Performance modeling for IEEE 802.11 vehicle-to-infrastructure networks with directional antennas

This paper proposes an analytical throughput model for IEEE 802.11-based vehicle-to-infrastructure networks with omni-directional antennas (OA) and directional antennas (DA) applied in three different ways. The model considers the antenna gain pattern, multipath effect, co-channel interference, variable link rates and mobility effects. When DAs are applied, the deafness and hidden terminal problems are considered. With the model, the paper compares throughputs of an 802.11g V2I network where (i) all-omni: all nodes (its access point and mobile stations) always employ OAs, (ii) half-omni: all nodes use OAs for RTS/CTS and DAs for DATA/ACK transmissions, and (iii) all-directional: all nodes always employ DAs for all transmissions. The mobility effect is modeled as a throughput scaling factor considering the antenna beam coverage. Numerical evaluation of the models reveals consistently best performance with the half-omni scheme due to the higher link rate and effective avoidance of interference caused by deafness and hidden terminal problems.

I. Introduction

Vehicular networks have drawn significant recent attention as the automotive and communication industries announce plans to bring ubiquitous broadband Internet connectivity to moving cars [1]. Envisioned applications include road safety, driver assistance, infotainment, and vehicle telematics utilizing a range of wireless communication methods based on Wi-Fi, dedicated short range radios (IEEE 802.11p), or 4G radios such as Mobile WiMAX and LTE. Depending on the applications, such networks can be realized as an ad hoc network, an infrastructure network, or a hybrid combination of the two. Vehicle ad hoc networks (VANET), also referred to as vehicle-to-vehicle networks, have been studied by many, e.g., [2]–[5], utilizing ad hoc multi-hop communication among cars with diverse mobility patterns. Vehicle-to-infrastructure (V2I) networks, also called vehicle-to-roadside (V2R) networks, employ statically deployed access points (APs) or base stations (BSs) to connect moving cars. Despite the higher costs to deploy and maintain the AP/BS infrastructure, V2I networks are of high interest to industries and transportation authorities due to their higher reliability and constant availability where such infrastructure exists.