  Transparent topology is common in many mobile ad hoc networks (MANETs) such
as vehicle ad hoc networks (VANETs), unmanned aerial vehicle (UAV) ad hoc
networks, and wireless sensor networks due to their decentralization and
mobility nature. There are many existing works on distributed scheduling scheme
design for topology-transparent MANETs. Most of them focus on
delay-unconstrained settings. However, with the proliferation of real-time
applications over wireless communications, it becomes more and more important
to support delay-constrained traffic in MANETs. In such applications, each
packet has a given hard deadline: if it is not delivered before its deadline,
its validity will expire and it will be removed from the system. This feature
is fundamentally different from the traditional delay-unconstrained one. In
this paper, we for the first time investigate distributed scheduling schemes
for a topology-transparent MANET to support delay-constrained traffic. We
analyze and compare probabilistic ALOHA scheme and deterministic sequence
schemes, including the conventional time division multiple access (TDMA), the
Galois field (GF) sequence scheme proposed in \cite{chlamtac1994making}, and
the combination sequence scheme that we propose for a special type of sparse
network topology.We use both theoretical analysis and empirical simulations to
compare all these schemes and summarize the conditions under which different
individual schemes perform best.
