Micro base station aided vehicular ad hoc networking

We consider a heterogeneous network system in which micro base station nodes receive critical message flows from their associated wireless cellular backbone infrastructure and multicast them directly to vehicles that travel in their close vicinity. To assure delivery of these critical messages to all other vehicles traveling along the highway, we make use of a vehicular ad hoc network (VANET) system to provide for vehicle-to-vehicle transport of these messages. For this purpose, it is essential to design a network that achieves a high throughput rate while assuring a high packet delivery ratio and minimal in-transit queueing delays. We propose a VANET networking scheme that is identified as a vehicular backbone network (VBN) through which vehicles that are located close to properly selected nominal positions along a linear highway segment are elected to serve as relay nodes. We employ a flow admission control mechanism at the source, regulating the pace of transmission of admitted packets. Closed form analytical expressions are derived for the approximate computation of the system's end-to-end throughput capacity rate. Through simulation analyses, we confirm the precision of these analytical calculations. We show the ability of the system to employ vehicular CSMA/CA access schemes to well emulate the operations of the system when managed by the use of spatial-reuse TDMA schemes. In designing the heterogeneous network, we allocate system resources and assign system parameters in a manner that equalizes the throughput rates incurred across the cellular wireless access and VANET components of the hybrid network system.