  A distributed antenna system is studied whose goal is to provide data
communication and positioning functionalities to Mobile Stations (MSs). Each MS
receives data from a number of Base Stations (BSs), and uses the received
signal not only to extract the information but also to determine its location.
This is done based on Time of Arrival (TOA) or Time Difference of Arrival
(TDOA) measurements, depending on the assumed synchronization conditions. The
problem of minimizing the overall power expenditure of the BSs under data
throughput and localization accuracy requirements is formulated with respect to
the beamforming vectors used at the BSs. The analysis covers both
frequency-flat and frequency-selective channels, and accounts also for
robustness constraints in the presence of parameter uncertainty. The proposed
algorithmic solutions are based on rank-relaxation and Difference-of-Convex
(DC) programming.
