# Modeling and Performance of the IEEE 802.11p Broadcasting for Intra-Platoon Communication
## 2 Related Works  
The main technique for the 802.11 MAC is the distributed coordination function (DCF). Many studies analyze the performance of VANET based on 802.11 DCF. [PERSON] et al. [21] presented a probabilistic analytical model of IEEE 802.11p DCF under a saturated condition. In [22], they derived performance metrics employing a performance analysis of IEEE 802.11p DCF under an unsaturated condition. However, these two studies focus on inter-platoon communications rather than intra-platoon communication.  
A multi-priority Markov model is derived for investigating the change of the platoon throughput with the connectivity probability [23], but it does not analyze the delay and packet dropping rate. The analytical formulations developing by [PERSON] [24] has estimated messages propagation delay via VANETs, but vehicles on roads do not form a platoon. [PERSON] et al. [25] developed a 4-D Markov chain to model the cooperative retransmission process to discuss delay and uplink throughput of drive-thru Internet. The deficiency of this paper is that the assumed communication network is saturated and the packet loss of platoon communication is not taken into account.  
Some analytical studies investigate the communication performance of V2V communication based on the IEEE 802.11 broadcast. [PERSON] [26] analyzed the successful reception ratio, conflict probability, and throughput of IEEE 802.11p broadcast without queuing process. An improved analytical model supporting two access modes was established by [PERSON] et al. [27] to assess the throughput of IEEE 802.11p EDCA. [PERSON] et al. [28] extended the existing model by taking the character of multichannel switching, virtual collision, and AIFS differentiation into account. [PERSON]'s model only considered a saturated condition, while [PERSON]'s method supported both saturated and unsaturated conditions. Although [PERSON] [29] obtained delay distribution of typical scenes by implementing an experiment platform for platoon of inter-vehicle communication enabled autonomous vehicles in Matlab, the corresponding theoretical research is absent. [PERSON] et al. [30] proposed an analytical model and established a periodic broadcast scheme for VANETs. [PERSON]'s work makes an improvement by applying freezing back-off time counter and a D/M/1 queue. Considering the MAC queue with a finite capacity, two Markov chain models for ACs with different priorities were proposed by [PERSON] et al. [31] to analyze the reliability of the safety-related information propagated on the CCH. However, no channel errors were considered by [PERSON] et al. and [PERSON] et al.  
These existing studies have significantly promoted the development of platoon; nevertheless, the value of these studies in practical application is degraded because the treatment methods of platoon communication model and performance are too idealistic or not comprehensive. Furthermore, there is not sufficient study focusing on the quantitative analysis for inter-vehicle communication process and performance of platoon. Motivated by the aforementioned points, our work concentrates on communication process modeling and communication performance metrics analysis of IEEE 802.11p in a single platoon scene. Taking back-off process of channel competition and queuing process in buffers into account. Moreover, we take an unsaturated and imperfect condition into design consideration, including the imperfect wireless channels, various platoon size, and distribution of packet generation rate.