A switched-beam based multiple-input-multipleoutput (MIMO) vehicle-to-infrastructure (V2I) system can grant better system reliability as the signal-to-interference-plus-noise ratio (SINR) can be significantly optimized. In order to maximize the number of served vehicles by the simple switched-beam based V2I system, it is crucial to additionally introduce vehicle-to-vehicle (V2V) communication because (i) more than one vehicle might occupy a beam coverage, and (ii) vehicles may be out of the coverage region of a beam. In this paper, we proposed a cooperative infrastructure-beam allocation (IBA) and location-estimation (LE) scheme to optimize system coverage and reliability. IBA is an SINR optimization algorithm, and LE is a location-based proximity service for V2I and V2V communications respectively. Our simulation results show that a reliable beam coverage region in switched-beam V2I can be achieved with flexible value of SINR threshold. Also, the outage probability and average rates are directly dependent on set SINR thresholds. Finally, cooperation between V2I and V2V communication significantly improves the utility ratio which is further used as a metric for reliability.

In vehicular communication systems, maximizing the number of served vehicles while simultaneously guaranteeing reliable coverage at all the vehicles can be a challenging proposition. A switched-beam based infrastructure can provide better reliability as the signal-to-interference-plus-noise ratio (SINR) can be improved. However, a simple switched-beam based vehicle-toinfrastructure (V2I) system alone may not suffice for serving all the vehicles because (i) the number of vehicle is more than the number of beam, and (ii) a vehicle may be out of the coverage region of a beam. Therefore, introducing vehicle-to-vehicle (V2V) communication becomes crucial in extending the number of served vehicles. In this paper, a joint vehicle-beam allocation (VBA) and vehicular proximity (VP) algorithms for V2I and V2V, respectively are proposed to guarantee reliable coverage for vehicles. VBA is an SINR optimization algorithm, and VP is based on LTE Mode 4, a proximity based service for V2V communications. It is shown that setting a flexible SINR threshold helps in attaining a reliable beam coverage region in switched-beam based V2I communication. It is proven that the outage probability are also directly dependent on SINR thresholds. Lastly, the concept of utility ratio is also introduced as a metric for reliability. Simulation results show that joint V2I and V2V communication significantly improves the utility ratio.

Autonomous driving in future vehicle system has imposed a high demand for reliable and power efficient communication to provide safe-driving to vehicular users. In order to achieve reliability and power efficiency, in this paper, a vehicular trellis architecture (VTA) is proposed. VTA allows traffic information to be transmitted either via vehicle-to-infrastructure (V2I), through the dedicated remote radio head (RRH) and its dynamically select vehicle(s) or, direct vehicle-to-vehicle (V2V) communication. We investigated the adaptive switching over V2I/V2V, to enhance efficient system reliability while optimizing the average power consumption of VTA. This paper presents a vehicular trellis algorithm (VTRA), which approximate solutions to the optimization problem. Simulation results demonstrate that the selection of joint V2I/V2V communication reduces the total power consumption of the system for a varying number of threshold distance and vehicles.