  We consider evacuation of a group of $n \geq 2$ autonomous mobile agents (or
robots) from an unknown exit on an infinite line. The agents are initially
placed at the origin of the line and can move with any speed up to the maximum
speed $1$ in any direction they wish and they all can communicate when they are
co-located. However, the agents have different wireless communication
abilities: while some are fully wireless and can send and receive messages at
any distance, a subset of the agents are senders, they can only transmit
messages wirelessly, and the rest are receivers, they can only receive messages
wirelessly. The agents start at the same time and their communication abilities
are known to each other from the start. Starting at the origin of the line, the
goal of the agents is to collectively find a target/exit at an unknown location
on the line while minimizing the evacuation time, defined as the time when the
last agent reaches the target.
  We investigate the impact of such a mixed communication model on evacuation
time on an infinite line for a group of cooperating agents. In particular, we
provide evacuation algorithms and analyze the resulting competitive ratio
($CR$) of the evacuation time for such a group of agents. If the group has two
agents of two different types, we give an optimal evacuation algorithm with
competitive ratio $CR=3+2 \sqrt{2}$. If there is a single sender or fully
wireless agent, and multiple receivers we prove that $CR \in [2+\sqrt{5},5]$,
and if there are multiple senders and a single receiver or fully wireless
agent, we show that $CR \in [3,5.681319]$. Any group consisting of only senders
or only receivers requires competitive ratio 9, and any other combination of
agents has competitive ratio 3.

Data Structures and Algorithms