Maintaining contiguous ground coverage with high altitude platforms

Abstract

Example methods and systems for adjusting the beam width of radio frequency (RF) signals for purposes of balloon-to-ground communication are described. One example method includes determining, based on respective locations of a plurality of balloons and areas covered by respective ground-facing communication beams of the balloons, a contiguous ground coverage area served by the plurality of balloons, where the communication beam of a balloon defines a corresponding individual coverage area within the ground coverage area, determining a change in position of at least one of the balloons, based on the change in position of the at least one balloon, determining an adjustment to a first of the individual coverage areas in an effort to maintain the contiguous ground coverage area after the change in position of at least one of the balloons, and adjusting a width of the ground-facing communication beam of the balloon corresponding to the first individual coverage area in order to make the determined adjustment to the first individual coverage area.

We claim: 
     
         1 . A method comprising:
 determining, by one or more processors, state information for a plurality of high altitude platforms forming at least part of a wireless communication network, the state information including location data for each of the plurality of high altitude platforms, communication link information and meteorological information;   predicting, by the one or more processors, a potential coverage gap of the wireless communication network based on expected movement of one or more of the plurality of high altitude platforms and at least a portion of the state information;   in response to the predicted potential coverage gap, selecting one of a plurality of antennas of a given one of the plurality of high altitude platforms to adjust a coverage area of the given one of the plurality of the plurality of high altitude platforms; and   transmitting a communication signal to a receiver device via the selected antenna of the given one of the plurality of high altitude platforms.   
     
     
         2 . The method of  claim 1 , wherein selecting one of the plurality of antennas includes switching from a first antenna having a first beam width to a second antenna having a second beam width, the first beam width being narrower than the second beam width. 
     
     
         3 . The method of  claim 1 , wherein selecting one of the plurality of antennas includes switching from a first antenna having a first beam width to a second antenna having a second beam width, the first beam width being wider than the second beam width. 
     
     
         4 . The method of  claim 3 , wherein the antenna with the second beam width is selected to decrease a coverage area size and to provide a stronger signal to a smaller area on the ground. 
     
     
         5 . The method of  claim 1 , wherein selecting one of the plurality of antennas includes adjusting a beam width to provide a certain amount of coverage to particular areas on the ground based on demand level. 
     
     
         6 . The method of  claim 1 , wherein:
 the given one of the plurality of high altitude platforms comprises a balloon; and   predicting the potential coverage gap of the wireless communication network includes evaluating the meteorological information associated with the balloon to determine an expected altitude or lateral position change to the balloon.   
     
     
         7 . The method of  claim 1 , further comprising:
 determining a contiguous ground coverage area by the plurality of high altitude platforms based on individual coverage areas for each of the high altitude platforms;   wherein selecting one of the plurality of antennas includes choosing an antenna beam width to provide the contiguous ground coverage area with a minimal amount of overlap between the individual coverage areas.   
     
     
         8 . The method of  claim 1 , further comprising:
 determining a contiguous ground coverage area by the plurality of high altitude platforms based on individual coverage areas for each of the high altitude platforms;   wherein selecting one of the plurality of antennas includes choosing an antenna beam width to provide the contiguous ground coverage area with a determined amount of overlap between the individual coverage areas to provide redundancy between at least some of the plurality of high altitude platforms.   
     
     
         9 . The method of  claim 1 , further comprising:
 determining a service level demand within a first region of a contiguous coverage area;   wherein selecting one of the plurality of antennas includes choosing from among the plurality of antennas to satisfy the service level demand within the first region of the contiguous coverage area.   
     
     
         10 . A system comprising:
 a plurality of high altitude platforms forming at least part of a wireless communication network; and   a control system including one or more processors, the one or more processors being configured to:   determine state information for the plurality of high altitude platforms, the state information including location data for each of the plurality of high altitude platforms, communication link information and meteorological information;   predict a potential coverage gap of the wireless communication network based on expected movement of one or more of the plurality of high altitude platforms and at least a portion of the state information;   in response to the predicted potential coverage gap, select one of a plurality of antennas of a given one of the plurality of high altitude platforms to adjust a coverage area of the given one of the plurality of the plurality of high altitude platforms; and   instruct the given high altitude platform to use the selected antenna when transmitting a communication signal to a receiver device.   
     
     
         11 . The system of  claim 10 , wherein:
 the given one of the plurality of high altitude platforms comprises a balloon; and   prediction of the potential coverage gap of the wireless communication network includes an evaluation the meteorological information associated with the balloon to determine an expected altitude or lateral position change to the balloon.   
     
     
         12 . A signal routing method comprising:
 determining, by one or more processors in a communication network, state information for a plurality of high altitude platforms forming at least part of the communication network, the state information including one or more of location data for each of the plurality of high altitude platforms, communication link information or meteorological information;   determining, by the one or more processors according to the state information, one or more routing paths for a communication signal through a subset of the plurality of high altitude platforms, at least one of the one or more routing paths is transparent without signal conversion;   selecting, by the one or more processors, a transparent routing path from among the one or more routing paths; and   transmitting the communication signal to a receiver device via the transparent routing path.   
     
     
         13 . The signal routing method of  claim 12 , wherein the transparent routing path comprises a plurality of free-space optical links between the subset of high altitude platforms. 
     
     
         14 . The signal routing method of  claim 12 , wherein determining the one or more routing paths includes identifying adaptive routing between first and second high altitude platforms of the plurality of high altitude platforms, where a lightpath between the first and second high altitude platforms is determined and set-up when a connection is needed and released at a later time. 
     
     
         15 . The signal routing method of  claim 14 , wherein the lightpath is determined dynamically depending upon at least one of a current state, a past state, or a predicted state of the plurality of high altitude platforms. 
     
     
         16 . The signal routing method of  claim 12 , wherein determining the one or more routing paths includes evaluating which paths implement wavelength division multiplexing. 
     
     
         17 . The signal routing method of  claim 16 , wherein selecting the transparent routing path includes assigning a same wavelength for all optical links on the transparent routing path. 
     
     
         18 . The signal routing method of  claim 12 , wherein one or more of the plurality of high altitude platforms comprises a balloon. 
     
     
         19 . A system comprising:
 a plurality of high altitude platforms forming at least part of a wireless communication network; and   a control system including one or more processors, the one or more processors being configured to:
 determine state information for the plurality of high altitude platforms, the state information including one or more of location data for each of the plurality of high altitude platforms, communication link information or meteorological information; 
 determine, according to the state information, one or more routing paths for a communication signal through a subset of the plurality of high altitude platforms, at least one of the one or more routing paths is transparent without signal conversion; 
 select a transparent routing path from among the one or more routing paths; and 
 inform all high altitude platforms along the transparent routing path of the selection. 
   
     
     
         20 . The system of  claim 19 , wherein one or more of the high altitude platforms along the transparent routing path comprises a balloon.