Abstract:
In one aspect, a method to discover and prevent a communications disruption in a mobile environment includes receiving data at a mobile platform from a geographical database, determining if the mobile platform will be blocked by a blockage event from accessing a network in response to data extracted from the geographical database and avoiding the blockage event if the mobile platform will be blocked from accessing the network.

Description:
RELATED APPLICATIONS 
     This patent application claims priority to Application Ser. No. 61/366,332, filed Jul. 21, 2010 entitled “REAL TIME DYNAMIC OUTAGE ANTICIPATION IN MOBILE ENVIRONMENTS” which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     A communications device in a mobile environment may lose communications with a wireless network due to a blockage event. The blockage event may be caused by terrain. For example, a mountain may block the line of sight of a signal from the communications device thereby preventing or degrading the quality of access to the wireless network. The communications device may also lose connectivity or encounter degraded performance with the wireless network due to weather conditions; however, often times the design of a waveform incorporates power margin to accommodate for such performance degradations due to weather. For example, a waveform used by the communications device actually uses approximately an order of magnitude (e.g. 10 decibels) more power to connect to the wireless network than it minimally requires, thereby allowing communications to continue in a heavy rain storm. 
     SUMMARY 
     In one aspect, a method to discover and prevent a communications disruption in a mobile environment includes receiving data at a mobile platform from a geographical database, determining if the mobile platform will be blocked by a blockage event from accessing a network in response to data extracted from the geographical database and avoiding the blockage event if the mobile platform will be blocked from accessing the network. 
     In another aspect, an article includes a machine-readable medium that stores executable instructions to discover and prevent a communications disruption in a mobile environment. The instructions cause a machine to receive data at a mobile platform from a geographical database, determine if the mobile platform will be blocked by a blockage event from accessing a network in response to data extracted from the geographical database and avoid the blockage event if the mobile platform will be blocked from accessing the network. 
     In a further aspect, an apparatus to discover and prevent a communications disruption in a mobile environment includes circuitry to receive data at a mobile platform from a geographical database, determine if the mobile platform will be blocked by a blockage event from accessing a network in response to data extracted from the geographical database and avoid the blockage event if the mobile platform will be blocked from accessing the network. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a system to discover and prevent a communications disruption in a mobile environment. 
         FIG. 2  is a diagram of an example of an outage determination along an arbitrary path. 
         FIG. 3  is a diagram of an example of a terrain map used to determine blockages. 
         FIG. 4  is a flowchart of an example of a process to discover and prevent a communications disruption in a mobile environment. 
         FIG. 5  is a block diagram of an example of a computer to perform the process of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     Described herein is an approach that allows systems disposed on mobile platforms to anticipate blockage events that will disrupt communications and to take the necessary actions to prevent disruption of the communications. In one example, the techniques described herein may anticipate a blockage event so that both directional and omni-directional waveforms can be used to pre-compensate for the blockage event by performing a modem reconfiguration or by alternating a path of the mobile platform. In another example, weather databases may be used to optimize communication capacity based on the predicted weather. In some examples, the user is able to configure whether the techniques to discover and prevent blockage events and degraded performance occurs automatically or manually. 
     With mobile ad-hoc networks gaining more attention, managing the dynamics of its topology while optimizing throughput and delay has presented many challenges. For instance, incorporating directional waveforms in a mobile environment requires knowledge of topology dynamics. Thus, prediction of blockage or degraded performance events is crucial to maintaining connectivity and optimizing throughput. 
     The dynamics of a directional waveform have typically included ships and airborne platforms. Attempts to solve this problem on such platforms have been to monitor and track multiple beams at once; however, this approach provides a reactionary mechanism to overcome a blockage or degraded performance event rather than being an anticipatory mechanism. Contrary to the conventional fixed positional environment in which directional waveforms operate, introducing mobility and dynamic topology changes has a greater likelihood of creating a blockage between the platform and the payload. 
     Referring to  FIG. 1 , an example of a system to discover and prevent blockage events is a system  10 . System  10  includes a blockage discovery and prevention (BDP) module  12  coupled to a user interface (UI)  16 , a database  22  and a controller  28 . The system  10  also includes a modem  32  coupled to the controller  28 , a radio frequency (RF) switch  46  and to an antenna control  42  that controls an antenna  48 . In one example, the system  10  is disposed on a mobile platform (e.g., an airplane, a car, a truck, a tank, a train and so forth). 
