determine that the free-space optical communications link has deteriorated for a threshold amount of time, and switch from operating the free-space optical communications link to operating a millimeter wave link using the millimeter wave antenna based on the deterioration of the free-space optical communications link.

[0004] In one example, the one or more processors are configured to determine that the free-space optical communications link has deteriorated for a threshold amount of time by determining that a rate of data reception is slower than a threshold rate or determining that a length of detected interruptions to the free-space optical communications link exceeds a threshold length of time. In another example, the tether includes a plurality of sensors along the tether at regular intervals. In this instance, the one or more processors are further configured to receive weather conditions from the plurality of sensors, determine that the received weather conditions are unfavorable to the operation of the free-space optical communications link, and adjust a height of the aerostat based on the determination of unfavorable weather conditions.

[0005] Optionally in this instance, the received weather conditions are unfavorable when it is determined that there is fog at a same or similar altitude as the antenna assembly. Further in this instance, the system also includes a mooring system to which the aerostat is tethered, and the one or more processors are further configured to retract or release the tether from the mooring system to adjust the height of the aerostat. The one or more processors, in this instance, are also optionally further configured to receive updated weather conditions from the plurality of sensors, determine that the updated weather conditions are favorable to the operation of the free-space optical communications link, and reinitiate the operation of the free-space optical communications link when the updated weather conditions are favorable.

[0006] In a further example, the one or more processors are configured to switch from operating the free-space optical communications link to operating a millimeter wave link by initiating the millimeter wave link when the deterioration of the free-space optical communications link is first detected, and, when the deterioration is determined to last for the threshold amount of time, ceasing operation of the free-space optical communications link.

[0007] Other aspects of the disclosure provide for a method. The method includes operating, by one or more processors, a free-space optical communications link using a free-space optical antenna that is attached to an aerostat; determining, by the one or more processors, that the free-space optical communications link has deteriorated for a threshold amount of time; and switching, by the one or more processors, from operating the free-space optical communications link to operating a millimeter wave link using the millimeter wave antenna based on the deterioration of the free-space optical communications link, the millimeter wave antenna being attached to the aerostat.

[0008] In one example, determining that the free-space optical communications link has deteriorated for a threshold amount of time includes determining that a rate of data reception is slower than a threshold rate or determining that a length of detected interruptions to the free-space optical communications link exceeds a threshold length of time. In another example, the method also includes receiving, by the one or more processors, weather conditions from a plurality of sensors positioned along a tether connected to the aerostat; determining, by the one or more processors, that the received weather conditions are unfavorable to the operation of the free-space optical communications link; and adjusting, by the one or more processors, a height of the aerostat based on the determination of unfavorable weather conditions.

[0009] The received weather conditions, in this instance, are unfavorable when it is determined that there is fog at a same or similar altitude as the antenna assembly. Optionally in this instance, the method also includes retracting or releasing, by the one or more processors, the tether from a mooring system to adjust the height of the aerostat. Further in this instance, the method also includes receiving, by the one or more processors, updated weather conditions from the plurality of sensors; determining, by the one or more processors, that the updated weather conditions are favorable to the operation of the free-space optical communications link; and reinitiating, by the one or more processors, the operation of the free- space optical communications link when the updated weather conditions are favorable.

[0010] In a further example, switching from operating the free-space optical communications link to operating a millimeter wave link includes initiating the millimeter wave link when the deterioration of the free-space optical communications link is first detected, and, when the deterioration is determined to last for the threshold amount of time, ceasing operation of the free-space optical communications link.

[0011] Further aspects of the disclosure provide for a non-transitory, tangible computer-readable storage medium on which computer readable instructions of a program are stored. The instructions, when executed by one or more computing devices, cause the one or more computing devices to perform a method. The method includes operating a free-space optical communications link using a free-space optical antenna that is attached to an aerostat, determining that the free-space optical communications link has deteriorated for a threshold amount of time, and switching from operating the free- space optical communications link to operating a millimeter wave link using the millimeter wave antenna based on the deterioration of the free-space optical communications link, the millimeter wave antenna being attached to the aerostat.

