Benjamin E. Henty

Mobile Vehicle-to-Vehicle Narrow-Band Channel Measurement and Characterization of the 5.9 GHz Dedicated Short Range Communication (DSRC) Frequency Band

This study presents narrow-band measurements of the mobile vehicle-to-vehicle propagation channel at 5.9 GHz, under realistic suburban driving conditions in Pittsburgh, Pennsylvania. Our system includes differential Global Positioning System (DGPS) receivers, thereby enabling dynamic measurements of how large-scale path loss, Doppler spectrum, and coherence time depend on vehicle location and separation. A Nakagami distribution is used for describing the fading statistics. The speed-separation diagram is introduced as a new tool for analyzing and understanding the vehicle-to-vehicle propagation environment. We show that this diagram can be used to model and predict channel Doppler spread and coherence time using vehicle speed and separation.

A Measurement Study of Time-Scaled 802.11a Waveforms Over The Mobile-to-Mobile Vehicular Channel at 5.9 GHz

We have studied the effects of the mobile vehicle-to-vehicle (V2V) channel on scaled versions of the current IEEE 802.11 a standard to investigate how readily they can be applied to vehicular networks. In particular, measured parameters for the V2V channel at 5.9 GHz in suburban, highway, and rural environments are studied in the context of critical parameters for OFDM. Actual performance of scaled OFDM waveforms with bandwidths of 20 MHz (bandwidth of IEEE 802.11 a), 10 MHz (bandwidth of the draft IEEE 802.11 p), and 5 MHz (halved bandwidth of IEEE 802.11 p) are described and interpreted in light of the channel parameters. At 20 MHz the guard interval is not long enough, while at 5 MHz errors increase from lack of channel stationarity over the packet duration. For these choices of the scaled 802.11 a OFDM waveform, 10 MHz appears to be the best choice.

Highway and rural propagation channel modeling for vehicle-to-vehicle communications at 5.9 GHz

In this article, we have reported experimental studies of signal strength as a function of vehicle separation for outdoor vehicle-to-vehicle propagation at 5.9 GHz. Statistical measurement campaigns were conducted in highway and rural driving environments. These measurements were used to obtain parameters for a dual-slope log-normal propagation model. The effects of antenna pattern variations for passing vehicles were also discussed.

Multi-Path Propagation Measurements for Vehicular Networks at 5.9 GHz

Broadband sounding of the vehicle-to-vehicle channel is reported in suburban, rural, and highway environments. A direct sequence spread spectrum waveform based on zero correlation zone sequences was used with an instantaneous bandwidth of about 40 MHz. Cumulative distribution functions are presented for the maximum excess delay, RMS delay spread, and coherence bandwidth using a threshold of 15 dB below the peak. The highway environment showed the largest median RMS delay spread (about 110 ns), the largest median maximum excess delay (about 600 ns) and the smallest median 90% coherence bandwidth (about 900 kHz). In general, the distributions of these quantities for the suburban environment were narrower than those for the rural and highway environments. This is interpreted in terms of the more restricted range of distances to scattering objects in the suburban environment.

Doppler component analysis of the suburban vehicle-to-vehicle DSRC propagation channel at 5.9 GHz

This study presents Doppler component analysis of the mobile vehicle-to-vehicle propagation channel at 5.9 GHz. The measurements were conducted via a VANET field implementation under realistic suburban driving conditions in Pittsburgh, Pennsylvania. Different components in the observed spectrum were analyzed with vehicle speeds and compared with theoretical mobile-to-mobile scenarios. Intuitive understandings are also provided based on our analysis from on-road measurements.

A fully mobile, GPS enabled, vehicle-to-vehicle measurement platform for characterization of the 5.9 GHz DSRC channel

To understand the characteristics of vehicle-to-vehicle channels, in this paper, we describe a mobile channel measurement platform operating at the 5.9 GHz designated dedicated short range communications (DSRC) frequency band. Our system uses programmable instrumentation for both the transmitter and receiver, enabling the use of a wide range of waveforms. Our system permits the generation and analysis of arbitrary waveforms with instantaneous bandwidth up to 40 MHz. Our system also has several key features which distinguish it from other similar systems. First, our RF measurement system is operating in the 5.9 GHz frequency band designated for DSRC. Second, we have taken the additional step of incorporating location-based information via GPS receivers. The GPS receiver provides far richer statistics to characterize the channel, which allows us to better understand the relationship between this highly mobile V2V channel and location information.

Single antenna time reversal adaptive interference cancellation

This paper presents the time reversal adaptive interferer canceller (TRAIC), a novel algorithm that uses time reversal techniques to cancel the presence of interferers. TRAIC is developed for broadband signals and a single emitting antenna. Experimental tests in the electromagnetic domain show the viability and the power of TRAIC.

Wireless RF distribution in buildings using heating and ventilation ducts

An alternative method of distributing RF in buildings is proposed in which the heating and ventilation ducts are used as wave guides. Because of the relatively low wave guide loss, this method may lead to more efficient RF distribution than possible with radiation through walls or the use of leaky coax. Further, the use of existing infrastructure could lead to a lower-cost system. Initial experimental results are presented that demonstrate duct-assisted propagation between nearby offices in a university building. An example method is described for obtaining efficient coupling between coax and 8″x12″ rectangular duct over the 902-928 MHz ISM band.

Single antenna target detection using broadband frequency selection time reversal method

In this paper, we present a broadband single antenna target detection scheme using frequency selection time reversal method to further improve the target detection in a cluttered environment. By re-transmitting time-reversed difference signal between reflections from the environment with and without the target, constructive interferences between the target and the background scatterers are utilized to enhance the return signal from target. Meanwhile, frequency selection time reversal emphasizes on the section of wavelengths with more constructive interferences and filters out the broadband white noise at the other spectrum. Thus, signal to noise ratio (SNR) is substantially increased. The effectiveness of the proposed detection scheme has been demonstrated by numerical simulation. The simulation results show that using frequency selection time reversal method, the detection probability is significantly enhanced and SNR can be improved 2-5 dB

Properties and Applications of the Suburban Vehicle-to-Vehicle Propagation Channel at 5.9 GHz

We describe a system capable of making channel measurements as a function of location while the vehicles are in motion to study the properties of the vehicle-to-vehicle wireless channel. We present results from on-road experimental tests in suburban areas of Pittsburgh. The dependence of Doppler spread on both velocity and vehicle separation is discussed. We introduce the speed-separation (S-S) diagram as a new tool for understanding and estimating Doppler spread in the vehicle-to-vehicle environment.