Modeling the Interference Generated from Car Base Stations towards Indoor Femto-cells

TL;DR

This paper models the interference from car base stations to indoor femto-cells to assess spectrum sharing feasibility, recommending separate spectrum allocation for vehicle-to-infrastructure links due to high interference levels.

Contribution

It introduces a novel interference model for moving and parked cars affecting indoor femto-cells, analyzing spectrum sharing scenarios in vehicular networks.

Findings

Roof-mounted antennas cause high interference to indoor femto-cells.

In-vehicle communication can share spectrum with indoor cells due to vehicle shielding.

Separate spectrum allocation is recommended for V2I and indoor femto-cells.

Abstract

In future wireless networks, a significant number of users will be vehicular. One promising solution to improve the capacity for these vehicular users is to employ moving relays or car base stations. The system forms cell inside the vehicle and then uses rooftop antenna for back-hauling to overcome the vehicular penetration loss. In this paper, we develop a model for aggregate interference distribution generated from moving/parked cars to indoor users in order to study whether indoor femto-cells can coexist on the same spectrum with vehicular communications. Since spectrum authorization for vehicular communications is open at moment, we consider two spectrum sharing scenarios (i) communication from mounted antennas on the roof of the vehicles to the infrastructure network utilizes same spectrum with indoor femto-cells (ii) in-vehicle communication utilizes same spectrum with indoor femto-cells while vehicular to infrastructure (V2I) communication is allocated at different spectrum. Based on our findings we suggest that V2I and indoor femto-cells should be allocated at different spectrum. The reason being that mounted roof-top antennas facing the indoor cells generate unacceptable interference levels. On the other hand, in-vehicle communication and indoor cells can share the spectrum thanks to the vehicle body isolation and the lower transmit power levels that can be used inside the vehicle.