O ct 2 01 5 Latency and Resource Utilization Analysis for V 2 X Communication over LTE MBSFN Transmission

In this paper, we investigate the performance of LTE Multicast-Broadcast Single-Frequency Networks (MBSFN). LTE-MBSFN is viewed as one of the most promising candidates for vehicular communications which can enhance reliabilit y of vehicular application traffic. This is achieved due to the possibility to efficiently support message exchange in-bet ween vehicles by multicasting information to several vehicles i n parallel (point-to-multipoint transmission) employing an Mult imedia Broadcast/Multicast Service (MBMS). We investigate two me trics to gauge the performance of MBMS/MBSFN transmissions in comparison with standard unicast transmissions for vehicular communications: latency of packet delivery and overhead ca used by vehicular traffic, i.e., network utilization. Additiona lly, we present technique of prediction of system behaviour and exp lore the influence of transmission bandwidth and transmission rate on mentioned metrics. Keywords—Multicasting, MBSFN, Vehicular Communications, V2X, Latency. I. I NTRODUCTION Multimedia Broadcast/Multicast Service (MBMS) was introduced by the 3rd Generation Partnership Project (3GPP) as means to broadcast and multicast information to 3G and 4G mobile users, with mobile TV being the main service offered [1], [2]. In the context of LTE systems, MBMS was evolved into e-MBMS increasing the performance of the air interface with a new transmission scheme called MulticastBroadcast Single-Frequency Network (MBSFN). In MBSFN operation, MBMS data are transmitted simultaneously from multiple strictly time and frequency synchronized cells. A group of such cells transmitting these data establishes the ocalled MBSFN area [3]. The increase in performance of the air interface is obtained in MBSFN due to great enhancement in the Signal to Interference and Noise Ratio (SINR) which is especially beneficial for the users at cell edge [4]. Substantial developments have taken place over the past few years in the area of vehicular communication systems. After the deployment of various vehicular technologies, such as t oll collection or active road signs, vehicular communication ( VC) systems have emerged. These systems include network nodes, that is, vehicles and road-side infrastructure units (RSUs ) equipped with onboard sensory, processing, and wireless co mmunication modules [5]. Vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) communication allows a range of applications to increase transportation safety and efficie ncy, as well as video streaming [6]. Especially road safety applica tions play a very important role in vehicular communications. Roa d safety applications rely on short-message broadcasting in a Fig. 1: Illustration of a cellular network serving vehicles via LTE’s MBMS/MBSFN feature as well as ordinary static users over uni cast transmission. vehicle’s neighbourhood to inform other vehicles in order to reduce accidents on the road. As a new traffic model, these applications exhibit some unique features in terms of generation patterns and delivery requirements. Particula rly, delivery requirements of road safety applications are of hi gh importance, since any signal delay increases the danger of accidents. Additionally, the possibility to support ordin ary unicast users is highly preferable. In order to sustain such requirements, MBSFN can be considered as a potential way to handle vehicular applications [7]. The remainder of this paper is organized as follows. In Section II we define MBMS/MBSFN transmission and explain our traffic model. Our performance metrics, i.e., the latenc y definitions as well as the network utilization are discussed in Section III. Next in Section IV, methods for adaptation of Channel Quality Indicator (CQI) are motivated and explaine d. Final simulation results and discussions are described in S ection V. Concluding remarks are provided in Section VI.