  LTE based Cellular Vehicle-To-Everything (C-V2X) allows vehicles to
communicate with each other directly without the need for infrastructure and is
expected to be a critical enabler for connected and autonomous vehicles. V2X
communication based safety applications are built on periodic broadcast of
basic safety messages with vehicle state information. Vehicles use this
information to identify collision threats and take appropriate countermeasures.
As the vehicle density increases, these broadcasts can congest the
communication channel resulting in increased packet loss; fundamentally
impacting the ability to identify threats in a timely manner. To address this
issue, it is important to incorporate a congestion control mechanism.
Congestion management scheme based on rate and power control has proved to be
effective for DSRC. In this paper, we investigate the suitability of similar
congestion control to C-V2X with particular focus on transmit power control. In
our evaluation, we include periodic basic safety messages and high priority
event messages that are generated when an event such as hard braking occurs.
Our study reveals that while power control does not improve packet delivery
performance of basic safety messages, it is beneficial to high priority event
message delivery. In this paper, we investigate the reasons for this behavior
using simulations and analysis.
