Channel Impulse Response Estimation in IEEE 802.11p via Data Fusion and MMSE Estimator

Giulio Ministeri,Lorenzo Vangelista

doi:10.1155/2015/670482

Giulio Ministeri, Lorenzo Vangelista

Open Access

https://doi.org/10.1155/2015/670482

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Abstract

Tracking the channel impulse response in systems based on the IEEE 802.11p standard, the most widely accepted standard for the physical layer in vehicular area networks (VANETs), is still an open research topic. In this paper we aim to improve previously proposed channel estimators by utilizing data aided algorithm that includes the channel decoding to enhance the quality of the estimated data. Moreover we propose a novel technique that exploits information provided by external sensors like GPS or speedometer, usually present in vehicles. The algorithm proposed so far has been analyzed in non-line-of-sight link conditions; in this paper we present an analysis of performances in the line-of-sight condition as well. Simulations show that both proposals give considerable improvements in terms of packet error rate and channel estimation error in the highway scenario which is surely the most stressing environment for the channel response tracker.

Highlights

Vehicular ad hoc networks (VANETs) aim at improving safety in vehicular transportation systems; new cars will be equipped with devices capable of sharing information, through wireless links, about the current status, preventing collisions and alarming drivers of incoming hazardous situations
As showed in many papers [3, 4], receiver schemes used for WLANs poorly fit VANETs: higher speed of terminals leads to shorter coherence time of the channel so the initial channel response (CR) estimate is valid for a much shorter period
We focused on road to vehicle (RTV) in highway scenario where vehicle speed and Doppler effect have a more direct relationship and we show that considerable improvements in terms of receiver efficiency can be obtained

Summary

Introduction

Vehicular ad hoc networks (VANETs) aim at improving safety in vehicular transportation systems; new cars will be equipped with devices capable of sharing information, through wireless links, about the current status, preventing collisions and alarming drivers of incoming hazardous situations. VANETs mean safety and connectivity and Internet access for a wide range of onboard applications known as infotainment, that is, information for improving traffic efficiency and entertainment for drivers and passengers. In IEEE 802.11a, wireless links are typically created between an access point, always considered in a static position, and terminals, which are assumed to have very slow speed, at most 15 km/h, and nomadic behaviors, that is, stationary for most of the time. In VANETs terminals are seldom stationary, and they can have a very wide range of speeds, from few km/h in metropolitan areas up to 150 km/h in highways. As showed in many papers [3, 4], receiver schemes used for WLANs poorly fit VANETs: higher speed of terminals leads to shorter coherence time of the channel so the initial channel response (CR) estimate is valid for a much shorter period

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