     In one example, the system  10  is in communications with a mobile ad-hoc network (MANET) that includes a collection of mobile assets (e.g., sensors, radios and so forth) whose connectivity is maintained by means of dynamic routing while lacking any central infrastructure. A MANET&#39;s performance in terms of delay and throughput are topology dependent. 
     The BDP module  12  receives spatial data from the database  22  to determine if the system  10  will enter a location where a blockage event would occur. If the BDP module  12  determines that a blockage event will occur, the BDP  12  will enable the controller  28  to modify the modem  32  to avoid the blockage event. For example, a waveform presently used will be switched to another of the waveforms  50 ; power of the transmitted signal is increased, the data rate is increased; the modulation and/or coding is adapted; the antenna  48  is redirected; beams are switched; a transition to other satellites, airborne payloads and so forth occurs or any combination thereof. 
     The BDP module  12  also may use the weather data to determine whether the system  10  will be in a performance degrading environment or not. For example, many waveforms incorporate a weather margin (also known as a link margin) to maintain link closure during precipitation events. This weather margin can be viewed as wasted resources during clear sky conditions. Thus, anticipating that there will be no precipitation, for example, is a means to increase channel capacity. 
     In one example, the database  22  is an open source database (e.g., POSTGRES, POSTGIS) of spatial information (terrain, structures, foliage and so forth). In other examples, the database  22  may include databases (e.g., weather) which can facilitate in overcoming environmental constraints on communication performance. 
     In one example, the user interface  16  includes at least one of a keyboard, mouse, a display, a touch screen. In one particular example, the user interface  16  renders three-dimensional (3D) spatial terrain data accompanied with Doppler weather overlays to the user. 
     The modem  32  stores waveforms  50  that are used in communications (e.g., a multi-waveform programmable small form factor modem). A waveform  50  is defined as the collection of signal processing functions and attributes pertaining to a carrier signal, which can include frequency, modulation, coding, multiple access schema, bandwidth utilization, and power consumption and so forth. Examples of waveforms include but are not limited to commercial cellular networks (e.g., 3G and 4G-LTE), and military waveforms (e.g., Military Strategic and Tactical Relay (Milstar), Advanced Extremely High Frequency (AEHF), and Common Data Link (CDL)). Waveforms may also differ by constellation/payload, but could share some similarities. The waveforms  50  include, for example, constellation data (i.e., azimuth and elevation data). In one example, the waveforms are directional waveforms for use with a directional antenna. 
     The ability to use multiple waveforms (e.g., SATCOM waveforms) and satellites, airborne payloads and so forth provides many routing and bandwidth options. This is particularly important in an environment with many different types of blockage events as well as potential threats (e.g., jamming, weather events and so forth). In one example, the modem  32  runs a single waveform at a time but can be reconfigured to run another waveform. In another example, the modem  32  runs multiple waveforms simultaneously. 
     To illustrate some of the benefits of anticipating outage events, consider an arbitrary path  110  of a system  10  on a mobile platform in  FIG. 2 . Along the path  110 , at a determined sampling rate, T, the system  10  projects a velocity vector and considers relevant spatial terrain map (e.g., see  FIG. 3 ) over a particular blockage volume, V. For example, at a first position  120   a , the system  10  generates a velocity vector  130   a  with the blockage volume  140   a ; at a second position  120   b , the system  10  generates a velocity vector  130   b  with the blockage volume  140   b ; at a third position  120   c , the system  10  generates a velocity vector  130   c  with the blockage volume  140   c ; at a fourth position  120   d , the system  10  generates a velocity vector  130   d  with the blockage volume  140   d ; at a fifth position  120   e , the system  10  generates a velocity vector  130   e  with the blockage volume  140   e ; and at a sixth position  120   f , the system  10  generates a velocity vector  130   f  with the blockage volume  140   f . In other examples, a weather volume (e.g., a weather volume  145   a  and a weather volume  145   b ) is used to determine, for example, whether weather precipitation will occur so that the weather margin may be adjusted as shown in  FIG. 4 . 
     The spatial terrain map candidate is used to determine structure locations and anticipate line-of-sight (LOS) blockage events from these structures. Depending upon the terrain environment the volume and frequency of these spatial candidates can vary drastically. Urban environments will typically require frequent sampling of the environment due to structure density, whereas a flat, open desert may require only a few samples and never encounter a blockage candidate. 
