Abstract:
This technology herein relates to methods and systems for determining cellular and other radio transmitter mappings based upon calculated and actual values. Cellular and other radio transmitter mappings are calculated based upon factors including transmitter locations, projected signal strength maps, and signal strength measurements. This technique can be used to determine prospective and actual locations of communications towers, and which communications providers would be interested in leasing space on those towers.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/827,903, filed Oct. 3, 2006, the entire contents of which is hereby incorporated by reference. 
    
    
     FIELD 
     The technology herein relates to methods and systems for determining cellular and other radio transmitter mappings. More particularly, the technology herein provides methods and systems which enable the calculation of cellular and other radio transmitter mappings based upon factors including transmitter locations, projected signal strength maps, and signal strength measurements. The methods and systems provided by exemplary illustrative non-limiting implementations are useful for determining potential locations of new communications towers, and predicting which communications providers would be interested in leasing space on those towers. The technology herein thus has applications in the fields of electronics, computing, and telecommunications. 
     BACKGROUND AND SUMMARY 
     Cellular operators often rely on maps of cellular signal strength calculated on the basis of signal propagation theory, terrain, tower location, and transmitter power. These calculations are sometimes imprecise and result in locations being erroneously reported as having acceptable signal levels when actual coverage is inadequate. These deficiencies can lead to poor signal quality, which results in cellular users complaining about bad call quality and dropped calls. Cellular operators thus have a strong interest in determining where their cellular signals are weak. They often will install additional transmitters, at additional expense and effort, to provide better signal coverage. 
     A map that associates cellular transmitters, cellular operators, and signal strength by cellular operator is often not readily available using current estimation methods. Nevertheless, enterprising third-party tower owners often attempt to obtain land and construct towers. Often, they attempt to purchase land and sometimes construct a radio tower before cellular operators determine that they have a signal quality problem that requires an additional transmitter. Such third parties thus are in a position to lease tower or other radio transmitter locations to cellular operators, providing a return on investment and better service to cellular customers. 
     Thus, there is an urgent need for better methods and systems to estimate signal strength for cellular and other radio signals. The technology herein meets these and other needs. 
     In one aspect, the exemplary illustrative non-limiting technology herein provides methods to estimate the location of at least one cellular transceiver tower used by a cellular telephone carrier. In another aspect, the exemplary illustrative non-limiting technology herein provides methods to estimate a network or sub-network of cellular transceiver towers used by a cellular telephone carrier. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages will be better and more completely understood by referring to the following detailed description of exemplary non-limiting illustrative implementations in conjunction with the drawings of which: 
         FIG. 1  is an exemplary illustrative non-limiting example use of an algorithm that projects signal strength indicated by bands surrounding towers; 
         FIG. 2  is an exemplary illustrative non-limiting flowchart; and 
         FIG. 3  is an exemplary illustrative non-limiting system. 
     
    
    
     DETAILED DESCRIPTION 
     An exemplary illustrative non-limiting implementation provides methods and systems for determining cellular signal strength in a geographical location. A non-limiting exemplary implementation includes the following operations: 
     Steps 
     An initial step identifies locations of existing cellular towers and transmitters ( FIG. 3  block  202 ). The set of identified existing cellular towers and transmitters is called T(x) below. The set of identified cellular towers can be commercially obtained in various databases of cellular towers and locations and/or by observation. 
     The exemplary illustrative implementation then determines the projected signal strength for each transmitter in T(x) at one or more locations L(i), to produce a set of projected signal strengths according to each tower and location ( FIG. 3  block  204 ). The set of projected strengths is referred to below as P(T(x), L(i)). Various models and calculations can be used to estimate the signal strength around a tower or other transmitter. One example of such as model is the well-known Longley-Rice model, which approximates signal strength at a specific location to within +/− 10 dB. 
     Actual signal strength may range in value depending upon the distance and terrain between the transmitter (tower) and the measurement location. Expected values are in the −40 dBm to −100 dBm range, where −40 dBm is present at the transmitter (tower) and −100 dBm may be at the minimum level for a usable signal. 
     The measuring equipment and predictive modeling software is, in one exemplary illustrative non-limiting implementation, “ground truthed” before starting measurements using this algorithm. Ground truthing is a process by which the several known locations and cellular transmitters/towers are measured to determine the correlation between the actual transmission strength from specific cellular transmitters/tower and the projected transmission strength using the preferred model. In some cases, a plurality of models may be used and the measurements cross-correlated between them. 
     For each location L(i), the exemplary illustrative non-limiting implementation identifies the projected signal strength for each transmitter with a projected non-zero signal strength, and measures the actual signal strength, transmitter identification, and cellular operator information attributes for each non-zero signal at location L(i) (block  206 ). This yields a set of signals, their strengths, their associated transmitter ID, and other information about each signal. This set is called S(j, L(i)) below. 
     One example illustrative non-limiting implementation then associates S(j, L(i)) with T(x) using P(T(x), L(i)) to make a correlation (block  208 ). The exemplary illustrative non-limiting implementation then associates cellular operator information attributes from S(j, L(i)) with tower T(x) to determine coverage by cellular operator (block  210 ). In one example illustrative non-limiting implementation, the correlation will occur when the difference between the actual measurement and P(T(x), L(i)) is +/−6 dBm. 
     Results 
     The resulting set of associations of cellular operators with towers T(x) provides useful information about:
         where each cellular operator might want to lease tower space to fill in low signal strength areas.   the existing cellular infrastructure, allowing companies to identify locations where specific operators may wish to locate additional transmitters on existing towers (block  212 ).       

