| CPC H04W 56/001 (2013.01) [G01S 11/12 (2013.01); G01S 11/16 (2013.01); G01S 13/87 (2013.01); H04W 4/023 (2013.01); H04W 56/002 (2013.01); H04W 64/00 (2013.01); H04W 84/18 (2013.01)] | 20 Claims | 

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               1. A method comprising: 
            transmitting a first electromagnetic signal from a first node to a second node; 
                receiving a second electromagnetic signal from the second node at the first node; 
                repeating the transmission of the first electromagnetic signal and the reception of the second electromagnetic signal multiple times; and 
                identifying, based on the repeated transmissions and receptions, a time-of-flight of one of the electromagnetic signals based on dividing (i) a combined travel time for the electromagnetic signals to repeatedly travel between the first and second nodes by (ii) a number of the electromagnetic signals; 
                wherein the time-of-flight multiplied by a speed of the electromagnetic signals is indicative of a distance between the nodes. 
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