# Experimental Demonstration of MmWave Vehicle-to-Vehicle Communications Using IEEE 802.11 ad
## 2 Related Works  
In the last decade, the mmWave spectrum was popularly explored to enlarge the bandwidth and increase the throughput in mobile communications for a last decade. [PERSON] et al. introduced seminal results of the experiments using a wideband sliding correlator channel sounder with steerable directional horn antennas at both the transmitter and receiver in New York city in [1] from 2011 to 2013, and presented more results on the frequency bands of 28, 38, and 73 GHz bands in [2; 3]. Based on those studies, mmWave channel models are demonstrated in [4; 5], where empirically-based propagation channel models are proposed for the 28, 38, 60, and 73 GHz mmWave bands. [PERSON] et al. presented a 3-D statistical channel impulse response model for urban LOS and non-LOS (NLOS) channels developed from the 28 and 73 GHz ultra-wideband propagation measurements presented [6; 7]. They later added small-scale fading measurements for the 28 GHz outdoor mmWave ultrawideband channels using directional horn antennas [23]. Additionally, 28 GHz wideband propagation channel characteristics for mmWave urban cellular communication systems are presented in [24]. [PERSON] et al. characterized a mmWave indoor propagation channel based on a wideband measurement campaign at 73 GHz in an office-type environment [25]. For outdoor access channel modeling at 60 GHz mmWave spectrum, [PERSON] et al. [26] established a quasi-deterministic channel model and a link level-focused channel model and, subsequently, the authors of [27] introduced a new quasi-deterministic (Q-D) approach for modeling mmWave channels, which allows natural description of scenario-specific geometric properties, reflection attenuation and scattering, ray blockage, and mobility effects. [PERSON] et al. provided a comprehensive overview of mathematical models and analytical techniques for mmWave cellular systems based on stochastic geometry [28]. In addition, a system-level analysis of the success probability for cell selection and random access delay in the mmWave cellular systems is conducted in [29]. Currently, the mmWave communication is now considered for V2V or V2I communications, which are required for autonomous or proxy driving in future smart cars [9]. We survey existing works related to the mmWave V2X communications as in Table 1.  
Several studies on measurement campaigns and channel modeling for the mmWave V2V or V2I communications are reported. [PERSON] et al. conducted multipath and angle-of-arrival (AOA) measurements at 60 GHz of outdoor peer-to-peer channels in an urban campus courtyard for transmission and into a vehicle [30] in 2011, demonstrating that varying the transmitter and receiver separation provides different root mean square (RMS) delay spreads from 2.73 ns to a maximum value of 12.3 ns for the LOS and NLOS antenna pointing scenarios. [PERSON] et al. developed a practical mmWave vehicular testbed to evaluate performance, where fixed beam-steering approach enables the RSUs to transmit large amounts of data in a considerably short amount of time for a wide range of speeds [10]. [PERSON] et al. investigated mmWave blockage characteristics based on measurements collected in a typical V2V environment at 28 GHz [11]. Based on these measurements and simulations, the V2X channel models are exploited. [PERSON] et al. reviewed the state-of-the-art in measurements related to mmWave vehicular channels [12]. In contrast to the previous studies conducted with the two-ray model on flat road surfaces, more realistic settings with road undulation, road surface curvature, and blockage by other vehicles are considered to improve the accuracy of pathloss prediction. The propagation mechanisms reflection and diffraction of mmWave on realistic road surfaces and geometries at 60-77 GHz are demonstrated in [31; 32]. Further, [PERSON] et al. proposed channel propagation models for mmWave V2X communications using ray-tracing simulations [13], which include the effects of link blockage, scattering and multipath fading. [PERSON] et al.