     An example illustrative non-limiting system  100  includes a processor  102  programmed with signal strength modeling software. The processor  102  has access to a database  104  of cellular telephone site information including cellular telephone operators. Local or remote receiver(s)  110  coupled to antennas  112  can measure actual signal strength. An input device  108  inputs collected data, and a display  106  or other output device displays results. 
     Example 
       FIG. 1  illustrates an example use of the algorithm when applied using a set of towers T(x), with projected signal strength indicated by bands surrounding towers T(x). Each band represents the set of points L(i), such that the values of P(T(x), L(i)) for each point L(i) are approximately equal. 
     Points M(1), M(2), and M(3) represent three example actual measurements at locations L(M(1)), L(M(2)), L(M(3)). The table below presents these example measurements: 
     
       
         
               
               
               
               
               
             
           
               
                   
               
               
                   
                 Estimated T(1) 
                 Estimated T(2) 
                 Estimated T(3) 
                   
               
               
                 Location 
                 P(T(1), L(M(1)) 
                 P(T(2), L(M(2)) 
                 P(T(3), L(M(3)) 
                 Actual Measurement(s) 
               
               
                   
               
             
             
               
                 L(M(1)) 
                 −73 dBm 
                 0 
                 0 
                 Cingular 123 - −70 dBm 
               
               
                 L(M(2)) 
                 −71 dBm 
                 −76 dBm 
                 −96 dBm 
                 Cingular 123 - −70 dBm 
               
               
                   
                   
                   
                   
                 T-Mobile 456 - −81 dBm 
               
               
                   
                   
                   
                   
                 Verizon 789 - −102 bDm 
               
               
                 L(M(3)) 
                 0 
                 0 
                 −65 dBm 
                 Vertzon 789 - −66 dBm 
               
               
                   
               
             
          
         
       
     
     Based upon the above information, we can correlate the non-zero P(T(i), L(M(j)) with the actual readings to determine T(1) is likely Cingular transmitter #123, T(2) is likely T-Mobile transmitter #456, and T(3) is likely Verizon transmitter #789. Furthermore, we can conclude that both T-Mobile and Verizon would be candidates to lease tower space on Tower T(1), and that both Cingular and T-Mobile would be candidates to lease tower space on Tower T(3) in order to complete their coverage of the area. Furthermore, after correlation, we can determine that location T(4) would be an advantageous location to construct a tower and offer to lease space on it to Verizon because the coverage from T(4) for Verizon would save them having to place transmitters on either T(1) or T(2). 
     It should be noted that the example has been simplified to facilitate understanding. In normal usage, each tower generally has a plurality of transmitters from a plurality of vendors, and each location will have a plurality of transmitters from each vendor visible. 
     While the technology herein has been described in connection with exemplary illustrative non-limiting implementations, the invention is not to be limited by the disclosure. The invention is intended to be defined by the claims and to cover all corresponding and equivalent arrangements whether or not specifically disclosed herein.