Patent Application
20090318138
Personal wireless communication continues to grow in popularity and expand into new geographic areas as technology improves and decreases in cost. For example, the number of cell phone users continues to increase each year. Also, wireless service is available for more laptop computers through increased numbers of Wi-Fi spots and wireless adapter cards for access via cellular networks. However, one area in which personal wireless communication is prohibitively expensive or unavailable is on aircraft during flights. Wireless communication, if available, is provided through satellite communication which is expensive compared to the cost of similar non-flight service through cellular carriers. However, to avoid interference with aircraft communication, regulatory agencies, such as the Federal Aviation Administration in the United States, do not allow wireless communication via typical cellular carriers.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for an improved system and method of delivering in-flight personal wireless communication which does not interfere with aircraft communication.
The above mentioned problems and other problems are resolved by the present invention and will be understood by reading and studying the following specification.
In one embodiment, an aircraft radio is provided. The aircraft radio comprises a transmitter configured to transmit wireless signals over a transmit frequency; a receiver configured to receive wireless signals over a receive frequency; and a processing unit configured to adjust the transmission frequency of the aircraft radio based on received sensor data in order to avoid interference with other wireless transmissions; wherein the processing unit is further configured to determine if a ground station is in range of the aircraft radio and to communicate directly with a second aircraft radio on another aircraft when a ground station is not in range.
Features of the present invention will become apparent to those skilled in the art from the following description with reference to the drawings. Understanding that the drawings depict only typical embodiments of the invention and are not therefore to be considered limiting in scope, the invention will be described with additional specificity and detail through the use of the accompanying drawings, in which:
In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize specific features relevant to the present invention. Like reference numbers and designations in the various drawings indicate like elements.
In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific illustrative embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that logical, mechanical, and electrical changes may be made without departing from the scope of the present invention. Furthermore, the method presented in the drawing figures or the specification is not to be construed as limiting the order in which the individual steps may be performed. The following detailed description is, therefore, not to be taken in a limiting sense.
Embodiments of the present invention use previously unavailable frequencies to provide sufficient bandwidth for personal wireless communication on aircraft such as video services, cell phone service, internet service, etc. In particular, embodiments of the present invention utilize the frequency range previously reserved for over-the-air analog television broadcasts. In the United States this frequency range covers channels 2-51, with each channel being 6 MHz wide, and spans the following ranges: 54-72 MHz, 76-88 MHz, 174-216 MHz, and 470-698 MHz. The Federal Communications Commission (FCC) has announced that the channels in these frequency ranges will be available for unlicensed use when analog TV broadcasts switch to digital broadcasts. Other nations have also expressed interest in allowing unlicensed use of analog television frequencies. Hence, embodiments of the present invention can also be configured to transmit in the unused TV frequencies when flying over any such nation and during transoceanic flights.
In order to use these frequencies, however, aircraft radio transmission can not interfere with the broadcasts of incumbent users of the frequency spectrum, such as TV broadcasters. Although the IEEE 802.22 working group is working on an international standard for the use of this frequency spectrum without causing interference in terrestrial applications, the standard, as outlined, is not well-suited for aircraft communications. For example, IEEE 802.22 specifies the use of a fixed point-to-multipoint network with a base station controlling frequency assignments and changes. However, aircraft are often flying where a ground base station is not available, such as during transoceanic flights.
Hence, embodiments of the present invention are configured to use both a fixed point-to-multipoint network and a wireless ad hoc network. As used herein, a wireless ad hoc network is a network in which each aircraft is directly coupled to at least one other network and forwards data for other aircraft. Embodiments of the present invention automatically discover the current topology of an ad hoc or point-to-multipoint network in order to route data to its destination. For example,
In
Once a ground station is reached, nodes D and E respond to node B while nodes F and G respond to node C. Node B aggregates the responses from nodes D and E with its own response and sends the aggregated response to node A. Similarly, node C aggregates the responses from nodes F and G and sends the aggregated response to node A. Node A then analyzes the results to discover the topology of the ad hoc network. Based on the discovered topology, node A is able to determine a route from node A to a ground station. Since the network topology changes frequently, node A updates the topology discovery periodically by repeating the above process.
Alternatively,
Node D receives the forwarded discovery message and forwards it to additional nodes not shown until a ground station is reached. Once a ground station is reached, node D responds to node C (indicated by arrow 3). Node C aggregates the response from node D with its own response and sends the aggregated response to node A (indicated by arrow 4). Node A then analyzes the results to discover the topology of the ad hoc network. Based on the discovered topology, node A is able to determine a route from node A to a ground station. Since the network topology changes frequently, node A updates the topology discovery periodically by repeating the above process.
