  We study reliable communication in uncoordinated vehicular communication from
the perspective of Shannon theory. Our system model for the information
transmission is that of an Arbitrarily Varying Channel (AVC): One
sender-receiver pair wants to communicate reliably, no matter what the input of
a second sender is. The second sender is assumed to be uncoordinated and
interfering, but is supposed to follow the rational goal of transmitting
information otherwise. We prove that repetition coding can increase the
capacity of such a system by relating the notion of symmetrizability of an
arbitrarily varying channel to invertibility of the corresponding channel
matrix. Explicit upper bounds on the number of repetitions needed to prevent
system breakdown through diversity are provided. Further we introduce the
notion of block-restricted jamming and present a lower and an upper bound on
the maximum error capacity of the corresponding restricted AVC.