       FIG. 3  depicts a notional terrain candidate under clear skies for the system  10  with the modem  32 , which has four waveforms loaded. A high level description of the process is that the system  10  predicts what it expects to observe based on the best available information at the prediction time and corrects its actions accordingly (for example, using a process  200  ( FIG. 4 ), when real-time data becomes available to reinforce or correct predictions. 
     At a more detailed level, the operation may be interpreted as outlined herein. At a specific scan instant kT at a point P along the mobile platform&#39;s route, the BDP  12  requests certain spatial terrain information from the database  22  based on current estimates of position and time. A spatial terrain map  150  of a terrain  152  is located around a given blockage volume V of the best estimate of current location of the system  10 . System  10  projects vectors from its own current position (as well as future positions within the blockage volume V based on velocity estimates) to the position of each payload (e.g., a satellite, air borne platform, and so forth) corresponding to a waveform. For example, a projected vector  160   a  of a first waveform is associated with a first satellite (SAT 1 ), a projected vector  160   b  of a second waveform is associated with a second satellite (SAT 2 ), a projected vector  160   c  of a third waveform is associated with a third satellite (SAT 3 ) and a projected vector  160   d  of a fourth waveform is associated with a fourth satellite (SAT 4 ). The constellation ephemeris, which contains the position and motion rates of the payload, for each waveform is local to the system  10  to enable such processing. 
     Once the vector projections are performed, blockage candidates along the map  150  can be determined. If an active waveform is a candidate for blockage, the application is envisioned to provide recommendation of either an alternate route or an alternate waveform. This example illustrates that satellites, SAT 1 , SAT 2  and SAT 4  are subject to a blockage event for the shown vector projection. If the system  10  happened to be communicating on SAT 3 , a blockage event will not occur and the user can continue along the route. However, if the active waveform is one of the other three satellites (SAT 1 , SAT 2  and SAT 4 ), an alternate candidate waveform or route will be displayed to the user. In one example, the preference of the user interaction can be predetermined before being deployed. 
     Referring to  FIG. 4 , an example of a process to discover and prevent blockage events is a process  200 . Process  200  receives user input ( 202 ). For example, a user using the user interface  16  to indicate whether the remaining process blocks will be automatically performed or manually performed. This determines if the decision point is to be executed automatically by the system or to await user confirmation of the system&#39;s desired actions. In another example, the user using the user interface  16  provides geographic route parameters of a rigid route to be taken e.g., an example of a route option from a consumer GPS would be “no toll roads may be used.” In another example, a user may require maintaining connectivity on a particular waveform and allowing the user interface to direct the user on a new geographic route. 
     Process  200  determines if the user selected an automatic or manual operation ( 212 ). If the user indicates an automatic operation, then the processing blocks  212 - 276  are performed automatically (i.e., without user intervention). 
     Process  200  plans a route ( 218 ). For example, the process  200  uses a known aerial layer flight plan of the aerial layer platform it desires to communicate with and, the process  200  plans a route for the mobile platform (with the system  10 ) to travel. In another example, process  200 , using a satellite table, determines a route for data communications to travel (e.g., which satellites to access). In other examples, GPS data, POST-GIS terrain Maps and weather databases are used to determine a route. 
     Process  200  determines, after the first sampling instant, if there will be a blockage event along the route determined in processing block  218  ( 222 ). For example, navigation aids (e.g., GPS) are used for determining best routes based on current positional information. In one particular example, since GPS uses map structures, position, timing, and velocity estimates to provide real time feedback to users (drivers) to facilitate navigation, GPS is expanded from the two-dimensional (2D) map concept to incorporate three-dimensional (3-D) spatial terrain system  10  that can anticipate blockage events. 
     If there will be a blockage event along the route, process  200  determines if the user has indicated to continue using the current waveform ( 228 ) and if so, the geographic route is altered to service this user desired constraint. For example, the user pre-stores an indicator of what the user&#39;s preference when process  200  executes processing block  228 . 