[0012] In one example, determining that the free-space optical communications link has deteriorated for a threshold amount of time includes determining that a rate of data reception is slower than a threshold rate or determining that a length of detected interruptions to the free-space optical communications link exceeds a threshold amount of time. In another example, the method also includes receiving weather conditions from a plurality of sensors positioned along a tether connected to the aerostat, determining that the received weather conditions are unfavorable to the operation of the free-space optical communications link, and adjusting a height of the aerostat based on the determination of unfavorable weather conditions.

[0013] In this instance, the received weather conditions are unfavorable when it is determined that there is fog at a same or similar altitude as the antenna assembly. Also in this instance, the method also includes retracting or releasing the tether from a mooring system to adjust the height of the aerostat. The method, in this instance, also optionally includes receiving updated weather conditions from the plurality of sensors, determining that the updated weather conditions are favorable to the operation of the free- space optical communications link, and reinitiating the operation of the free-space optical communications link when the updated weather conditions are favorable.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIGURE 1A is a pictorial diagram of an example communication system 100 in accordance with aspects of the disclosure.

[0015] FIGURE IB is a functional diagram of the example communication system 100 of FIGURE 1A in accordance with aspects of the disclosure.

[0016] FIGURE 2 is a pictorial diagram of an example system 200 in accordance with aspects of the disclosure.

[0017] FIGURE 3A is another pictorial diagram of the example system 200 of FIGURE 2 in accordance with aspects of the disclosure.

[0018] FIGURE 3B is a functional diagram of the example system 200 of FIGURE 2 in accordance with aspects of the disclosure.

[0019] FIGURE 4 is a functional diagram of a communication system 400 in accordance with aspects of the disclosure.

[0020] FIGURE 5 is an example flow diagram 500 in accordance with aspects of the disclosure. DETAILED DESCRIPTION

OVERVIEW

[0021] The technology relates to a communication system including an antenna assembly that is configured to transmit and receive both optical signals and radio frequency (RF) signals. The system may use free space optical communications (FSOC) for long distance communication and/or high data transfers and a second communication mode, such as millimeter wave (MMW) communications, for communication in conditions in which FSOC is less reliable. In this regard, to provide reliable coverage, the communication system may establish an FSOC link and an MMW link sequentially or in parallel.

[0022] The antenna assembly may be mounted on an aerostat, suspended from the aerostat via the tether and other cables, or mounted on a ground station. For transmitting and receiving signals, the antenna assembly of the communication system may have at least a FSOC antenna and a MMW radio frequency antenna. Both the FSOC antenna and the MMW antenna may be mounted on a pointing system, such as, for example, a gimbal, which stabilizes and points the antenna. The FSOC antenna and the MMW antenna may be arranged on the pointing system such that, when the FSOC antenna is pointed by the pointing system in one direction, the MMW antenna is pointed in the same direction, and vice versa.

[0023] An FSOC link may be established using the FSOC antenna. When a deterioration of the FSOC link is detected, the communication system may begin to transmit MMW RF signals. An MMW link may be established and be used in place of the FSOC link.

[0024] In some embodiments, a third communication mode, such as signals utilizing IEEE 802.11 standards, may be used by the communication system in conditions in which both FSOC and MMW communications are less reliable. In these cases, the antenna assembly may include another antenna for a third communication signal, such as a wireless access point configured to transmit signals utilizing IEEE 802.11 standards. The communication system may establish the three different types of links sequentially or in parallel. When a deterioration of both the FSOC link and the MMW link is detected, the communication system may begin to transmit the third communication signal, such as signals utilizing IEEE 802.11 standards.

[0025] Regarding use of the aerostat, the aerostat of the communication system may additionally be configured to float in the air and may be attached to the ground via a tether connected to a mooring system. The tether may include a plurality of sensors that detect weather conditions, such as, for example, moisture levels indicative of foggy conditions. Using the mooring system, the height of the aerostat may be adjusted by retracting or advancing a length of the tether.

[0026] In response to detecting weather conditions that distort optical signals, the height of the aerostat of the communication system may be adjusted in response until the aerostat reaches an altitude where the weather conditions no longer distort optical signals. Once the weather conditions surrounding the aerostat and the antenna assembly are improved to allow for reliable optical signal transmission, the communication system may switch from transmitting MMW RF signals or other communication signals to transmitting optical signals. [0027] In addition, as discussed in detail below, the features described herein allow for various alternatives.

