  The bistatic backscatter architecture enables flexible deployment
opportunities for backscatter devices by extending communication range. In this
paper, we study the placement of power beacons (PBs) in bistatic backscatter
networks to maximize the guaranteed coverage distance (GCD), defined as the
distance from the reader within which the backscatter devices are able to
satisfy a given quality-of-service constraint. This work departs from
conventional energy source placement problems by considering the performance of
the additional backscatter link on top of the energy transfer link. We adopt
and optimize a symmetric PB placement scheme to maximize the GCD. The optimal
PB placement under this scheme is obtained using either analytically tractable
expressions or an efficient algorithm. Numerical results provide useful
insights into the impacts of various system parameters on the PB placement and
the resulting GCD, plus the advantages of the adopted symmetric placement
scheme over other benchmark schemes.