     If the user indicates not to use the current waveform or its current parameters, process  200  adjusts the system parameters ( 232 ). In one example, the controller  28  changes the waveform on the modem  32 . In another example, the controller  28  increases at least one of the following, a transmit power and a data rate generated by the modem  32 . In a further example, optimization of waveform parameters such as modulation or coding or both are changed at the modern  32 . In still further examples, the controller  28  switches constellations/payloads. In other examples, the controller  28  executes any combination of changes at the modem  32  previously mentioned. 
     Process  200  determines if there is a weather margin on the waveform ( 270 ). If there is a weather margin on the waveform, process  200  optimizes the waveform ( 262 ). For example, if there is not going to be any precipitation then we can use the transmit power weather margin to increase channel capacity. The modem  32  uses this information to optimize waveform parameters such as transmit power to effectively increase the achievable data rate under the current weather environment. 
     If the user has indicated to use the current waveform, the route is re-planned ( 232 ). For example, the route of the mobile platform is rerouted to avoid the blockage event. In another example, the data path is rerouted to avoid the blockage event. 
     Process  200  determines if there is a weather margin on the waveform ( 270 ). If there is a weather margin on the waveform, process  200  optimizes the waveform ( 262 ) by performing processing block  262 . 
     After performing processing block  262 , the process  200  resumes initial or re-planned route depending on the result of processing block  228  ( 276 ). Process  200  returns to processing block  222  for subsequent sampling instants. 
     If the user selects a manual process at processing block  212 , the process  200  performs a manual operation that includes the same processing blocks (processing blocks  218  to  276 ) as an automatic processing except at the processing block  228  the user enters their desire at that time (e.g., using the user interface  16 ) unlike the automatic operation where the user&#39;s pre-stored desire is used. 
     Referring to  FIG. 5 , an example of an implementation of the BDP module  12  is a computer  500 . The computer  500  includes a processor  502 , a volatile memory  504  and a non-volatile memory  506  (e.g., a hard disk). The non-volatile memory  506  stores computer instructions  512 , an operating system  516  and data  518 . In one example, the computer instructions  518  are executed by the processor  502  out of volatile memory  504  to perform all or part of the process  200 . In other examples, the computer  500  may represent additional elements of system  10  in  FIG. 1 . For example, the computer  500  may represent both the BDP module  12  and the controller  28 . 
     The processes described herein (e.g., the process  200 ) are not limited to use with the hardware and software configuration shown in  FIG. 5 ; they may find applicability in any computing or processing environment and with any type of machine or set of machines that are capable of running a computer program. The processes described herein may be implemented in hardware, software, or a combination of the two. The processes described herein may be implemented as a set or subset of services in computer programs executed on programmable computers/machines that each includes a processor, a storage medium or other article of manufacture that is readable by the processor (including volatile and non-volatile memory and/or storage elements), at least one input device, one or more output devices, and a network connection. Program code may be applied to data entered using an input device to perform the processes described herein and to generate output information. 
     The system may be implemented, at least in part, via a computer program product, (e.g., in a machine-readable storage device), for execution by, or to control the operation of, data processing apparatus (e.g., a programmable processor, a computer or multiple computers)). Each such program may be implemented in a high level procedural or object-oriented programming language to communicate with a computer system. However, the programs may be implemented in assembly or machine language. The language may be a compiled or an interpreted language and it may be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program may be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network. A computer program may be stored on a storage medium or device (e.g., CD-ROM, hard disk, or magnetic diskette) that is readable by a general or special purpose programmable computer for configuring and operating the computer when the storage medium or device is read by the computer to perform the processes described herein. The processes described herein may also be implemented as a machine-readable storage medium, configured with a computer program, where upon execution, instructions in the computer program cause the computer to operate in accordance with the processes. 
     The processes described herein are not limited to the specific embodiments described. For example, the process  200  is not limited to the specific processing order of  FIG. 4 . Rather, any of the processing blocks of  FIG. 4  may be re-ordered, combined or removed, performed in parallel or in serial, as necessary, to achieve the results set forth above. 
     The processing blocks in  FIG. 4  associated with implementing the system may be performed by one or more programmable processors executing one or more computer programs to perform the functions of the system. All or part of the system may be implemented as, special purpose logic circuitry (e.g., an FPGA (field programmable gate array) and/or an ASIC (application-specific integrated circuit)). 
     The processes described herein are not limited to the specific embodiments described. Elements of different embodiments described herein may be combined to form other embodiments not specifically set forth above. Other embodiments not specifically described herein are also within the scope of the following claims.