  In Release 14, 3GPP completed a first version of cellular
vehicle--to--everything (C-V2X) communications wherein two modalities were
introduced. One of these schemes, known as \textit{mode-3}, requires support
from eNodeBs in order to realize subchannel scheduling. This paper discusses a
graph theoretical approach for semi-persistent scheduling (SPS) in
\textit{mode-3} harnessing a sensing mechanism whereby vehicles can monitor
signal--to--interference--plus--noise ratio (SINR) levels across sidelink
subchannels. eNodeBs request such measurements from vehicles and utilize them
to accomplish suitable subchannel assignments. However, since SINR
values---herein also referred to as side information---span a wide range,
quantization is required. We conclude that 3 bits per vehicle every 100 ms can
provide sufficient granularity to maintain appropriate performance without
severe degradation. Furthermore, the proposed algorithm is compared against
pseudo-random and greedy SPS algorithms.
