  This paper considers N mobile nodes that move together in the vicinity of
each other, whose initial poses as well as subsequent movements must be
accurately tracked in real time with the assist of M(>=3) reference nodes. By
engaging the neighboring mobile nodes in a simple but effective cooperation,
and by exploiting both the time-of-arrival (TOA) information (between mobile
nodes and reference nodes) and the received-signal-strength (RSS) information
(between mobile nodes), an effective new localization strategy, termed
cooperative TOA and RSS (COTAR), is developed. An optimal maximum likelihood
detector is first formulated, followed by the derivation of a low-complexity
iterative approach that can practically achieve the Cramer-Rao lower bound.
Instead of using simplified channel models as in many previous studies, a
sophisticated and realistic channel model is used, which can effectively
account for the critical fact that the direct path is not necessarily the
strongest path. Extensive simulations are conducted in static and mobile
settings, and various practical issues and system parameters are evaluated. It
is shown that COTAR significantly outperforms the existing strategies,
achieving a localization accuracy of only a few tenths of a meter in clear
environments and a couple of meters in heavily obstructed environments.

Distributed, Parallel, and Cluster Computing