EXAMPLE SYSTEMS

[0028] As shown in FIGURES 1A and IB, a communication system 100 comprises an aerostat 110, antenna assembly 120, tether 130, and mooring system 140. The surface of aerostat 110 may be made of multi-layered Mylar or polyethylene. Other material that allows for the average density of the aerostat 110 to be less than the density of air when the aerostat 110 is filled with a lighter-than-air gas may be used. The average density of the aerostat 110 may be less than the density of air between ground level. In one example, aerostat 110 is at least 300 feet above ground level.

[0029] With continued reference to FIGURES 1A and IB, antenna assembly 120 of the communication system 100 is suspended from aerostat 110 via tether 130 and other cables. In some other embodiments, at least a portion of antenna assembly 120 is mounted on aerostat 110. Antenna assembly 120 includes an FSOC antenna 122 and an MMW antenna 124, as shown in FIGURE IB. FSOC antenna 122 may be configured to transmit and receive optical signals, which can reach long distances, can transfer large amounts of data, and are fairly reliable in rainy weather conditions. MMW antenna 124 may be configured to transmit and receive RF signals, which have a wider solid angle than optical signals and also are more reliable in foggy conditions than optical signals. Specifically, MMW antenna 124 may transmit and receive RF signals at about 50 or 60 gigahertz.

[0030] FSOC antenna 122 and MMW antenna 124 are mounted on pointing system 126. Pointing system 126 is used to stabilize and to position the FSOC antenna 122 and the MMW antenna 124 so that signals from the FSOC antenna 122 and the MMW antenna 124 may be directed to a particular location. For example, pointing system 126 may be a gimbal that is configured to move in at least two degrees of freedom, such as, for example, yaw and pitch. FSOC antenna 122 and MMW antenna 124 may be mounted on pointing system 126 such that, when the pointing system 126 aims the FSOC antenna 122 at a particular location, the MMW antenna 124 is aimed in the same location, and vice versa. Other mechanical and/or electronic means of pointing or steering transmitted optical or RF signal may additionally or alternatively be included in pointing system 126.

[0031] As depicted in FIGURE IB, the antenna assembly 120 includes one or more processors 128. The one or more processors 128 may be any conventional processors, such as, for example, commercially available CPUs or may be a dedicated device such as, for example, an ASIC or other hardware-based processor. The one or more processors 128 are configured to receive data received at FSOC antenna 122 or MMW antenna 124, and process the received data as further described below. For example, the one or more processors 128 may receive signals from FSOC antenna 122 or MMW antenna 124 and may process the signals to determine whether to use an FSOC link or a MMW link.

[0032] Additionally, the one or more processors 128 are configured to operate the antenna assembly 120, which includes transmitting signals via FSOC antenna 122 and MMW antenna 124, receiving signals via the antennas, and moving the antennas via pointing system 126. The one or more processors 128 may also be configured to track a location of signal source, such as, for example an antenna of another communication system and adjust the direction and/or location of antennas 122, 124 using pointing system 126 based on the tracked location.

[0033] With reference to FIGURES 1 A and IB, aerostat 110 and antenna assembly 120 are connected to tether 130. In one particular embodiment, tether 130 may be made of high strength cable material, such as, for example, those used in nautical ropes or cables. In other embodiments, tether 130 may be long enough to allow aerostat 110 connected to tether 130 to reach a predetermined maximum height from ground level. For example, the length may be 50 feet or 300 feet or 1000 feet. Tether 130 carries wires including, for example, power cables, fiber optic cables, and/or wiring for antenna assembly 120 and sensors 132. A plurality of sensors 132 are attached along the length of tether 130. In communication system 100, sensors 132 are spaced apart at regular intervals, such as, for example, 10 meter intervals or smaller. Sensors 132 are configured to detect one or more conditions of the atmosphere. For example, sensors 132 are configured to detect changes in moisture levels, or humidity, in the atmosphere.

[0034] As further shown in FIGURE 1A and IB, the end of tether 130 opposite the aerostat 110 is connected to mooring system 140. Mooring system 140 is configured to secure aerostat 110, process data from antenna assembly 120 and sensors 132, and operate the antenna assembly 120. To secure aerostat 110, mooring system 140 may include hardware configured to hold, retract, and release tether 130, such as, for example, a winch. Tether 130 may be wound about a winch, and may be controlled to raise or lower aerostat 110 by, respectively, unwinding or winding the tether 130. In addition, mooring system 140 may be mobile and thereby may be used to change the location of the aerostat 110 by moving to a different location. For example, mooring system 140 includes a vehicle that may be driven from location to location. In other alternatives, mooring system 140 may be stationary.

