  The paper investigates the improvement of using maximum ratio combining (MRC)
in cooperative vehicular communications (VCs) transmission schemes considering
non-orthogonal multiple access scheme (NOMA) at intersections. The transmission
occurs between a source and two destination nodes with a help of a relay. The
transmission is subject to interference originated from vehicles that are
located on the roads. Closed form outage probability expressions are obtained.
We compare the performance of MRC cooperative NOMA with a classical cooperative
NOMA, and show that implementing MRC in cooperative NOMA transmission offers a
significant improvement over the classical cooperative NOMA in terms of outage
probability. We also compare the performance of MRC cooperative NOMA with MRC
cooperative orthogonal multiple access (OMA), and we show that NOMA has a
better performance than OMA. Finally, we show that the outage probability
increases when the nodes come closer to the intersection, and that using MRC
considering NOMA improves the performance in this context. The analysis is
verified with Monte Carlo simulations.
