As the traffic safety has become of utmost importance, much attention is given to intelligent transportation systems (ITSs), and more particularly to vehicular communications (VCs). Moreover, 50 % of all crashes happen at road intersections, which makes theme critical areas. In this paper, we investigate the improvement when implementing maximum ratio combining (MRC) in cooperative VCs transmission schemes using non-orthogonal multiple access scheme (NOMA) at road intersections. We consider that a source transmits a message to two destinations with an aid of a relay. The transmission undergoes interference generated from a set of vehicles on the roads. We obtained closed form outage probability expressions, and we extended the derivations for a scenario involving $K$ destination nodes and several road lanes. The performance of MRC cooperative NOMA are compared with the standard cooperative NOMA, and we show that implementing MRC with NOMA offers a significant improvement over the standard cooperative NOMA. Also, we compare the performance of MRC using NOMA with MRC cooperative orthogonal multiple access (OMA), and demonstrate that NOMA significantly outperforms OMA. We conclude that, it is always beneficial for vehicles to use MRC and NOMA even at the cost of implementation complexity. Finally, we demonstrate that the outage probability increases drastically when vehicles are closer to the road intersection, and that using MRC with NOMA improves significantly the performance in this context. To verify the correctness of our analysis, extensive Monte-Carlo simulations are carried out.

由于交通安全已变得极为重要，因此人们对智能交通系统（ITS），尤其是车辆通信（VC）给予了极大的关注。此外，所有撞车事故中有50％发生在道路交叉口，这成为主题的关键区域。在本文中，我们研究了在道路交叉口使用非正交多路访问方案（NOMA）在合作VC传输方案中实现最大比率合并（MRC）时的改进。我们认为，源在中继的帮助下将消息发送到两个目的地。传输受到道路上一组车辆产生的干扰。我们获得了封闭式停机概率表达式，并扩展了涉及以下情形的推导$ķ$目的地节点和数条行车线。将MRC合作NOMA的性能与标准合作NOMA进行了比较，我们证明，与NOMA一起实施MRC与标准合作NOMA相比有显着改进。此外，我们比较了使用NOMA和MRC协作正交多址（OMA）的MRC的性能，并证明了NOMA明显优于OMA。我们得出的结论是，即使以实施复杂性为代价，使用MRC和NOMA始终对车辆有利。最后，我们证明了当车辆离道路交叉点较近时，停电概率会急剧增加，并且在这种情况下，将MRC与NOMA结合使用可显着提高性能。为了验证我们分析的正确性，我们进行了广泛的蒙特卡洛模拟。