[0035] As illustrated in FIGURE IB, to process data from sensors 132, mooring system 140 includes one or more processors 142 and memory 144. The one or more processors 142 may be any conventional processors, similar to the one or more processors 128. The one or more processors 142 are configured to receive data received at sensors 132 via wiring in tether 130, and process the received data as further described below. For example, the one or more processors 142 may receive humidity measurements from the plurality of sensors 132 and may process the humidity measurements to determine whether to use an FSOC link or a MMW link. In addition, the one or more processors 142 are configured to communicate with the one or more processors 128 of antenna assembly 120 via wiring in tether 130.

[0036] Memory 144 of mooring system 140 stores information accessible by the one or more processors 128, 142, including instructions 146 and data 148 that may be executed or otherwise used by the one or more processors 128, 142, in order to perform some or all of the features described herein. Memory 144 may be any type of computerized storage capable of storing information accessible by one or more processors 128, 142, such as, for example, a hard-drive, memory card, ROM, RAM, DVD, CD-ROM, write-capable, and read-only memories.

[0037] The instructions 146 may be any set of instructions to be executed directly (such as machine code) or indirectly (such as scripts) by the one or more processors 128, 142. For example, the instructions 146 may be stored as computing device code on the computing device-readable medium. In that regard, the terms "instructions" and "programs" may be used interchangeably herein. The instructions 146 may be stored in object code format for direct processing by the processor, or in any other computing device language including scripts or collections of independent source code modules that are interpreted on demand or compiled in advance.

[0038] The data 148 may be retrieved, stored or modified by the one or more processors 128, 142 in accordance with the instructions 146. For instance, although the claimed subject matter is not limited by any particular data structure, the data 148 may be stored in computing device registers, in a relational database as a table having a plurality of different fields and records, XML documents or flat files. The data 148 may also be formatted in any computing device-readable format. Data 148 may include one or more weather conditions that are unfavorable for transmission of optical signals, such as, for example, fog, and that are favorable for transmission of optical signals. Also included one or more weather conditions that are unfavorable for transmission of MMW signals, such as, for example, rain, and that are favorable for transmission of MMW signals. In addition, data 148 may include threshold values related to determining whether the weather conditions are favorable or unfavorable to a type of signal, such as a threshold moisture level. Unfavorable and favorable weather conditions for other types of signals may be included in data 148 as well.

[0039] In FIGURES 2, 3A and 3B, an example system 200 in which communication system 100 may be used is shown. The example system 200 includes communication systems 100 and 102. Communication system 102 may, like communication 100, have an aerostat 210, antenna assembly 220, tether 230, and mooring system 240, which may have the same configuration as aerostat 110, antenna assembly 120, tether 130, and mooring system 140 described above. Alternatively, mooring system 240 may be positioned on a building, as shown FIGURE 2.

[0040] As further shown in FIGURE 2, communication systems 100, 102 are configured to establish a point-to-multipoint communication link, such as, for example, a link utilizing IEEE 802.11 standards, with user devices and/or storage systems in surrounding geographic areas. For example, communication system 100 has communication links 250, 252 with one or more devices and systems in geographic areas 260, 262, respectively, and communication system 102 has communication links 254 with one or more user devices in geographic area 264. The geographic areas 260, 262, 264 may be about 4 square miles (about 10 square kilometers) or more or less. Communication systems 100, 102 are also configured to establish at least one communication link 270 with each other and other communication systems. Other communication systems may include stationary ground systems, high-altitude platform systems, and satellites. The at least one communication link 270 may be an FSOC link established between the FSOC antennas of communication systems 100, 102 and/or an MMW link established between the MMW antennas of the communication systems 100, 102.

[0041] As depicted in FIGURE 3A, devices from the nearby geographic areas with which communication systems 100, 102 may establish communication links may include computing devices and storage systems. As shown in FIGURE 3A, system 200 includes a plurality of computing devices 310, 320, 330 and a storage system 340. Computing device 310 is in geographic area 260, computing device 320 and storage device 340 are in geographic area 262, and computing device 330 is in geographic area 264. Although only a few computing devices are depicted for simplicity, a typical system may include significantly more.

