  Wireless powered communication network (WPCN) is a novel networking paradigm
that uses radio frequency (RF) wireless energy transfer (WET) technology to
power the information transmissions of wireless devices (WDs). When energy and
information are transferred in the same frequency band, a major design issue is
transmission scheduling to avoid interference and achieve high communication
performance. Commonly used centralized scheduling methods in WPCN may result in
high control signaling overhead and thus are not suitable for wireless networks
constituting a large number of WDs with random locations and dynamic
operations. To tackle this issue, we propose in this paper a distributed
scheduling protocol for energy and information transmissions in WPCN.
Specifically, we allow a WD that is about to deplete its battery to broadcast
an energy request buzz (ERB), which triggers WET from its associated hybrid
access point (HAP) to recharge the battery. If no ERB is sent, the WDs contend
to transmit data to the HAP using the conventional $p$-persistent CSMA (carrier
sensing multiple access). In particular, we propose an energy queueing model
based on an energy decoupling property to derive the throughput performance.
Our analysis is verified through simulations under practical network
parameters, which demonstrate good throughput performance of the distributed
scheduling protocol and reveal some interesting design insights that are
different from conventional contention-based communication network assuming the
WDs are powered with unlimited energy supplies.
