Low bounds of the GDOP in absolute-range based 2-D wireless location systems

The geometric dilution of precision (GDOP) in absolute-range based 2-dimension (2-D) wireless location systems is investigated with emphasis on its low bounds. Angle of coverage (AOC) is introduced as a parameter to describe the geometry between a target and measuring points. With the AOC, it is proved that when the AOC is less than π/2, the GDOP cannot reach 2/√N, where N is the number of the measuring points. Instead of 2/√N, a new low bound of the GDOP is derived as well as its corresponding geometry. The low bound is a function of both the AOC and N.