[0042] As shown in FIGURE 3B, each of computing devices 310, 320, 330 may include one or more processors, memory, instructions and data. Such processors, memories, instructions and data, such as one or more processors 312, memory 314, instructions 316 and data 318 of computing device 310, may be configured similarly to one or more processors 128, memory 144, instructions 146, and data 148 of communication system 100.

[0043] Using communication links, such as communication links 250, 252, 254, 270, server computing devices 310 may transmit and present information to a user, such as user 322, 332 on a display, such as displays 324, 334 of computing devices 320, 330. In this regard, computing devices 320, 330 may be considered client computing devices. Each client computing device 320, 330 may be a personal computing device intended for use by a user 322, 332, and have all of the components normally used in connection with a personal computing device including one or more processors (e.g., a central processing unit (CPU)), memory (e.g., RAM and internal hard drives) storing data and instructions, a display such as displays 324, 334 (e.g., a monitor having a screen, a touch-screen, a projector, a television, or other device that is operable to display information), and user input devices 326, 336 (e.g., a mouse, keyboard, touch screen or microphone). The client computing devices may also include a camera for recording video streams, speakers, a network interface device, and all of the components used for connecting these elements to one another. In addition, the client computing devices 320, 330 may also include components 328, 338 for determining the position and orientation of client computing devices. For example, these components may include a GPS receiver to determine the device's latitude, longitude and/or altitude as well as an accelerometer, gyroscope or another direction/speed detection device.

[0044] Although the client computing devices 320, 330 may each comprise a full-sized personal computing device, they may alternatively comprise mobile computing devices capable of wirelessly exchanging data with a server over a network such as, for example, the Internet. By way of example only, client computing device 330 may be a mobile phone or a device such as, for example, a wireless- enabled PDA, a tablet PC, a wearable computing device or system, or a netbook that is capable of obtaining information via the Internet or other networks. As an example the user may input information using a small keyboard, a keypad, microphone, using visual signals with a camera, or a touch screen.

[0045] Storage system 340 may store various types of information that may be retrieved or otherwise accessed by one or more processors, such as the one or more processors of computing devices 310, 320, 330 and communication systems 100, 102, in order to perform some or all of the features described herein. The storage system 340 may also store data and communications received at communication systems 100, 102.

[0046] As with memories 144, 314, storage system 340 may be any type of computerized storage capable of storing information accessible by the one or more processors of computing devices 310, 320, 330 and communication systems 100, 102, such as, for example, a hard-drive, memory card, ROM, RAM, DVD, CD-ROM, write-capable, and read-only memories. In addition, storage system 340 may include a distributed storage system where data is stored on a plurality of different storage devices which may be physically located at the same or different geographic locations. Storage system 340 may be connected to the one or more processors via one or more communication links 250, 252, 254, 270 as shown in FIGURES 3A and 3B and/or may be directly connected to or incorporated into any of the computing devices 310, 320, 330, communication systems 100, 102, etc.

[0047] Alternatively, the communication system 100 may be a ground station rather than an aerostat with a tether and a mooring system. The antenna assembly 120 may be mounted on a ground station at a fixed height. Sensors 132 may be located at different heights on the body of the ground station rather than on the tether.

[0048] As shown in FIGURE 4, the antenna assembly 120 of the communication system 400 may include a third antenna in another embodiment. The communication system 400 may otherwise have the same or similar components as communication system 100. The third antenna may also be mounted on pointing system 126 such that the third antenna is consistently aimed in the same direction as the FSOC antenna 122 and the MMW antenna 124. The third antenna may be a wireless access point 125 configured to transmit and receive signals utilizing IEEE 802.11 standards, which can reach shorter distance than either the optical signals or the MMW RF signals and are more reliable than the MMW RF signals in certain conditions, such as, for example, dense fog. The third antenna may also be an LTE antenna or any other type of antenna configured to transmit and receive a communication signal having different properties than the FSOC signals and the MMW signals. The LTE antenna may be configured to transmit and receive LTE signals, which may be more reliable than FSOC and MMW RF signals in certain circumstances.

[0049] While the examples discussed above describe communications systems that have two or three antennae and two or three communication modes, it should be understood that communication systems may have more than three antennae and more than three communication modes. Communication systems may also have different types and combinations of antennae and communication modes than those described above.

