Considered the directed topology structure of the sensor network

on the basis of introducing the optimal centralized strategy and myopic decentralized strategy established by the rule of the minimum global Bayesian risk

and analyzing their merits and demerits

and considering the limitation of the team-theory solution

and combining the belief propagation with some algorithms in graphical models

a new strategy method to this sensor network is proposed by the rule of person-by-person optimality.It consists of online computation and offline computation

the former task is to obtain one class-conditional-probability density based on the online measurements

the later task is get some parameters which are used to calculate one threshold

parameter calculation procedure comprises one forward transmitting process of likelihood function message and another backward receiving process of cost-to-go function message.The new method capability

to trade off the conflict between calculated complexity and energy consumption from the optimal centralized strategy and myopic decentralized strategy

is analyzed

other advantage is also validated by computer simulation.