Nodes A-F in
Radio 302 uses the data received from sensors 304 and scanner 306 to adjust the power, frequency, modulation scheme, and/or other parameters to avoid interference with other transmissions and use the available spectrum. Additionally, radio 302 is configured to avoid interfering with communication on-board the aircraft. For example, in some embodiments, techniques described in co-pending U.S. patent application Ser. No. ______ (attorney docket no. H0018694), incorporated herein by reference, are used to avoid interference with both on-board communication and other transmissions to/from the aircraft. Radio 302 then transmits data received from devices 301 on-board the aircraft using the selected frequencies from the analog TV spectrum. Devices 301 can include, but are not limited to, cell phones, laptop computers, personal digital assistants, etc. In addition, devices 301 can be connected wirelessly or via a wired connection to radio 301. Alternatively, devices 301 can be connected to a separate processing unit which processes the data and provides the data to radio 302.
Processor 410 also causes discovery messages to be transmitted over a selected frequency or set of frequencies, to discover the topology as discussed above. In particular, processor 410 determines if an ad hoc network connection or a fixed point-to-multipoint network connection is being used. For example, if processor 410 determines that a ground station is not in range, processor 410 is configured to process and transmit data for an ad hoc network connection. However, if processor 410 determines that a ground station is in range, processor 410 switches to a point-to-multipoint connection in which the ground station is responsible for directing processor 410 to switch frequencies when necessary.
Processor 410 includes or functions with software programs, firmware or computer readable instructions for carrying out various methods, process tasks, calculations, and control functions, used in calculating the desired speeds for an autonomous vehicle. These instructions are typically tangibly embodied on any appropriate medium used for storage of computer readable instructions or data structures. Such computer readable media can be any available media that can be accessed by a general purpose or special purpose computer or processor, or any programmable logic device. Suitable computer readable media may include storage or memory media such as magnetic or optical media, e.g., disk or CD-ROM, volatile or non-volatile media such as RAM (e.g. SDRAM, DDR SDRAM, RDRAM, SRAM, etc.), ROM, EEPROM, flash memory, etc. as well as transmission media such as electrical, electromagnetic, or digital signals, conveyed via a communication medium such as a network and/or a wireless link. In this embodiment, the instructions are stored on storage medium 408.
When radio 302 receives a broadcast from another aircraft radio, processor 410 determines if the data is addressed to a device on the aircraft. If it is, processor 410 processes the data and provides it to the device. If not, processor 410 forwards the data over a selected frequency to one or more other aircraft. Processor 410 selects the frequency or set of frequencies independently of the frequency on which it was received. In this way, each aircraft radio in a transmission path of an ad hoc network is responsible for determining the frequency to use for forwarding and transmitting data in order to avoid interference. In some embodiments, one set of frequencies is selected for forwarding data and another is selected for transmission of data from devices on the aircraft. In other embodiments, the same set of frequencies are used.
Hence, unlike the standard defined by IEEE 802.22, each aircraft's radio is configured to make decisions regarding transmission power, transmission frequency, etc. and to make necessary changes. In addition, each aircraft's radio is configured to adjust modes when a ground station is in range to allow the ground station to control channel assignment, power levels, etc. similar to a wireless device under control of a base station in the IEEE 802.22 standard. In one embodiment, the radio determines if a ground station is in range by submitting a discovery message and detecting if a ground station responds.
At 510, the aircraft radio selects a route for data to be sent from the aircraft to a ground station. In particular, the aircraft radio transmits with the data information identifying the aircraft that are to forward the data. Hence, an aircraft which hears the data but is not identified as a forwarding aircraft can simply drop the data. In some embodiments, the aircraft radio selects the route based on the location of the aircraft discovered during topology discovery. In other embodiments, the aircraft are selected based on airline agreements. Exemplary methods of selecting the route are further described in the '977 application.
At 512, the aircraft radio selects the frequency or set of frequencies on which to transmit the data. In particular, the aircraft radio performs detect and avoid techniques as known to one of skill in the art. At 514, the aircraft radio transmits the data on the selected frequency. In particular, the frequency selected is in the range of analog TV frequencies as described above.
At 710, the surrounding aircraft with highest priority forwards the discovery message. The other surrounding aircraft, which hear the forwarded message, do not forward the discovery message. If the other surrounding aircraft do not hear the forwarded message, the next highest priority aircraft forwards the discovery message. Additional aircraft in range of the priority aircraft forward the received discovery message at 712. The discovery message is forwarded again until, at 714, it is determined that a ground station has received the discovery message. The ground station broadcasts a discovery response, at 716, which each additional receiving aircraft in range receives. The discovery message contains information identifying the ground station. Each additional receiving aircraft in range of the ground station aggregates the ground station information with information identifying itself and forwards the aggregated response at 718. Each receiving aircraft continues to aggregate and forward the response until all the aggregated responses are received by the first aircraft, at 720, which originated the discovery message. The first aircraft then analyzes the response to determine the topology of the network at 722.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.