EXAMPLE METHODS

[0050] FIGURE 5 is a flow diagram 500 in accordance with some of the aspects described above that may be performed by one or more processors 142 of communication system 100. While FIGURE 5 shows blocks in a particular order, the order may be varied and that multiple operations may be performed simultaneously. Also, operations may be added or omitted.

[0051] At block 502, an FSOC link is operated using an FSOC antenna that is attached to an aerostat. An FSOC link may be established between communication systems 100, 102 using FSOC antennas 122. Optical signals may be transmitted and received using FSOC antenna 122 of communication system 100 by the one or more processors 128 of antenna assembly 120. The optical signals may carry communications and data transmitted from one or more computing devices 310, 320, 330 and/or retrieved from storage system 340. [0052] At block 504, the one or more processors 128 may determine that there is deterioration of the FSOC link. For example, the determination of deterioration may be made based on at least one indication of link quality that is monitored by the one or more processors 128. Indications of link quality may include a bit error rate (BER), latency, a rate of data reception, a length of detected interruptions in the optical signals received from communication system 102, a received signal strength indicator (RSSI), and a number of signal quality events (SQEs). For example, a BER may be detected and compared to a threshold BER. When the detected BER meets or exceeds the threshold BER, the one or more processors 128 may determine the FSOC link has deteriorated. Additionally or alternatively, determination of deterioration may be made when the rate of data reception slows to below a threshold data reception rate, the latency exceeds a threshold amount of time, an interruption in the received optical signals lasts over a threshold interruption time amount, the RSSI lowers to below a threshold value, and/or the number of SQEs exceeds a threshold number. The threshold values of each indication of link quality may be determined based on customer availability requirements.

[0053] At block 506, when deterioration of the FSOC link is detected, the one or more processors 128 may initiate the second communications link using the second antenna, such as MMW antenna 124, in a low power mode. The initial MMW signals may carry communications and data that instruct the one or more processors of communication system 102 to initiate MMW communication as well.

[0054] At block 508, the one or more processors 128 may determine which link has a higher overall quality. In the low power mode, the one or more processor 128 may monitor one or more indications of link quality of the established MMW link. The one or more indications of link quality of the MMW link may be compared with the indications of link quality of the FSOC link to see which link may have better overall quality. The link having more indications of link quality that indicate higher quality than the other link may have the better overall quality.

[0055] Additionally or alternatively, the deterioration of FSOC link may be determined to last for over a threshold deterioration time amount. For example, the threshold deterioration time amount may be one minute or more or less. The deterioration of the FSOC link may be determined to exceed the threshold deterioration time amount when, for example, the data reception rate remains below a threshold data reception rate for over a minute and/or when the interruption in the received optical signal lasts over a minute after the threshold interruption time amount is reached. In other embodiments, the threshold deterioration time amount may be set as more or less than one minute.

[0056] At block 510, under certain conditions, a MMW link may be operated using an MMW antenna instead of the FSOC link at block 506. In other words, when either the MMW link is determined to have the better overall quality or the maximum threshold deterioration time amount is met, the one or more processors 128 may switch from operating FSOC antenna 122 to operating MMW antenna 124 in order to use the MMW link. MMW signals may be transmitted and received using MMW antenna 124 of communication system 100 by the one or more processors 128. After switching to using the MMW link between communication systems 100, 102, MMW signals may carry communications and data transmitted from one or more computing devices 310, 320, 330 or retrieved from storage system 340. In some alternatives, the one or more processors 128 may further attempt to reestablish the FSOC link at least one time before switching from operating FSOC antenna 122 to operating MMW antenna 124.

[0057] The one or more processors 128 may switch back to operating FSOC antenna 122 after a predetermined amount of time. The one or more processors 128 may also switch from operating MMW antenna 124 to operating FSOC antenna 122 when the MMW link is detected to have deteriorated such that the FSOC link has the better overall quality. The deterioration of the MMW link may be detected using the indications of link quality described above. For the switch back to operating FSOC antenna 122, the MMW link may be operated at full power while the FSOC link is initiated. Once the FSOC link is established, the MMW link may be ceased.

