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 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.   
     
     
         2 . The signal routing method of  claim 1 , wherein the transparent routing path comprises a plurality of free-space optical links between the subset of high altitude platforms. 
     
     
         3 . The signal routing method of  claim 1 , 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. 
     
     
         4 . The signal routing method of  claim 3 , 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. 
     
     
         5 . The signal routing method of  claim 1 , wherein determining the one or more routing paths includes evaluating which paths implement wavelength division multiplexing. 
     
     
         6 . The signal routing method of  claim 1 , wherein selecting the transparent routing path includes assigning a same wavelength for all optical links on the transparent routing path. 
     
     
         7 . The signal routing method of  claim 1 , wherein one or more of the plurality of high altitude platforms comprises a balloon. 
     
     
         8 . 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.   
     
     
         9 . The system of  claim 8 , wherein one or more of the high altitude platforms along the transparent routing path comprise one or more lighter-than-air platforms. 
     
     
         10 . The system of  claim 9 , wherein the one or more lighter-than-air platforms comprise one or more balloons. 
     
     
         11 . The system of  claim 8 , wherein the transparent routing path comprises a plurality of free-space optical links between the subset of high altitude platforms. 
     
     
         12 . The system of  claim 8 , wherein the determination of the one or more routing paths includes identification of 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. 
     
     
         13 . The system of  claim 12 , 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. 
     
     
         14 . The system of  claim 8 , wherein determination of the one or more routing paths includes evaluation of which paths implement wavelength division multiplexing. 
     
     
         15 . The system of  claim 8 , wherein selection of the transparent routing path includes assignment of a same wavelength for all optical links on the transparent routing path. 
     
     
         16 . A non-transitory computer readable medium having instructions stored therein, the instructions, when executed by a computing system, cause the computing system to perform a signal routing method comprising:
 determining 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, 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 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.   
     
     
         17 . The non-transitory computer readable medium of  claim 16 , 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. 
     
     
         18 . The non-transitory computer readable medium of  claim 17 , 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. 
     
     
         19 . The non-transitory computer readable medium of  claim 16 , wherein determining the one or more routing paths includes evaluating which paths implement wavelength division multiplexing. 
     
     
         20 . The non-transitory computer readable medium of  claim 16 , wherein selecting the transparent routing path includes assigning a same wavelength for all optical links on the transparent routing path.