  Stateless geographic routing provides relatively good performance at a fixed
overhead, which is typically much lower than conventional routing protocols
such as AODV. However, the performance of geographic routing is impacted by
physical voids, and localization errors. Accordingly, virtual coordinate
systems (VCS) were proposed as an alternative approach that is resilient to
localization errors and that naturally routes around physical voids. However,
VCS also faces virtual anomalies, causing their performance to trail geographic
routing. In existing VCS routing protocols, there is a lack of an effective
stateless and delivery guaranteed complementary routing algorithm that can be
used to traverse voids. Most proposed solutions use variants of flooding or
blind searching when a void is encountered. In this paper, we propose a
spanning-path virtual coordinate system which can be used as a complete routing
algorithm or as the complementary algorithm to greedy forwarding that is
invoked when voids are encountered. With this approach, and for the first time,
we demonstrate a stateless and delivery guaranteed geometric routing algorithm
on VCS. When used in conjunction with our previously proposed aligned virtual
coordinate system (AVCS), it out-performs not only all geometric routing
protocols on VCS, but also geographic routing with accurate location
information.