[0058] For the embodiment in which the antenna assembly 120 includes a third antenna, such as wireless access point 125 in communication system 400, the one or more processors 128 may switch to operating the third antenna under certain conditions. In this embodiment, the link utilizing IEEE 802.11 standards may be initiated at block 506 in the low power mode when the FSOC link is determined to have deteriorated a threshold amount as described above. The initial signals utilizing IEEE 802.11 standards may carry communications and data that instruct the one or more processors of communication system 102 to initiate communication utilizing IEEE 802.11 standards as well. The one or more processors 128 may monitor the link utilizing IEEE 802.11 standards and may switch to operating wireless access point 125 to use the link utilizing IEEE 802.11 standards when the link utilizing IEEE 802.11 standards is determined to have a better overall quality than both the FSOC link and the MMW link based on the indications of link quality, as described above. In some other embodiments, the link utilizing IEEE 802.11 standards may be initiated when the one or more processors 128 is operating the MMW antenna and the overall quality of the link utilizing IEEE 802.11 standards is determined to be higher than that of the FSOC and MMW links.

[0059] Alternatively, the third antenna may be an LTE antenna in communication system 400, and the one or more processors 128 may switch to operating the LTE antenna under certain conditions. In this embodiment, the LTE link may be initiated at block 506 in the low power mode when the FSOC link is determined to have deteriorated a threshold amount as described above. The initial LTE signals may carry communications and data that instruct the one or more processors of communication system 102 to initiate LTE communication as well. The one or more processors 128 may monitor the LTE link and may switch to operating the LTE antenna to use the LTE link when the LTE link is determined to have a better overall quality than both the FSOC link and the MMW link based on the indications of link quality, as described above. In some other embodiments, the LTE link may be initiated when the one or more processors 128 is operating the MMW antenna and the overall quality of the LTE link is determined to be higher than that of the FSOC and MMW links.

[0060] Alternatively, FSOC, MMW, and links utilizing IEEE 802.11 standards may be run in parallel, rather than sequentially as described above. One type of link may be a primary link that is run at full power while the one or two other links may be secondary links that are run in the low power mode. While in low power mode, the one or two other links may be monitored by the one or more processors 128 to determine whether one of the other links has a higher quality than the primary link. Initially, the FSOC link may be the primary link, and the MMW and/or links utilizing IEEE 802.11 standards may be the secondary link(s). When the FSOC link deteriorates, the MMW link or the link utilizing IEEE 802.11 standards may be the primary link, and the FSOC link may be the secondary link along with the other non-primary link, if any. By operating in parallel, the switch from one type of link to the other may be near instantaneous. In addition, while operating all antennae in parallel, the one or more processors 128 may determine which of the links have a highest overall quality at any given moment, rather than make the determination after deterioration of a link is detected, and switch to operating the link having the highest overall quality. The one or more processors 128 may determine which link has the highest overall quality at set intervals, such as every five minutes, or may continually make the determination. The intervals may also be more or less than five minutes.

[0061] Furthermore, in some alternatives, deterioration of the FSOC link may be also determined based in part on what the signal indicates regarding the favorability of the weather condition. The one or more processors 128 of antenna assembly 120 may receive the signal from the one or more processors 142 of mooring system 140. The signal may be received at regular intervals or may be sent in response to a request from the one or more processors 142. When the signal indicates that weather conditions are unfavorable to optical signals and/or favorable to MMW signals, the one or more processors 128 may weigh the indication in favor of operating MMW antenna 124 instead of FSOC antenna 122. When the signal indicates that weather conditions are favorable to optical signals and/or unfavorable to MMW signals, the one or more processors 128 may weigh the favorability indication in favor of operating FSOC antenna 122 instead of MMW antenna 124. Similar determinations may be performed based on the signal regarding the favorability of the weather condition for signals utilizing IEEE 802.11 standards or other communication mode included in the antenna assembly 120.

