The 3rd Generation Partnership Project (3GPP) has recently established in
Rel. 14 a network-assisted resource allocation scheme for vehicular broadcast
communications. Such novel paradigm is known as vehicle--to--vehicle (V2V)
\textit{mode-3} and consists in eNodeBs engaging only in the distribution of
sidelink subchannels among vehicles in coverage. Thereupon, without further
intervention of the former, vehicles will broadcast their respective signals
directly to their counterparts. Because the allotment of subchannels takes
place intermittently to reduce signaling, it must primarily be conflict-free in
order not to jeopardize the reception of signals. We have identified four
pivotal types of allocation requirements that must be guaranteed: one quality
of service (QoS) requirement and three conflict conditions which must be
precluded in order to preserve reception reliability. The underlying problem is
formulated as a maximization of the system sum-capacity with four types of
constraints that must be enforced. In addition, we propose a three-stage
suboptimal approach that is cast as multiple independent knapsack problems
(MIKPs). We compare the two approaches through simulations and show that the
latter formulation can attain acceptable performance at lesser complexity