Factor graphs for mobile position location

Making use of the network side time-of-arrival (TOA) measurements, we propose a low-complexity high-accuracy algorithm to estimate the location of a target mobile station (MS). Under a factor graph framework, the proposed algorithm efficiently exchange soft information among local processing units in the mobile switching center (MSC) to iteratively purify the estimate of the MS location. Numerical results show that the proposed algorithm not only enjoys advantages of low complexity, suitable for integrated-circuit implementation, but it is also able to achieve performance very close to the optimum achievable bound, the maximum likelihood (ML) bound.