[0062] Weather conditions in geographic locations of communication systems 100 may be determined to be unfavorable for optical signals by the one or more processors 142 of mooring system 140. The weather conditions may be detected via sensors 132 of communication systems 100 and received at the one or more processors 142, determined via weather reports received at the one or more processors 142, or a combination of the two. For example, the detected weather conditions may include moisture or humidity measurements at varying altitudes of sensors 132. Based on the humidity measurements, the one or more processors 142 may determine that there is weather condition at a particular altitude or altitudes, e.g., a range of altitudes. The one or more processors 142 may determine that the weather condition at the particular altitude or altitudes affects optical signals transmitted or received at FSOC antenna 122. For example, it may be determined that fog is present from 225 feet to 275 feet. The one or more processors 142 may then access the one or more weather conditions that are unfavorable for optical signals, and determine that fog is one of the unfavorable weather conditions. Because the height of the antenna assembly 120 of 246 feet falls within the altitude range of the fog, the one or more processors 142 may determine that the fog would affect optical signals being transmitted or received at FSOC antenna 122. [0063] When the unfavorable weather condition is detected, the one or more processors 142 may change the height of the aerostat 110 using mooring system 140. The one or more processors 142 may determine a change in height that would prevent the unfavorable weather conditions from interfering with FSOC antenna 122 of communication system 100. The one or more processors 142 may then retract or release a length of tether 130 from mooring system 140 based on the determined change in height. The length of tether 130 may be the same or a longer distance than the determined change in height. As a result of retracting or releasing the length tether 130, the aerostat 110 may be lowered or float higher, thereby changing the height of antenna assembly 120. For example, aerostat 110 of communication system 100 may be floating at a height of about 250 feet above ground level. Antenna assembly 120 may be suspended at about 246 feet above ground level. When fog is detected around tether 130 between 225 and 275 feet, the one or more processors 142 may determine the change in height to be 30 feet higher so that the height of antenna assembly 120 may change from 246 feet to 276 feet, which would be above the detected fog. Mooring system 140 may then release at least 30 feet of tether 130, and the buoyancy of aerostat 110 lifts antenna assembly 120 up to at least 276 feet. The one or more processors 142 may further be configured to communicate with processors of other mooring stations, such as mooring station 240, to coordinate a simultaneous or near simultaneous heightening or lowering of other aerostats, such as aerostat 210, in order to maintain one or more communication links 270 between the antenna assemblies, such as antenna assemblies 120, 220.

[0064] When weather conditions are determined to be favorable for optical signals at a later point in time, the one or more processors 142 may send a signal to the one or more processors 128 of antenna assembly 120. The determined weather conditions may be updated continually or at regular intervals based on measurements from sensors 132, received weather reports, or a combination of the two. The one or more processors 142 may determine that the weather conditions are favorable for optical signals when, for example, fog is no longer detected at the altitude of antenna assembly 120. When the weather conditions become favorable for optical signals, the one or more processors 142 may transmit a signal indicating favorable weather conditions for optical signals to the one or more processors 128 of communication system 100 to initiate an FSOC link. Based on what the signal indicates, the one or more processors 128 of antenna assembly 120 may switch from operating MMW antenna 124 to operating FSOC antenna 122 to establish an FSOC link. Additionally, the one or more processors 142 may transmit a signal to the one or more processors of the mooring system of communication system 102 indicating favorable weather conditions for optical signals. The communication system 102 may, in response to the received signal from the one or more processors 142, also initiate an FSOC link.

[0065] Weather conditions may alternatively be determined using one or more processors that are located on antenna assembly 120, tether 130, and/or sensors 132, such as the one or more processors 128. In this alternative, the one or more processors on antenna assembly 120, tether 130, and/or sensors 132 may form a closed loop that may be configured to switch between the FSOC link and the MMW link without using the one or more processors 142 at mooring system 140. [0066] The features described above may provide for an integrated approach for using FSOC, MMW RF, and other wireless access technology that allows for users to have access to a network even in remote areas. The integrated approach adapts to changing weather conditions that may affect one type of link, thereby providing users with a more reliable and faster connections to the network. That the technology may be used on an aerostat allows for reduced cost as well as easy transportability to more remote areas. A user is therefore more likely to use the network because it may be cheaper and easier to set up and may provide more reliable coverage.

[0067] Unless otherwise stated, the foregoing alternative embodiments are not mutually exclusive, but may be implemented in various combinations to achieve unique advantages. As these and other variations and combinations of the features discussed above can be utilized without departing from the subject matter defined by the claims, the foregoing description of the embodiments should be taken by way of illustration rather than by way of limitation of the subject matter defined by the claims. In addition, the provision of the examples described herein, as well as clauses phrased as "such as," "including" and the like, should not be interpreted as limiting the subject matter of the claims to the specific examples; rather, the examples are intended to illustrate only one of many possible embodiments. Further, the same reference numbers in different drawings can identify the same or similar elements.