  Wireless power transmission (WPT) is envisioned to be a promising technology
for prolonging the lifetime of wireless devices in energy-constrained networks.
This paper presents a general power beacon (PB) assisted multi-source
transmission, where a practical source selection scheme with information
transmission (IT) mode or non-IT mode is developed to maximize the transmission
reliability. In the IT mode, a zero-forcing (ZF) beamformed signal with no
interference to the destination is transmitted at the multi-antenna PB to
supply wireless energy for the sources, and bring non-negative effect to the
destination. Among multiple sources, the energy-sufficient source with the best
channel quality is selected for wireless information transmission (WIT), while
the other sources remain for energy harvesting. In the non-IT mode, the equal
power transmission is adopted at PB to focus on energy delivery. Using Markov
chain theory, the energy arrival and departure of each finite-capacity storage
at the source is characterized mathematically, and the comprehensive analytical
expressions of the energy outage probability (EOP), the connection outage
probability (COP), and the average transmission delay (ATD) are formulated and
derived. Our results reveal that the EOP, COP, and ATD can be significantly
improved via increasing the number of sources deployed in the proposed network
with finite transmit power of PB. We also prove that the multi-source network
will never experience energy outage with infinite transmit power of PB.
